Move TypeSourceInfo to Type.h

[rnk]

Summary

TypeSourceInfo is a thin wrapper around TypeLocs. Notionally, the best
place for it to live would be TypeLoc.h, but Decl.h requires it to be
complete, so it needs to be lower in the dependency graph. Type.h seems
like the next best place.

By itself, this change has no impact on build time, because it doesn't
remove a single dependency edge from a .cpp file to a .h file, but it is
an incremental step towards making the AST headers less interdependent.

clang/include/clang/AST/Decl.h

 class TemplateArgumentList;
 class TemplateArgumentListInfo;
 class TemplateParameterList;
 class TypeAliasTemplateDecl;
 class TypeLoc;
 class UnresolvedSetImpl;
 class VarTemplateDecl;
 
-/// A container of type source information.
-///
-/// A client can read the relevant info using TypeLoc wrappers, e.g:
-/// @code
-/// TypeLoc TL = TypeSourceInfo->getTypeLoc();
-/// TL.getBeginLoc().print(OS, SrcMgr);
-/// @endcode
-class alignas(8) TypeSourceInfo {
-  // Contains a memory block after the class, used for type source information,
-  // allocated by ASTContext.
-  friend class ASTContext;
-
-  QualType Ty;
-
-  TypeSourceInfo(QualType ty) : Ty(ty) {}
-
-public:
-  /// Return the type wrapped by this type source info.
-  QualType getType() const { return Ty; }
-
-  /// Return the TypeLoc wrapper for the type source info.
-  TypeLoc getTypeLoc() const; // implemented in TypeLoc.h
-
-  /// Override the type stored in this TypeSourceInfo. Use with caution!
-  void overrideType(QualType T) { Ty = T; }
-};
-
 /// The top declaration context.
 class TranslationUnitDecl : public Decl, public DeclContext {
   ASTContext &Ctx;
 
   /// The (most recently entered) anonymous namespace for this
   /// translation unit, if one has been created.
   NamespaceDecl *AnonymousNamespace = nullptr;
 

clang/include/clang/AST/Type.h

public:
 
   /// Apply the collected qualifiers to the given type.
   QualType apply(const ASTContext &Context, QualType QT) const;
 
   /// Apply the collected qualifiers to the given type.
   QualType apply(const ASTContext &Context, const Type* T) const;
 };
 
+/// A container of type source information.
+///
+/// A client can read the relevant info using TypeLoc wrappers, e.g:
+/// @code
+/// TypeLoc TL = TypeSourceInfo->getTypeLoc();
+/// TL.getBeginLoc().print(OS, SrcMgr);
+/// @endcode
+class alignas(8) TypeSourceInfo {
+  // Contains a memory block after the class, used for type source information,
+  // allocated by ASTContext.
+  friend class ASTContext;
+
+  QualType Ty;
+
+  TypeSourceInfo(QualType ty) : Ty(ty) {}
+
+public:
+  /// Return the type wrapped by this type source info.
+  QualType getType() const { return Ty; }
+
+  /// Return the TypeLoc wrapper for the type source info.
+  TypeLoc getTypeLoc() const; // implemented in TypeLoc.h
+
+  /// Override the type stored in this TypeSourceInfo. Use with caution!
+  void overrideType(QualType T) { Ty = T; }
+};
+
 // Inline function definitions.
 
 inline SplitQualType SplitQualType::getSingleStepDesugaredType() const {
   SplitQualType desugar =
     Ty->getLocallyUnqualifiedSingleStepDesugaredType().split();
   desugar.Quals.addConsistentQualifiers(Quals);
   return desugar;
 }

clang/include/clang/AST/TypeLoc.h

 //===- TypeLoc.h - Type Source Info Wrapper ---------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 /// \file
 /// Defines the clang::TypeLoc interface and its subclasses.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_AST_TYPELOC_H
 #define LLVM_CLANG_AST_TYPELOC_H
 
-#include "clang/AST/Decl.h"
 #include "clang/AST/NestedNameSpecifier.h"
 #include "clang/AST/TemplateBase.h"
 #include "clang/AST/Type.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/Specifiers.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/MathExtras.h"
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
 #include <cstring>
 
 namespace clang {
 
 class Attr;
 class ASTContext;
 class CXXRecordDecl;
 class Expr;
 class ObjCInterfaceDecl;
 class ObjCProtocolDecl;
 class ObjCTypeParamDecl;
+class ParmVarDecl;
 class TemplateTypeParmDecl;
 class UnqualTypeLoc;
 class UnresolvedUsingTypenameDecl;
 
 // Predeclare all the type nodes.
 #define ABSTRACT_TYPELOC(Class, Base)
 #define TYPELOC(Class, Base) \
   class Class##TypeLoc;

 /// creating an ElaboratedType node for so many type references in C.
 class TagTypeLoc : public InheritingConcreteTypeLoc<TypeSpecTypeLoc,
                                                     TagTypeLoc,
                                                     TagType> {
 public:
   TagDecl *getDecl() const { return getTypePtr()->getDecl(); }
 
   /// True if the tag was defined in this type specifier.
-  bool isDefinition() const {
-    TagDecl *D = getDecl();
-    return D->isCompleteDefinition() &&
-           (D->getIdentifier() == nullptr || D->getLocation() == getNameLoc());
-  }
+  bool isDefinition() const;
 };
 
 /// Wrapper for source info for record types.
 class RecordTypeLoc : public InheritingConcreteTypeLoc<TagTypeLoc,
                                                        RecordTypeLoc,
                                                        RecordType> {
 public:
   RecordDecl *getDecl() const { return getTypePtr()->getDecl(); }

clang/lib/AST/TypeLoc.cpp

 /// because it's a convenient base class.  Ideally we would not accept
 /// those here, but ideally we would have better implementations for
 /// them.
 bool TypeSpecTypeLoc::isKind(const TypeLoc &TL) {
   if (TL.getType().hasLocalQualifiers()) return false;
   return TSTChecker().Visit(TL);
 }
 
+bool TagTypeLoc::isDefinition() const {
+  TagDecl *D = getDecl();
+  return D->isCompleteDefinition() &&
+         (D->getIdentifier() == nullptr || D->getLocation() == getNameLoc());
+}
+
 // Reimplemented to account for GNU/C++ extension
 //     typeof unary-expression
 // where there are no parentheses.
 SourceRange TypeOfExprTypeLoc::getLocalSourceRange() const {
   if (getRParenLoc().isValid())
     return SourceRange(getTypeofLoc(), getRParenLoc());
   else
     return SourceRange(getTypeofLoc(),