8 files changed, 2293 insertions, 2182 deletions

diff --git a/externals/demangle/ItaniumDemangle.cpp b/externals/demangle/ItaniumDemangle.cpp
index b055a2fd7..47dd5d301 100644
--- a/externals/demangle/ItaniumDemangle.cpp
+++ b/externals/demangle/ItaniumDemangle.cpp
@@ -20,9 +20,7 @@
 #include <cstdlib>
 #include <cstring>
 #include <functional>
-#include <numeric>
 #include <utility>
-#include <vector>
 
 using namespace llvm;
 using namespace llvm::itanium_demangle;
@@ -81,8 +79,8 @@ struct DumpVisitor {
   }
 
   void printStr(const char *S) { fprintf(stderr, "%s", S); }
-  void print(StringView SV) {
-    fprintf(stderr, "\"%.*s\"", (int)SV.size(), SV.begin());
+  void print(std::string_view SV) {
+    fprintf(stderr, "\"%.*s\"", (int)SV.size(), SV.data());
   }
   void print(const Node *N) {
     if (N)
@@ -90,14 +88,6 @@ struct DumpVisitor {
     else
       printStr("<null>");
   }
-  void print(NodeOrString NS) {
-    if (NS.isNode())
-      print(NS.asNode());
-    else if (NS.isString())
-      print(NS.asString());
-    else
-      printStr("NodeOrString()");
-  }
   void print(NodeArray A) {
     ++Depth;
     printStr("{");
@@ -116,13 +106,11 @@ struct DumpVisitor {
   // Overload used when T is exactly 'bool', not merely convertible to 'bool'.
   void print(bool B) { printStr(B ? "true" : "false"); }
 
-  template <class T>
-  typename std::enable_if<std::is_unsigned<T>::value>::type print(T N) {
+  template <class T> std::enable_if_t<std::is_unsigned<T>::value> print(T N) {
     fprintf(stderr, "%llu", (unsigned long long)N);
   }
 
-  template <class T>
-  typename std::enable_if<std::is_signed<T>::value>::type print(T N) {
+  template <class T> std::enable_if_t<std::is_signed<T>::value> print(T N) {
     fprintf(stderr, "%lld", (long long)N);
   }
 
@@ -185,6 +173,50 @@ struct DumpVisitor {
       return printStr("TemplateParamKind::Template");
     }
   }
+  void print(Node::Prec P) {
+    switch (P) {
+    case Node::Prec::Primary:
+      return printStr("Node::Prec::Primary");
+    case Node::Prec::Postfix:
+      return printStr("Node::Prec::Postfix");
+    case Node::Prec::Unary:
+      return printStr("Node::Prec::Unary");
+    case Node::Prec::Cast:
+      return printStr("Node::Prec::Cast");
+    case Node::Prec::PtrMem:
+      return printStr("Node::Prec::PtrMem");
+    case Node::Prec::Multiplicative:
+      return printStr("Node::Prec::Multiplicative");
+    case Node::Prec::Additive:
+      return printStr("Node::Prec::Additive");
+    case Node::Prec::Shift:
+      return printStr("Node::Prec::Shift");
+    case Node::Prec::Spaceship:
+      return printStr("Node::Prec::Spaceship");
+    case Node::Prec::Relational:
+      return printStr("Node::Prec::Relational");
+    case Node::Prec::Equality:
+      return printStr("Node::Prec::Equality");
+    case Node::Prec::And:
+      return printStr("Node::Prec::And");
+    case Node::Prec::Xor:
+      return printStr("Node::Prec::Xor");
+    case Node::Prec::Ior:
+      return printStr("Node::Prec::Ior");
+    case Node::Prec::AndIf:
+      return printStr("Node::Prec::AndIf");
+    case Node::Prec::OrIf:
+      return printStr("Node::Prec::OrIf");
+    case Node::Prec::Conditional:
+      return printStr("Node::Prec::Conditional");
+    case Node::Prec::Assign:
+      return printStr("Node::Prec::Assign");
+    case Node::Prec::Comma:
+      return printStr("Node::Prec::Comma");
+    case Node::Prec::Default:
+      return printStr("Node::Prec::Default");
+    }
+  }
 
   void newLine() {
     printStr("\n");
@@ -334,36 +366,21 @@ public:
 
 using Demangler = itanium_demangle::ManglingParser<DefaultAllocator>;
 
-char *llvm::itaniumDemangle(const char *MangledName, char *Buf,
-                            size_t *N, int *Status) {
-  if (MangledName == nullptr || (Buf != nullptr && N == nullptr)) {
-    if (Status)
-      *Status = demangle_invalid_args;
+char *llvm::itaniumDemangle(std::string_view MangledName) {
+  if (MangledName.empty())
     return nullptr;
-  }
-
-  int InternalStatus = demangle_success;
-  Demangler Parser(MangledName, MangledName + std::strlen(MangledName));
-  OutputStream S;
 
+  Demangler Parser(MangledName.data(),
+                   MangledName.data() + MangledName.length());
   Node *AST = Parser.parse();
+  if (!AST)
+    return nullptr;
 
-  if (AST == nullptr)
-    InternalStatus = demangle_invalid_mangled_name;
-  else if (!initializeOutputStream(Buf, N, S, 1024))
-    InternalStatus = demangle_memory_alloc_failure;
-  else {
-    assert(Parser.ForwardTemplateRefs.empty());
-    AST->print(S);
-    S += '\0';
-    if (N != nullptr)
-      *N = S.getCurrentPosition();
-    Buf = S.getBuffer();
-  }
-
-  if (Status)
-    *Status = InternalStatus;
-  return InternalStatus == demangle_success ? Buf : nullptr;
+  OutputBuffer OB;
+  assert(Parser.ForwardTemplateRefs.empty());
+  AST->print(OB);
+  OB += '\0';
+  return OB.getBuffer();
 }
 
 ItaniumPartialDemangler::ItaniumPartialDemangler()
@@ -396,14 +413,12 @@ bool ItaniumPartialDemangler::partialDemangle(const char *MangledName) {
 }
 
 static char *printNode(const Node *RootNode, char *Buf, size_t *N) {
-  OutputStream S;
-  if (!initializeOutputStream(Buf, N, S, 128))
-    return nullptr;
-  RootNode->print(S);
-  S += '\0';
+  OutputBuffer OB(Buf, N);
+  RootNode->print(OB);
+  OB += '\0';
   if (N != nullptr)
-    *N = S.getCurrentPosition();
-  return S.getBuffer();
+    *N = OB.getCurrentPosition();
+  return OB.getBuffer();
 }
 
 char *ItaniumPartialDemangler::getFunctionBaseName(char *Buf, size_t *N) const {
@@ -417,8 +432,8 @@ char *ItaniumPartialDemangler::getFunctionBaseName(char *Buf, size_t *N) const {
     case Node::KAbiTagAttr:
       Name = static_cast<const AbiTagAttr *>(Name)->Base;
       continue;
-    case Node::KStdQualifiedName:
-      Name = static_cast<const StdQualifiedName *>(Name)->Child;
+    case Node::KModuleEntity:
+      Name = static_cast<const ModuleEntity *>(Name)->Name;
       continue;
     case Node::KNestedName:
       Name = static_cast<const NestedName *>(Name)->Name;
@@ -441,9 +456,7 @@ char *ItaniumPartialDemangler::getFunctionDeclContextName(char *Buf,
     return nullptr;
   const Node *Name = static_cast<const FunctionEncoding *>(RootNode)->getName();
 
-  OutputStream S;
-  if (!initializeOutputStream(Buf, N, S, 128))
-    return nullptr;
+  OutputBuffer OB(Buf, N);
 
  KeepGoingLocalFunction:
   while (true) {
@@ -458,27 +471,27 @@ char *ItaniumPartialDemangler::getFunctionDeclContextName(char *Buf,
     break;
   }
 
+  if (Name->getKind() == Node::KModuleEntity)
+    Name = static_cast<const ModuleEntity *>(Name)->Name;
+
   switch (Name->getKind()) {
-  case Node::KStdQualifiedName:
-    S += "std";
-    break;
   case Node::KNestedName:
-    static_cast<const NestedName *>(Name)->Qual->print(S);
+    static_cast<const NestedName *>(Name)->Qual->print(OB);
     break;
   case Node::KLocalName: {
     auto *LN = static_cast<const LocalName *>(Name);
-    LN->Encoding->print(S);
-    S += "::";
+    LN->Encoding->print(OB);
+    OB += "::";
     Name = LN->Entity;
     goto KeepGoingLocalFunction;
   }
   default:
     break;
   }
-  S += '\0';
+  OB += '\0';
   if (N != nullptr)
-    *N = S.getCurrentPosition();
-  return S.getBuffer();
+    *N = OB.getCurrentPosition();
+  return OB.getBuffer();
 }
 
 char *ItaniumPartialDemangler::getFunctionName(char *Buf, size_t *N) const {
@@ -494,17 +507,15 @@ char *ItaniumPartialDemangler::getFunctionParameters(char *Buf,
     return nullptr;
   NodeArray Params = static_cast<FunctionEncoding *>(RootNode)->getParams();
 
-  OutputStream S;
-  if (!initializeOutputStream(Buf, N, S, 128))
-    return nullptr;
+  OutputBuffer OB(Buf, N);
 
-  S += '(';
-  Params.printWithComma(S);
-  S += ')';
-  S += '\0';
+  OB += '(';
+  Params.printWithComma(OB);
+  OB += ')';
+  OB += '\0';
   if (N != nullptr)
-    *N = S.getCurrentPosition();
-  return S.getBuffer();
+    *N = OB.getCurrentPosition();
+  return OB.getBuffer();
 }
 
 char *ItaniumPartialDemangler::getFunctionReturnType(
@@ -512,18 +523,16 @@ char *ItaniumPartialDemangler::getFunctionReturnType(
   if (!isFunction())
     return nullptr;
 
-  OutputStream S;
-  if (!initializeOutputStream(Buf, N, S, 128))
-    return nullptr;
+  OutputBuffer OB(Buf, N);
 
   if (const Node *Ret =
           static_cast<const FunctionEncoding *>(RootNode)->getReturnType())
-    Ret->print(S);
+    Ret->print(OB);
 
-  S += '\0';
+  OB += '\0';
   if (N != nullptr)
-    *N = S.getCurrentPosition();
-  return S.getBuffer();
+    *N = OB.getCurrentPosition();
+  return OB.getBuffer();
 }
 
 char *ItaniumPartialDemangler::finishDemangle(char *Buf, size_t *N) const {
@@ -563,8 +572,8 @@ bool ItaniumPartialDemangler::isCtorOrDtor() const {
     case Node::KNestedName:
       N = static_cast<const NestedName *>(N)->Name;
       break;
-    case Node::KStdQualifiedName:
-      N = static_cast<const StdQualifiedName *>(N)->Child;
+    case Node::KModuleEntity:
+      N = static_cast<const ModuleEntity *>(N)->Name;
       break;
     }
   }
diff --git a/externals/demangle/llvm/Demangle/Demangle.h b/externals/demangle/llvm/Demangle/Demangle.h
index 5b673e4e1..1552a501a 100644
--- a/externals/demangle/llvm/Demangle/Demangle.h
+++ b/externals/demangle/llvm/Demangle/Demangle.h
@@ -12,6 +12,7 @@
 
 #include <cstddef>
 #include <string>
+#include <string_view>
 
 namespace llvm {
 /// This is a llvm local version of __cxa_demangle. Other than the name and
@@ -29,9 +30,10 @@ enum : int {
   demangle_success = 0,
 };
 
-char *itaniumDemangle(const char *mangled_name, char *buf, size_t *n,
-                      int *status);
-
+/// Returns a non-NULL pointer to a NUL-terminated C style string
+/// that should be explicitly freed, if successful. Otherwise, may return
+/// nullptr if mangled_name is not a valid mangling or is nullptr.
+char *itaniumDemangle(std::string_view mangled_name);
 
 enum MSDemangleFlags {
   MSDF_None = 0,
@@ -40,10 +42,34 @@ enum MSDemangleFlags {
   MSDF_NoCallingConvention = 1 << 2,
   MSDF_NoReturnType = 1 << 3,
   MSDF_NoMemberType = 1 << 4,
+  MSDF_NoVariableType = 1 << 5,
 };
-char *microsoftDemangle(const char *mangled_name, char *buf, size_t *n,
+
+/// Demangles the Microsoft symbol pointed at by mangled_name and returns it.
+/// Returns a pointer to the start of a null-terminated demangled string on
+/// success, or nullptr on error.
+/// If n_read is non-null and demangling was successful, it receives how many
+/// bytes of the input string were consumed.
+/// status receives one of the demangle_ enum entries above if it's not nullptr.
+/// Flags controls various details of the demangled representation.
+char *microsoftDemangle(std::string_view mangled_name, size_t *n_read,
                         int *status, MSDemangleFlags Flags = MSDF_None);
 
+// Demangles a Rust v0 mangled symbol.
+char *rustDemangle(std::string_view MangledName);
+
+// Demangles a D mangled symbol.
+char *dlangDemangle(std::string_view MangledName);
+
+/// Attempt to demangle a string using different demangling schemes.
+/// The function uses heuristics to determine which demangling scheme to use.
+/// \param MangledName - reference to string to demangle.
+/// \returns - the demangled string, or a copy of the input string if no
+/// demangling occurred.
+std::string demangle(std::string_view MangledName);
+
+bool nonMicrosoftDemangle(std::string_view MangledName, std::string &Result);
+
 /// "Partial" demangler. This supports demangling a string into an AST
 /// (typically an intermediate stage in itaniumDemangle) and querying certain
 /// properties or partially printing the demangled name.
@@ -59,7 +85,7 @@ struct ItaniumPartialDemangler {
   bool partialDemangle(const char *MangledName);
 
   /// Just print the entire mangled name into Buf. Buf and N behave like the
-  /// second and third parameters to itaniumDemangle.
+  /// second and third parameters to __cxa_demangle.
   char *finishDemangle(char *Buf, size_t *N) const;
 
   /// Get the base name of a function. This doesn't include trailing template
@@ -95,6 +121,7 @@ struct ItaniumPartialDemangler {
   bool isSpecialName() const;
 
   ~ItaniumPartialDemangler();
+
 private:
   void *RootNode;
   void *Context;
diff --git a/externals/demangle/llvm/Demangle/DemangleConfig.h b/externals/demangle/llvm/Demangle/DemangleConfig.h
index a8aef9df1..c7f86d766 100644
--- a/externals/demangle/llvm/Demangle/DemangleConfig.h
+++ b/externals/demangle/llvm/Demangle/DemangleConfig.h
@@ -13,8 +13,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_DEMANGLE_COMPILER_H
-#define LLVM_DEMANGLE_COMPILER_H
+#ifndef LLVM_DEMANGLE_DEMANGLECONFIG_H
+#define LLVM_DEMANGLE_DEMANGLECONFIG_H
 
 #ifndef __has_feature
 #define __has_feature(x) 0
diff --git a/externals/demangle/llvm/Demangle/ItaniumDemangle.h b/externals/demangle/llvm/Demangle/ItaniumDemangle.h
index 64b35c142..0dc3d7337 100644
--- a/externals/demangle/llvm/Demangle/ItaniumDemangle.h
+++ b/externals/demangle/llvm/Demangle/ItaniumDemangle.h
@@ -1,5 +1,5 @@
-//===------------------------- ItaniumDemangle.h ----------------*- C++ -*-===//
-//
+//===--- ItaniumDemangle.h -----------*- mode:c++;eval:(read-only-mode) -*-===//
+//       Do not edit! See README.txt.
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-FileCopyrightText: Part of the LLVM Project
@@ -7,144 +7,220 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// Generic itanium demangler library. This file has two byte-per-byte identical
-// copies in the source tree, one in libcxxabi, and the other in llvm.
+// Generic itanium demangler library.
+// There are two copies of this file in the source tree.  The one under
+// libcxxabi is the original and the one under llvm is the copy.  Use
+// cp-to-llvm.sh to update the copy.  See README.txt for more details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef DEMANGLE_ITANIUMDEMANGLE_H
 #define DEMANGLE_ITANIUMDEMANGLE_H
 
-// FIXME: (possibly) incomplete list of features that clang mangles that this
-// file does not yet support:
-//   - C++ modules TS
-
 #include "DemangleConfig.h"
-#include "StringView.h"
+#include "StringViewExtras.h"
 #include "Utility.h"
+#include <algorithm>
 #include <cassert>
 #include <cctype>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
-#include <numeric>
+#include <limits>
+#include <new>
+#include <string_view>
+#include <type_traits>
 #include <utility>
 
-#define FOR_EACH_NODE_KIND(X) \
-    X(NodeArrayNode) \
-    X(DotSuffix) \
-    X(VendorExtQualType) \
-    X(QualType) \
-    X(ConversionOperatorType) \
-    X(PostfixQualifiedType) \
-    X(ElaboratedTypeSpefType) \
-    X(NameType) \
-    X(AbiTagAttr) \
-    X(EnableIfAttr) \
-    X(ObjCProtoName) \
-    X(PointerType) \
-    X(ReferenceType) \
-    X(PointerToMemberType) \
-    X(ArrayType) \
-    X(FunctionType) \
-    X(NoexceptSpec) \
-    X(DynamicExceptionSpec) \
-    X(FunctionEncoding) \
-    X(LiteralOperator) \
-    X(SpecialName) \
-    X(CtorVtableSpecialName) \
-    X(QualifiedName) \
-    X(NestedName) \
-    X(LocalName) \
-    X(VectorType) \
-    X(PixelVectorType) \
-    X(SyntheticTemplateParamName) \
-    X(TypeTemplateParamDecl) \
-    X(NonTypeTemplateParamDecl) \
-    X(TemplateTemplateParamDecl) \
-    X(TemplateParamPackDecl) \
-    X(ParameterPack) \
-    X(TemplateArgumentPack) \
-    X(ParameterPackExpansion) \
-    X(TemplateArgs) \
-    X(ForwardTemplateReference) \
-    X(NameWithTemplateArgs) \
-    X(GlobalQualifiedName) \
-    X(StdQualifiedName) \
-    X(ExpandedSpecialSubstitution) \
-    X(SpecialSubstitution) \
-    X(CtorDtorName) \
-    X(DtorName) \
-    X(UnnamedTypeName) \
-    X(ClosureTypeName) \
-    X(StructuredBindingName) \
-    X(BinaryExpr) \
-    X(ArraySubscriptExpr) \
-    X(PostfixExpr) \
-    X(ConditionalExpr) \
-    X(MemberExpr) \
-    X(EnclosingExpr) \
-    X(CastExpr) \
-    X(SizeofParamPackExpr) \
-    X(CallExpr) \
-    X(NewExpr) \
-    X(DeleteExpr) \
-    X(PrefixExpr) \
-    X(FunctionParam) \
-    X(ConversionExpr) \
-    X(InitListExpr) \
-    X(FoldExpr) \
-    X(ThrowExpr) \
-    X(UUIDOfExpr) \
-    X(BoolExpr) \
-    X(StringLiteral) \
-    X(LambdaExpr) \
-    X(IntegerCastExpr) \
-    X(IntegerLiteral) \
-    X(FloatLiteral) \
-    X(DoubleLiteral) \
-    X(LongDoubleLiteral) \
-    X(BracedExpr) \
-    X(BracedRangeExpr)
-
 DEMANGLE_NAMESPACE_BEGIN
 
+template <class T, size_t N> class PODSmallVector {
+  static_assert(std::is_pod<T>::value,
+                "T is required to be a plain old data type");
+
+  T *First = nullptr;
+  T *Last = nullptr;
+  T *Cap = nullptr;
+  T Inline[N] = {0};
+
+  bool isInline() const { return First == Inline; }
+
+  void clearInline() {
+    First = Inline;
+    Last = Inline;
+    Cap = Inline + N;
+  }
+
+  void reserve(size_t NewCap) {
+    size_t S = size();
+    if (isInline()) {
+      auto *Tmp = static_cast<T *>(std::malloc(NewCap * sizeof(T)));
+      if (Tmp == nullptr)
+        std::terminate();
+      std::copy(First, Last, Tmp);
+      First = Tmp;
+    } else {
+      First = static_cast<T *>(std::realloc(First, NewCap * sizeof(T)));
+      if (First == nullptr)
+        std::terminate();
+    }
+    Last = First + S;
+    Cap = First + NewCap;
+  }
+
+public:
+  PODSmallVector() : First(Inline), Last(First), Cap(Inline + N) {}
+
+  PODSmallVector(const PODSmallVector &) = delete;
+  PODSmallVector &operator=(const PODSmallVector &) = delete;
+
+  PODSmallVector(PODSmallVector &&Other) : PODSmallVector() {
+    if (Other.isInline()) {
+      std::copy(Other.begin(), Other.end(), First);
+      Last = First + Other.size();
+      Other.clear();
+      return;
+    }
+
+    First = Other.First;
+    Last = Other.Last;
+    Cap = Other.Cap;
+    Other.clearInline();
+  }
+
+  PODSmallVector &operator=(PODSmallVector &&Other) {
+    if (Other.isInline()) {
+      if (!isInline()) {
+        std::free(First);
+        clearInline();
+      }
+      std::copy(Other.begin(), Other.end(), First);
+      Last = First + Other.size();
+      Other.clear();
+      return *this;
+    }
+
+    if (isInline()) {
+      First = Other.First;
+      Last = Other.Last;
+      Cap = Other.Cap;
+      Other.clearInline();
+      return *this;
+    }
+
+    std::swap(First, Other.First);
+    std::swap(Last, Other.Last);
+    std::swap(Cap, Other.Cap);
+    Other.clear();
+    return *this;
+  }
+
+  // NOLINTNEXTLINE(readability-identifier-naming)
+  void push_back(const T &Elem) {
+    if (Last == Cap)
+      reserve(size() * 2);
+    *Last++ = Elem;
+  }
+
+  // NOLINTNEXTLINE(readability-identifier-naming)
+  void pop_back() {
+    assert(Last != First && "Popping empty vector!");
+    --Last;
+  }
+
+  void dropBack(size_t Index) {
+    assert(Index <= size() && "dropBack() can't expand!");
+    Last = First + Index;
+  }
+
+  T *begin() { return First; }
+  T *end() { return Last; }
+
+  bool empty() const { return First == Last; }
+  size_t size() const { return static_cast<size_t>(Last - First); }
+  T &back() {
+    assert(Last != First && "Calling back() on empty vector!");
+    return *(Last - 1);
+  }
+  T &operator[](size_t Index) {
+    assert(Index < size() && "Invalid access!");
+    return *(begin() + Index);
+  }
+  void clear() { Last = First; }
+
+  ~PODSmallVector() {
+    if (!isInline())
+      std::free(First);
+  }
+};
+
 // Base class of all AST nodes. The AST is built by the parser, then is
 // traversed by the printLeft/Right functions to produce a demangled string.
 class Node {
 public:
   enum Kind : unsigned char {
-#define ENUMERATOR(NodeKind) K ## NodeKind,
-    FOR_EACH_NODE_KIND(ENUMERATOR)
-#undef ENUMERATOR
+#define NODE(NodeKind) K##NodeKind,
+#include "ItaniumNodes.def"
   };
 
   /// Three-way bool to track a cached value. Unknown is possible if this node
   /// has an unexpanded parameter pack below it that may affect this cache.
   enum class Cache : unsigned char { Yes, No, Unknown, };
 
+  /// Operator precedence for expression nodes. Used to determine required
+  /// parens in expression emission.
+  enum class Prec {
+    Primary,
+    Postfix,
+    Unary,
+    Cast,
+    PtrMem,
+    Multiplicative,
+    Additive,
+    Shift,
+    Spaceship,
+    Relational,
+    Equality,
+    And,
+    Xor,
+    Ior,
+    AndIf,
+    OrIf,
+    Conditional,
+    Assign,
+    Comma,
+    Default,
+  };
+
 private:
   Kind K;
 
+  Prec Precedence : 6;
+
   // FIXME: Make these protected.
 public:
   /// Tracks if this node has a component on its right side, in which case we
   /// need to call printRight.
-  Cache RHSComponentCache;
+  Cache RHSComponentCache : 2;
 
   /// Track if this node is a (possibly qualified) array type. This can affect
   /// how we format the output string.
-  Cache ArrayCache;
+  Cache ArrayCache : 2;
 
   /// Track if this node is a (possibly qualified) function type. This can
   /// affect how we format the output string.
-  Cache FunctionCache;
+  Cache FunctionCache : 2;
 
 public:
-  Node(Kind K_, Cache RHSComponentCache_ = Cache::No,
-       Cache ArrayCache_ = Cache::No, Cache FunctionCache_ = Cache::No)
-      : K(K_), RHSComponentCache(RHSComponentCache_), ArrayCache(ArrayCache_),
-        FunctionCache(FunctionCache_) {}
+  Node(Kind K_, Prec Precedence_ = Prec::Primary,
+       Cache RHSComponentCache_ = Cache::No, Cache ArrayCache_ = Cache::No,
+       Cache FunctionCache_ = Cache::No)
+      : K(K_), Precedence(Precedence_), RHSComponentCache(RHSComponentCache_),
+        ArrayCache(ArrayCache_), FunctionCache(FunctionCache_) {}
+  Node(Kind K_, Cache RHSComponentCache_, Cache ArrayCache_ = Cache::No,
+       Cache FunctionCache_ = Cache::No)
+      : Node(K_, Prec::Primary, RHSComponentCache_, ArrayCache_,
+             FunctionCache_) {}
 
   /// Visit the most-derived object corresponding to this object.
   template<typename Fn> void visit(Fn F) const;
@@ -155,52 +231,65 @@ public:
   // would construct an equivalent node.
   //template<typename Fn> void match(Fn F) const;
 
-  bool hasRHSComponent(OutputStream &S) const {
+  bool hasRHSComponent(OutputBuffer &OB) const {
     if (RHSComponentCache != Cache::Unknown)
       return RHSComponentCache == Cache::Yes;
-    return hasRHSComponentSlow(S);
+    return hasRHSComponentSlow(OB);
   }
 
-  bool hasArray(OutputStream &S) const {
+  bool hasArray(OutputBuffer &OB) const {
     if (ArrayCache != Cache::Unknown)
       return ArrayCache == Cache::Yes;
-    return hasArraySlow(S);
+    return hasArraySlow(OB);
   }
 
-  bool hasFunction(OutputStream &S) const {
+  bool hasFunction(OutputBuffer &OB) const {
     if (FunctionCache != Cache::Unknown)
       return FunctionCache == Cache::Yes;
-    return hasFunctionSlow(S);
+    return hasFunctionSlow(OB);
   }
 
   Kind getKind() const { return K; }
 
-  virtual bool hasRHSComponentSlow(OutputStream &) const { return false; }
-  virtual bool hasArraySlow(OutputStream &) const { return false; }
-  virtual bool hasFunctionSlow(OutputStream &) const { return false; }
+  Prec getPrecedence() const { return Precedence; }
+
+  virtual bool hasRHSComponentSlow(OutputBuffer &) const { return false; }
+  virtual bool hasArraySlow(OutputBuffer &) const { return false; }
+  virtual bool hasFunctionSlow(OutputBuffer &) const { return false; }
 
   // Dig through "glue" nodes like ParameterPack and ForwardTemplateReference to
   // get at a node that actually represents some concrete syntax.
-  virtual const Node *getSyntaxNode(OutputStream &) const {
-    return this;
-  }
-
-  void print(OutputStream &S) const {
-    printLeft(S);
+  virtual const Node *getSyntaxNode(OutputBuffer &) const { return this; }
+
+  // Print this node as an expression operand, surrounding it in parentheses if
+  // its precedence is [Strictly] weaker than P.
+  void printAsOperand(OutputBuffer &OB, Prec P = Prec::Default,
+                      bool StrictlyWorse = false) const {
+    bool Paren =
+        unsigned(getPrecedence()) >= unsigned(P) + unsigned(StrictlyWorse);
+    if (Paren)
+      OB.printOpen();
+    print(OB);
+    if (Paren)
+      OB.printClose();
+  }
+
+  void print(OutputBuffer &OB) const {
+    printLeft(OB);
     if (RHSComponentCache != Cache::No)
-      printRight(S);
+      printRight(OB);
   }
 
-  // Print the "left" side of this Node into OutputStream.
-  virtual void printLeft(OutputStream &) const = 0;
+  // Print the "left" side of this Node into OutputBuffer.
+  virtual void printLeft(OutputBuffer &) const = 0;
 
   // Print the "right". This distinction is necessary to represent C++ types
   // that appear on the RHS of their subtype, such as arrays or functions.
   // Since most types don't have such a component, provide a default
   // implementation.
-  virtual void printRight(OutputStream &) const {}
+  virtual void printRight(OutputBuffer &) const {}
 
-  virtual StringView getBaseName() const { return StringView(); }
+  virtual std::string_view getBaseName() const { return {}; }
 
   // Silence compiler warnings, this dtor will never be called.
   virtual ~Node() = default;
@@ -227,19 +316,19 @@ public:
 
   Node *operator[](size_t Idx) const { return Elements[Idx]; }
 
-  void printWithComma(OutputStream &S) const {
+  void printWithComma(OutputBuffer &OB) const {
     bool FirstElement = true;
     for (size_t Idx = 0; Idx != NumElements; ++Idx) {
-      size_t BeforeComma = S.getCurrentPosition();
+      size_t BeforeComma = OB.getCurrentPosition();
       if (!FirstElement)
-        S += ", ";
-      size_t AfterComma = S.getCurrentPosition();
-      Elements[Idx]->print(S);
+        OB += ", ";
+      size_t AfterComma = OB.getCurrentPosition();
+      Elements[Idx]->printAsOperand(OB, Node::Prec::Comma);
 
       // Elements[Idx] is an empty parameter pack expansion, we should erase the
       // comma we just printed.
-      if (AfterComma == S.getCurrentPosition()) {
-        S.setCurrentPosition(BeforeComma);
+      if (AfterComma == OB.getCurrentPosition()) {
+        OB.setCurrentPosition(BeforeComma);
         continue;
       }
 
@@ -254,43 +343,48 @@ struct NodeArrayNode : Node {
 
   template<typename Fn> void match(Fn F) const { F(Array); }
 
-  void printLeft(OutputStream &S) const override {
-    Array.printWithComma(S);
-  }
+  void printLeft(OutputBuffer &OB) const override { Array.printWithComma(OB); }
 };
 
 class DotSuffix final : public Node {
   const Node *Prefix;
-  const StringView Suffix;
+  const std::string_view Suffix;
 
 public:
-  DotSuffix(const Node *Prefix_, StringView Suffix_)
+  DotSuffix(const Node *Prefix_, std::string_view Suffix_)
       : Node(KDotSuffix), Prefix(Prefix_), Suffix(Suffix_) {}
 
   template<typename Fn> void match(Fn F) const { F(Prefix, Suffix); }
 
-  void printLeft(OutputStream &s) const override {
-    Prefix->print(s);
-    s += " (";
-    s += Suffix;
-    s += ")";
+  void printLeft(OutputBuffer &OB) const override {
+    Prefix->print(OB);
+    OB += " (";
+    OB += Suffix;
+    OB += ")";
   }
 };
 
 class VendorExtQualType final : public Node {
   const Node *Ty;
-  StringView Ext;
+  std::string_view Ext;
+  const Node *TA;
 
 public:
-  VendorExtQualType(const Node *Ty_, StringView Ext_)
-      : Node(KVendorExtQualType), Ty(Ty_), Ext(Ext_) {}
+  VendorExtQualType(const Node *Ty_, std::string_view Ext_, const Node *TA_)
+      : Node(KVendorExtQualType), Ty(Ty_), Ext(Ext_), TA(TA_) {}
+
+  const Node *getTy() const { return Ty; }
+  std::string_view getExt() const { return Ext; }
+  const Node *getTA() const { return TA; }
 
-  template<typename Fn> void match(Fn F) const { F(Ty, Ext); }
+  template <typename Fn> void match(Fn F) const { F(Ty, Ext, TA); }
 
-  void printLeft(OutputStream &S) const override {
-    Ty->print(S);
-    S += " ";
-    S += Ext;
+  void printLeft(OutputBuffer &OB) const override {
+    Ty->print(OB);
+    OB += " ";
+    OB += Ext;
+    if (TA != nullptr)
+      TA->print(OB);
   }
 };
 
@@ -316,13 +410,13 @@ protected:
   const Qualifiers Quals;
   const Node *Child;
 
-  void printQuals(OutputStream &S) const {
+  void printQuals(OutputBuffer &OB) const {
     if (Quals & QualConst)
-      S += " const";
+      OB += " const";
     if (Quals & QualVolatile)
-      S += " volatile";
+      OB += " volatile";
     if (Quals & QualRestrict)
-      S += " restrict";
+      OB += " restrict";
   }
 
 public:
@@ -331,24 +425,27 @@ public:
              Child_->ArrayCache, Child_->FunctionCache),
         Quals(Quals_), Child(Child_) {}
 
+  Qualifiers getQuals() const { return Quals; }
+  const Node *getChild() const { return Child; }
+
   template<typename Fn> void match(Fn F) const { F(Child, Quals); }
 
-  bool hasRHSComponentSlow(OutputStream &S) const override {
-    return Child->hasRHSComponent(S);
+  bool hasRHSComponentSlow(OutputBuffer &OB) const override {
+    return Child->hasRHSComponent(OB);
   }
-  bool hasArraySlow(OutputStream &S) const override {
-    return Child->hasArray(S);
+  bool hasArraySlow(OutputBuffer &OB) const override {
+    return Child->hasArray(OB);
   }
-  bool hasFunctionSlow(OutputStream &S) const override {
-    return Child->hasFunction(S);
+  bool hasFunctionSlow(OutputBuffer &OB) const override {
+    return Child->hasFunction(OB);
   }
 
-  void printLeft(OutputStream &S) const override {
-    Child->printLeft(S);
-    printQuals(S);
+  void printLeft(OutputBuffer &OB) const override {
+    Child->printLeft(OB);
+    printQuals(OB);
   }
 
-  void printRight(OutputStream &S) const override { Child->printRight(S); }
+  void printRight(OutputBuffer &OB) const override { Child->printRight(OB); }
 };
 
 class ConversionOperatorType final : public Node {
@@ -360,74 +457,96 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Ty); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "operator ";
-    Ty->print(S);
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "operator ";
+    Ty->print(OB);
   }
 };
 
 class PostfixQualifiedType final : public Node {
   const Node *Ty;
-  const StringView Postfix;
+  const std::string_view Postfix;
 
 public:
-  PostfixQualifiedType(Node *Ty_, StringView Postfix_)
+  PostfixQualifiedType(const Node *Ty_, std::string_view Postfix_)
       : Node(KPostfixQualifiedType), Ty(Ty_), Postfix(Postfix_) {}
 
   template<typename Fn> void match(Fn F) const { F(Ty, Postfix); }
 
-  void printLeft(OutputStream &s) const override {
-    Ty->printLeft(s);
-    s += Postfix;
+  void printLeft(OutputBuffer &OB) const override {
+    Ty->printLeft(OB);
+    OB += Postfix;
   }
 };
 
 class NameType final : public Node {
-  const StringView Name;
+  const std::string_view Name;
 
 public:
-  NameType(StringView Name_) : Node(KNameType), Name(Name_) {}
+  NameType(std::string_view Name_) : Node(KNameType), Name(Name_) {}
 
   template<typename Fn> void match(Fn F) const { F(Name); }
 
-  StringView getName() const { return Name; }
-  StringView getBaseName() const override { return Name; }
+  std::string_view getName() const { return Name; }
+  std::string_view getBaseName() const override { return Name; }
+
+  void printLeft(OutputBuffer &OB) const override { OB += Name; }
+};
+
+class BitIntType final : public Node {
+  const Node *Size;
+  bool Signed;
+
+public:
+  BitIntType(const Node *Size_, bool Signed_)
+      : Node(KBitIntType), Size(Size_), Signed(Signed_) {}
+
+  template <typename Fn> void match(Fn F) const { F(Size, Signed); }
 
-  void printLeft(OutputStream &s) const override { s += Name; }
+  void printLeft(OutputBuffer &OB) const override {
+    if (!Signed)
+      OB += "unsigned ";
+    OB += "_BitInt";
+    OB.printOpen();
+    Size->printAsOperand(OB);
+    OB.printClose();
+  }
 };
 
 class ElaboratedTypeSpefType : public Node {
-  StringView Kind;
+  std::string_view Kind;
   Node *Child;
 public:
-  ElaboratedTypeSpefType(StringView Kind_, Node *Child_)
+  ElaboratedTypeSpefType(std::string_view Kind_, Node *Child_)
       : Node(KElaboratedTypeSpefType), Kind(Kind_), Child(Child_) {}
 
   template<typename Fn> void match(Fn F) const { F(Kind, Child); }
 
-  void printLeft(OutputStream &S) const override {
-    S += Kind;
-    S += ' ';
-    Child->print(S);
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Kind;
+    OB += ' ';
+    Child->print(OB);
   }
 };
 
 struct AbiTagAttr : Node {
   Node *Base;
-  StringView Tag;
+  std::string_view Tag;
 
-  AbiTagAttr(Node* Base_, StringView Tag_)
-      : Node(KAbiTagAttr, Base_->RHSComponentCache,
-             Base_->ArrayCache, Base_->FunctionCache),
+  AbiTagAttr(Node *Base_, std::string_view Tag_)
+      : Node(KAbiTagAttr, Base_->RHSComponentCache, Base_->ArrayCache,
+             Base_->FunctionCache),
         Base(Base_), Tag(Tag_) {}
 
   template<typename Fn> void match(Fn F) const { F(Base, Tag); }
 
-  void printLeft(OutputStream &S) const override {
-    Base->printLeft(S);
-    S += "[abi:";
-    S += Tag;
-    S += "]";
+  std::string_view getBaseName() const override { return Base->getBaseName(); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Base->printLeft(OB);
+    OB += "[abi:";
+    OB += Tag;
+    OB += "]";
   }
 };
 
@@ -439,21 +558,21 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Conditions); }
 
-  void printLeft(OutputStream &S) const override {
-    S += " [enable_if:";
-    Conditions.printWithComma(S);
-    S += ']';
+  void printLeft(OutputBuffer &OB) const override {
+    OB += " [enable_if:";
+    Conditions.printWithComma(OB);
+    OB += ']';
   }
 };
 
 class ObjCProtoName : public Node {
   const Node *Ty;
-  StringView Protocol;
+  std::string_view Protocol;
 
   friend class PointerType;
 
 public:
-  ObjCProtoName(const Node *Ty_, StringView Protocol_)
+  ObjCProtoName(const Node *Ty_, std::string_view Protocol_)
       : Node(KObjCProtoName), Ty(Ty_), Protocol(Protocol_) {}
 
   template<typename Fn> void match(Fn F) const { F(Ty, Protocol); }
@@ -463,11 +582,11 @@ public:
            static_cast<const NameType *>(Ty)->getName() == "objc_object";
   }
 
-  void printLeft(OutputStream &S) const override {
-    Ty->print(S);
-    S += "<";
-    S += Protocol;
-    S += ">";
+  void printLeft(OutputBuffer &OB) const override {
+    Ty->print(OB);
+    OB += "<";
+    OB += Protocol;
+    OB += ">";
   }
 };
 
@@ -479,36 +598,38 @@ public:
       : Node(KPointerType, Pointee_->RHSComponentCache),
         Pointee(Pointee_) {}
 
+  const Node *getPointee() const { return Pointee; }
+
   template<typename Fn> void match(Fn F) const { F(Pointee); }
 
-  bool hasRHSComponentSlow(OutputStream &S) const override {
-    return Pointee->hasRHSComponent(S);
+  bool hasRHSComponentSlow(OutputBuffer &OB) const override {
+    return Pointee->hasRHSComponent(OB);
   }
 
-  void printLeft(OutputStream &s) const override {
+  void printLeft(OutputBuffer &OB) const override {
     // We rewrite objc_object<SomeProtocol>* into id<SomeProtocol>.
     if (Pointee->getKind() != KObjCProtoName ||
         !static_cast<const ObjCProtoName *>(Pointee)->isObjCObject()) {
-      Pointee->printLeft(s);
-      if (Pointee->hasArray(s))
-        s += " ";
-      if (Pointee->hasArray(s) || Pointee->hasFunction(s))
-        s += "(";
-      s += "*";
+      Pointee->printLeft(OB);
+      if (Pointee->hasArray(OB))
+        OB += " ";
+      if (Pointee->hasArray(OB) || Pointee->hasFunction(OB))
+        OB += "(";
+      OB += "*";
     } else {
       const auto *objcProto = static_cast<const ObjCProtoName *>(Pointee);
-      s += "id<";
-      s += objcProto->Protocol;
-      s += ">";
+      OB += "id<";
+      OB += objcProto->Protocol;
+      OB += ">";
     }
   }
 
-  void printRight(OutputStream &s) const override {
+  void printRight(OutputBuffer &OB) const override {
     if (Pointee->getKind() != KObjCProtoName ||
         !static_cast<const ObjCProtoName *>(Pointee)->isObjCObject()) {
-      if (Pointee->hasArray(s) || Pointee->hasFunction(s))
-        s += ")";
-      Pointee->printRight(s);
+      if (Pointee->hasArray(OB) || Pointee->hasFunction(OB))
+        OB += ")";
+      Pointee->printRight(OB);
     }
   }
 };
@@ -528,15 +649,30 @@ class ReferenceType : public Node {
   // Dig through any refs to refs, collapsing the ReferenceTypes as we go. The
   // rule here is rvalue ref to rvalue ref collapses to a rvalue ref, and any
   // other combination collapses to a lvalue ref.
-  std::pair<ReferenceKind, const Node *> collapse(OutputStream &S) const {
+  //
+  // A combination of a TemplateForwardReference and a back-ref Substitution
+  // from an ill-formed string may have created a cycle; use cycle detection to
+  // avoid looping forever.
+  std::pair<ReferenceKind, const Node *> collapse(OutputBuffer &OB) const {
     auto SoFar = std::make_pair(RK, Pointee);
+    // Track the chain of nodes for the Floyd's 'tortoise and hare'
+    // cycle-detection algorithm, since getSyntaxNode(S) is impure
+    PODSmallVector<const Node *, 8> Prev;
     for (;;) {
-      const Node *SN = SoFar.second->getSyntaxNode(S);
+      const Node *SN = SoFar.second->getSyntaxNode(OB);
       if (SN->getKind() != KReferenceType)
         break;
       auto *RT = static_cast<const ReferenceType *>(SN);
       SoFar.second = RT->Pointee;
       SoFar.first = std::min(SoFar.first, RT->RK);
+
+      // The middle of Prev is the 'slow' pointer moving at half speed
+      Prev.push_back(SoFar.second);
+      if (Prev.size() > 1 && SoFar.second == Prev[(Prev.size() - 1) / 2]) {
+        // Cycle detected
+        SoFar.second = nullptr;
+        break;
+      }
     }
     return SoFar;
   }
@@ -548,31 +684,35 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Pointee, RK); }
 
-  bool hasRHSComponentSlow(OutputStream &S) const override {
-    return Pointee->hasRHSComponent(S);
+  bool hasRHSComponentSlow(OutputBuffer &OB) const override {
+    return Pointee->hasRHSComponent(OB);
   }
 
-  void printLeft(OutputStream &s) const override {
+  void printLeft(OutputBuffer &OB) const override {
     if (Printing)
       return;
-    SwapAndRestore<bool> SavePrinting(Printing, true);
-    std::pair<ReferenceKind, const Node *> Collapsed = collapse(s);
-    Collapsed.second->printLeft(s);
-    if (Collapsed.second->hasArray(s))
-      s += " ";
-    if (Collapsed.second->hasArray(s) || Collapsed.second->hasFunction(s))
-      s += "(";
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    std::pair<ReferenceKind, const Node *> Collapsed = collapse(OB);
+    if (!Collapsed.second)
+      return;
+    Collapsed.second->printLeft(OB);
+    if (Collapsed.second->hasArray(OB))
+      OB += " ";
+    if (Collapsed.second->hasArray(OB) || Collapsed.second->hasFunction(OB))
+      OB += "(";
 
-    s += (Collapsed.first == ReferenceKind::LValue ? "&" : "&&");
+    OB += (Collapsed.first == ReferenceKind::LValue ? "&" : "&&");
   }
-  void printRight(OutputStream &s) const override {
+  void printRight(OutputBuffer &OB) const override {
     if (Printing)
       return;
-    SwapAndRestore<bool> SavePrinting(Printing, true);
-    std::pair<ReferenceKind, const Node *> Collapsed = collapse(s);
-    if (Collapsed.second->hasArray(s) || Collapsed.second->hasFunction(s))
-      s += ")";
-    Collapsed.second->printRight(s);
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    std::pair<ReferenceKind, const Node *> Collapsed = collapse(OB);
+    if (!Collapsed.second)
+      return;
+    if (Collapsed.second->hasArray(OB) || Collapsed.second->hasFunction(OB))
+      OB += ")";
+    Collapsed.second->printRight(OB);
   }
 };
 
@@ -587,69 +727,33 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(ClassType, MemberType); }
 
-  bool hasRHSComponentSlow(OutputStream &S) const override {
-    return MemberType->hasRHSComponent(S);
+  bool hasRHSComponentSlow(OutputBuffer &OB) const override {
+    return MemberType->hasRHSComponent(OB);
   }
 
-  void printLeft(OutputStream &s) const override {
-    MemberType->printLeft(s);
-    if (MemberType->hasArray(s) || MemberType->hasFunction(s))
-      s += "(";
+  void printLeft(OutputBuffer &OB) const override {
+    MemberType->printLeft(OB);
+    if (MemberType->hasArray(OB) || MemberType->hasFunction(OB))
+      OB += "(";
     else
-      s += " ";
-    ClassType->print(s);
-    s += "::*";
-  }
-
-  void printRight(OutputStream &s) const override {
-    if (MemberType->hasArray(s) || MemberType->hasFunction(s))
-      s += ")";
-    MemberType->printRight(s);
-  }
-};
-
-class NodeOrString {
-  const void *First;
-  const void *Second;
-
-public:
-  /* implicit */ NodeOrString(StringView Str) {
-    const char *FirstChar = Str.begin();
-    const char *SecondChar = Str.end();
-    if (SecondChar == nullptr) {
-      assert(FirstChar == SecondChar);
-      ++FirstChar, ++SecondChar;
-    }
-    First = static_cast<const void *>(FirstChar);
-    Second = static_cast<const void *>(SecondChar);
+      OB += " ";
+    ClassType->print(OB);
+    OB += "::*";
   }
 
-  /* implicit */ NodeOrString(Node *N)
-      : First(static_cast<const void *>(N)), Second(nullptr) {}
-  NodeOrString() : First(nullptr), Second(nullptr) {}
-
-  bool isString() const { return Second && First; }
-  bool isNode() const { return First && !Second; }
-  bool isEmpty() const { return !First && !Second; }
-
-  StringView asString() const {
-    assert(isString());
-    return StringView(static_cast<const char *>(First),
-                      static_cast<const char *>(Second));
-  }
-
-  const Node *asNode() const {
-    assert(isNode());
-    return static_cast<const Node *>(First);
+  void printRight(OutputBuffer &OB) const override {
+    if (MemberType->hasArray(OB) || MemberType->hasFunction(OB))
+      OB += ")";
+    MemberType->printRight(OB);
   }
 };
 
 class ArrayType final : public Node {
   const Node *Base;
-  NodeOrString Dimension;
+  Node *Dimension;
 
 public:
-  ArrayType(const Node *Base_, NodeOrString Dimension_)
+  ArrayType(const Node *Base_, Node *Dimension_)
       : Node(KArrayType,
              /*RHSComponentCache=*/Cache::Yes,
              /*ArrayCache=*/Cache::Yes),
@@ -657,21 +761,19 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Base, Dimension); }
 
-  bool hasRHSComponentSlow(OutputStream &) const override { return true; }
-  bool hasArraySlow(OutputStream &) const override { return true; }
+  bool hasRHSComponentSlow(OutputBuffer &) const override { return true; }
+  bool hasArraySlow(OutputBuffer &) const override { return true; }
 
-  void printLeft(OutputStream &S) const override { Base->printLeft(S); }
+  void printLeft(OutputBuffer &OB) const override { Base->printLeft(OB); }
 
-  void printRight(OutputStream &S) const override {
-    if (S.back() != ']')
-      S += " ";
-    S += "[";
-    if (Dimension.isString())
-      S += Dimension.asString();
-    else if (Dimension.isNode())
-      Dimension.asNode()->print(S);
-    S += "]";
-    Base->printRight(S);
+  void printRight(OutputBuffer &OB) const override {
+    if (OB.back() != ']')
+      OB += " ";
+    OB += "[";
+    if (Dimension)
+      Dimension->print(OB);
+    OB += "]";
+    Base->printRight(OB);
   }
 };
 
@@ -695,8 +797,8 @@ public:
     F(Ret, Params, CVQuals, RefQual, ExceptionSpec);
   }
 
-  bool hasRHSComponentSlow(OutputStream &) const override { return true; }
-  bool hasFunctionSlow(OutputStream &) const override { return true; }
+  bool hasRHSComponentSlow(OutputBuffer &) const override { return true; }
+  bool hasFunctionSlow(OutputBuffer &) const override { return true; }
 
   // Handle C++'s ... quirky decl grammar by using the left & right
   // distinction. Consider:
@@ -705,32 +807,32 @@ public:
   // that takes a char and returns an int. If we're trying to print f, start
   // by printing out the return types's left, then print our parameters, then
   // finally print right of the return type.
-  void printLeft(OutputStream &S) const override {
-    Ret->printLeft(S);
-    S += " ";
+  void printLeft(OutputBuffer &OB) const override {
+    Ret->printLeft(OB);
+    OB += " ";
   }
 
-  void printRight(OutputStream &S) const override {
-    S += "(";
-    Params.printWithComma(S);
-    S += ")";
-    Ret->printRight(S);
+  void printRight(OutputBuffer &OB) const override {
+    OB.printOpen();
+    Params.printWithComma(OB);
+    OB.printClose();
+    Ret->printRight(OB);
 
     if (CVQuals & QualConst)
-      S += " const";
+      OB += " const";
     if (CVQuals & QualVolatile)
-      S += " volatile";
+      OB += " volatile";
     if (CVQuals & QualRestrict)
-      S += " restrict";
+      OB += " restrict";
 
     if (RefQual == FrefQualLValue)
-      S += " &";
+      OB += " &";
     else if (RefQual == FrefQualRValue)
-      S += " &&";
+      OB += " &&";
 
     if (ExceptionSpec != nullptr) {
-      S += ' ';
-      ExceptionSpec->print(S);
+      OB += ' ';
+      ExceptionSpec->print(OB);
     }
   }
 };
@@ -742,10 +844,11 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(E); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "noexcept(";
-    E->print(S);
-    S += ")";
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "noexcept";
+    OB.printOpen();
+    E->printAsOperand(OB);
+    OB.printClose();
   }
 };
 
@@ -757,10 +860,11 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Types); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "throw(";
-    Types.printWithComma(S);
-    S += ')';
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "throw";
+    OB.printOpen();
+    Types.printWithComma(OB);
+    OB.printClose();
   }
 };
 
@@ -791,41 +895,41 @@ public:
   NodeArray getParams() const { return Params; }
   const Node *getReturnType() const { return Ret; }
 
-  bool hasRHSComponentSlow(OutputStream &) const override { return true; }
-  bool hasFunctionSlow(OutputStream &) const override { return true; }
+  bool hasRHSComponentSlow(OutputBuffer &) const override { return true; }
+  bool hasFunctionSlow(OutputBuffer &) const override { return true; }
 
   const Node *getName() const { return Name; }
 
-  void printLeft(OutputStream &S) const override {
+  void printLeft(OutputBuffer &OB) const override {
     if (Ret) {
-      Ret->printLeft(S);
-      if (!Ret->hasRHSComponent(S))
-        S += " ";
+      Ret->printLeft(OB);
+      if (!Ret->hasRHSComponent(OB))
+        OB += " ";
     }
-    Name->print(S);
+    Name->print(OB);
   }
 
-  void printRight(OutputStream &S) const override {
-    S += "(";
-    Params.printWithComma(S);
-    S += ")";
+  void printRight(OutputBuffer &OB) const override {
+    OB.printOpen();
+    Params.printWithComma(OB);
+    OB.printClose();
     if (Ret)
-      Ret->printRight(S);
+      Ret->printRight(OB);
 
     if (CVQuals & QualConst)
-      S += " const";
+      OB += " const";
     if (CVQuals & QualVolatile)
-      S += " volatile";
+      OB += " volatile";
     if (CVQuals & QualRestrict)
-      S += " restrict";
+      OB += " restrict";
 
     if (RefQual == FrefQualLValue)
-      S += " &";
+      OB += " &";
     else if (RefQual == FrefQualRValue)
-      S += " &&";
+      OB += " &&";
 
     if (Attrs != nullptr)
-      Attrs->print(S);
+      Attrs->print(OB);
   }
 };
 
@@ -838,25 +942,25 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(OpName); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "operator\"\" ";
-    OpName->print(S);
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "operator\"\" ";
+    OpName->print(OB);
   }
 };
 
 class SpecialName final : public Node {
-  const StringView Special;
+  const std::string_view Special;
   const Node *Child;
 
 public:
-  SpecialName(StringView Special_, const Node *Child_)
+  SpecialName(std::string_view Special_, const Node *Child_)
       : Node(KSpecialName), Special(Special_), Child(Child_) {}
 
   template<typename Fn> void match(Fn F) const { F(Special, Child); }
 
-  void printLeft(OutputStream &S) const override {
-    S += Special;
-    Child->print(S);
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Special;
+    Child->print(OB);
   }
 };
 
@@ -871,11 +975,11 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(FirstType, SecondType); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "construction vtable for ";
-    FirstType->print(S);
-    S += "-in-";
-    SecondType->print(S);
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "construction vtable for ";
+    FirstType->print(OB);
+    OB += "-in-";
+    SecondType->print(OB);
   }
 };
 
@@ -888,12 +992,52 @@ struct NestedName : Node {
 
   template<typename Fn> void match(Fn F) const { F(Qual, Name); }
 
-  StringView getBaseName() const override { return Name->getBaseName(); }
+  std::string_view getBaseName() const override { return Name->getBaseName(); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    Qual->print(OB);
+    OB += "::";
+    Name->print(OB);
+  }
+};
+
+struct ModuleName : Node {
+  ModuleName *Parent;
+  Node *Name;
+  bool IsPartition;
+
+  ModuleName(ModuleName *Parent_, Node *Name_, bool IsPartition_ = false)
+      : Node(KModuleName), Parent(Parent_), Name(Name_),
+        IsPartition(IsPartition_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(Parent, Name, IsPartition);
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    if (Parent)
+      Parent->print(OB);
+    if (Parent || IsPartition)
+      OB += IsPartition ? ':' : '.';
+    Name->print(OB);
+  }
+};
+
+struct ModuleEntity : Node {
+  ModuleName *Module;
+  Node *Name;
+
+  ModuleEntity(ModuleName *Module_, Node *Name_)
+      : Node(KModuleEntity), Module(Module_), Name(Name_) {}
+
+  template <typename Fn> void match(Fn F) const { F(Module, Name); }
+
+  std::string_view getBaseName() const override { return Name->getBaseName(); }
 
-  void printLeft(OutputStream &S) const override {
-    Qual->print(S);
-    S += "::";
-    Name->print(S);
+  void printLeft(OutputBuffer &OB) const override {
+    Name->print(OB);
+    OB += '@';
+    Module->print(OB);
   }
 };
 
@@ -906,10 +1050,10 @@ struct LocalName : Node {
 
   template<typename Fn> void match(Fn F) const { F(Encoding, Entity); }
 
-  void printLeft(OutputStream &S) const override {
-    Encoding->print(S);
-    S += "::";
-    Entity->print(S);
+  void printLeft(OutputBuffer &OB) const override {
+    Encoding->print(OB);
+    OB += "::";
+    Entity->print(OB);
   }
 };
 
@@ -924,51 +1068,66 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Qualifier, Name); }
 
-  StringView getBaseName() const override { return Name->getBaseName(); }
+  std::string_view getBaseName() const override { return Name->getBaseName(); }
 
-  void printLeft(OutputStream &S) const override {
-    Qualifier->print(S);
-    S += "::";
-    Name->print(S);
+  void printLeft(OutputBuffer &OB) const override {
+    Qualifier->print(OB);
+    OB += "::";
+    Name->print(OB);
   }
 };
 
 class VectorType final : public Node {
   const Node *BaseType;
-  const NodeOrString Dimension;
+  const Node *Dimension;
 
 public:
-  VectorType(const Node *BaseType_, NodeOrString Dimension_)
-      : Node(KVectorType), BaseType(BaseType_),
-        Dimension(Dimension_) {}
+  VectorType(const Node *BaseType_, const Node *Dimension_)
+      : Node(KVectorType), BaseType(BaseType_), Dimension(Dimension_) {}
+
+  const Node *getBaseType() const { return BaseType; }
+  const Node *getDimension() const { return Dimension; }
 
   template<typename Fn> void match(Fn F) const { F(BaseType, Dimension); }
 
-  void printLeft(OutputStream &S) const override {
-    BaseType->print(S);
-    S += " vector[";
-    if (Dimension.isNode())
-      Dimension.asNode()->print(S);
-    else if (Dimension.isString())
-      S += Dimension.asString();
-    S += "]";
+  void printLeft(OutputBuffer &OB) const override {
+    BaseType->print(OB);
+    OB += " vector[";
+    if (Dimension)
+      Dimension->print(OB);
+    OB += "]";
   }
 };
 
 class PixelVectorType final : public Node {
-  const NodeOrString Dimension;
+  const Node *Dimension;
 
 public:
-  PixelVectorType(NodeOrString Dimension_)
+  PixelVectorType(const Node *Dimension_)
       : Node(KPixelVectorType), Dimension(Dimension_) {}
 
   template<typename Fn> void match(Fn F) const { F(Dimension); }
 
-  void printLeft(OutputStream &S) const override {
+  void printLeft(OutputBuffer &OB) const override {
     // FIXME: This should demangle as "vector pixel".
-    S += "pixel vector[";
-    S += Dimension.asString();
-    S += "]";
+    OB += "pixel vector[";
+    Dimension->print(OB);
+    OB += "]";
+  }
+};
+
+class BinaryFPType final : public Node {
+  const Node *Dimension;
+
+public:
+  BinaryFPType(const Node *Dimension_)
+      : Node(KBinaryFPType), Dimension(Dimension_) {}
+
+  template<typename Fn> void match(Fn F) const { F(Dimension); }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "_Float";
+    Dimension->print(OB);
   }
 };
 
@@ -990,20 +1149,20 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Kind, Index); }
 
-  void printLeft(OutputStream &S) const override {
+  void printLeft(OutputBuffer &OB) const override {
     switch (Kind) {
     case TemplateParamKind::Type:
-      S += "$T";
+      OB += "$T";
       break;
     case TemplateParamKind::NonType:
-      S += "$N";
+      OB += "$N";
       break;
     case TemplateParamKind::Template:
-      S += "$TT";
+      OB += "$TT";
       break;
     }
     if (Index > 0)
-      S << Index - 1;
+      OB << Index - 1;
   }
 };
 
@@ -1017,13 +1176,9 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Name); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "typename ";
-  }
+  void printLeft(OutputBuffer &OB) const override { OB += "typename "; }
 
-  void printRight(OutputStream &S) const override {
-    Name->print(S);
-  }
+  void printRight(OutputBuffer &OB) const override { Name->print(OB); }
 };
 
 /// A non-type template parameter declaration, 'int N'.
@@ -1037,15 +1192,15 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Name, Type); }
 
-  void printLeft(OutputStream &S) const override {
-    Type->printLeft(S);
-    if (!Type->hasRHSComponent(S))
-      S += " ";
+  void printLeft(OutputBuffer &OB) const override {
+    Type->printLeft(OB);
+    if (!Type->hasRHSComponent(OB))
+      OB += " ";
   }
 
-  void printRight(OutputStream &S) const override {
-    Name->print(S);
-    Type->printRight(S);
+  void printRight(OutputBuffer &OB) const override {
+    Name->print(OB);
+    Type->printRight(OB);
   }
 };
 
@@ -1062,15 +1217,14 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Name, Params); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "template<";
-    Params.printWithComma(S);
-    S += "> typename ";
+  void printLeft(OutputBuffer &OB) const override {
+    ScopedOverride<unsigned> LT(OB.GtIsGt, 0);
+    OB += "template<";
+    Params.printWithComma(OB);
+    OB += "> typename ";
   }
 
-  void printRight(OutputStream &S) const override {
-    Name->print(S);
-  }
+  void printRight(OutputBuffer &OB) const override { Name->print(OB); }
 };
 
 /// A template parameter pack declaration, 'typename ...T'.
@@ -1083,14 +1237,12 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Param); }
 
-  void printLeft(OutputStream &S) const override {
-    Param->printLeft(S);
-    S += "...";
+  void printLeft(OutputBuffer &OB) const override {
+    Param->printLeft(OB);
+    OB += "...";
   }
 
-  void printRight(OutputStream &S) const override {
-    Param->printRight(S);
-  }
+  void printRight(OutputBuffer &OB) const override { Param->printRight(OB); }
 };
 
 /// An unexpanded parameter pack (either in the expression or type context). If
@@ -1104,11 +1256,12 @@ public:
 class ParameterPack final : public Node {
   NodeArray Data;
 
-  // Setup OutputStream for a pack expansion unless we're already expanding one.
-  void initializePackExpansion(OutputStream &S) const {
-    if (S.CurrentPackMax == std::numeric_limits<unsigned>::max()) {
-      S.CurrentPackMax = static_cast<unsigned>(Data.size());
-      S.CurrentPackIndex = 0;
+  // Setup OutputBuffer for a pack expansion, unless we're already expanding
+  // one.
+  void initializePackExpansion(OutputBuffer &OB) const {
+    if (OB.CurrentPackMax == std::numeric_limits<unsigned>::max()) {
+      OB.CurrentPackMax = static_cast<unsigned>(Data.size());
+      OB.CurrentPackIndex = 0;
     }
   }
 
@@ -1131,38 +1284,38 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Data); }
 
-  bool hasRHSComponentSlow(OutputStream &S) const override {
-    initializePackExpansion(S);
-    size_t Idx = S.CurrentPackIndex;
-    return Idx < Data.size() && Data[Idx]->hasRHSComponent(S);
+  bool hasRHSComponentSlow(OutputBuffer &OB) const override {
+    initializePackExpansion(OB);
+    size_t Idx = OB.CurrentPackIndex;
+    return Idx < Data.size() && Data[Idx]->hasRHSComponent(OB);
   }
-  bool hasArraySlow(OutputStream &S) const override {
-    initializePackExpansion(S);
-    size_t Idx = S.CurrentPackIndex;
-    return Idx < Data.size() && Data[Idx]->hasArray(S);
+  bool hasArraySlow(OutputBuffer &OB) const override {
+    initializePackExpansion(OB);
+    size_t Idx = OB.CurrentPackIndex;
+    return Idx < Data.size() && Data[Idx]->hasArray(OB);
   }
-  bool hasFunctionSlow(OutputStream &S) const override {
-    initializePackExpansion(S);
-    size_t Idx = S.CurrentPackIndex;
-    return Idx < Data.size() && Data[Idx]->hasFunction(S);
+  bool hasFunctionSlow(OutputBuffer &OB) const override {
+    initializePackExpansion(OB);
+    size_t Idx = OB.CurrentPackIndex;
+    return Idx < Data.size() && Data[Idx]->hasFunction(OB);
   }
-  const Node *getSyntaxNode(OutputStream &S) const override {
-    initializePackExpansion(S);
-    size_t Idx = S.CurrentPackIndex;
-    return Idx < Data.size() ? Data[Idx]->getSyntaxNode(S) : this;
+  const Node *getSyntaxNode(OutputBuffer &OB) const override {
+    initializePackExpansion(OB);
+    size_t Idx = OB.CurrentPackIndex;
+    return Idx < Data.size() ? Data[Idx]->getSyntaxNode(OB) : this;
   }
 
-  void printLeft(OutputStream &S) const override {
-    initializePackExpansion(S);
-    size_t Idx = S.CurrentPackIndex;
+  void printLeft(OutputBuffer &OB) const override {
+    initializePackExpansion(OB);
+    size_t Idx = OB.CurrentPackIndex;
     if (Idx < Data.size())
-      Data[Idx]->printLeft(S);
+      Data[Idx]->printLeft(OB);
   }
-  void printRight(OutputStream &S) const override {
-    initializePackExpansion(S);
-    size_t Idx = S.CurrentPackIndex;
+  void printRight(OutputBuffer &OB) const override {
+    initializePackExpansion(OB);
+    size_t Idx = OB.CurrentPackIndex;
     if (Idx < Data.size())
-      Data[Idx]->printRight(S);
+      Data[Idx]->printRight(OB);
   }
 };
 
@@ -1181,8 +1334,8 @@ public:
 
   NodeArray getElements() const { return Elements; }
 
-  void printLeft(OutputStream &S) const override {
-    Elements.printWithComma(S);
+  void printLeft(OutputBuffer &OB) const override {
+    Elements.printWithComma(OB);
   }
 };
 
@@ -1199,35 +1352,35 @@ public:
 
   const Node *getChild() const { return Child; }
 
-  void printLeft(OutputStream &S) const override {
+  void printLeft(OutputBuffer &OB) const override {
     constexpr unsigned Max = std::numeric_limits<unsigned>::max();
-    SwapAndRestore<unsigned> SavePackIdx(S.CurrentPackIndex, Max);
-    SwapAndRestore<unsigned> SavePackMax(S.CurrentPackMax, Max);
-    size_t StreamPos = S.getCurrentPosition();
+    ScopedOverride<unsigned> SavePackIdx(OB.CurrentPackIndex, Max);
+    ScopedOverride<unsigned> SavePackMax(OB.CurrentPackMax, Max);
+    size_t StreamPos = OB.getCurrentPosition();
 
     // Print the first element in the pack. If Child contains a ParameterPack,
     // it will set up S.CurrentPackMax and print the first element.
-    Child->print(S);
+    Child->print(OB);
 
     // No ParameterPack was found in Child. This can occur if we've found a pack
     // expansion on a <function-param>.
-    if (S.CurrentPackMax == Max) {
-      S += "...";
+    if (OB.CurrentPackMax == Max) {
+      OB += "...";
       return;
     }
 
     // We found a ParameterPack, but it has no elements. Erase whatever we may
     // of printed.
-    if (S.CurrentPackMax == 0) {
-      S.setCurrentPosition(StreamPos);
+    if (OB.CurrentPackMax == 0) {
+      OB.setCurrentPosition(StreamPos);
       return;
     }
 
     // Else, iterate through the rest of the elements in the pack.
-    for (unsigned I = 1, E = S.CurrentPackMax; I < E; ++I) {
-      S += ", ";
-      S.CurrentPackIndex = I;
-      Child->print(S);
+    for (unsigned I = 1, E = OB.CurrentPackMax; I < E; ++I) {
+      OB += ", ";
+      OB.CurrentPackIndex = I;
+      Child->print(OB);
     }
   }
 };
@@ -1242,12 +1395,11 @@ public:
 
   NodeArray getParams() { return Params; }
 
-  void printLeft(OutputStream &S) const override {
-    S += "<";
-    Params.printWithComma(S);
-    if (S.back() == '>')
-      S += " ";
-    S += ">";
+  void printLeft(OutputBuffer &OB) const override {
+    ScopedOverride<unsigned> LT(OB.GtIsGt, 0);
+    OB += "<";
+    Params.printWithComma(OB);
+    OB += ">";
   }
 };
 
@@ -1289,42 +1441,42 @@ struct ForwardTemplateReference : Node {
   // special handling.
   template<typename Fn> void match(Fn F) const = delete;
 
-  bool hasRHSComponentSlow(OutputStream &S) const override {
+  bool hasRHSComponentSlow(OutputBuffer &OB) const override {
     if (Printing)
       return false;
-    SwapAndRestore<bool> SavePrinting(Printing, true);
-    return Ref->hasRHSComponent(S);
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    return Ref->hasRHSComponent(OB);
   }
-  bool hasArraySlow(OutputStream &S) const override {
+  bool hasArraySlow(OutputBuffer &OB) const override {
     if (Printing)
       return false;
-    SwapAndRestore<bool> SavePrinting(Printing, true);
-    return Ref->hasArray(S);
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    return Ref->hasArray(OB);
   }
-  bool hasFunctionSlow(OutputStream &S) const override {
+  bool hasFunctionSlow(OutputBuffer &OB) const override {
     if (Printing)
       return false;
-    SwapAndRestore<bool> SavePrinting(Printing, true);
-    return Ref->hasFunction(S);
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    return Ref->hasFunction(OB);
   }
-  const Node *getSyntaxNode(OutputStream &S) const override {
+  const Node *getSyntaxNode(OutputBuffer &OB) const override {
     if (Printing)
       return this;
-    SwapAndRestore<bool> SavePrinting(Printing, true);
-    return Ref->getSyntaxNode(S);
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    return Ref->getSyntaxNode(OB);
   }
 
-  void printLeft(OutputStream &S) const override {
+  void printLeft(OutputBuffer &OB) const override {
     if (Printing)
       return;
-    SwapAndRestore<bool> SavePrinting(Printing, true);
-    Ref->printLeft(S);
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    Ref->printLeft(OB);
   }
-  void printRight(OutputStream &S) const override {
+  void printRight(OutputBuffer &OB) const override {
     if (Printing)
       return;
-    SwapAndRestore<bool> SavePrinting(Printing, true);
-    Ref->printRight(S);
+    ScopedOverride<bool> SavePrinting(Printing, true);
+    Ref->printRight(OB);
   }
 };
 
@@ -1338,11 +1490,11 @@ struct NameWithTemplateArgs : Node {
 
   template<typename Fn> void match(Fn F) const { F(Name, TemplateArgs); }
 
-  StringView getBaseName() const override { return Name->getBaseName(); }
+  std::string_view getBaseName() const override { return Name->getBaseName(); }
 
-  void printLeft(OutputStream &S) const override {
-    Name->print(S);
-    TemplateArgs->print(S);
+  void printLeft(OutputBuffer &OB) const override {
+    Name->print(OB);
+    TemplateArgs->print(OB);
   }
 };
 
@@ -1355,26 +1507,11 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Child); }
 
-  StringView getBaseName() const override { return Child->getBaseName(); }
+  std::string_view getBaseName() const override { return Child->getBaseName(); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "::";
-    Child->print(S);
-  }
-};
-
-struct StdQualifiedName : Node {
-  Node *Child;
-
-  StdQualifiedName(Node *Child_) : Node(KStdQualifiedName), Child(Child_) {}
-
-  template<typename Fn> void match(Fn F) const { F(Child); }
-
-  StringView getBaseName() const override { return Child->getBaseName(); }
-
-  void printLeft(OutputStream &S) const override {
-    S += "std::";
-    Child->print(S);
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "::";
+    Child->print(OB);
   }
 };
 
@@ -1387,109 +1524,81 @@ enum class SpecialSubKind {
   iostream,
 };
 
-class ExpandedSpecialSubstitution final : public Node {
+class SpecialSubstitution;
+class ExpandedSpecialSubstitution : public Node {
+protected:
   SpecialSubKind SSK;
 
+  ExpandedSpecialSubstitution(SpecialSubKind SSK_, Kind K_)
+      : Node(K_), SSK(SSK_) {}
 public:
   ExpandedSpecialSubstitution(SpecialSubKind SSK_)
-      : Node(KExpandedSpecialSubstitution), SSK(SSK_) {}
+      : ExpandedSpecialSubstitution(SSK_, KExpandedSpecialSubstitution) {}
+  inline ExpandedSpecialSubstitution(SpecialSubstitution const *);
 
   template<typename Fn> void match(Fn F) const { F(SSK); }
 
-  StringView getBaseName() const override {
+protected:
+  bool isInstantiation() const {
+    return unsigned(SSK) >= unsigned(SpecialSubKind::string);
+  }
+
+  std::string_view getBaseName() const override {
     switch (SSK) {
     case SpecialSubKind::allocator:
-      return StringView("allocator");
+      return {"allocator"};
     case SpecialSubKind::basic_string:
-      return StringView("basic_string");
+      return {"basic_string"};
     case SpecialSubKind::string:
-      return StringView("basic_string");
+      return {"basic_string"};
     case SpecialSubKind::istream:
-      return StringView("basic_istream");
+      return {"basic_istream"};
     case SpecialSubKind::ostream:
-      return StringView("basic_ostream");
+      return {"basic_ostream"};
     case SpecialSubKind::iostream:
-      return StringView("basic_iostream");
+      return {"basic_iostream"};
     }
     DEMANGLE_UNREACHABLE;
   }
 
-  void printLeft(OutputStream &S) const override {
-    switch (SSK) {
-    case SpecialSubKind::allocator:
-      S += "std::allocator";
-      break;
-    case SpecialSubKind::basic_string:
-      S += "std::basic_string";
-      break;
-    case SpecialSubKind::string:
-      S += "std::basic_string<char, std::char_traits<char>, "
-           "std::allocator<char> >";
-      break;
-    case SpecialSubKind::istream:
-      S += "std::basic_istream<char, std::char_traits<char> >";
-      break;
-    case SpecialSubKind::ostream:
-      S += "std::basic_ostream<char, std::char_traits<char> >";
-      break;
-    case SpecialSubKind::iostream:
-      S += "std::basic_iostream<char, std::char_traits<char> >";
-      break;
+private:
+  void printLeft(OutputBuffer &OB) const override {
+    OB << "std::" << getBaseName();
+    if (isInstantiation()) {
+      OB << "<char, std::char_traits<char>";
+      if (SSK == SpecialSubKind::string)
+        OB << ", std::allocator<char>";
+      OB << ">";
     }
   }
 };
 
-class SpecialSubstitution final : public Node {
+class SpecialSubstitution final : public ExpandedSpecialSubstitution {
 public:
-  SpecialSubKind SSK;
-
   SpecialSubstitution(SpecialSubKind SSK_)
-      : Node(KSpecialSubstitution), SSK(SSK_) {}
+      : ExpandedSpecialSubstitution(SSK_, KSpecialSubstitution) {}
 
   template<typename Fn> void match(Fn F) const { F(SSK); }
 
-  StringView getBaseName() const override {
-    switch (SSK) {
-    case SpecialSubKind::allocator:
-      return StringView("allocator");
-    case SpecialSubKind::basic_string:
-      return StringView("basic_string");
-    case SpecialSubKind::string:
-      return StringView("string");
-    case SpecialSubKind::istream:
-      return StringView("istream");
-    case SpecialSubKind::ostream:
-      return StringView("ostream");
-    case SpecialSubKind::iostream:
-      return StringView("iostream");
+  std::string_view getBaseName() const override {
+    std::string_view SV = ExpandedSpecialSubstitution::getBaseName();
+    if (isInstantiation()) {
+      // The instantiations are typedefs that drop the "basic_" prefix.
+      assert(llvm::itanium_demangle::starts_with(SV, "basic_"));
+      SV.remove_prefix(sizeof("basic_") - 1);
     }
-    DEMANGLE_UNREACHABLE;
+    return SV;
   }
 
-  void printLeft(OutputStream &S) const override {
-    switch (SSK) {
-    case SpecialSubKind::allocator:
-      S += "std::allocator";
-      break;
-    case SpecialSubKind::basic_string:
-      S += "std::basic_string";
-      break;
-    case SpecialSubKind::string:
-      S += "std::string";
-      break;
-    case SpecialSubKind::istream:
-      S += "std::istream";
-      break;
-    case SpecialSubKind::ostream:
-      S += "std::ostream";
-      break;
-    case SpecialSubKind::iostream:
-      S += "std::iostream";
-      break;
-    }
+  void printLeft(OutputBuffer &OB) const override {
+    OB << "std::" << getBaseName();
   }
 };
 
+inline ExpandedSpecialSubstitution::ExpandedSpecialSubstitution(
+    SpecialSubstitution const *SS)
+    : ExpandedSpecialSubstitution(SS->SSK) {}
+
 class CtorDtorName final : public Node {
   const Node *Basename;
   const bool IsDtor;
@@ -1502,10 +1611,10 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Basename, IsDtor, Variant); }
 
-  void printLeft(OutputStream &S) const override {
+  void printLeft(OutputBuffer &OB) const override {
     if (IsDtor)
-      S += "~";
-    S += Basename->getBaseName();
+      OB += "~";
+    OB += Basename->getBaseName();
   }
 };
 
@@ -1517,35 +1626,36 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Base); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "~";
-    Base->printLeft(S);
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "~";
+    Base->printLeft(OB);
   }
 };
 
 class UnnamedTypeName : public Node {
-  const StringView Count;
+  const std::string_view Count;
 
 public:
-  UnnamedTypeName(StringView Count_) : Node(KUnnamedTypeName), Count(Count_) {}
+  UnnamedTypeName(std::string_view Count_)
+      : Node(KUnnamedTypeName), Count(Count_) {}
 
   template<typename Fn> void match(Fn F) const { F(Count); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "'unnamed";
-    S += Count;
-    S += "\'";
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "'unnamed";
+    OB += Count;
+    OB += "\'";
   }
 };
 
 class ClosureTypeName : public Node {
   NodeArray TemplateParams;
   NodeArray Params;
-  StringView Count;
+  std::string_view Count;
 
 public:
   ClosureTypeName(NodeArray TemplateParams_, NodeArray Params_,
-                  StringView Count_)
+                  std::string_view Count_)
       : Node(KClosureTypeName), TemplateParams(TemplateParams_),
         Params(Params_), Count(Count_) {}
 
@@ -1553,22 +1663,23 @@ public:
     F(TemplateParams, Params, Count);
   }
 
-  void printDeclarator(OutputStream &S) const {
+  void printDeclarator(OutputBuffer &OB) const {
     if (!TemplateParams.empty()) {
-      S += "<";
-      TemplateParams.printWithComma(S);
-      S += ">";
+      ScopedOverride<unsigned> LT(OB.GtIsGt, 0);
+      OB += "<";
+      TemplateParams.printWithComma(OB);
+      OB += ">";
     }
-    S += "(";
-    Params.printWithComma(S);
-    S += ")";
+    OB.printOpen();
+    Params.printWithComma(OB);
+    OB.printClose();
   }
 
-  void printLeft(OutputStream &S) const override {
-    S += "\'lambda";
-    S += Count;
-    S += "\'";
-    printDeclarator(S);
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "\'lambda";
+    OB += Count;
+    OB += "\'";
+    printDeclarator(OB);
   }
 };
 
@@ -1580,10 +1691,10 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Bindings); }
 
-  void printLeft(OutputStream &S) const override {
-    S += '[';
-    Bindings.printWithComma(S);
-    S += ']';
+  void printLeft(OutputBuffer &OB) const override {
+    OB.printOpen('[');
+    Bindings.printWithComma(OB);
+    OB.printClose(']');
   }
 };
 
@@ -1591,32 +1702,35 @@ public:
 
 class BinaryExpr : public Node {
   const Node *LHS;
-  const StringView InfixOperator;
+  const std::string_view InfixOperator;
   const Node *RHS;
 
 public:
-  BinaryExpr(const Node *LHS_, StringView InfixOperator_, const Node *RHS_)
-      : Node(KBinaryExpr), LHS(LHS_), InfixOperator(InfixOperator_), RHS(RHS_) {
-  }
-
-  template<typename Fn> void match(Fn F) const { F(LHS, InfixOperator, RHS); }
-
-  void printLeft(OutputStream &S) const override {
-    // might be a template argument expression, then we need to disambiguate
-    // with parens.
-    if (InfixOperator == ">")
-      S += "(";
-
-    S += "(";
-    LHS->print(S);
-    S += ") ";
-    S += InfixOperator;
-    S += " (";
-    RHS->print(S);
-    S += ")";
-
-    if (InfixOperator == ">")
-      S += ")";
+  BinaryExpr(const Node *LHS_, std::string_view InfixOperator_,
+             const Node *RHS_, Prec Prec_)
+      : Node(KBinaryExpr, Prec_), LHS(LHS_), InfixOperator(InfixOperator_),
+        RHS(RHS_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(LHS, InfixOperator, RHS, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    bool ParenAll = OB.isGtInsideTemplateArgs() &&
+                    (InfixOperator == ">" || InfixOperator == ">>");
+    if (ParenAll)
+      OB.printOpen();
+    // Assignment is right associative, with special LHS precedence.
+    bool IsAssign = getPrecedence() == Prec::Assign;
+    LHS->printAsOperand(OB, IsAssign ? Prec::OrIf : getPrecedence(), !IsAssign);
+    // No space before comma operator
+    if (!(InfixOperator == ","))
+      OB += " ";
+    OB += InfixOperator;
+    OB += " ";
+    RHS->printAsOperand(OB, getPrecedence(), IsAssign);
+    if (ParenAll)
+      OB.printClose();
   }
 };
 
@@ -1625,35 +1739,36 @@ class ArraySubscriptExpr : public Node {
   const Node *Op2;
 
 public:
-  ArraySubscriptExpr(const Node *Op1_, const Node *Op2_)
-      : Node(KArraySubscriptExpr), Op1(Op1_), Op2(Op2_) {}
+  ArraySubscriptExpr(const Node *Op1_, const Node *Op2_, Prec Prec_)
+      : Node(KArraySubscriptExpr, Prec_), Op1(Op1_), Op2(Op2_) {}
 
-  template<typename Fn> void match(Fn F) const { F(Op1, Op2); }
+  template <typename Fn> void match(Fn F) const {
+    F(Op1, Op2, getPrecedence());
+  }
 
-  void printLeft(OutputStream &S) const override {
-    S += "(";
-    Op1->print(S);
-    S += ")[";
-    Op2->print(S);
-    S += "]";
+  void printLeft(OutputBuffer &OB) const override {
+    Op1->printAsOperand(OB, getPrecedence());
+    OB.printOpen('[');
+    Op2->printAsOperand(OB);
+    OB.printClose(']');
   }
 };
 
 class PostfixExpr : public Node {
   const Node *Child;
-  const StringView Operator;
+  const std::string_view Operator;
 
 public:
-  PostfixExpr(const Node *Child_, StringView Operator_)
-      : Node(KPostfixExpr), Child(Child_), Operator(Operator_) {}
+  PostfixExpr(const Node *Child_, std::string_view Operator_, Prec Prec_)
+      : Node(KPostfixExpr, Prec_), Child(Child_), Operator(Operator_) {}
 
-  template<typename Fn> void match(Fn F) const { F(Child, Operator); }
+  template <typename Fn> void match(Fn F) const {
+    F(Child, Operator, getPrecedence());
+  }
 
-  void printLeft(OutputStream &S) const override {
-    S += "(";
-    Child->print(S);
-    S += ")";
-    S += Operator;
+  void printLeft(OutputBuffer &OB) const override {
+    Child->printAsOperand(OB, getPrecedence(), true);
+    OB += Operator;
   }
 };
 
@@ -1663,78 +1778,128 @@ class ConditionalExpr : public Node {
   const Node *Else;
 
 public:
-  ConditionalExpr(const Node *Cond_, const Node *Then_, const Node *Else_)
-      : Node(KConditionalExpr), Cond(Cond_), Then(Then_), Else(Else_) {}
+  ConditionalExpr(const Node *Cond_, const Node *Then_, const Node *Else_,
+                  Prec Prec_)
+      : Node(KConditionalExpr, Prec_), Cond(Cond_), Then(Then_), Else(Else_) {}
 
-  template<typename Fn> void match(Fn F) const { F(Cond, Then, Else); }
+  template <typename Fn> void match(Fn F) const {
+    F(Cond, Then, Else, getPrecedence());
+  }
 
-  void printLeft(OutputStream &S) const override {
-    S += "(";
-    Cond->print(S);
-    S += ") ? (";
-    Then->print(S);
-    S += ") : (";
-    Else->print(S);
-    S += ")";
+  void printLeft(OutputBuffer &OB) const override {
+    Cond->printAsOperand(OB, getPrecedence());
+    OB += " ? ";
+    Then->printAsOperand(OB);
+    OB += " : ";
+    Else->printAsOperand(OB, Prec::Assign, true);
   }
 };
 
 class MemberExpr : public Node {
   const Node *LHS;
-  const StringView Kind;
+  const std::string_view Kind;
   const Node *RHS;
 
 public:
-  MemberExpr(const Node *LHS_, StringView Kind_, const Node *RHS_)
-      : Node(KMemberExpr), LHS(LHS_), Kind(Kind_), RHS(RHS_) {}
+  MemberExpr(const Node *LHS_, std::string_view Kind_, const Node *RHS_,
+             Prec Prec_)
+      : Node(KMemberExpr, Prec_), LHS(LHS_), Kind(Kind_), RHS(RHS_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(LHS, Kind, RHS, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    LHS->printAsOperand(OB, getPrecedence(), true);
+    OB += Kind;
+    RHS->printAsOperand(OB, getPrecedence(), false);
+  }
+};
+
+class SubobjectExpr : public Node {
+  const Node *Type;
+  const Node *SubExpr;
+  std::string_view Offset;
+  NodeArray UnionSelectors;
+  bool OnePastTheEnd;
 
-  template<typename Fn> void match(Fn F) const { F(LHS, Kind, RHS); }
+public:
+  SubobjectExpr(const Node *Type_, const Node *SubExpr_,
+                std::string_view Offset_, NodeArray UnionSelectors_,
+                bool OnePastTheEnd_)
+      : Node(KSubobjectExpr), Type(Type_), SubExpr(SubExpr_), Offset(Offset_),
+        UnionSelectors(UnionSelectors_), OnePastTheEnd(OnePastTheEnd_) {}
 
-  void printLeft(OutputStream &S) const override {
-    LHS->print(S);
-    S += Kind;
-    RHS->print(S);
+  template<typename Fn> void match(Fn F) const {
+    F(Type, SubExpr, Offset, UnionSelectors, OnePastTheEnd);
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    SubExpr->print(OB);
+    OB += ".<";
+    Type->print(OB);
+    OB += " at offset ";
+    if (Offset.empty()) {
+      OB += "0";
+    } else if (Offset[0] == 'n') {
+      OB += "-";
+      OB += std::string_view(Offset.data() + 1, Offset.size() - 1);
+    } else {
+      OB += Offset;
+    }
+    OB += ">";
   }
 };
 
 class EnclosingExpr : public Node {
-  const StringView Prefix;
+  const std::string_view Prefix;
   const Node *Infix;
-  const StringView Postfix;
+  const std::string_view Postfix;
 
 public:
-  EnclosingExpr(StringView Prefix_, Node *Infix_, StringView Postfix_)
-      : Node(KEnclosingExpr), Prefix(Prefix_), Infix(Infix_),
-        Postfix(Postfix_) {}
+  EnclosingExpr(std::string_view Prefix_, const Node *Infix_,
+                Prec Prec_ = Prec::Primary)
+      : Node(KEnclosingExpr, Prec_), Prefix(Prefix_), Infix(Infix_) {}
 
-  template<typename Fn> void match(Fn F) const { F(Prefix, Infix, Postfix); }
+  template <typename Fn> void match(Fn F) const {
+    F(Prefix, Infix, getPrecedence());
+  }
 
-  void printLeft(OutputStream &S) const override {
-    S += Prefix;
-    Infix->print(S);
-    S += Postfix;
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Prefix;
+    OB.printOpen();
+    Infix->print(OB);
+    OB.printClose();
+    OB += Postfix;
   }
 };
 
 class CastExpr : public Node {
   // cast_kind<to>(from)
-  const StringView CastKind;
+  const std::string_view CastKind;
   const Node *To;
   const Node *From;
 
 public:
-  CastExpr(StringView CastKind_, const Node *To_, const Node *From_)
-      : Node(KCastExpr), CastKind(CastKind_), To(To_), From(From_) {}
+  CastExpr(std::string_view CastKind_, const Node *To_, const Node *From_,
+           Prec Prec_)
+      : Node(KCastExpr, Prec_), CastKind(CastKind_), To(To_), From(From_) {}
 
-  template<typename Fn> void match(Fn F) const { F(CastKind, To, From); }
+  template <typename Fn> void match(Fn F) const {
+    F(CastKind, To, From, getPrecedence());
+  }
 
-  void printLeft(OutputStream &S) const override {
-    S += CastKind;
-    S += "<";
-    To->printLeft(S);
-    S += ">(";
-    From->printLeft(S);
-    S += ")";
+  void printLeft(OutputBuffer &OB) const override {
+    OB += CastKind;
+    {
+      ScopedOverride<unsigned> LT(OB.GtIsGt, 0);
+      OB += "<";
+      To->printLeft(OB);
+      OB += ">";
+    }
+    OB.printOpen();
+    From->printAsOperand(OB);
+    OB.printClose();
   }
 };
 
@@ -1747,11 +1912,12 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Pack); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "sizeof...(";
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "sizeof...";
+    OB.printOpen();
     ParameterPackExpansion PPE(Pack);
-    PPE.printLeft(S);
-    S += ")";
+    PPE.printLeft(OB);
+    OB.printClose();
   }
 };
 
@@ -1760,16 +1926,18 @@ class CallExpr : public Node {
   NodeArray Args;
 
 public:
-  CallExpr(const Node *Callee_, NodeArray Args_)
-      : Node(KCallExpr), Callee(Callee_), Args(Args_) {}
+  CallExpr(const Node *Callee_, NodeArray Args_, Prec Prec_)
+      : Node(KCallExpr, Prec_), Callee(Callee_), Args(Args_) {}
 
-  template<typename Fn> void match(Fn F) const { F(Callee, Args); }
+  template <typename Fn> void match(Fn F) const {
+    F(Callee, Args, getPrecedence());
+  }
 
-  void printLeft(OutputStream &S) const override {
-    Callee->print(S);
-    S += "(";
-    Args.printWithComma(S);
-    S += ")";
+  void printLeft(OutputBuffer &OB) const override {
+    Callee->print(OB);
+    OB.printOpen();
+    Args.printWithComma(OB);
+    OB.printClose();
   }
 };
 
@@ -1782,33 +1950,32 @@ class NewExpr : public Node {
   bool IsArray;  // new[] ?
 public:
   NewExpr(NodeArray ExprList_, Node *Type_, NodeArray InitList_, bool IsGlobal_,
-          bool IsArray_)
-      : Node(KNewExpr), ExprList(ExprList_), Type(Type_), InitList(InitList_),
-        IsGlobal(IsGlobal_), IsArray(IsArray_) {}
+          bool IsArray_, Prec Prec_)
+      : Node(KNewExpr, Prec_), ExprList(ExprList_), Type(Type_),
+        InitList(InitList_), IsGlobal(IsGlobal_), IsArray(IsArray_) {}
 
   template<typename Fn> void match(Fn F) const {
-    F(ExprList, Type, InitList, IsGlobal, IsArray);
+    F(ExprList, Type, InitList, IsGlobal, IsArray, getPrecedence());
   }
 
-  void printLeft(OutputStream &S) const override {
+  void printLeft(OutputBuffer &OB) const override {
     if (IsGlobal)
-      S += "::operator ";
-    S += "new";
+      OB += "::";
+    OB += "new";
     if (IsArray)
-      S += "[]";
-    S += ' ';
+      OB += "[]";
     if (!ExprList.empty()) {
-      S += "(";
-      ExprList.printWithComma(S);
-      S += ")";
+      OB.printOpen();
+      ExprList.printWithComma(OB);
+      OB.printClose();
     }
-    Type->print(S);
+    OB += " ";
+    Type->print(OB);
     if (!InitList.empty()) {
-      S += "(";
-      InitList.printWithComma(S);
-      S += ")";
+      OB.printOpen();
+      InitList.printWithComma(OB);
+      OB.printClose();
     }
-
   }
 };
 
@@ -1818,50 +1985,55 @@ class DeleteExpr : public Node {
   bool IsArray;
 
 public:
-  DeleteExpr(Node *Op_, bool IsGlobal_, bool IsArray_)
-      : Node(KDeleteExpr), Op(Op_), IsGlobal(IsGlobal_), IsArray(IsArray_) {}
+  DeleteExpr(Node *Op_, bool IsGlobal_, bool IsArray_, Prec Prec_)
+      : Node(KDeleteExpr, Prec_), Op(Op_), IsGlobal(IsGlobal_),
+        IsArray(IsArray_) {}
 
-  template<typename Fn> void match(Fn F) const { F(Op, IsGlobal, IsArray); }
+  template <typename Fn> void match(Fn F) const {
+    F(Op, IsGlobal, IsArray, getPrecedence());
+  }
 
-  void printLeft(OutputStream &S) const override {
+  void printLeft(OutputBuffer &OB) const override {
     if (IsGlobal)
-      S += "::";
-    S += "delete";
+      OB += "::";
+    OB += "delete";
     if (IsArray)
-      S += "[] ";
-    Op->print(S);
+      OB += "[]";
+    OB += ' ';
+    Op->print(OB);
   }
 };
 
 class PrefixExpr : public Node {
-  StringView Prefix;
+  std::string_view Prefix;
   Node *Child;
 
 public:
-  PrefixExpr(StringView Prefix_, Node *Child_)
-      : Node(KPrefixExpr), Prefix(Prefix_), Child(Child_) {}
+  PrefixExpr(std::string_view Prefix_, Node *Child_, Prec Prec_)
+      : Node(KPrefixExpr, Prec_), Prefix(Prefix_), Child(Child_) {}
 
-  template<typename Fn> void match(Fn F) const { F(Prefix, Child); }
+  template <typename Fn> void match(Fn F) const {
+    F(Prefix, Child, getPrecedence());
+  }
 
-  void printLeft(OutputStream &S) const override {
-    S += Prefix;
-    S += "(";
-    Child->print(S);
-    S += ")";
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Prefix;
+    Child->printAsOperand(OB, getPrecedence());
   }
 };
 
 class FunctionParam : public Node {
-  StringView Number;
+  std::string_view Number;
 
 public:
-  FunctionParam(StringView Number_) : Node(KFunctionParam), Number(Number_) {}
+  FunctionParam(std::string_view Number_)
+      : Node(KFunctionParam), Number(Number_) {}
 
   template<typename Fn> void match(Fn F) const { F(Number); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "fp";
-    S += Number;
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "fp";
+    OB += Number;
   }
 };
 
@@ -1870,17 +2042,45 @@ class ConversionExpr : public Node {
   NodeArray Expressions;
 
 public:
-  ConversionExpr(const Node *Type_, NodeArray Expressions_)
-      : Node(KConversionExpr), Type(Type_), Expressions(Expressions_) {}
+  ConversionExpr(const Node *Type_, NodeArray Expressions_, Prec Prec_)
+      : Node(KConversionExpr, Prec_), Type(Type_), Expressions(Expressions_) {}
+
+  template <typename Fn> void match(Fn F) const {
+    F(Type, Expressions, getPrecedence());
+  }
+
+  void printLeft(OutputBuffer &OB) const override {
+    OB.printOpen();
+    Type->print(OB);
+    OB.printClose();
+    OB.printOpen();
+    Expressions.printWithComma(OB);
+    OB.printClose();
+  }
+};
+
+class PointerToMemberConversionExpr : public Node {
+  const Node *Type;
+  const Node *SubExpr;
+  std::string_view Offset;
+
+public:
+  PointerToMemberConversionExpr(const Node *Type_, const Node *SubExpr_,
+                                std::string_view Offset_, Prec Prec_)
+      : Node(KPointerToMemberConversionExpr, Prec_), Type(Type_),
+        SubExpr(SubExpr_), Offset(Offset_) {}
 
-  template<typename Fn> void match(Fn F) const { F(Type, Expressions); }
+  template <typename Fn> void match(Fn F) const {
+    F(Type, SubExpr, Offset, getPrecedence());
+  }
 
-  void printLeft(OutputStream &S) const override {
-    S += "(";
-    Type->print(S);
-    S += ")(";
-    Expressions.printWithComma(S);
-    S += ")";
+  void printLeft(OutputBuffer &OB) const override {
+    OB.printOpen();
+    Type->print(OB);
+    OB.printClose();
+    OB.printOpen();
+    SubExpr->print(OB);
+    OB.printClose();
   }
 };
 
@@ -1893,12 +2093,12 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Ty, Inits); }
 
-  void printLeft(OutputStream &S) const override {
+  void printLeft(OutputBuffer &OB) const override {
     if (Ty)
-      Ty->print(S);
-    S += '{';
-    Inits.printWithComma(S);
-    S += '}';
+      Ty->print(OB);
+    OB += '{';
+    Inits.printWithComma(OB);
+    OB += '}';
   }
 };
 
@@ -1912,18 +2112,18 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Elem, Init, IsArray); }
 
-  void printLeft(OutputStream &S) const override {
+  void printLeft(OutputBuffer &OB) const override {
     if (IsArray) {
-      S += '[';
-      Elem->print(S);
-      S += ']';
+      OB += '[';
+      Elem->print(OB);
+      OB += ']';
     } else {
-      S += '.';
-      Elem->print(S);
+      OB += '.';
+      Elem->print(OB);
     }
     if (Init->getKind() != KBracedExpr && Init->getKind() != KBracedRangeExpr)
-      S += " = ";
-    Init->print(S);
+      OB += " = ";
+    Init->print(OB);
   }
 };
 
@@ -1937,25 +2137,25 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(First, Last, Init); }
 
-  void printLeft(OutputStream &S) const override {
-    S += '[';
-    First->print(S);
-    S += " ... ";
-    Last->print(S);
-    S += ']';
+  void printLeft(OutputBuffer &OB) const override {
+    OB += '[';
+    First->print(OB);
+    OB += " ... ";
+    Last->print(OB);
+    OB += ']';
     if (Init->getKind() != KBracedExpr && Init->getKind() != KBracedRangeExpr)
-      S += " = ";
-    Init->print(S);
+      OB += " = ";
+    Init->print(OB);
   }
 };
 
 class FoldExpr : public Node {
   const Node *Pack, *Init;
-  StringView OperatorName;
+  std::string_view OperatorName;
   bool IsLeftFold;
 
 public:
-  FoldExpr(bool IsLeftFold_, StringView OperatorName_, const Node *Pack_,
+  FoldExpr(bool IsLeftFold_, std::string_view OperatorName_, const Node *Pack_,
            const Node *Init_)
       : Node(KFoldExpr), Pack(Pack_), Init(Init_), OperatorName(OperatorName_),
         IsLeftFold(IsLeftFold_) {}
@@ -1964,43 +2164,35 @@ public:
     F(IsLeftFold, OperatorName, Pack, Init);
   }
 
-  void printLeft(OutputStream &S) const override {
+  void printLeft(OutputBuffer &OB) const override {
     auto PrintPack = [&] {
-      S += '(';
-      ParameterPackExpansion(Pack).print(S);
-      S += ')';
+      OB.printOpen();
+      ParameterPackExpansion(Pack).print(OB);
+      OB.printClose();
     };
 
-    S += '(';
-
-    if (IsLeftFold) {
-      // init op ... op pack
-      if (Init != nullptr) {
-        Init->print(S);
-        S += ' ';
-        S += OperatorName;
-        S += ' ';
-      }
-      // ... op pack
-      S += "... ";
-      S += OperatorName;
-      S += ' ';
-      PrintPack();
-    } else { // !IsLeftFold
-      // pack op ...
-      PrintPack();
-      S += ' ';
-      S += OperatorName;
-      S += " ...";
-      // pack op ... op init
-      if (Init != nullptr) {
-        S += ' ';
-        S += OperatorName;
-        S += ' ';
-        Init->print(S);
-      }
+    OB.printOpen();
+    // Either '[init op ]... op pack' or 'pack op ...[ op init]'
+    // Refactored to '[(init|pack) op ]...[ op (pack|init)]'
+    // Fold expr operands are cast-expressions
+    if (!IsLeftFold || Init != nullptr) {
+      // '(init|pack) op '
+      if (IsLeftFold)
+        Init->printAsOperand(OB, Prec::Cast, true);
+      else
+        PrintPack();
+      OB << " " << OperatorName << " ";
+    }
+    OB << "...";
+    if (IsLeftFold || Init != nullptr) {
+      // ' op (init|pack)'
+      OB << " " << OperatorName << " ";
+      if (IsLeftFold)
+        PrintPack();
+      else
+        Init->printAsOperand(OB, Prec::Cast, true);
     }
-    S += ')';
+    OB.printClose();
   }
 };
 
@@ -2012,24 +2204,9 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Op); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "throw ";
-    Op->print(S);
-  }
-};
-
-// MSVC __uuidof extension, generated by clang in -fms-extensions mode.
-class UUIDOfExpr : public Node {
-  Node *Operand;
-public:
-  UUIDOfExpr(Node *Operand_) : Node(KUUIDOfExpr), Operand(Operand_) {}
-
-  template<typename Fn> void match(Fn F) const { F(Operand); }
-
-  void printLeft(OutputStream &S) const override {
-    S << "__uuidof(";
-    Operand->print(S);
-    S << ")";
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "throw ";
+    Op->print(OB);
   }
 };
 
@@ -2041,8 +2218,8 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Value); }
 
-  void printLeft(OutputStream &S) const override {
-    S += Value ? StringView("true") : StringView("false");
+  void printLeft(OutputBuffer &OB) const override {
+    OB += Value ? std::string_view("true") : std::string_view("false");
   }
 };
 
@@ -2054,10 +2231,10 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Type); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "\"<";
-    Type->print(S);
-    S += ">\"";
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "\"<";
+    Type->print(OB);
+    OB += ">\"";
   }
 };
 
@@ -2069,58 +2246,61 @@ public:
 
   template<typename Fn> void match(Fn F) const { F(Type); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "[]";
+  void printLeft(OutputBuffer &OB) const override {
+    OB += "[]";
     if (Type->getKind() == KClosureTypeName)
-      static_cast<const ClosureTypeName *>(Type)->printDeclarator(S);
-    S += "{...}";
+      static_cast<const ClosureTypeName *>(Type)->printDeclarator(OB);
+    OB += "{...}";
   }
 };
 
-class IntegerCastExpr : public Node {
+class EnumLiteral : public Node {
   // ty(integer)
   const Node *Ty;
-  StringView Integer;
+  std::string_view Integer;
 
 public:
-  IntegerCastExpr(const Node *Ty_, StringView Integer_)
-      : Node(KIntegerCastExpr), Ty(Ty_), Integer(Integer_) {}
+  EnumLiteral(const Node *Ty_, std::string_view Integer_)
+      : Node(KEnumLiteral), Ty(Ty_), Integer(Integer_) {}
 
   template<typename Fn> void match(Fn F) const { F(Ty, Integer); }
 
-  void printLeft(OutputStream &S) const override {
-    S += "(";
-    Ty->print(S);
-    S += ")";
-    S += Integer;
+  void printLeft(OutputBuffer &OB) const override {
+    OB.printOpen();
+    Ty->print(OB);
+    OB.printClose();
+
+    if (Integer[0] == 'n')
+      OB << '-' << std::string_view(Integer.data() + 1, Integer.size() - 1);
+    else
+      OB << Integer;
   }
 };
 
 class IntegerLiteral : public Node {
-  StringView Type;
-  StringView Value;
+  std::string_view Type;
+  std::string_view Value;
 
 public:
-  IntegerLiteral(StringView Type_, StringView Value_)
+  IntegerLiteral(std::string_view Type_, std::string_view Value_)
       : Node(KIntegerLiteral), Type(Type_), Value(Value_) {}
 
   template<typename Fn> void match(Fn F) const { F(Type, Value); }
 
-  void printLeft(OutputStream &S) const override {
+  void printLeft(OutputBuffer &OB) const override {
     if (Type.size() > 3) {
-      S += "(";
-      S += Type;
-      S += ")";
+      OB.printOpen();
+      OB += Type;
+      OB.printClose();
     }
 
-    if (Value[0] == 'n') {
-      S += "-";
-      S += Value.dropFront(1);
-    } else
-      S += Value;
+    if (Value[0] == 'n')
+      OB << '-' << std::string_view(Value.data() + 1, Value.size() - 1);
+    else
+      OB += Value;
 
     if (Type.size() <= 3)
-      S += Type;
+      OB += Type;
   }
 };
 
@@ -2139,29 +2319,26 @@ constexpr Node::Kind getFloatLiteralKind(long double *) {
 }
 
 template <class Float> class FloatLiteralImpl : public Node {
-  const StringView Contents;
+  const std::string_view Contents;
 
   static constexpr Kind KindForClass =
       float_literal_impl::getFloatLiteralKind((Float *)nullptr);
 
 public:
-  FloatLiteralImpl(StringView Contents_)
+  FloatLiteralImpl(std::string_view Contents_)
       : Node(KindForClass), Contents(Contents_) {}
 
   template<typename Fn> void match(Fn F) const { F(Contents); }
 
-  void printLeft(OutputStream &s) const override {
-    const char *first = Contents.begin();
-    const char *last = Contents.end() + 1;
-
+  void printLeft(OutputBuffer &OB) const override {
     const size_t N = FloatData<Float>::mangled_size;
-    if (static_cast<std::size_t>(last - first) > N) {
-      last = first + N;
+    if (Contents.size() >= N) {
       union {
         Float value;
         char buf[sizeof(Float)];
       };
-      const char *t = first;
+      const char *t = Contents.data();
+      const char *last = t + N;
       char *e = buf;
       for (; t != last; ++t, ++e) {
         unsigned d1 = isdigit(*t) ? static_cast<unsigned>(*t - '0')
@@ -2176,7 +2353,7 @@ public:
 #endif
       char num[FloatData<Float>::max_demangled_size] = {0};
       int n = snprintf(num, sizeof(num), FloatData<Float>::spec, value);
-      s += StringView(num, num + n);
+      OB += std::string_view(num, n);
     }
   }
 };
@@ -2190,143 +2367,22 @@ using LongDoubleLiteral = FloatLiteralImpl<long double>;
 template<typename Fn>
 void Node::visit(Fn F) const {
   switch (K) {
-#define CASE(X) case K ## X: return F(static_cast<const X*>(this));
-    FOR_EACH_NODE_KIND(CASE)
-#undef CASE
+#define NODE(X)                                                                \
+  case K##X:                                                                   \
+    return F(static_cast<const X *>(this));
+#include "ItaniumNodes.def"
   }
   assert(0 && "unknown mangling node kind");
 }
 
 /// Determine the kind of a node from its type.
 template<typename NodeT> struct NodeKind;
-#define SPECIALIZATION(X) \
-  template<> struct NodeKind<X> { \
-    static constexpr Node::Kind Kind = Node::K##X; \
-    static constexpr const char *name() { return #X; } \
+#define NODE(X)                                                                \
+  template <> struct NodeKind<X> {                                             \
+    static constexpr Node::Kind Kind = Node::K##X;                             \
+    static constexpr const char *name() { return #X; }                         \
   };
-FOR_EACH_NODE_KIND(SPECIALIZATION)
-#undef SPECIALIZATION
-
-#undef FOR_EACH_NODE_KIND
-
-template <class T, size_t N>
-class PODSmallVector {
-  static_assert(std::is_pod<T>::value,
-                "T is required to be a plain old data type");
-
-  T* First;
-  T* Last;
-  T* Cap;
-  T Inline[N];
-
-  bool isInline() const { return First == Inline; }
-
-  void clearInline() {
-    First = Inline;
-    Last = Inline;
-    Cap = Inline + N;
-  }
-
-  void reserve(size_t NewCap) {
-    size_t S = size();
-    if (isInline()) {
-      auto* Tmp = static_cast<T*>(std::malloc(NewCap * sizeof(T)));
-      if (Tmp == nullptr)
-        std::terminate();
-      std::copy(First, Last, Tmp);
-      First = Tmp;
-    } else {
-      First = static_cast<T*>(std::realloc(First, NewCap * sizeof(T)));
-      if (First == nullptr)
-        std::terminate();
-    }
-    Last = First + S;
-    Cap = First + NewCap;
-  }
-
-public:
-  PODSmallVector() : First(Inline), Last(First), Cap(Inline + N) {}
-
-  PODSmallVector(const PODSmallVector&) = delete;
-  PODSmallVector& operator=(const PODSmallVector&) = delete;
-
-  PODSmallVector(PODSmallVector&& Other) : PODSmallVector() {
-    if (Other.isInline()) {
-      std::copy(Other.begin(), Other.end(), First);
-      Last = First + Other.size();
-      Other.clear();
-      return;
-    }
-
-    First = Other.First;
-    Last = Other.Last;
-    Cap = Other.Cap;
-    Other.clearInline();
-  }
-
-  PODSmallVector& operator=(PODSmallVector&& Other) {
-    if (Other.isInline()) {
-      if (!isInline()) {
-        std::free(First);
-        clearInline();
-      }
-      std::copy(Other.begin(), Other.end(), First);
-      Last = First + Other.size();
-      Other.clear();
-      return *this;
-    }
-
-    if (isInline()) {
-      First = Other.First;
-      Last = Other.Last;
-      Cap = Other.Cap;
-      Other.clearInline();
-      return *this;
-    }
-
-    std::swap(First, Other.First);
-    std::swap(Last, Other.Last);
-    std::swap(Cap, Other.Cap);
-    Other.clear();
-    return *this;
-  }
-
-  void push_back(const T& Elem) {
-    if (Last == Cap)
-      reserve(size() * 2);
-    *Last++ = Elem;
-  }
-
-  void pop_back() {
-    assert(Last != First && "Popping empty vector!");
-    --Last;
-  }
-
-  void dropBack(size_t Index) {
-    assert(Index <= size() && "dropBack() can't expand!");
-    Last = First + Index;
-  }
-
-  T* begin() { return First; }
-  T* end() { return Last; }
-
-  bool empty() const { return First == Last; }
-  size_t size() const { return static_cast<size_t>(Last - First); }
-  T& back() {
-    assert(Last != First && "Calling back() on empty vector!");
-    return *(Last - 1);
-  }
-  T& operator[](size_t Index) {
-    assert(Index < size() && "Invalid access!");
-    return *(begin() + Index);
-  }
-  void clear() { Last = First; }
-
-  ~PODSmallVector() {
-    if (!isInline())
-      std::free(First);
-  }
-};
+#include "ItaniumNodes.def"
 
 template <typename Derived, typename Alloc> struct AbstractManglingParser {
   const char *First;
@@ -2350,9 +2406,9 @@ template <typename Derived, typename Alloc> struct AbstractManglingParser {
     TemplateParamList Params;
 
   public:
-    ScopedTemplateParamList(AbstractManglingParser *Parser)
-        : Parser(Parser),
-          OldNumTemplateParamLists(Parser->TemplateParams.size()) {
+    ScopedTemplateParamList(AbstractManglingParser *TheParser)
+        : Parser(TheParser),
+          OldNumTemplateParamLists(TheParser->TemplateParams.size()) {
       Parser->TemplateParams.push_back(&Params);
     }
     ~ScopedTemplateParamList() {
@@ -2424,8 +2480,9 @@ template <typename Derived, typename Alloc> struct AbstractManglingParser {
     return res;
   }
 
-  bool consumeIf(StringView S) {
-    if (StringView(First, Last).startsWith(S)) {
+  bool consumeIf(std::string_view S) {
+    if (llvm::itanium_demangle::starts_with(
+            std::string_view(First, Last - First), S)) {
       First += S.size();
       return true;
     }
@@ -2442,7 +2499,7 @@ template <typename Derived, typename Alloc> struct AbstractManglingParser {
 
   char consume() { return First != Last ? *First++ : '\0'; }
 
-  char look(unsigned Lookahead = 0) {
+  char look(unsigned Lookahead = 0) const {
     if (static_cast<size_t>(Last - First) <= Lookahead)
       return '\0';
     return First[Lookahead];
@@ -2450,10 +2507,10 @@ template <typename Derived, typename Alloc> struct AbstractManglingParser {
 
   size_t numLeft() const { return static_cast<size_t>(Last - First); }
 
-  StringView parseNumber(bool AllowNegative = false);
+  std::string_view parseNumber(bool AllowNegative = false);
   Qualifiers parseCVQualifiers();
   bool parsePositiveInteger(size_t *Out);
-  StringView parseBareSourceName();
+  std::string_view parseBareSourceName();
 
   bool parseSeqId(size_t *Out);
   Node *parseSubstitution();
@@ -2464,16 +2521,17 @@ template <typename Derived, typename Alloc> struct AbstractManglingParser {
 
   /// Parse the <expr> production.
   Node *parseExpr();
-  Node *parsePrefixExpr(StringView Kind);
-  Node *parseBinaryExpr(StringView Kind);
-  Node *parseIntegerLiteral(StringView Lit);
+  Node *parsePrefixExpr(std::string_view Kind, Node::Prec Prec);
+  Node *parseBinaryExpr(std::string_view Kind, Node::Prec Prec);
+  Node *parseIntegerLiteral(std::string_view Lit);
   Node *parseExprPrimary();
   template <class Float> Node *parseFloatingLiteral();
   Node *parseFunctionParam();
-  Node *parseNewExpr();
   Node *parseConversionExpr();
   Node *parseBracedExpr();
   Node *parseFoldExpr();
+  Node *parsePointerToMemberConversionExpr(Node::Prec Prec);
+  Node *parseSubobjectExpr();
 
   /// Parse the <type> production.
   Node *parseType();
@@ -2520,17 +2578,81 @@ template <typename Derived, typename Alloc> struct AbstractManglingParser {
   Node *parseName(NameState *State = nullptr);
   Node *parseLocalName(NameState *State);
   Node *parseOperatorName(NameState *State);
-  Node *parseUnqualifiedName(NameState *State);
+  bool parseModuleNameOpt(ModuleName *&Module);
+  Node *parseUnqualifiedName(NameState *State, Node *Scope, ModuleName *Module);
   Node *parseUnnamedTypeName(NameState *State);
   Node *parseSourceName(NameState *State);
-  Node *parseUnscopedName(NameState *State);
+  Node *parseUnscopedName(NameState *State, bool *isSubstName);
   Node *parseNestedName(NameState *State);
   Node *parseCtorDtorName(Node *&SoFar, NameState *State);
 
   Node *parseAbiTags(Node *N);
 
+  struct OperatorInfo {
+    enum OIKind : unsigned char {
+      Prefix,      // Prefix unary: @ expr
+      Postfix,     // Postfix unary: expr @
+      Binary,      // Binary: lhs @ rhs
+      Array,       // Array index:  lhs [ rhs ]
+      Member,      // Member access: lhs @ rhs
+      New,         // New
+      Del,         // Delete
+      Call,        // Function call: expr (expr*)
+      CCast,       // C cast: (type)expr
+      Conditional, // Conditional: expr ? expr : expr
+      NameOnly,    // Overload only, not allowed in expression.
+      // Below do not have operator names
+      NamedCast, // Named cast, @<type>(expr)
+      OfIdOp,    // alignof, sizeof, typeid
+
+      Unnameable = NamedCast,
+    };
+    char Enc[2];      // Encoding
+    OIKind Kind;      // Kind of operator
+    bool Flag : 1;    // Entry-specific flag
+    Node::Prec Prec : 7; // Precedence
+    const char *Name; // Spelling
+
+  public:
+    constexpr OperatorInfo(const char (&E)[3], OIKind K, bool F, Node::Prec P,
+                           const char *N)
+        : Enc{E[0], E[1]}, Kind{K}, Flag{F}, Prec{P}, Name{N} {}
+
+  public:
+    bool operator<(const OperatorInfo &Other) const {
+      return *this < Other.Enc;
+    }
+    bool operator<(const char *Peek) const {
+      return Enc[0] < Peek[0] || (Enc[0] == Peek[0] && Enc[1] < Peek[1]);
+    }
+    bool operator==(const char *Peek) const {
+      return Enc[0] == Peek[0] && Enc[1] == Peek[1];
+    }
+    bool operator!=(const char *Peek) const { return !this->operator==(Peek); }
+
+  public:
+    std::string_view getSymbol() const {
+      std::string_view Res = Name;
+      if (Kind < Unnameable) {
+        assert(llvm::itanium_demangle::starts_with(Res, "operator") &&
+               "operator name does not start with 'operator'");
+        Res.remove_prefix(sizeof("operator") - 1);
+        if (llvm::itanium_demangle::starts_with(Res, ' '))
+          Res.remove_prefix(1);
+      }
+      return Res;
+    }
+    std::string_view getName() const { return Name; }
+    OIKind getKind() const { return Kind; }
+    bool getFlag() const { return Flag; }
+    Node::Prec getPrecedence() const { return Prec; }
+  };
+  static const OperatorInfo Ops[];
+  static const size_t NumOps;
+  const OperatorInfo *parseOperatorEncoding();
+
   /// Parse the <unresolved-name> production.
-  Node *parseUnresolvedName();
+  Node *parseUnresolvedName(bool Global);
   Node *parseSimpleId();
   Node *parseBaseUnresolvedName();
   Node *parseUnresolvedType();
@@ -2551,41 +2673,35 @@ const char* parse_discriminator(const char* first, const char* last);
 //                          ::= <substitution>
 template <typename Derived, typename Alloc>
 Node *AbstractManglingParser<Derived, Alloc>::parseName(NameState *State) {
-  consumeIf('L'); // extension
-
   if (look() == 'N')
     return getDerived().parseNestedName(State);
   if (look() == 'Z')
     return getDerived().parseLocalName(State);
 
-  //        ::= <unscoped-template-name> <template-args>
-  if (look() == 'S' && look(1) != 't') {
-    Node *S = getDerived().parseSubstitution();
-    if (S == nullptr)
-      return nullptr;
-    if (look() != 'I')
-      return nullptr;
-    Node *TA = getDerived().parseTemplateArgs(State != nullptr);
-    if (TA == nullptr)
-      return nullptr;
-    if (State) State->EndsWithTemplateArgs = true;
-    return make<NameWithTemplateArgs>(S, TA);
-  }
+  Node *Result = nullptr;
+  bool IsSubst = false;
 
-  Node *N = getDerived().parseUnscopedName(State);
-  if (N == nullptr)
+  Result = getDerived().parseUnscopedName(State, &IsSubst);
+  if (!Result)
     return nullptr;
-  //        ::= <unscoped-template-name> <template-args>
+
   if (look() == 'I') {
-    Subs.push_back(N);
+    //        ::= <unscoped-template-name> <template-args>
+    if (!IsSubst)
+      // An unscoped-template-name is substitutable.
+      Subs.push_back(Result);
     Node *TA = getDerived().parseTemplateArgs(State != nullptr);
     if (TA == nullptr)
       return nullptr;
-    if (State) State->EndsWithTemplateArgs = true;
-    return make<NameWithTemplateArgs>(N, TA);
+    if (State)
+      State->EndsWithTemplateArgs = true;
+    Result = make<NameWithTemplateArgs>(Result, TA);
+  } else if (IsSubst) {
+    // The substitution case must be followed by <template-args>.
+    return nullptr;
   }
-  //        ::= <unscoped-name>
-  return N;
+
+  return Result;
 }
 
 // <local-name> := Z <function encoding> E <entity name> [<discriminator>]
@@ -2626,34 +2742,63 @@ Node *AbstractManglingParser<Derived, Alloc>::parseLocalName(NameState *State) {
 
 // <unscoped-name> ::= <unqualified-name>
 //                 ::= St <unqualified-name>   # ::std::
-// extension       ::= StL<unqualified-name>
+// [*] extension
 template <typename Derived, typename Alloc>
 Node *
-AbstractManglingParser<Derived, Alloc>::parseUnscopedName(NameState *State) {
-  if (consumeIf("StL") || consumeIf("St")) {
-    Node *R = getDerived().parseUnqualifiedName(State);
-    if (R == nullptr)
+AbstractManglingParser<Derived, Alloc>::parseUnscopedName(NameState *State,
+                                                          bool *IsSubst) {
+
+  Node *Std = nullptr;
+  if (consumeIf("St")) {
+    Std = make<NameType>("std");
+    if (Std == nullptr)
       return nullptr;
-    return make<StdQualifiedName>(R);
   }
-  return getDerived().parseUnqualifiedName(State);
+
+  Node *Res = nullptr;
+  ModuleName *Module = nullptr;
+  if (look() == 'S') {
+    Node *S = getDerived().parseSubstitution();
+    if (!S)
+      return nullptr;
+    if (S->getKind() == Node::KModuleName)
+      Module = static_cast<ModuleName *>(S);
+    else if (IsSubst && Std == nullptr) {
+      Res = S;
+      *IsSubst = true;
+    } else {
+      return nullptr;
+    }
+  }
+
+  if (Res == nullptr || Std != nullptr) {
+    Res = getDerived().parseUnqualifiedName(State, Std, Module);
+  }
+
+  return Res;
 }
 
-// <unqualified-name> ::= <operator-name> [abi-tags]
-//                    ::= <ctor-dtor-name>
-//                    ::= <source-name>
-//                    ::= <unnamed-type-name>
-//                    ::= DC <source-name>+ E      # structured binding declaration
+// <unqualified-name> ::= [<module-name>] L? <operator-name> [<abi-tags>]
+//                    ::= [<module-name>] <ctor-dtor-name> [<abi-tags>]
+//                    ::= [<module-name>] L? <source-name> [<abi-tags>]
+//                    ::= [<module-name>] L? <unnamed-type-name> [<abi-tags>]
+//			# structured binding declaration
+//                    ::= [<module-name>] L? DC <source-name>+ E
 template <typename Derived, typename Alloc>
-Node *
-AbstractManglingParser<Derived, Alloc>::parseUnqualifiedName(NameState *State) {
-  // <ctor-dtor-name>s are special-cased in parseNestedName().
+Node *AbstractManglingParser<Derived, Alloc>::parseUnqualifiedName(
+    NameState *State, Node *Scope, ModuleName *Module) {
+  if (getDerived().parseModuleNameOpt(Module))
+    return nullptr;
+
+  consumeIf('L');
+
   Node *Result;
-  if (look() == 'U')
-    Result = getDerived().parseUnnamedTypeName(State);
-  else if (look() >= '1' && look() <= '9')
+  if (look() >= '1' && look() <= '9') {
     Result = getDerived().parseSourceName(State);
-  else if (consumeIf("DC")) {
+  } else if (look() == 'U') {
+    Result = getDerived().parseUnnamedTypeName(State);
+  } else if (consumeIf("DC")) {
+    // Structured binding
     size_t BindingsBegin = Names.size();
     do {
       Node *Binding = getDerived().parseSourceName(State);
@@ -2662,13 +2807,46 @@ AbstractManglingParser<Derived, Alloc>::parseUnqualifiedName(NameState *State) {
       Names.push_back(Binding);
     } while (!consumeIf('E'));
     Result = make<StructuredBindingName>(popTrailingNodeArray(BindingsBegin));
-  } else
+  } else if (look() == 'C' || look() == 'D') {
+    // A <ctor-dtor-name>.
+    if (Scope == nullptr || Module != nullptr)
+      return nullptr;
+    Result = getDerived().parseCtorDtorName(Scope, State);
+  } else {
     Result = getDerived().parseOperatorName(State);
+  }
+
+  if (Result != nullptr && Module != nullptr)
+    Result = make<ModuleEntity>(Module, Result);
   if (Result != nullptr)
     Result = getDerived().parseAbiTags(Result);
+  if (Result != nullptr && Scope != nullptr)
+    Result = make<NestedName>(Scope, Result);
+
   return Result;
 }
 
+// <module-name> ::= <module-subname>
+// 	 	 ::= <module-name> <module-subname>
+//		 ::= <substitution>  # passed in by caller
+// <module-subname> ::= W <source-name>
+//		    ::= W P <source-name>
+template <typename Derived, typename Alloc>
+bool AbstractManglingParser<Derived, Alloc>::parseModuleNameOpt(
+    ModuleName *&Module) {
+  while (consumeIf('W')) {
+    bool IsPartition = consumeIf('P');
+    Node *Sub = getDerived().parseSourceName(nullptr);
+    if (!Sub)
+      return true;
+    Module =
+        static_cast<ModuleName *>(make<ModuleName>(Module, Sub, IsPartition));
+    Subs.push_back(Module);
+  }
+
+  return false;
+}
+
 // <unnamed-type-name> ::= Ut [<nonnegative number>] _
 //                     ::= <closure-type-name>
 //
@@ -2684,19 +2862,19 @@ AbstractManglingParser<Derived, Alloc>::parseUnnamedTypeName(NameState *State) {
     TemplateParams.clear();
 
   if (consumeIf("Ut")) {
-    StringView Count = parseNumber();
+    std::string_view Count = parseNumber();
     if (!consumeIf('_'))
       return nullptr;
     return make<UnnamedTypeName>(Count);
   }
   if (consumeIf("Ul")) {
-    SwapAndRestore<size_t> SwapParams(ParsingLambdaParamsAtLevel,
+    ScopedOverride<size_t> SwapParams(ParsingLambdaParamsAtLevel,
                                       TemplateParams.size());
     ScopedTemplateParamList LambdaTemplateParams(this);
 
     size_t ParamsBegin = Names.size();
     while (look() == 'T' &&
-           StringView("yptn").find(look(1)) != StringView::npos) {
+           std::string_view("yptn").find(look(1)) != std::string_view::npos) {
       Node *T = parseTemplateParamDecl();
       if (!T)
         return nullptr;
@@ -2739,7 +2917,7 @@ AbstractManglingParser<Derived, Alloc>::parseUnnamedTypeName(NameState *State) {
     }
     NodeArray Params = popTrailingNodeArray(ParamsBegin);
 
-    StringView Count = parseNumber();
+    std::string_view Count = parseNumber();
     if (!consumeIf('_'))
       return nullptr;
     return make<ClosureTypeName>(TempParams, Params, Count);
@@ -2761,104 +2939,138 @@ Node *AbstractManglingParser<Derived, Alloc>::parseSourceName(NameState *) {
     return nullptr;
   if (numLeft() < Length || Length == 0)
     return nullptr;
-  StringView Name(First, First + Length);
+  std::string_view Name(First, Length);
   First += Length;
-  if (Name.startsWith("_GLOBAL__N"))
+  if (llvm::itanium_demangle::starts_with(Name, "_GLOBAL__N"))
     return make<NameType>("(anonymous namespace)");
   return make<NameType>(Name);
 }
 
-//   <operator-name> ::= aa    # &&
-//                   ::= ad    # & (unary)
-//                   ::= an    # &
-//                   ::= aN    # &=
-//                   ::= aS    # =
-//                   ::= cl    # ()
-//                   ::= cm    # ,
-//                   ::= co    # ~
-//                   ::= cv <type>    # (cast)
-//                   ::= da    # delete[]
-//                   ::= de    # * (unary)
-//                   ::= dl    # delete
-//                   ::= dv    # /
-//                   ::= dV    # /=
-//                   ::= eo    # ^
-//                   ::= eO    # ^=
-//                   ::= eq    # ==
-//                   ::= ge    # >=
-//                   ::= gt    # >
-//                   ::= ix    # []
-//                   ::= le    # <=
+// Operator encodings
+template <typename Derived, typename Alloc>
+const typename AbstractManglingParser<
+    Derived, Alloc>::OperatorInfo AbstractManglingParser<Derived,
+                                                         Alloc>::Ops[] = {
+    // Keep ordered by encoding
+    {"aN", OperatorInfo::Binary, false, Node::Prec::Assign, "operator&="},
+    {"aS", OperatorInfo::Binary, false, Node::Prec::Assign, "operator="},
+    {"aa", OperatorInfo::Binary, false, Node::Prec::AndIf, "operator&&"},
+    {"ad", OperatorInfo::Prefix, false, Node::Prec::Unary, "operator&"},
+    {"an", OperatorInfo::Binary, false, Node::Prec::And, "operator&"},
+    {"at", OperatorInfo::OfIdOp, /*Type*/ true, Node::Prec::Unary, "alignof "},
+    {"aw", OperatorInfo::NameOnly, false, Node::Prec::Primary,
+     "operator co_await"},
+    {"az", OperatorInfo::OfIdOp, /*Type*/ false, Node::Prec::Unary, "alignof "},
+    {"cc", OperatorInfo::NamedCast, false, Node::Prec::Postfix, "const_cast"},
+    {"cl", OperatorInfo::Call, false, Node::Prec::Postfix, "operator()"},
+    {"cm", OperatorInfo::Binary, false, Node::Prec::Comma, "operator,"},
+    {"co", OperatorInfo::Prefix, false, Node::Prec::Unary, "operator~"},
+    {"cv", OperatorInfo::CCast, false, Node::Prec::Cast, "operator"}, // C Cast
+    {"dV", OperatorInfo::Binary, false, Node::Prec::Assign, "operator/="},
+    {"da", OperatorInfo::Del, /*Ary*/ true, Node::Prec::Unary,
+     "operator delete[]"},
+    {"dc", OperatorInfo::NamedCast, false, Node::Prec::Postfix, "dynamic_cast"},
+    {"de", OperatorInfo::Prefix, false, Node::Prec::Unary, "operator*"},
+    {"dl", OperatorInfo::Del, /*Ary*/ false, Node::Prec::Unary,
+     "operator delete"},
+    {"ds", OperatorInfo::Member, /*Named*/ false, Node::Prec::PtrMem,
+     "operator.*"},
+    {"dt", OperatorInfo::Member, /*Named*/ false, Node::Prec::Postfix,
+     "operator."},
+    {"dv", OperatorInfo::Binary, false, Node::Prec::Assign, "operator/"},
+    {"eO", OperatorInfo::Binary, false, Node::Prec::Assign, "operator^="},
+    {"eo", OperatorInfo::Binary, false, Node::Prec::Xor, "operator^"},
+    {"eq", OperatorInfo::Binary, false, Node::Prec::Equality, "operator=="},
+    {"ge", OperatorInfo::Binary, false, Node::Prec::Relational, "operator>="},
+    {"gt", OperatorInfo::Binary, false, Node::Prec::Relational, "operator>"},
+    {"ix", OperatorInfo::Array, false, Node::Prec::Postfix, "operator[]"},
+    {"lS", OperatorInfo::Binary, false, Node::Prec::Assign, "operator<<="},
+    {"le", OperatorInfo::Binary, false, Node::Prec::Relational, "operator<="},
+    {"ls", OperatorInfo::Binary, false, Node::Prec::Shift, "operator<<"},
+    {"lt", OperatorInfo::Binary, false, Node::Prec::Relational, "operator<"},
+    {"mI", OperatorInfo::Binary, false, Node::Prec::Assign, "operator-="},
+    {"mL", OperatorInfo::Binary, false, Node::Prec::Assign, "operator*="},
+    {"mi", OperatorInfo::Binary, false, Node::Prec::Additive, "operator-"},
+    {"ml", OperatorInfo::Binary, false, Node::Prec::Multiplicative,
+     "operator*"},
+    {"mm", OperatorInfo::Postfix, false, Node::Prec::Postfix, "operator--"},
+    {"na", OperatorInfo::New, /*Ary*/ true, Node::Prec::Unary,
+     "operator new[]"},
+    {"ne", OperatorInfo::Binary, false, Node::Prec::Equality, "operator!="},
+    {"ng", OperatorInfo::Prefix, false, Node::Prec::Unary, "operator-"},
+    {"nt", OperatorInfo::Prefix, false, Node::Prec::Unary, "operator!"},
+    {"nw", OperatorInfo::New, /*Ary*/ false, Node::Prec::Unary, "operator new"},
+    {"oR", OperatorInfo::Binary, false, Node::Prec::Assign, "operator|="},
+    {"oo", OperatorInfo::Binary, false, Node::Prec::OrIf, "operator||"},
+    {"or", OperatorInfo::Binary, false, Node::Prec::Ior, "operator|"},
+    {"pL", OperatorInfo::Binary, false, Node::Prec::Assign, "operator+="},
+    {"pl", OperatorInfo::Binary, false, Node::Prec::Additive, "operator+"},
+    {"pm", OperatorInfo::Member, /*Named*/ false, Node::Prec::PtrMem,
+     "operator->*"},
+    {"pp", OperatorInfo::Postfix, false, Node::Prec::Postfix, "operator++"},
+    {"ps", OperatorInfo::Prefix, false, Node::Prec::Unary, "operator+"},
+    {"pt", OperatorInfo::Member, /*Named*/ true, Node::Prec::Postfix,
+     "operator->"},
+    {"qu", OperatorInfo::Conditional, false, Node::Prec::Conditional,
+     "operator?"},
+    {"rM", OperatorInfo::Binary, false, Node::Prec::Assign, "operator%="},
+    {"rS", OperatorInfo::Binary, false, Node::Prec::Assign, "operator>>="},
+    {"rc", OperatorInfo::NamedCast, false, Node::Prec::Postfix,
+     "reinterpret_cast"},
+    {"rm", OperatorInfo::Binary, false, Node::Prec::Multiplicative,
+     "operator%"},
+    {"rs", OperatorInfo::Binary, false, Node::Prec::Shift, "operator>>"},
+    {"sc", OperatorInfo::NamedCast, false, Node::Prec::Postfix, "static_cast"},
+    {"ss", OperatorInfo::Binary, false, Node::Prec::Spaceship, "operator<=>"},
+    {"st", OperatorInfo::OfIdOp, /*Type*/ true, Node::Prec::Unary, "sizeof "},
+    {"sz", OperatorInfo::OfIdOp, /*Type*/ false, Node::Prec::Unary, "sizeof "},
+    {"te", OperatorInfo::OfIdOp, /*Type*/ false, Node::Prec::Postfix,
+     "typeid "},
+    {"ti", OperatorInfo::OfIdOp, /*Type*/ true, Node::Prec::Postfix, "typeid "},
+};
+template <typename Derived, typename Alloc>
+const size_t AbstractManglingParser<Derived, Alloc>::NumOps = sizeof(Ops) /
+                                                              sizeof(Ops[0]);
+
+// If the next 2 chars are an operator encoding, consume them and return their
+// OperatorInfo.  Otherwise return nullptr.
+template <typename Derived, typename Alloc>
+const typename AbstractManglingParser<Derived, Alloc>::OperatorInfo *
+AbstractManglingParser<Derived, Alloc>::parseOperatorEncoding() {
+  if (numLeft() < 2)
+    return nullptr;
+
+  // We can't use lower_bound as that can link to symbols in the C++ library,
+  // and this must remain independant of that.
+  size_t lower = 0u, upper = NumOps - 1; // Inclusive bounds.
+  while (upper != lower) {
+    size_t middle = (upper + lower) / 2;
+    if (Ops[middle] < First)
+      lower = middle + 1;
+    else
+      upper = middle;
+  }
+  if (Ops[lower] != First)
+    return nullptr;
+
+  First += 2;
+  return &Ops[lower];
+}
+
+//   <operator-name> ::= See parseOperatorEncoding()
 //                   ::= li <source-name>  # operator ""
-//                   ::= ls    # <<
-//                   ::= lS    # <<=
-//                   ::= lt    # <
-//                   ::= mi    # -
-//                   ::= mI    # -=
-//                   ::= ml    # *
-//                   ::= mL    # *=
-//                   ::= mm    # -- (postfix in <expression> context)
-//                   ::= na    # new[]
-//                   ::= ne    # !=
-//                   ::= ng    # - (unary)
-//                   ::= nt    # !
-//                   ::= nw    # new
-//                   ::= oo    # ||
-//                   ::= or    # |
-//                   ::= oR    # |=
-//                   ::= pm    # ->*
-//                   ::= pl    # +
-//                   ::= pL    # +=
-//                   ::= pp    # ++ (postfix in <expression> context)
-//                   ::= ps    # + (unary)
-//                   ::= pt    # ->
-//                   ::= qu    # ?
-//                   ::= rm    # %
-//                   ::= rM    # %=
-//                   ::= rs    # >>
-//                   ::= rS    # >>=
-//                   ::= ss    # <=> C++2a
-//                   ::= v <digit> <source-name>        # vendor extended operator
+//                   ::= v <digit> <source-name>  # vendor extended operator
 template <typename Derived, typename Alloc>
 Node *
 AbstractManglingParser<Derived, Alloc>::parseOperatorName(NameState *State) {
-  switch (look()) {
-  case 'a':
-    switch (look(1)) {
-    case 'a':
-      First += 2;
-      return make<NameType>("operator&&");
-    case 'd':
-    case 'n':
-      First += 2;
-      return make<NameType>("operator&");
-    case 'N':
-      First += 2;
-      return make<NameType>("operator&=");
-    case 'S':
-      First += 2;
-      return make<NameType>("operator=");
-    }
-    return nullptr;
-  case 'c':
-    switch (look(1)) {
-    case 'l':
-      First += 2;
-      return make<NameType>("operator()");
-    case 'm':
-      First += 2;
-      return make<NameType>("operator,");
-    case 'o':
-      First += 2;
-      return make<NameType>("operator~");
-    //                   ::= cv <type>    # (cast)
-    case 'v': {
-      First += 2;
-      SwapAndRestore<bool> SaveTemplate(TryToParseTemplateArgs, false);
+  if (const auto *Op = parseOperatorEncoding()) {
+    if (Op->getKind() == OperatorInfo::CCast) {
+      //              ::= cv <type>    # (cast)
+      ScopedOverride<bool> SaveTemplate(TryToParseTemplateArgs, false);
       // If we're parsing an encoding, State != nullptr and the conversion
       // operators' <type> could have a <template-param> that refers to some
       // <template-arg>s further ahead in the mangled name.
-      SwapAndRestore<bool> SavePermit(PermitForwardTemplateReferences,
+      ScopedOverride<bool> SavePermit(PermitForwardTemplateReferences,
                                       PermitForwardTemplateReferences ||
                                           State != nullptr);
       Node *Ty = getDerived().parseType();
@@ -2867,185 +3079,29 @@ AbstractManglingParser<Derived, Alloc>::parseOperatorName(NameState *State) {
       if (State) State->CtorDtorConversion = true;
       return make<ConversionOperatorType>(Ty);
     }
-    }
-    return nullptr;
-  case 'd':
-    switch (look(1)) {
-    case 'a':
-      First += 2;
-      return make<NameType>("operator delete[]");
-    case 'e':
-      First += 2;
-      return make<NameType>("operator*");
-    case 'l':
-      First += 2;
-      return make<NameType>("operator delete");
-    case 'v':
-      First += 2;
-      return make<NameType>("operator/");
-    case 'V':
-      First += 2;
-      return make<NameType>("operator/=");
-    }
-    return nullptr;
-  case 'e':
-    switch (look(1)) {
-    case 'o':
-      First += 2;
-      return make<NameType>("operator^");
-    case 'O':
-      First += 2;
-      return make<NameType>("operator^=");
-    case 'q':
-      First += 2;
-      return make<NameType>("operator==");
-    }
-    return nullptr;
-  case 'g':
-    switch (look(1)) {
-    case 'e':
-      First += 2;
-      return make<NameType>("operator>=");
-    case 't':
-      First += 2;
-      return make<NameType>("operator>");
-    }
-    return nullptr;
-  case 'i':
-    if (look(1) == 'x') {
-      First += 2;
-      return make<NameType>("operator[]");
-    }
-    return nullptr;
-  case 'l':
-    switch (look(1)) {
-    case 'e':
-      First += 2;
-      return make<NameType>("operator<=");
+
+    if (Op->getKind() >= OperatorInfo::Unnameable)
+      /* Not a nameable operator.  */
+      return nullptr;
+    if (Op->getKind() == OperatorInfo::Member && !Op->getFlag())
+      /* Not a nameable MemberExpr */
+      return nullptr;
+
+    return make<NameType>(Op->getName());
+  }
+
+  if (consumeIf("li")) {
     //                   ::= li <source-name>  # operator ""
-    case 'i': {
-      First += 2;
-      Node *SN = getDerived().parseSourceName(State);
-      if (SN == nullptr)
-        return nullptr;
-      return make<LiteralOperator>(SN);
-    }
-    case 's':
-      First += 2;
-      return make<NameType>("operator<<");
-    case 'S':
-      First += 2;
-      return make<NameType>("operator<<=");
-    case 't':
-      First += 2;
-      return make<NameType>("operator<");
-    }
-    return nullptr;
-  case 'm':
-    switch (look(1)) {
-    case 'i':
-      First += 2;
-      return make<NameType>("operator-");
-    case 'I':
-      First += 2;
-      return make<NameType>("operator-=");
-    case 'l':
-      First += 2;
-      return make<NameType>("operator*");
-    case 'L':
-      First += 2;
-      return make<NameType>("operator*=");
-    case 'm':
-      First += 2;
-      return make<NameType>("operator--");
-    }
-    return nullptr;
-  case 'n':
-    switch (look(1)) {
-    case 'a':
-      First += 2;
-      return make<NameType>("operator new[]");
-    case 'e':
-      First += 2;
-      return make<NameType>("operator!=");
-    case 'g':
-      First += 2;
-      return make<NameType>("operator-");
-    case 't':
-      First += 2;
-      return make<NameType>("operator!");
-    case 'w':
-      First += 2;
-      return make<NameType>("operator new");
-    }
-    return nullptr;
-  case 'o':
-    switch (look(1)) {
-    case 'o':
-      First += 2;
-      return make<NameType>("operator||");
-    case 'r':
-      First += 2;
-      return make<NameType>("operator|");
-    case 'R':
-      First += 2;
-      return make<NameType>("operator|=");
-    }
-    return nullptr;
-  case 'p':
-    switch (look(1)) {
-    case 'm':
-      First += 2;
-      return make<NameType>("operator->*");
-    case 'l':
-      First += 2;
-      return make<NameType>("operator+");
-    case 'L':
-      First += 2;
-      return make<NameType>("operator+=");
-    case 'p':
-      First += 2;
-      return make<NameType>("operator++");
-    case 's':
-      First += 2;
-      return make<NameType>("operator+");
-    case 't':
-      First += 2;
-      return make<NameType>("operator->");
-    }
-    return nullptr;
-  case 'q':
-    if (look(1) == 'u') {
-      First += 2;
-      return make<NameType>("operator?");
-    }
-    return nullptr;
-  case 'r':
-    switch (look(1)) {
-    case 'm':
-      First += 2;
-      return make<NameType>("operator%");
-    case 'M':
-      First += 2;
-      return make<NameType>("operator%=");
-    case 's':
-      First += 2;
-      return make<NameType>("operator>>");
-    case 'S':
-      First += 2;
-      return make<NameType>("operator>>=");
-    }
-    return nullptr;
-  case 's':
-    if (look(1) == 's') {
-      First += 2;
-      return make<NameType>("operator<=>");
-    }
-    return nullptr;
-  // ::= v <digit> <source-name>        # vendor extended operator
-  case 'v':
-    if (std::isdigit(look(1))) {
-      First += 2;
+    Node *SN = getDerived().parseSourceName(State);
+    if (SN == nullptr)
+      return nullptr;
+    return make<LiteralOperator>(SN);
+  }
+
+  if (consumeIf('v')) {
+    // ::= v <digit> <source-name>        # vendor extended operator
+    if (look() >= '0' && look() <= '9') {
+      First++;
       Node *SN = getDerived().parseSourceName(State);
       if (SN == nullptr)
         return nullptr;
@@ -3053,6 +3109,7 @@ AbstractManglingParser<Derived, Alloc>::parseOperatorName(NameState *State) {
     }
     return nullptr;
   }
+
   return nullptr;
 }
 
@@ -3071,19 +3128,11 @@ Node *
 AbstractManglingParser<Derived, Alloc>::parseCtorDtorName(Node *&SoFar,
                                                           NameState *State) {
   if (SoFar->getKind() == Node::KSpecialSubstitution) {
-    auto SSK = static_cast<SpecialSubstitution *>(SoFar)->SSK;
-    switch (SSK) {
-    case SpecialSubKind::string:
-    case SpecialSubKind::istream:
-    case SpecialSubKind::ostream:
-    case SpecialSubKind::iostream:
-      SoFar = make<ExpandedSpecialSubstitution>(SSK);
-      if (!SoFar)
-        return nullptr;
-      break;
-    default:
-      break;
-    }
+    // Expand the special substitution.
+    SoFar = make<ExpandedSpecialSubstitution>(
+        static_cast<SpecialSubstitution *>(SoFar));
+    if (!SoFar)
+      return nullptr;
   }
 
   if (consumeIf('C')) {
@@ -3112,8 +3161,10 @@ AbstractManglingParser<Derived, Alloc>::parseCtorDtorName(Node *&SoFar,
   return nullptr;
 }
 
-// <nested-name> ::= N [<CV-Qualifiers>] [<ref-qualifier>] <prefix> <unqualified-name> E
-//               ::= N [<CV-Qualifiers>] [<ref-qualifier>] <template-prefix> <template-args> E
+// <nested-name> ::= N [<CV-Qualifiers>] [<ref-qualifier>] <prefix>
+// 			<unqualified-name> E
+//               ::= N [<CV-Qualifiers>] [<ref-qualifier>] <template-prefix>
+//               	<template-args> E
 //
 // <prefix> ::= <prefix> <unqualified-name>
 //          ::= <template-prefix> <template-args>
@@ -3122,7 +3173,7 @@ AbstractManglingParser<Derived, Alloc>::parseCtorDtorName(Node *&SoFar,
 //          ::= # empty
 //          ::= <substitution>
 //          ::= <prefix> <data-member-prefix>
-//  extension ::= L
+// [*] extension
 //
 // <data-member-prefix> := <member source-name> [<template-args>] M
 //
@@ -3142,90 +3193,76 @@ AbstractManglingParser<Derived, Alloc>::parseNestedName(NameState *State) {
     if (State) State->ReferenceQualifier = FrefQualRValue;
   } else if (consumeIf('R')) {
     if (State) State->ReferenceQualifier = FrefQualLValue;
-  } else
+  } else {
     if (State) State->ReferenceQualifier = FrefQualNone;
-
-  Node *SoFar = nullptr;
-  auto PushComponent = [&](Node *Comp) {
-    if (!Comp) return false;
-    if (SoFar) SoFar = make<NestedName>(SoFar, Comp);
-    else       SoFar = Comp;
-    if (State) State->EndsWithTemplateArgs = false;
-    return SoFar != nullptr;
-  };
-
-  if (consumeIf("St")) {
-    SoFar = make<NameType>("std");
-    if (!SoFar)
-      return nullptr;
   }
 
+  Node *SoFar = nullptr;
   while (!consumeIf('E')) {
-    consumeIf('L'); // extension
+    if (State)
+      // Only set end-with-template on the case that does that.
+      State->EndsWithTemplateArgs = false;
 
-    // <data-member-prefix> := <member source-name> [<template-args>] M
-    if (consumeIf('M')) {
-      if (SoFar == nullptr)
-        return nullptr;
-      continue;
-    }
-
-    //          ::= <template-param>
     if (look() == 'T') {
-      if (!PushComponent(getDerived().parseTemplateParam()))
-        return nullptr;
-      Subs.push_back(SoFar);
-      continue;
-    }
-
-    //          ::= <template-prefix> <template-args>
-    if (look() == 'I') {
+      //          ::= <template-param>
+      if (SoFar != nullptr)
+        return nullptr; // Cannot have a prefix.
+      SoFar = getDerived().parseTemplateParam();
+    } else if (look() == 'I') {
+      //          ::= <template-prefix> <template-args>
+      if (SoFar == nullptr)
+        return nullptr; // Must have a prefix.
       Node *TA = getDerived().parseTemplateArgs(State != nullptr);
-      if (TA == nullptr || SoFar == nullptr)
-        return nullptr;
-      SoFar = make<NameWithTemplateArgs>(SoFar, TA);
-      if (!SoFar)
-        return nullptr;
-      if (State) State->EndsWithTemplateArgs = true;
-      Subs.push_back(SoFar);
-      continue;
-    }
-
-    //          ::= <decltype>
-    if (look() == 'D' && (look(1) == 't' || look(1) == 'T')) {
-      if (!PushComponent(getDerived().parseDecltype()))
+      if (TA == nullptr)
         return nullptr;
-      Subs.push_back(SoFar);
-      continue;
-    }
-
-    //          ::= <substitution>
-    if (look() == 'S' && look(1) != 't') {
-      Node *S = getDerived().parseSubstitution();
-      if (!PushComponent(S))
+      if (SoFar->getKind() == Node::KNameWithTemplateArgs)
+        // Semantically <template-args> <template-args> cannot be generated by a
+        // C++ entity.  There will always be [something like] a name between
+        // them.
         return nullptr;
-      if (SoFar != S)
-        Subs.push_back(S);
-      continue;
-    }
+      if (State)
+        State->EndsWithTemplateArgs = true;
+      SoFar = make<NameWithTemplateArgs>(SoFar, TA);
+    } else if (look() == 'D' && (look(1) == 't' || look(1) == 'T')) {
+      //          ::= <decltype>
+      if (SoFar != nullptr)
+        return nullptr; // Cannot have a prefix.
+      SoFar = getDerived().parseDecltype();
+    } else {
+      ModuleName *Module = nullptr;
+
+      if (look() == 'S') {
+        //          ::= <substitution>
+        Node *S = nullptr;
+        if (look(1) == 't') {
+          First += 2;
+          S = make<NameType>("std");
+        } else {
+          S = getDerived().parseSubstitution();
+        }
+        if (!S)
+          return nullptr;
+        if (S->getKind() == Node::KModuleName) {
+          Module = static_cast<ModuleName *>(S);
+        } else if (SoFar != nullptr) {
+          return nullptr; // Cannot have a prefix.
+        } else {
+          SoFar = S;
+          continue; // Do not push a new substitution.
+        }
+      }
 
-    // Parse an <unqualified-name> thats actually a <ctor-dtor-name>.
-    if (look() == 'C' || (look() == 'D' && look(1) != 'C')) {
-      if (SoFar == nullptr)
-        return nullptr;
-      if (!PushComponent(getDerived().parseCtorDtorName(SoFar, State)))
-        return nullptr;
-      SoFar = getDerived().parseAbiTags(SoFar);
-      if (SoFar == nullptr)
-        return nullptr;
-      Subs.push_back(SoFar);
-      continue;
+      //          ::= [<prefix>] <unqualified-name>
+      SoFar = getDerived().parseUnqualifiedName(State, SoFar, Module);
     }
 
-    //          ::= <prefix> <unqualified-name>
-    if (!PushComponent(getDerived().parseUnqualifiedName(State)))
+    if (SoFar == nullptr)
       return nullptr;
     Subs.push_back(SoFar);
+
+    // No longer used.
+    // <data-member-prefix> := <member source-name> [<template-args>] M
+    consumeIf('M');
   }
 
   if (SoFar == nullptr || Subs.empty())
@@ -3320,6 +3357,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseBaseUnresolvedName() {
 //                   ::= [gs] <base-unresolved-name>                     # x or (with "gs") ::x
 //                   ::= [gs] sr <unresolved-qualifier-level>+ E <base-unresolved-name>
 //                                                                       # A::x, N::y, A<T>::z; "gs" means leading "::"
+// [gs] has been parsed by caller.
 //                   ::= sr <unresolved-type> <base-unresolved-name>     # T::x / decltype(p)::x
 //  extension        ::= sr <unresolved-type> <template-args> <base-unresolved-name>
 //                                                                       # T::N::x /decltype(p)::N::x
@@ -3327,7 +3365,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseBaseUnresolvedName() {
 //
 // <unresolved-qualifier-level> ::= <simple-id>
 template <typename Derived, typename Alloc>
-Node *AbstractManglingParser<Derived, Alloc>::parseUnresolvedName() {
+Node *AbstractManglingParser<Derived, Alloc>::parseUnresolvedName(bool Global) {
   Node *SoFar = nullptr;
 
   // srN <unresolved-type> [<template-args>] <unresolved-qualifier-level>* E <base-unresolved-name>
@@ -3361,8 +3399,6 @@ Node *AbstractManglingParser<Derived, Alloc>::parseUnresolvedName() {
     return make<QualifiedName>(SoFar, Base);
   }
 
-  bool Global = consumeIf("gs");
-
   // [gs] <base-unresolved-name>                     # x or (with "gs") ::x
   if (!consumeIf("sr")) {
     SoFar = getDerived().parseBaseUnresolvedName();
@@ -3419,7 +3455,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseUnresolvedName() {
 template <typename Derived, typename Alloc>
 Node *AbstractManglingParser<Derived, Alloc>::parseAbiTags(Node *N) {
   while (consumeIf('B')) {
-    StringView SN = parseBareSourceName();
+    std::string_view SN = parseBareSourceName();
     if (SN.empty())
       return nullptr;
     N = make<AbiTagAttr>(N, SN);
@@ -3431,16 +3467,16 @@ Node *AbstractManglingParser<Derived, Alloc>::parseAbiTags(Node *N) {
 
 // <number> ::= [n] <non-negative decimal integer>
 template <typename Alloc, typename Derived>
-StringView
+std::string_view
 AbstractManglingParser<Alloc, Derived>::parseNumber(bool AllowNegative) {
   const char *Tmp = First;
   if (AllowNegative)
     consumeIf('n');
   if (numLeft() == 0 || !std::isdigit(*First))
-    return StringView();
+    return std::string_view();
   while (numLeft() != 0 && std::isdigit(*First))
     ++First;
-  return StringView(Tmp, First);
+  return std::string_view(Tmp, First - Tmp);
 }
 
 // <positive length number> ::= [0-9]*
@@ -3457,11 +3493,11 @@ bool AbstractManglingParser<Alloc, Derived>::parsePositiveInteger(size_t *Out) {
 }
 
 template <typename Alloc, typename Derived>
-StringView AbstractManglingParser<Alloc, Derived>::parseBareSourceName() {
+std::string_view AbstractManglingParser<Alloc, Derived>::parseBareSourceName() {
   size_t Int = 0;
   if (parsePositiveInteger(&Int) || numLeft() < Int)
-    return StringView();
-  StringView R(First, First + Int);
+    return {};
+  std::string_view R(First, Int);
   First += Int;
   return R;
 }
@@ -3549,7 +3585,9 @@ Node *AbstractManglingParser<Derived, Alloc>::parseVectorType() {
   if (!consumeIf("Dv"))
     return nullptr;
   if (look() >= '1' && look() <= '9') {
-    StringView DimensionNumber = parseNumber();
+    Node *DimensionNumber = make<NameType>(parseNumber());
+    if (!DimensionNumber)
+      return nullptr;
     if (!consumeIf('_'))
       return nullptr;
     if (consumeIf('p'))
@@ -3574,7 +3612,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseVectorType() {
   Node *ElemType = getDerived().parseType();
   if (!ElemType)
     return nullptr;
-  return make<VectorType>(ElemType, StringView());
+  return make<VectorType>(ElemType, /*Dimension=*/nullptr);
 }
 
 // <decltype>  ::= Dt <expression> E  # decltype of an id-expression or class member access (C++0x)
@@ -3590,7 +3628,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseDecltype() {
     return nullptr;
   if (!consumeIf('E'))
     return nullptr;
-  return make<EnclosingExpr>("decltype(", E, ")");
+  return make<EnclosingExpr>("decltype", E);
 }
 
 // <array-type> ::= A <positive dimension number> _ <element type>
@@ -3600,10 +3638,12 @@ Node *AbstractManglingParser<Derived, Alloc>::parseArrayType() {
   if (!consumeIf('A'))
     return nullptr;
 
-  NodeOrString Dimension;
+  Node *Dimension = nullptr;
 
   if (std::isdigit(look())) {
-    Dimension = parseNumber();
+    Dimension = make<NameType>(parseNumber());
+    if (!Dimension)
+      return nullptr;
     if (!consumeIf('_'))
       return nullptr;
   } else if (!consumeIf('_')) {
@@ -3641,7 +3681,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parsePointerToMemberType() {
 //                   ::= Te <name>  # dependent elaborated type specifier using 'enum'
 template <typename Derived, typename Alloc>
 Node *AbstractManglingParser<Derived, Alloc>::parseClassEnumType() {
-  StringView ElabSpef;
+  std::string_view ElabSpef;
   if (consumeIf("Ts"))
     ElabSpef = "struct";
   else if (consumeIf("Tu"))
@@ -3665,19 +3705,18 @@ Node *AbstractManglingParser<Derived, Alloc>::parseClassEnumType() {
 template <typename Derived, typename Alloc>
 Node *AbstractManglingParser<Derived, Alloc>::parseQualifiedType() {
   if (consumeIf('U')) {
-    StringView Qual = parseBareSourceName();
+    std::string_view Qual = parseBareSourceName();
     if (Qual.empty())
       return nullptr;
 
-    // FIXME parse the optional <template-args> here!
-
     // extension            ::= U <objc-name> <objc-type>  # objc-type<identifier>
-    if (Qual.startsWith("objcproto")) {
-      StringView ProtoSourceName = Qual.dropFront(std::strlen("objcproto"));
-      StringView Proto;
+    if (llvm::itanium_demangle::starts_with(Qual, "objcproto")) {
+      constexpr size_t Len = sizeof("objcproto") - 1;
+      std::string_view ProtoSourceName(Qual.data() + Len, Qual.size() - Len);
+      std::string_view Proto;
       {
-        SwapAndRestore<const char *> SaveFirst(First, ProtoSourceName.begin()),
-                                     SaveLast(Last, ProtoSourceName.end());
+        ScopedOverride<const char *> SaveFirst(First, ProtoSourceName.data()),
+            SaveLast(Last, &*ProtoSourceName.rbegin() + 1);
         Proto = parseBareSourceName();
       }
       if (Proto.empty())
@@ -3688,10 +3727,17 @@ Node *AbstractManglingParser<Derived, Alloc>::parseQualifiedType() {
       return make<ObjCProtoName>(Child, Proto);
     }
 
+    Node *TA = nullptr;
+    if (look() == 'I') {
+      TA = getDerived().parseTemplateArgs();
+      if (TA == nullptr)
+        return nullptr;
+    }
+
     Node *Child = getDerived().parseQualifiedType();
     if (Child == nullptr)
       return nullptr;
-    return make<VendorExtQualType>(Child, Qual);
+    return make<VendorExtQualType>(Child, Qual, TA);
   }
 
   Qualifiers Quals = parseCVQualifiers();
@@ -3838,7 +3884,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseType() {
   // <builtin-type> ::= u <source-name>    # vendor extended type
   case 'u': {
     ++First;
-    StringView Res = parseBareSourceName();
+    std::string_view Res = parseBareSourceName();
     if (Res.empty())
       return nullptr;
     // Typically, <builtin-type>s are not considered substitution candidates,
@@ -3864,7 +3910,33 @@ Node *AbstractManglingParser<Derived, Alloc>::parseType() {
     //                ::= Dh   # IEEE 754r half-precision floating point (16 bits)
     case 'h':
       First += 2;
-      return make<NameType>("decimal16");
+      return make<NameType>("half");
+    //                ::= DF <number> _ # ISO/IEC TS 18661 binary floating point (N bits)
+    case 'F': {
+      First += 2;
+      Node *DimensionNumber = make<NameType>(parseNumber());
+      if (!DimensionNumber)
+        return nullptr;
+      if (!consumeIf('_'))
+        return nullptr;
+      return make<BinaryFPType>(DimensionNumber);
+    }
+    //                ::= DB <number> _                             # C23 signed _BitInt(N)
+    //                ::= DB <instantiation-dependent expression> _ # C23 signed _BitInt(N)
+    //                ::= DU <number> _                             # C23 unsigned _BitInt(N)
+    //                ::= DU <instantiation-dependent expression> _ # C23 unsigned _BitInt(N)
+    case 'B':
+    case 'U': {
+      bool Signed = look(1) == 'B';
+      First += 2;
+      Node *Size = std::isdigit(look()) ? make<NameType>(parseNumber())
+                                        : getDerived().parseExpr();
+      if (!Size)
+        return nullptr;
+      if (!consumeIf('_'))
+        return nullptr;
+      return make<BitIntType>(Size, Signed);
+    }
     //                ::= Di   # char32_t
     case 'i':
       First += 2;
@@ -4012,9 +4084,10 @@ Node *AbstractManglingParser<Derived, Alloc>::parseType() {
   }
   //             ::= <substitution>  # See Compression below
   case 'S': {
-    if (look(1) && look(1) != 't') {
-      Node *Sub = getDerived().parseSubstitution();
-      if (Sub == nullptr)
+    if (look(1) != 't') {
+      bool IsSubst = false;
+      Result = getDerived().parseUnscopedName(nullptr, &IsSubst);
+      if (!Result)
         return nullptr;
 
       // Sub could be either of:
@@ -4027,17 +4100,19 @@ Node *AbstractManglingParser<Derived, Alloc>::parseType() {
       // If this is followed by some <template-args>, and we're permitted to
       // parse them, take the second production.
 
-      if (TryToParseTemplateArgs && look() == 'I') {
+      if (look() == 'I' && (!IsSubst || TryToParseTemplateArgs)) {
+        if (!IsSubst)
+          Subs.push_back(Result);
         Node *TA = getDerived().parseTemplateArgs();
         if (TA == nullptr)
           return nullptr;
-        Result = make<NameWithTemplateArgs>(Sub, TA);
-        break;
+        Result = make<NameWithTemplateArgs>(Result, TA);
+      } else if (IsSubst) {
+        // If all we parsed was a substitution, don't re-insert into the
+        // substitution table.
+        return Result;
       }
-
-      // If all we parsed was a substitution, don't re-insert into the
-      // substitution table.
-      return Sub;
+      break;
     }
     DEMANGLE_FALLTHROUGH;
   }
@@ -4057,28 +4132,32 @@ Node *AbstractManglingParser<Derived, Alloc>::parseType() {
 }
 
 template <typename Derived, typename Alloc>
-Node *AbstractManglingParser<Derived, Alloc>::parsePrefixExpr(StringView Kind) {
+Node *
+AbstractManglingParser<Derived, Alloc>::parsePrefixExpr(std::string_view Kind,
+                                                        Node::Prec Prec) {
   Node *E = getDerived().parseExpr();
   if (E == nullptr)
     return nullptr;
-  return make<PrefixExpr>(Kind, E);
+  return make<PrefixExpr>(Kind, E, Prec);
 }
 
 template <typename Derived, typename Alloc>
-Node *AbstractManglingParser<Derived, Alloc>::parseBinaryExpr(StringView Kind) {
+Node *
+AbstractManglingParser<Derived, Alloc>::parseBinaryExpr(std::string_view Kind,
+                                                        Node::Prec Prec) {
   Node *LHS = getDerived().parseExpr();
   if (LHS == nullptr)
     return nullptr;
   Node *RHS = getDerived().parseExpr();
   if (RHS == nullptr)
     return nullptr;
-  return make<BinaryExpr>(LHS, Kind, RHS);
+  return make<BinaryExpr>(LHS, Kind, RHS, Prec);
 }
 
 template <typename Derived, typename Alloc>
-Node *
-AbstractManglingParser<Derived, Alloc>::parseIntegerLiteral(StringView Lit) {
-  StringView Tmp = parseNumber(true);
+Node *AbstractManglingParser<Derived, Alloc>::parseIntegerLiteral(
+    std::string_view Lit) {
+  std::string_view Tmp = parseNumber(true);
   if (!Tmp.empty() && consumeIf('E'))
     return make<IntegerLiteral>(Lit, Tmp);
   return nullptr;
@@ -4101,11 +4180,14 @@ Qualifiers AbstractManglingParser<Alloc, Derived>::parseCVQualifiers() {
 //                  ::= fp <top-level CV-Qualifiers> <parameter-2 non-negative number> _   # L == 0, second and later parameters
 //                  ::= fL <L-1 non-negative number> p <top-level CV-Qualifiers> _         # L > 0, first parameter
 //                  ::= fL <L-1 non-negative number> p <top-level CV-Qualifiers> <parameter-2 non-negative number> _   # L > 0, second and later parameters
+//                  ::= fpT      # 'this' expression (not part of standard?)
 template <typename Derived, typename Alloc>
 Node *AbstractManglingParser<Derived, Alloc>::parseFunctionParam() {
+  if (consumeIf("fpT"))
+    return make<NameType>("this");
   if (consumeIf("fp")) {
     parseCVQualifiers();
-    StringView Num = parseNumber();
+    std::string_view Num = parseNumber();
     if (!consumeIf('_'))
       return nullptr;
     return make<FunctionParam>(Num);
@@ -4116,7 +4198,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseFunctionParam() {
     if (!consumeIf('p'))
       return nullptr;
     parseCVQualifiers();
-    StringView Num = parseNumber();
+    std::string_view Num = parseNumber();
     if (!consumeIf('_'))
       return nullptr;
     return make<FunctionParam>(Num);
@@ -4124,43 +4206,6 @@ Node *AbstractManglingParser<Derived, Alloc>::parseFunctionParam() {
   return nullptr;
 }
 
-// [gs] nw <expression>* _ <type> E                     # new (expr-list) type
-// [gs] nw <expression>* _ <type> <initializer>         # new (expr-list) type (init)
-// [gs] na <expression>* _ <type> E                     # new[] (expr-list) type
-// [gs] na <expression>* _ <type> <initializer>         # new[] (expr-list) type (init)
-// <initializer> ::= pi <expression>* E                 # parenthesized initialization
-template <typename Derived, typename Alloc>
-Node *AbstractManglingParser<Derived, Alloc>::parseNewExpr() {
-  bool Global = consumeIf("gs");
-  bool IsArray = look(1) == 'a';
-  if (!consumeIf("nw") && !consumeIf("na"))
-    return nullptr;
-  size_t Exprs = Names.size();
-  while (!consumeIf('_')) {
-    Node *Ex = getDerived().parseExpr();
-    if (Ex == nullptr)
-      return nullptr;
-    Names.push_back(Ex);
-  }
-  NodeArray ExprList = popTrailingNodeArray(Exprs);
-  Node *Ty = getDerived().parseType();
-  if (Ty == nullptr)
-    return Ty;
-  if (consumeIf("pi")) {
-    size_t InitsBegin = Names.size();
-    while (!consumeIf('E')) {
-      Node *Init = getDerived().parseExpr();
-      if (Init == nullptr)
-        return Init;
-      Names.push_back(Init);
-    }
-    NodeArray Inits = popTrailingNodeArray(InitsBegin);
-    return make<NewExpr>(ExprList, Ty, Inits, Global, IsArray);
-  } else if (!consumeIf('E'))
-    return nullptr;
-  return make<NewExpr>(ExprList, Ty, NodeArray(), Global, IsArray);
-}
-
 // cv <type> <expression>                               # conversion with one argument
 // cv <type> _ <expression>* E                          # conversion with a different number of arguments
 template <typename Derived, typename Alloc>
@@ -4169,7 +4214,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseConversionExpr() {
     return nullptr;
   Node *Ty;
   {
-    SwapAndRestore<bool> SaveTemp(TryToParseTemplateArgs, false);
+    ScopedOverride<bool> SaveTemp(TryToParseTemplateArgs, false);
     Ty = getDerived().parseType();
   }
 
@@ -4262,7 +4307,13 @@ Node *AbstractManglingParser<Derived, Alloc>::parseExprPrimary() {
     return getDerived().template parseFloatingLiteral<double>();
   case 'e':
     ++First;
+#if defined(__powerpc__) || defined(__s390__)
+    // Handle cases where long doubles encoded with e have the same size
+    // and representation as doubles.
+    return getDerived().template parseFloatingLiteral<double>();
+#else
     return getDerived().template parseFloatingLiteral<long double>();
+#endif
   case '_':
     if (consumeIf("_Z")) {
       Node *R = getDerived().parseEncoding();
@@ -4280,7 +4331,7 @@ Node *AbstractManglingParser<Derived, Alloc>::parseExprPrimary() {
     return nullptr;
   }
   case 'D':
-    if (consumeIf("DnE"))
+    if (consumeIf("Dn") && (consumeIf('0'), consumeIf('E')))
       return make<NameType>("nullptr");
     return nullptr;
   case 'T':
@@ -4301,12 +4352,12 @@ Node *AbstractManglingParser<Derived, Alloc>::parseExprPrimary() {
     Node *T = getDerived().parseType();
     if (T == nullptr)
       return nullptr;
-    StringView N = parseNumber();
+    std::string_view N = parseNumber(/*AllowNegative=*/true);
     if (N.empty())
       return nullptr;
     if (!consumeIf('E'))
       return nullptr;
-    return make<IntegerCastExpr>(T, N);
+    return make<EnumLiteral>(T, N);
   }
   }
 }
@@ -4367,55 +4418,38 @@ Node *AbstractManglingParser<Derived, Alloc>::parseFoldExpr() {
   if (!consumeIf('f'))
     return nullptr;
 
-  char FoldKind = look();
-  bool IsLeftFold, HasInitializer;
-  HasInitializer = FoldKind == 'L' || FoldKind == 'R';
-  if (FoldKind == 'l' || FoldKind == 'L')
-    IsLeftFold = true;
-  else if (FoldKind == 'r' || FoldKind == 'R')
-    IsLeftFold = false;
-  else
+  bool IsLeftFold = false, HasInitializer = false;
+  switch (look()) {
+  default:
     return nullptr;
+  case 'L':
+    IsLeftFold = true;
+    HasInitializer = true;
+    break;
+  case 'R':
+    HasInitializer = true;
+    break;
+  case 'l':
+    IsLeftFold = true;
+    break;
+  case 'r':
+    break;
+  }
   ++First;
 
-  // FIXME: This map is duplicated in parseOperatorName and parseExpr.
-  StringView OperatorName;
-  if      (consumeIf("aa")) OperatorName = "&&";
-  else if (consumeIf("an")) OperatorName = "&";
-  else if (consumeIf("aN")) OperatorName = "&=";
-  else if (consumeIf("aS")) OperatorName = "=";
-  else if (consumeIf("cm")) OperatorName = ",";
-  else if (consumeIf("ds")) OperatorName = ".*";
-  else if (consumeIf("dv")) OperatorName = "/";
-  else if (consumeIf("dV")) OperatorName = "/=";
-  else if (consumeIf("eo")) OperatorName = "^";
-  else if (consumeIf("eO")) OperatorName = "^=";
-  else if (consumeIf("eq")) OperatorName = "==";
-  else if (consumeIf("ge")) OperatorName = ">=";
-  else if (consumeIf("gt")) OperatorName = ">";
-  else if (consumeIf("le")) OperatorName = "<=";
-  else if (consumeIf("ls")) OperatorName = "<<";
-  else if (consumeIf("lS")) OperatorName = "<<=";
-  else if (consumeIf("lt")) OperatorName = "<";
-  else if (consumeIf("mi")) OperatorName = "-";
-  else if (consumeIf("mI")) OperatorName = "-=";
-  else if (consumeIf("ml")) OperatorName = "*";
-  else if (consumeIf("mL")) OperatorName = "*=";
-  else if (consumeIf("ne")) OperatorName = "!=";
-  else if (consumeIf("oo")) OperatorName = "||";
-  else if (consumeIf("or")) OperatorName = "|";
-  else if (consumeIf("oR")) OperatorName = "|=";
-  else if (consumeIf("pl")) OperatorName = "+";
-  else if (consumeIf("pL")) OperatorName = "+=";
-  else if (consumeIf("rm")) OperatorName = "%";
-  else if (consumeIf("rM")) OperatorName = "%=";
-  else if (consumeIf("rs")) OperatorName = ">>";
-  else if (consumeIf("rS")) OperatorName = ">>=";
-  else return nullptr;
-
-  Node *Pack = getDerived().parseExpr(), *Init = nullptr;
+  const auto *Op = parseOperatorEncoding();
+  if (!Op)
+    return nullptr;
+  if (!(Op->getKind() == OperatorInfo::Binary
+        || (Op->getKind() == OperatorInfo::Member
+            && Op->getName().back() == '*')))
+    return nullptr;
+
+  Node *Pack = getDerived().parseExpr();
   if (Pack == nullptr)
     return nullptr;
+
+  Node *Init = nullptr;
   if (HasInitializer) {
     Init = getDerived().parseExpr();
     if (Init == nullptr)
@@ -4425,7 +4459,53 @@ Node *AbstractManglingParser<Derived, Alloc>::parseFoldExpr() {
   if (IsLeftFold && Init)
     std::swap(Pack, Init);
 
-  return make<FoldExpr>(IsLeftFold, OperatorName, Pack, Init);
+  return make<FoldExpr>(IsLeftFold, Op->getSymbol(), Pack, Init);
+}
+
+// <expression> ::= mc <parameter type> <expr> [<offset number>] E
+//
+// Not yet in the spec: https://github.com/itanium-cxx-abi/cxx-abi/issues/47
+template <typename Derived, typename Alloc>
+Node *
+AbstractManglingParser<Derived, Alloc>::parsePointerToMemberConversionExpr(
+    Node::Prec Prec) {
+  Node *Ty = getDerived().parseType();
+  if (!Ty)
+    return nullptr;
+  Node *Expr = getDerived().parseExpr();
+  if (!Expr)
+    return nullptr;
+  std::string_view Offset = getDerived().parseNumber(true);
+  if (!consumeIf('E'))
+    return nullptr;
+  return make<PointerToMemberConversionExpr>(Ty, Expr, Offset, Prec);
+}
+
+// <expression> ::= so <referent type> <expr> [<offset number>] <union-selector>* [p] E
+// <union-selector> ::= _ [<number>]
+//
+// Not yet in the spec: https://github.com/itanium-cxx-abi/cxx-abi/issues/47
+template <typename Derived, typename Alloc>
+Node *AbstractManglingParser<Derived, Alloc>::parseSubobjectExpr() {
+  Node *Ty = getDerived().parseType();
+  if (!Ty)
+    return nullptr;
+  Node *Expr = getDerived().parseExpr();
+  if (!Expr)
+    return nullptr;
+  std::string_view Offset = getDerived().parseNumber(true);
+  size_t SelectorsBegin = Names.size();
+  while (consumeIf('_')) {
+    Node *Selector = make<NameType>(parseNumber());
+    if (!Selector)
+      return nullptr;
+    Names.push_back(Selector);
+  }
+  bool OnePastTheEnd = consumeIf('p');
+  if (!consumeIf('E'))
+    return nullptr;
+  return make<SubobjectExpr>(
+      Ty, Expr, Offset, popTrailingNodeArray(SelectorsBegin), OnePastTheEnd);
 }
 
 // <expression> ::= <unary operator-name> <expression>
@@ -4475,313 +4555,127 @@ Node *AbstractManglingParser<Derived, Alloc>::parseFoldExpr() {
 template <typename Derived, typename Alloc>
 Node *AbstractManglingParser<Derived, Alloc>::parseExpr() {
   bool Global = consumeIf("gs");
-  if (numLeft() < 2)
-    return nullptr;
 
-  switch (*First) {
-  case 'L':
-    return getDerived().parseExprPrimary();
-  case 'T':
-    return getDerived().parseTemplateParam();
-  case 'f': {
-    // Disambiguate a fold expression from a <function-param>.
-    if (look(1) == 'p' || (look(1) == 'L' && std::isdigit(look(2))))
-      return getDerived().parseFunctionParam();
-    return getDerived().parseFoldExpr();
-  }
-  case 'a':
-    switch (First[1]) {
-    case 'a':
-      First += 2;
-      return getDerived().parseBinaryExpr("&&");
-    case 'd':
-      First += 2;
-      return getDerived().parsePrefixExpr("&");
-    case 'n':
-      First += 2;
-      return getDerived().parseBinaryExpr("&");
-    case 'N':
-      First += 2;
-      return getDerived().parseBinaryExpr("&=");
-    case 'S':
-      First += 2;
-      return getDerived().parseBinaryExpr("=");
-    case 't': {
-      First += 2;
-      Node *Ty = getDerived().parseType();
-      if (Ty == nullptr)
-        return nullptr;
-      return make<EnclosingExpr>("alignof (", Ty, ")");
-    }
-    case 'z': {
-      First += 2;
-      Node *Ty = getDerived().parseExpr();
-      if (Ty == nullptr)
-        return nullptr;
-      return make<EnclosingExpr>("alignof (", Ty, ")");
-    }
-    }
-    return nullptr;
-  case 'c':
-    switch (First[1]) {
-    // cc <type> <expression>                               # const_cast<type>(expression)
-    case 'c': {
-      First += 2;
-      Node *Ty = getDerived().parseType();
-      if (Ty == nullptr)
-        return Ty;
-      Node *Ex = getDerived().parseExpr();
-      if (Ex == nullptr)
-        return Ex;
-      return make<CastExpr>("const_cast", Ty, Ex);
-    }
-    // cl <expression>+ E                                   # call
-    case 'l': {
-      First += 2;
-      Node *Callee = getDerived().parseExpr();
-      if (Callee == nullptr)
-        return Callee;
-      size_t ExprsBegin = Names.size();
-      while (!consumeIf('E')) {
-        Node *E = getDerived().parseExpr();
-        if (E == nullptr)
-          return E;
-        Names.push_back(E);
-      }
-      return make<CallExpr>(Callee, popTrailingNodeArray(ExprsBegin));
-    }
-    case 'm':
-      First += 2;
-      return getDerived().parseBinaryExpr(",");
-    case 'o':
-      First += 2;
-      return getDerived().parsePrefixExpr("~");
-    case 'v':
-      return getDerived().parseConversionExpr();
-    }
-    return nullptr;
-  case 'd':
-    switch (First[1]) {
-    case 'a': {
-      First += 2;
-      Node *Ex = getDerived().parseExpr();
-      if (Ex == nullptr)
-        return Ex;
-      return make<DeleteExpr>(Ex, Global, /*is_array=*/true);
-    }
-    case 'c': {
-      First += 2;
-      Node *T = getDerived().parseType();
-      if (T == nullptr)
-        return T;
+  const auto *Op = parseOperatorEncoding();
+  if (Op) {
+    auto Sym = Op->getSymbol();
+    switch (Op->getKind()) {
+    case OperatorInfo::Binary:
+      // Binary operator: lhs @ rhs
+      return getDerived().parseBinaryExpr(Sym, Op->getPrecedence());
+    case OperatorInfo::Prefix:
+      // Prefix unary operator: @ expr
+      return getDerived().parsePrefixExpr(Sym, Op->getPrecedence());
+    case OperatorInfo::Postfix: {
+      // Postfix unary operator: expr @
+      if (consumeIf('_'))
+        return getDerived().parsePrefixExpr(Sym, Op->getPrecedence());
       Node *Ex = getDerived().parseExpr();
       if (Ex == nullptr)
-        return Ex;
-      return make<CastExpr>("dynamic_cast", T, Ex);
-    }
-    case 'e':
-      First += 2;
-      return getDerived().parsePrefixExpr("*");
-    case 'l': {
-      First += 2;
-      Node *E = getDerived().parseExpr();
-      if (E == nullptr)
-        return E;
-      return make<DeleteExpr>(E, Global, /*is_array=*/false);
+        return nullptr;
+      return make<PostfixExpr>(Ex, Sym, Op->getPrecedence());
     }
-    case 'n':
-      return getDerived().parseUnresolvedName();
-    case 's': {
-      First += 2;
-      Node *LHS = getDerived().parseExpr();
-      if (LHS == nullptr)
+    case OperatorInfo::Array: {
+      // Array Index:  lhs [ rhs ]
+      Node *Base = getDerived().parseExpr();
+      if (Base == nullptr)
         return nullptr;
-      Node *RHS = getDerived().parseExpr();
-      if (RHS == nullptr)
+      Node *Index = getDerived().parseExpr();
+      if (Index == nullptr)
         return nullptr;
-      return make<MemberExpr>(LHS, ".*", RHS);
+      return make<ArraySubscriptExpr>(Base, Index, Op->getPrecedence());
     }
-    case 't': {
-      First += 2;
+    case OperatorInfo::Member: {
+      // Member access lhs @ rhs
       Node *LHS = getDerived().parseExpr();
       if (LHS == nullptr)
-        return LHS;
+        return nullptr;
       Node *RHS = getDerived().parseExpr();
       if (RHS == nullptr)
         return nullptr;
-      return make<MemberExpr>(LHS, ".", RHS);
-    }
-    case 'v':
-      First += 2;
-      return getDerived().parseBinaryExpr("/");
-    case 'V':
-      First += 2;
-      return getDerived().parseBinaryExpr("/=");
-    }
-    return nullptr;
-  case 'e':
-    switch (First[1]) {
-    case 'o':
-      First += 2;
-      return getDerived().parseBinaryExpr("^");
-    case 'O':
-      First += 2;
-      return getDerived().parseBinaryExpr("^=");
-    case 'q':
-      First += 2;
-      return getDerived().parseBinaryExpr("==");
-    }
-    return nullptr;
-  case 'g':
-    switch (First[1]) {
-    case 'e':
-      First += 2;
-      return getDerived().parseBinaryExpr(">=");
-    case 't':
-      First += 2;
-      return getDerived().parseBinaryExpr(">");
-    }
-    return nullptr;
-  case 'i':
-    switch (First[1]) {
-    case 'x': {
-      First += 2;
-      Node *Base = getDerived().parseExpr();
-      if (Base == nullptr)
+      return make<MemberExpr>(LHS, Sym, RHS, Op->getPrecedence());
+    }
+    case OperatorInfo::New: {
+      // New
+      // # new (expr-list) type [(init)]
+      // [gs] nw <expression>* _ <type> [pi <expression>*] E
+      // # new[] (expr-list) type [(init)]
+      // [gs] na <expression>* _ <type> [pi <expression>*] E
+      size_t Exprs = Names.size();
+      while (!consumeIf('_')) {
+        Node *Ex = getDerived().parseExpr();
+        if (Ex == nullptr)
+          return nullptr;
+        Names.push_back(Ex);
+      }
+      NodeArray ExprList = popTrailingNodeArray(Exprs);
+      Node *Ty = getDerived().parseType();
+      if (Ty == nullptr)
         return nullptr;
-      Node *Index = getDerived().parseExpr();
-      if (Index == nullptr)
-        return Index;
-      return make<ArraySubscriptExpr>(Base, Index);
-    }
-    case 'l': {
-      First += 2;
+      bool HaveInits = consumeIf("pi");
       size_t InitsBegin = Names.size();
       while (!consumeIf('E')) {
-        Node *E = getDerived().parseBracedExpr();
-        if (E == nullptr)
+        if (!HaveInits)
           return nullptr;
-        Names.push_back(E);
+        Node *Init = getDerived().parseExpr();
+        if (Init == nullptr)
+          return Init;
+        Names.push_back(Init);
       }
-      return make<InitListExpr>(nullptr, popTrailingNodeArray(InitsBegin));
-    }
+      NodeArray Inits = popTrailingNodeArray(InitsBegin);
+      return make<NewExpr>(ExprList, Ty, Inits, Global,
+                           /*IsArray=*/Op->getFlag(), Op->getPrecedence());
     }
-    return nullptr;
-  case 'l':
-    switch (First[1]) {
-    case 'e':
-      First += 2;
-      return getDerived().parseBinaryExpr("<=");
-    case 's':
-      First += 2;
-      return getDerived().parseBinaryExpr("<<");
-    case 'S':
-      First += 2;
-      return getDerived().parseBinaryExpr("<<=");
-    case 't':
-      First += 2;
-      return getDerived().parseBinaryExpr("<");
-    }
-    return nullptr;
-  case 'm':
-    switch (First[1]) {
-    case 'i':
-      First += 2;
-      return getDerived().parseBinaryExpr("-");
-    case 'I':
-      First += 2;
-      return getDerived().parseBinaryExpr("-=");
-    case 'l':
-      First += 2;
-      return getDerived().parseBinaryExpr("*");
-    case 'L':
-      First += 2;
-      return getDerived().parseBinaryExpr("*=");
-    case 'm':
-      First += 2;
-      if (consumeIf('_'))
-        return getDerived().parsePrefixExpr("--");
+    case OperatorInfo::Del: {
+      // Delete
       Node *Ex = getDerived().parseExpr();
       if (Ex == nullptr)
         return nullptr;
-      return make<PostfixExpr>(Ex, "--");
-    }
-    return nullptr;
-  case 'n':
-    switch (First[1]) {
-    case 'a':
-    case 'w':
-      return getDerived().parseNewExpr();
-    case 'e':
-      First += 2;
-      return getDerived().parseBinaryExpr("!=");
-    case 'g':
-      First += 2;
-      return getDerived().parsePrefixExpr("-");
-    case 't':
-      First += 2;
-      return getDerived().parsePrefixExpr("!");
-    case 'x':
-      First += 2;
-      Node *Ex = getDerived().parseExpr();
-      if (Ex == nullptr)
-        return Ex;
-      return make<EnclosingExpr>("noexcept (", Ex, ")");
-    }
-    return nullptr;
-  case 'o':
-    switch (First[1]) {
-    case 'n':
-      return getDerived().parseUnresolvedName();
-    case 'o':
-      First += 2;
-      return getDerived().parseBinaryExpr("||");
-    case 'r':
-      First += 2;
-      return getDerived().parseBinaryExpr("|");
-    case 'R':
-      First += 2;
-      return getDerived().parseBinaryExpr("|=");
+      return make<DeleteExpr>(Ex, Global, /*IsArray=*/Op->getFlag(),
+                              Op->getPrecedence());
     }
-    return nullptr;
-  case 'p':
-    switch (First[1]) {
-    case 'm':
-      First += 2;
-      return getDerived().parseBinaryExpr("->*");
-    case 'l':
-      First += 2;
-      return getDerived().parseBinaryExpr("+");
-    case 'L':
-      First += 2;
-      return getDerived().parseBinaryExpr("+=");
-    case 'p': {
-      First += 2;
-      if (consumeIf('_'))
-        return getDerived().parsePrefixExpr("++");
-      Node *Ex = getDerived().parseExpr();
-      if (Ex == nullptr)
-        return Ex;
-      return make<PostfixExpr>(Ex, "++");
+    case OperatorInfo::Call: {
+      // Function Call
+      Node *Callee = getDerived().parseExpr();
+      if (Callee == nullptr)
+        return nullptr;
+      size_t ExprsBegin = Names.size();
+      while (!consumeIf('E')) {
+        Node *E = getDerived().parseExpr();
+        if (E == nullptr)
+          return nullptr;
+        Names.push_back(E);
+      }
+      return make<CallExpr>(Callee, popTrailingNodeArray(ExprsBegin),
+                            Op->getPrecedence());
     }
-    case 's':
-      First += 2;
-      return getDerived().parsePrefixExpr("+");
-    case 't': {
-      First += 2;
-      Node *L = getDerived().parseExpr();
-      if (L == nullptr)
+    case OperatorInfo::CCast: {
+      // C Cast: (type)expr
+      Node *Ty;
+      {
+        ScopedOverride<bool> SaveTemp(TryToParseTemplateArgs, false);
+        Ty = getDerived().parseType();
+      }
+      if (Ty == nullptr)
         return nullptr;
-      Node *R = getDerived().parseExpr();
-      if (R == nullptr)
+
+      size_t ExprsBegin = Names.size();
+      bool IsMany = consumeIf('_');
+      while (!consumeIf('E')) {
+        Node *E = getDerived().parseExpr();
+        if (E == nullptr)
+          return E;
+        Names.push_back(E);
+        if (!IsMany)
+          break;
+      }
+      NodeArray Exprs = popTrailingNodeArray(ExprsBegin);
+      if (!IsMany && Exprs.size() != 1)
         return nullptr;
-      return make<MemberExpr>(L, "->", R);
+      return make<ConversionExpr>(Ty, Exprs, Op->getPrecedence());
     }
-    }
-    return nullptr;
-  case 'q':
-    if (First[1] == 'u') {
-      First += 2;
+    case OperatorInfo::Conditional: {
+      // Conditional operator: expr ? expr : expr
       Node *Cond = getDerived().parseExpr();
       if (Cond == nullptr)
         return nullptr;
@@ -4791,169 +4685,158 @@ Node *AbstractManglingParser<Derived, Alloc>::parseExpr() {
       Node *RHS = getDerived().parseExpr();
       if (RHS == nullptr)
         return nullptr;
-      return make<ConditionalExpr>(Cond, LHS, RHS);
-    }
-    return nullptr;
-  case 'r':
-    switch (First[1]) {
-    case 'c': {
-      First += 2;
-      Node *T = getDerived().parseType();
-      if (T == nullptr)
-        return T;
-      Node *Ex = getDerived().parseExpr();
-      if (Ex == nullptr)
-        return Ex;
-      return make<CastExpr>("reinterpret_cast", T, Ex);
+      return make<ConditionalExpr>(Cond, LHS, RHS, Op->getPrecedence());
     }
-    case 'm':
-      First += 2;
-      return getDerived().parseBinaryExpr("%");
-    case 'M':
-      First += 2;
-      return getDerived().parseBinaryExpr("%=");
-    case 's':
-      First += 2;
-      return getDerived().parseBinaryExpr(">>");
-    case 'S':
-      First += 2;
-      return getDerived().parseBinaryExpr(">>=");
-    }
-    return nullptr;
-  case 's':
-    switch (First[1]) {
-    case 'c': {
-      First += 2;
-      Node *T = getDerived().parseType();
-      if (T == nullptr)
-        return T;
-      Node *Ex = getDerived().parseExpr();
-      if (Ex == nullptr)
-        return Ex;
-      return make<CastExpr>("static_cast", T, Ex);
-    }
-    case 'p': {
-      First += 2;
-      Node *Child = getDerived().parseExpr();
-      if (Child == nullptr)
-        return nullptr;
-      return make<ParameterPackExpansion>(Child);
-    }
-    case 'r':
-      return getDerived().parseUnresolvedName();
-    case 't': {
-      First += 2;
+    case OperatorInfo::NamedCast: {
+      // Named cast operation, @<type>(expr)
       Node *Ty = getDerived().parseType();
       if (Ty == nullptr)
-        return Ty;
-      return make<EnclosingExpr>("sizeof (", Ty, ")");
-    }
-    case 'z': {
-      First += 2;
+        return nullptr;
       Node *Ex = getDerived().parseExpr();
       if (Ex == nullptr)
-        return Ex;
-      return make<EnclosingExpr>("sizeof (", Ex, ")");
-    }
-    case 'Z':
-      First += 2;
-      if (look() == 'T') {
-        Node *R = getDerived().parseTemplateParam();
-        if (R == nullptr)
-          return nullptr;
-        return make<SizeofParamPackExpr>(R);
-      } else if (look() == 'f') {
-        Node *FP = getDerived().parseFunctionParam();
-        if (FP == nullptr)
-          return nullptr;
-        return make<EnclosingExpr>("sizeof... (", FP, ")");
-      }
-      return nullptr;
-    case 'P': {
-      First += 2;
-      size_t ArgsBegin = Names.size();
-      while (!consumeIf('E')) {
-        Node *Arg = getDerived().parseTemplateArg();
-        if (Arg == nullptr)
-          return nullptr;
-        Names.push_back(Arg);
-      }
-      auto *Pack = make<NodeArrayNode>(popTrailingNodeArray(ArgsBegin));
-      if (!Pack)
         return nullptr;
-      return make<EnclosingExpr>("sizeof... (", Pack, ")");
+      return make<CastExpr>(Sym, Ty, Ex, Op->getPrecedence());
     }
+    case OperatorInfo::OfIdOp: {
+      // [sizeof/alignof/typeid] ( <type>|<expr> )
+      Node *Arg =
+          Op->getFlag() ? getDerived().parseType() : getDerived().parseExpr();
+      if (!Arg)
+        return nullptr;
+      return make<EnclosingExpr>(Sym, Arg, Op->getPrecedence());
     }
-    return nullptr;
-  case 't':
-    switch (First[1]) {
-    case 'e': {
-      First += 2;
-      Node *Ex = getDerived().parseExpr();
-      if (Ex == nullptr)
-        return Ex;
-      return make<EnclosingExpr>("typeid (", Ex, ")");
+    case OperatorInfo::NameOnly: {
+      // Not valid as an expression operand.
+      return nullptr;
     }
-    case 'i': {
-      First += 2;
-      Node *Ty = getDerived().parseType();
-      if (Ty == nullptr)
-        return Ty;
-      return make<EnclosingExpr>("typeid (", Ty, ")");
     }
-    case 'l': {
-      First += 2;
-      Node *Ty = getDerived().parseType();
-      if (Ty == nullptr)
+    DEMANGLE_UNREACHABLE;
+  }
+
+  if (numLeft() < 2)
+    return nullptr;
+
+  if (look() == 'L')
+    return getDerived().parseExprPrimary();
+  if (look() == 'T')
+    return getDerived().parseTemplateParam();
+  if (look() == 'f') {
+    // Disambiguate a fold expression from a <function-param>.
+    if (look(1) == 'p' || (look(1) == 'L' && std::isdigit(look(2))))
+      return getDerived().parseFunctionParam();
+    return getDerived().parseFoldExpr();
+  }
+  if (consumeIf("il")) {
+    size_t InitsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *E = getDerived().parseBracedExpr();
+      if (E == nullptr)
         return nullptr;
-      size_t InitsBegin = Names.size();
-      while (!consumeIf('E')) {
-        Node *E = getDerived().parseBracedExpr();
-        if (E == nullptr)
-          return nullptr;
-        Names.push_back(E);
-      }
-      return make<InitListExpr>(Ty, popTrailingNodeArray(InitsBegin));
+      Names.push_back(E);
     }
-    case 'r':
-      First += 2;
-      return make<NameType>("throw");
-    case 'w': {
-      First += 2;
-      Node *Ex = getDerived().parseExpr();
-      if (Ex == nullptr)
+    return make<InitListExpr>(nullptr, popTrailingNodeArray(InitsBegin));
+  }
+  if (consumeIf("mc"))
+    return parsePointerToMemberConversionExpr(Node::Prec::Unary);
+  if (consumeIf("nx")) {
+    Node *Ex = getDerived().parseExpr();
+    if (Ex == nullptr)
+      return Ex;
+    return make<EnclosingExpr>("noexcept ", Ex, Node::Prec::Unary);
+  }
+  if (consumeIf("so"))
+    return parseSubobjectExpr();
+  if (consumeIf("sp")) {
+    Node *Child = getDerived().parseExpr();
+    if (Child == nullptr)
+      return nullptr;
+    return make<ParameterPackExpansion>(Child);
+  }
+  if (consumeIf("sZ")) {
+    if (look() == 'T') {
+      Node *R = getDerived().parseTemplateParam();
+      if (R == nullptr)
         return nullptr;
-      return make<ThrowExpr>(Ex);
+      return make<SizeofParamPackExpr>(R);
     }
+    Node *FP = getDerived().parseFunctionParam();
+    if (FP == nullptr)
+      return nullptr;
+    return make<EnclosingExpr>("sizeof... ", FP);
+  }
+  if (consumeIf("sP")) {
+    size_t ArgsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *Arg = getDerived().parseTemplateArg();
+      if (Arg == nullptr)
+        return nullptr;
+      Names.push_back(Arg);
     }
-    return nullptr;
-  case '1':
-  case '2':
-  case '3':
-  case '4':
-  case '5':
-  case '6':
-  case '7':
-  case '8':
-  case '9':
-    return getDerived().parseUnresolvedName();
-  }
-
-  if (consumeIf("u8__uuidoft")) {
+    auto *Pack = make<NodeArrayNode>(popTrailingNodeArray(ArgsBegin));
+    if (!Pack)
+      return nullptr;
+    return make<EnclosingExpr>("sizeof... ", Pack);
+  }
+  if (consumeIf("tl")) {
     Node *Ty = getDerived().parseType();
-    if (!Ty)
+    if (Ty == nullptr)
       return nullptr;
-    return make<UUIDOfExpr>(Ty);
+    size_t InitsBegin = Names.size();
+    while (!consumeIf('E')) {
+      Node *E = getDerived().parseBracedExpr();
+      if (E == nullptr)
+        return nullptr;
+      Names.push_back(E);
+    }
+    return make<InitListExpr>(Ty, popTrailingNodeArray(InitsBegin));
   }
-
-  if (consumeIf("u8__uuidofz")) {
+  if (consumeIf("tr"))
+    return make<NameType>("throw");
+  if (consumeIf("tw")) {
     Node *Ex = getDerived().parseExpr();
-    if (!Ex)
+    if (Ex == nullptr)
       return nullptr;
-    return make<UUIDOfExpr>(Ex);
+    return make<ThrowExpr>(Ex);
+  }
+  if (consumeIf('u')) {
+    Node *Name = getDerived().parseSourceName(/*NameState=*/nullptr);
+    if (!Name)
+      return nullptr;
+    // Special case legacy __uuidof mangling. The 't' and 'z' appear where the
+    // standard encoding expects a <template-arg>, and would be otherwise be
+    // interpreted as <type> node 'short' or 'ellipsis'. However, neither
+    // __uuidof(short) nor __uuidof(...) can actually appear, so there is no
+    // actual conflict here.
+    bool IsUUID = false;
+    Node *UUID = nullptr;
+    if (Name->getBaseName() == "__uuidof") {
+      if (consumeIf('t')) {
+        UUID = getDerived().parseType();
+        IsUUID = true;
+      } else if (consumeIf('z')) {
+        UUID = getDerived().parseExpr();
+        IsUUID = true;
+      }
+    }
+    size_t ExprsBegin = Names.size();
+    if (IsUUID) {
+      if (UUID == nullptr)
+        return nullptr;
+      Names.push_back(UUID);
+    } else {
+      while (!consumeIf('E')) {
+        Node *E = getDerived().parseTemplateArg();
+        if (E == nullptr)
+          return E;
+        Names.push_back(E);
+      }
+    }
+    return make<CallExpr>(Name, popTrailingNodeArray(ExprsBegin),
+                          Node::Prec::Postfix);
   }
 
-  return nullptr;
+  // Only unresolved names remain.
+  return getDerived().parseUnresolvedName(Global);
 }
 
 // <call-offset> ::= h <nv-offset> _
@@ -4986,19 +4869,32 @@ bool AbstractManglingParser<Alloc, Derived>::parseCallOffset() {
 //                    # second call-offset is result adjustment
 //                ::= T <call-offset> <base encoding>
 //                    # base is the nominal target function of thunk
-//                ::= GV <object name> # Guard variable for one-time initialization
+//                # Guard variable for one-time initialization
+//                ::= GV <object name>
 //                                     # No <type>
 //                ::= TW <object name> # Thread-local wrapper
 //                ::= TH <object name> # Thread-local initialization
 //                ::= GR <object name> _             # First temporary
 //                ::= GR <object name> <seq-id> _    # Subsequent temporaries
-//      extension ::= TC <first type> <number> _ <second type> # construction vtable for second-in-first
+//                # construction vtable for second-in-first
+//      extension ::= TC <first type> <number> _ <second type>
 //      extension ::= GR <object name> # reference temporary for object
+//      extension ::= GI <module name> # module global initializer
 template <typename Derived, typename Alloc>
 Node *AbstractManglingParser<Derived, Alloc>::parseSpecialName() {
   switch (look()) {
   case 'T':
     switch (look(1)) {
+    // TA <template-arg>    # template parameter object
+    //
+    // Not yet in the spec: https://github.com/itanium-cxx-abi/cxx-abi/issues/63
+    case 'A': {
+      First += 2;
+      Node *Arg = getDerived().parseTemplateArg();
+      if (Arg == nullptr)
+        return nullptr;
+      return make<SpecialName>("template parameter object for ", Arg);
+    }
     // TV <type>    # virtual table
     case 'V': {
       First += 2;
@@ -5110,6 +5006,16 @@ Node *AbstractManglingParser<Derived, Alloc>::parseSpecialName() {
         return nullptr;
       return make<SpecialName>("reference temporary for ", Name);
     }
+    // GI <module-name> v
+    case 'I': {
+      First += 2;
+      ModuleName *Module = nullptr;
+      if (getDerived().parseModuleNameOpt(Module))
+        return nullptr;
+      if (Module == nullptr)
+        return nullptr;
+      return make<SpecialName>("initializer for module ", Module);
+    }
     }
   }
   return nullptr;
@@ -5120,6 +5026,26 @@ Node *AbstractManglingParser<Derived, Alloc>::parseSpecialName() {
 //            ::= <special-name>
 template <typename Derived, typename Alloc>
 Node *AbstractManglingParser<Derived, Alloc>::parseEncoding() {
+  // The template parameters of an encoding are unrelated to those of the
+  // enclosing context.
+  class SaveTemplateParams {
+    AbstractManglingParser *Parser;
+    decltype(TemplateParams) OldParams;
+    decltype(OuterTemplateParams) OldOuterParams;
+
+  public:
+    SaveTemplateParams(AbstractManglingParser *TheParser) : Parser(TheParser) {
+      OldParams = std::move(Parser->TemplateParams);
+      OldOuterParams = std::move(Parser->OuterTemplateParams);
+      Parser->TemplateParams.clear();
+      Parser->OuterTemplateParams.clear();
+    }
+    ~SaveTemplateParams() {
+      Parser->TemplateParams = std::move(OldParams);
+      Parser->OuterTemplateParams = std::move(OldOuterParams);
+    }
+  } SaveTemplateParams(this);
+
   if (look() == 'G' || look() == 'T')
     return getDerived().parseSpecialName();
 
@@ -5204,14 +5130,19 @@ template <>
 struct FloatData<long double>
 {
 #if defined(__mips__) && defined(__mips_n64) || defined(__aarch64__) || \
-    defined(__wasm__)
+    defined(__wasm__) || defined(__riscv) || defined(__loongarch__)
     static const size_t mangled_size = 32;
 #elif defined(__arm__) || defined(__mips__) || defined(__hexagon__)
     static const size_t mangled_size = 16;
 #else
     static const size_t mangled_size = 20;  // May need to be adjusted to 16 or 24 on other platforms
 #endif
-    static const size_t max_demangled_size = 40;
+    // `-0x1.ffffffffffffffffffffffffffffp+16383` + 'L' + '\0' == 42 bytes.
+    // 28 'f's * 4 bits == 112 bits, which is the number of mantissa bits.
+    // Negatives are one character longer than positives.
+    // `0x1.` and `p` are constant, and exponents `+16383` and `-16382` are the
+    // same length. 1 sign bit, 112 mantissa bits, and 15 exponent bits == 128.
+    static const size_t max_demangled_size = 42;
     static constexpr const char *spec = "%LaL";
 };
 
@@ -5221,7 +5152,7 @@ Node *AbstractManglingParser<Alloc, Derived>::parseFloatingLiteral() {
   const size_t N = FloatData<Float>::mangled_size;
   if (numLeft() <= N)
     return nullptr;
-  StringView Data(First, First + N);
+  std::string_view Data(First, N);
   for (char C : Data)
     if (!std::isxdigit(C))
       return nullptr;
@@ -5264,43 +5195,41 @@ bool AbstractManglingParser<Alloc, Derived>::parseSeqId(size_t *Out) {
 // <substitution> ::= Si # ::std::basic_istream<char,  std::char_traits<char> >
 // <substitution> ::= So # ::std::basic_ostream<char,  std::char_traits<char> >
 // <substitution> ::= Sd # ::std::basic_iostream<char, std::char_traits<char> >
+// The St case is handled specially in parseNestedName.
 template <typename Derived, typename Alloc>
 Node *AbstractManglingParser<Derived, Alloc>::parseSubstitution() {
   if (!consumeIf('S'))
     return nullptr;
 
-  if (std::islower(look())) {
-    Node *SpecialSub;
+  if (look() >= 'a' && look() <= 'z') {
+    SpecialSubKind Kind;
     switch (look()) {
     case 'a':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::allocator);
+      Kind = SpecialSubKind::allocator;
       break;
     case 'b':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::basic_string);
+      Kind = SpecialSubKind::basic_string;
       break;
-    case 's':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::string);
+    case 'd':
+      Kind = SpecialSubKind::iostream;
       break;
     case 'i':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::istream);
+      Kind = SpecialSubKind::istream;
       break;
     case 'o':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::ostream);
+      Kind = SpecialSubKind::ostream;
       break;
-    case 'd':
-      ++First;
-      SpecialSub = make<SpecialSubstitution>(SpecialSubKind::iostream);
+    case 's':
+      Kind = SpecialSubKind::string;
       break;
     default:
       return nullptr;
     }
+    ++First;
+    auto *SpecialSub = make<SpecialSubstitution>(Kind);
     if (!SpecialSub)
       return nullptr;
+
     // Itanium C++ ABI 5.1.2: If a name that would use a built-in <substitution>
     // has ABI tags, the tags are appended to the substitution; the result is a
     // substitutable component.
@@ -5543,7 +5472,8 @@ Node *AbstractManglingParser<Derived, Alloc>::parse() {
     if (Encoding == nullptr)
       return nullptr;
     if (look() == '.') {
-      Encoding = make<DotSuffix>(Encoding, StringView(First, Last));
+      Encoding =
+          make<DotSuffix>(Encoding, std::string_view(First, Last - First));
       First = Last;
     }
     if (numLeft() != 0)
diff --git a/externals/demangle/llvm/Demangle/ItaniumNodes.def b/externals/demangle/llvm/Demangle/ItaniumNodes.def
new file mode 100644
index 000000000..5985769ef
--- /dev/null
+++ b/externals/demangle/llvm/Demangle/ItaniumNodes.def
@@ -0,0 +1,96 @@
+//===--- ItaniumNodes.def ------------*- mode:c++;eval:(read-only-mode) -*-===//
+//       Do not edit! See README.txt.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-FileCopyrightText: Part of the LLVM Project
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// Define the demangler's node names
+
+#ifndef NODE
+#error Define NODE to handle nodes
+#endif
+
+NODE(NodeArrayNode)
+NODE(DotSuffix)
+NODE(VendorExtQualType)
+NODE(QualType)
+NODE(ConversionOperatorType)
+NODE(PostfixQualifiedType)
+NODE(ElaboratedTypeSpefType)
+NODE(NameType)
+NODE(AbiTagAttr)
+NODE(EnableIfAttr)
+NODE(ObjCProtoName)
+NODE(PointerType)
+NODE(ReferenceType)
+NODE(PointerToMemberType)
+NODE(ArrayType)
+NODE(FunctionType)
+NODE(NoexceptSpec)
+NODE(DynamicExceptionSpec)
+NODE(FunctionEncoding)
+NODE(LiteralOperator)
+NODE(SpecialName)
+NODE(CtorVtableSpecialName)
+NODE(QualifiedName)
+NODE(NestedName)
+NODE(LocalName)
+NODE(ModuleName)
+NODE(ModuleEntity)
+NODE(VectorType)
+NODE(PixelVectorType)
+NODE(BinaryFPType)
+NODE(BitIntType)
+NODE(SyntheticTemplateParamName)
+NODE(TypeTemplateParamDecl)
+NODE(NonTypeTemplateParamDecl)
+NODE(TemplateTemplateParamDecl)
+NODE(TemplateParamPackDecl)
+NODE(ParameterPack)
+NODE(TemplateArgumentPack)
+NODE(ParameterPackExpansion)
+NODE(TemplateArgs)
+NODE(ForwardTemplateReference)
+NODE(NameWithTemplateArgs)
+NODE(GlobalQualifiedName)
+NODE(ExpandedSpecialSubstitution)
+NODE(SpecialSubstitution)
+NODE(CtorDtorName)
+NODE(DtorName)
+NODE(UnnamedTypeName)
+NODE(ClosureTypeName)
+NODE(StructuredBindingName)
+NODE(BinaryExpr)
+NODE(ArraySubscriptExpr)
+NODE(PostfixExpr)
+NODE(ConditionalExpr)
+NODE(MemberExpr)
+NODE(SubobjectExpr)
+NODE(EnclosingExpr)
+NODE(CastExpr)
+NODE(SizeofParamPackExpr)
+NODE(CallExpr)
+NODE(NewExpr)
+NODE(DeleteExpr)
+NODE(PrefixExpr)
+NODE(FunctionParam)
+NODE(ConversionExpr)
+NODE(PointerToMemberConversionExpr)
+NODE(InitListExpr)
+NODE(FoldExpr)
+NODE(ThrowExpr)
+NODE(BoolExpr)
+NODE(StringLiteral)
+NODE(LambdaExpr)
+NODE(EnumLiteral)
+NODE(IntegerLiteral)
+NODE(FloatLiteral)
+NODE(DoubleLiteral)
+NODE(LongDoubleLiteral)
+NODE(BracedExpr)
+NODE(BracedRangeExpr)
+
+#undef NODE
diff --git a/externals/demangle/llvm/Demangle/StringView.h b/externals/demangle/llvm/Demangle/StringView.h
index 44d2b18a3..76b215252 100644
--- a/externals/demangle/llvm/Demangle/StringView.h
+++ b/externals/demangle/llvm/Demangle/StringView.h
@@ -1,5 +1,5 @@
-//===--- StringView.h -------------------------------------------*- C++ -*-===//
-//
+//===--- StringView.h ----------------*- mode:c++;eval:(read-only-mode) -*-===//
+//       Do not edit! See README.txt.
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-FileCopyrightText: Part of the LLVM Project
@@ -8,6 +8,9 @@
 //===----------------------------------------------------------------------===//
 //
 // FIXME: Use std::string_view instead when we support C++17.
+// There are two copies of this file in the source tree.  The one under
+// libcxxabi is the original and the one under llvm is the copy.  Use
+// cp-to-llvm.sh to update the copy.  See README.txt for more details.
 //
 //===----------------------------------------------------------------------===//
 
@@ -15,7 +18,6 @@
 #define DEMANGLE_STRINGVIEW_H
 
 #include "DemangleConfig.h"
-#include <algorithm>
 #include <cassert>
 #include <cstring>
 
@@ -37,29 +39,23 @@ public:
   StringView(const char *Str) : First(Str), Last(Str + std::strlen(Str)) {}
   StringView() : First(nullptr), Last(nullptr) {}
 
-  StringView substr(size_t From) const {
-    return StringView(begin() + From, size() - From);
+  StringView substr(size_t Pos, size_t Len = npos) const {
+    assert(Pos <= size());
+    if (Len > size() - Pos)
+      Len = size() - Pos;
+    return StringView(begin() + Pos, Len);
   }
 
   size_t find(char C, size_t From = 0) const {
-    size_t FindBegin = std::min(From, size());
     // Avoid calling memchr with nullptr.
-    if (FindBegin < size()) {
+    if (From < size()) {
       // Just forward to memchr, which is faster than a hand-rolled loop.
-      if (const void *P = ::memchr(First + FindBegin, C, size() - FindBegin))
+      if (const void *P = ::memchr(First + From, C, size() - From))
         return size_t(static_cast<const char *>(P) - First);
     }
     return npos;
   }
 
-  StringView substr(size_t From, size_t To) const {
-    if (To >= size())
-      To = size() - 1;
-    if (From >= size())
-      From = size() - 1;
-    return StringView(First + From, First + To);
-  }
-
   StringView dropFront(size_t N = 1) const {
     if (N >= size())
       N = size();
@@ -106,7 +102,7 @@ public:
   bool startsWith(StringView Str) const {
     if (Str.size() > size())
       return false;
-    return std::equal(Str.begin(), Str.end(), begin());
+    return std::strncmp(Str.begin(), begin(), Str.size()) == 0;
   }
 
   const char &operator[](size_t Idx) const { return *(begin() + Idx); }
@@ -119,7 +115,7 @@ public:
 
 inline bool operator==(const StringView &LHS, const StringView &RHS) {
   return LHS.size() == RHS.size() &&
-         std::equal(LHS.begin(), LHS.end(), RHS.begin());
+         std::strncmp(LHS.begin(), RHS.begin(), LHS.size()) == 0;
 }
 
 DEMANGLE_NAMESPACE_END
diff --git a/externals/demangle/llvm/Demangle/StringViewExtras.h b/externals/demangle/llvm/Demangle/StringViewExtras.h
new file mode 100644
index 000000000..83685c304
--- /dev/null
+++ b/externals/demangle/llvm/Demangle/StringViewExtras.h
@@ -0,0 +1,39 @@
+//===--- StringViewExtras.h ----------*- mode:c++;eval:(read-only-mode) -*-===//
+//       Do not edit! See README.txt.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-FileCopyrightText: Part of the LLVM Project
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// There are two copies of this file in the source tree.  The one under
+// libcxxabi is the original and the one under llvm is the copy.  Use
+// cp-to-llvm.sh to update the copy.  See README.txt for more details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef DEMANGLE_STRINGVIEW_H
+#define DEMANGLE_STRINGVIEW_H
+
+#include "DemangleConfig.h"
+
+#include <string_view>
+
+DEMANGLE_NAMESPACE_BEGIN
+
+inline bool starts_with(std::string_view self, char C) noexcept {
+  return !self.empty() && *self.begin() == C;
+}
+
+inline bool starts_with(std::string_view haystack,
+                        std::string_view needle) noexcept {
+  if (needle.size() > haystack.size())
+    return false;
+  haystack.remove_suffix(haystack.size() - needle.size());
+  return haystack == needle;
+}
+
+DEMANGLE_NAMESPACE_END
+
+#endif
diff --git a/externals/demangle/llvm/Demangle/Utility.h b/externals/demangle/llvm/Demangle/Utility.h
index 50d05c6b1..30dfbfc8d 100644
--- a/externals/demangle/llvm/Demangle/Utility.h
+++ b/externals/demangle/llvm/Demangle/Utility.h
@@ -1,5 +1,5 @@
-//===--- Utility.h ----------------------------------------------*- C++ -*-===//
-//
+//===--- Utility.h -------------------*- mode:c++;eval:(read-only-mode) -*-===//
+//       Do not edit! See README.txt.
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-FileCopyrightText: Part of the LLVM Project
@@ -7,70 +7,83 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// Provide some utility classes for use in the demangler(s).
+// Provide some utility classes for use in the demangler.
+// There are two copies of this file in the source tree.  The one in libcxxabi
+// is the original and the one in llvm is the copy.  Use cp-to-llvm.sh to update
+// the copy.  See README.txt for more details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef DEMANGLE_UTILITY_H
 #define DEMANGLE_UTILITY_H
 
-#include "StringView.h"
+#include "DemangleConfig.h"
+
+#include <array>
+#include <cassert>
 #include <cstdint>
 #include <cstdlib>
 #include <cstring>
-#include <iterator>
+#include <exception>
 #include <limits>
+#include <string_view>
 
 DEMANGLE_NAMESPACE_BEGIN
 
 // Stream that AST nodes write their string representation into after the AST
 // has been parsed.
-class OutputStream {
-  char *Buffer;
-  size_t CurrentPosition;
-  size_t BufferCapacity;
+class OutputBuffer {
+  char *Buffer = nullptr;
+  size_t CurrentPosition = 0;
+  size_t BufferCapacity = 0;
 
-  // Ensure there is at least n more positions in buffer.
+  // Ensure there are at least N more positions in the buffer.
   void grow(size_t N) {
-    if (N + CurrentPosition >= BufferCapacity) {
+    size_t Need = N + CurrentPosition;
+    if (Need > BufferCapacity) {
+      // Reduce the number of reallocations, with a bit of hysteresis. The
+      // number here is chosen so the first allocation will more-than-likely not
+      // allocate more than 1K.
+      Need += 1024 - 32;
       BufferCapacity *= 2;
-      if (BufferCapacity < N + CurrentPosition)
-        BufferCapacity = N + CurrentPosition;
+      if (BufferCapacity < Need)
+        BufferCapacity = Need;
       Buffer = static_cast<char *>(std::realloc(Buffer, BufferCapacity));
       if (Buffer == nullptr)
         std::terminate();
     }
   }
 
-  void writeUnsigned(uint64_t N, bool isNeg = false) {
-    // Handle special case...
-    if (N == 0) {
-      *this << '0';
-      return;
-    }
-
-    char Temp[21];
-    char *TempPtr = std::end(Temp);
+  OutputBuffer &writeUnsigned(uint64_t N, bool isNeg = false) {
+    std::array<char, 21> Temp;
+    char *TempPtr = Temp.data() + Temp.size();
 
-    while (N) {
-      *--TempPtr = '0' + char(N % 10);
+    // Output at least one character.
+    do {
+      *--TempPtr = char('0' + N % 10);
       N /= 10;
-    }
+    } while (N);
 
-    // Add negative sign...
+    // Add negative sign.
     if (isNeg)
       *--TempPtr = '-';
-    this->operator<<(StringView(TempPtr, std::end(Temp)));
+
+    return operator+=(
+        std::string_view(TempPtr, Temp.data() + Temp.size() - TempPtr));
   }
 
 public:
-  OutputStream(char *StartBuf, size_t Size)
-      : Buffer(StartBuf), CurrentPosition(0), BufferCapacity(Size) {}
-  OutputStream() = default;
-  void reset(char *Buffer_, size_t BufferCapacity_) {
-    CurrentPosition = 0;
-    Buffer = Buffer_;
-    BufferCapacity = BufferCapacity_;
+  OutputBuffer(char *StartBuf, size_t Size)
+      : Buffer(StartBuf), BufferCapacity(Size) {}
+  OutputBuffer(char *StartBuf, size_t *SizePtr)
+      : OutputBuffer(StartBuf, StartBuf ? *SizePtr : 0) {}
+  OutputBuffer() = default;
+  // Non-copyable
+  OutputBuffer(const OutputBuffer &) = delete;
+  OutputBuffer &operator=(const OutputBuffer &) = delete;
+
+  operator std::string_view() const {
+    return std::string_view(Buffer, CurrentPosition);
   }
 
   /// If a ParameterPackExpansion (or similar type) is encountered, the offset
@@ -78,115 +91,116 @@ public:
   unsigned CurrentPackIndex = std::numeric_limits<unsigned>::max();
   unsigned CurrentPackMax = std::numeric_limits<unsigned>::max();
 
-  OutputStream &operator+=(StringView R) {
-    size_t Size = R.size();
-    if (Size == 0)
-      return *this;
-    grow(Size);
-    std::memmove(Buffer + CurrentPosition, R.begin(), Size);
-    CurrentPosition += Size;
+  /// When zero, we're printing template args and '>' needs to be parenthesized.
+  /// Use a counter so we can simply increment inside parentheses.
+  unsigned GtIsGt = 1;
+
+  bool isGtInsideTemplateArgs() const { return GtIsGt == 0; }
+
+  void printOpen(char Open = '(') {
+    GtIsGt++;
+    *this += Open;
+  }
+  void printClose(char Close = ')') {
+    GtIsGt--;
+    *this += Close;
+  }
+
+  OutputBuffer &operator+=(std::string_view R) {
+    if (size_t Size = R.size()) {
+      grow(Size);
+      std::memcpy(Buffer + CurrentPosition, &*R.begin(), Size);
+      CurrentPosition += Size;
+    }
     return *this;
   }
 
-  OutputStream &operator+=(char C) {
+  OutputBuffer &operator+=(char C) {
     grow(1);
     Buffer[CurrentPosition++] = C;
     return *this;
   }
 
-  OutputStream &operator<<(StringView R) { return (*this += R); }
+  OutputBuffer &prepend(std::string_view R) {
+    size_t Size = R.size();
 
-  OutputStream &operator<<(char C) { return (*this += C); }
+    grow(Size);
+    std::memmove(Buffer + Size, Buffer, CurrentPosition);
+    std::memcpy(Buffer, &*R.begin(), Size);
+    CurrentPosition += Size;
 
-  OutputStream &operator<<(long long N) {
-    if (N < 0)
-      writeUnsigned(static_cast<unsigned long long>(-N), true);
-    else
-      writeUnsigned(static_cast<unsigned long long>(N));
     return *this;
   }
 
-  OutputStream &operator<<(unsigned long long N) {
-    writeUnsigned(N, false);
-    return *this;
+  OutputBuffer &operator<<(std::string_view R) { return (*this += R); }
+
+  OutputBuffer &operator<<(char C) { return (*this += C); }
+
+  OutputBuffer &operator<<(long long N) {
+    return writeUnsigned(static_cast<unsigned long long>(std::abs(N)), N < 0);
   }
 
-  OutputStream &operator<<(long N) {
+  OutputBuffer &operator<<(unsigned long long N) {
+    return writeUnsigned(N, false);
+  }
+
+  OutputBuffer &operator<<(long N) {
     return this->operator<<(static_cast<long long>(N));
   }
 
-  OutputStream &operator<<(unsigned long N) {
+  OutputBuffer &operator<<(unsigned long N) {
     return this->operator<<(static_cast<unsigned long long>(N));
   }
 
-  OutputStream &operator<<(int N) {
+  OutputBuffer &operator<<(int N) {
     return this->operator<<(static_cast<long long>(N));
   }
 
-  OutputStream &operator<<(unsigned int N) {
+  OutputBuffer &operator<<(unsigned int N) {
     return this->operator<<(static_cast<unsigned long long>(N));
   }
 
+  void insert(size_t Pos, const char *S, size_t N) {
+    assert(Pos <= CurrentPosition);
+    if (N == 0)
+      return;
+    grow(N);
+    std::memmove(Buffer + Pos + N, Buffer + Pos, CurrentPosition - Pos);
+    std::memcpy(Buffer + Pos, S, N);
+    CurrentPosition += N;
+  }
+
   size_t getCurrentPosition() const { return CurrentPosition; }
   void setCurrentPosition(size_t NewPos) { CurrentPosition = NewPos; }
 
   char back() const {
-    return CurrentPosition ? Buffer[CurrentPosition - 1] : '\0';
+    assert(CurrentPosition);
+    return Buffer[CurrentPosition - 1];
   }
 
   bool empty() const { return CurrentPosition == 0; }
 
   char *getBuffer() { return Buffer; }
   char *getBufferEnd() { return Buffer + CurrentPosition - 1; }
-  size_t getBufferCapacity() { return BufferCapacity; }
+  size_t getBufferCapacity() const { return BufferCapacity; }
 };
 
-template <class T> class SwapAndRestore {
-  T &Restore;
-  T OriginalValue;
-  bool ShouldRestore = true;
+template <class T> class ScopedOverride {
+  T &Loc;
+  T Original;
 
 public:
-  SwapAndRestore(T &Restore_) : SwapAndRestore(Restore_, Restore_) {}
-
-  SwapAndRestore(T &Restore_, T NewVal)
-      : Restore(Restore_), OriginalValue(Restore) {
-    Restore = std::move(NewVal);
-  }
-  ~SwapAndRestore() {
-    if (ShouldRestore)
-      Restore = std::move(OriginalValue);
-  }
+  ScopedOverride(T &Loc_) : ScopedOverride(Loc_, Loc_) {}
 
-  void shouldRestore(bool ShouldRestore_) { ShouldRestore = ShouldRestore_; }
-
-  void restoreNow(bool Force) {
-    if (!Force && !ShouldRestore)
-      return;
-
-    Restore = std::move(OriginalValue);
-    ShouldRestore = false;
+  ScopedOverride(T &Loc_, T NewVal) : Loc(Loc_), Original(Loc_) {
+    Loc_ = std::move(NewVal);
   }
+  ~ScopedOverride() { Loc = std::move(Original); }
 
-  SwapAndRestore(const SwapAndRestore &) = delete;
-  SwapAndRestore &operator=(const SwapAndRestore &) = delete;
+  ScopedOverride(const ScopedOverride &) = delete;
+  ScopedOverride &operator=(const ScopedOverride &) = delete;
 };
 
-inline bool initializeOutputStream(char *Buf, size_t *N, OutputStream &S,
-                                   size_t InitSize) {
-  size_t BufferSize;
-  if (Buf == nullptr) {
-    Buf = static_cast<char *>(std::malloc(InitSize));
-    if (Buf == nullptr)
-      return false;
-    BufferSize = InitSize;
-  } else
-    BufferSize = *N;
-
-  S.reset(Buf, BufferSize);
-  return true;
-}
-
 DEMANGLE_NAMESPACE_END
 
 #endif