Make tag declarations redeclarable. This change has three purposes:

  1) Allow the Index library (and any other interested client) to walk
  the set of declarations for a given tag (enum, union, class,
  whatever). At the moment, this information is not readily available.

  2) Reduce our dependence on TagDecl::TypeForDecl being mapped down
  to a TagType (for which getDecl() will return the tag definition, if
  one exists). This property won't exist for class template partial
  specializations.

  3) Make the canonical declaration of a TagDecl actually canonical,
  e.g., so that it does not change when the tag is defined.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@77523 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 30 insertions, 10 deletions

diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index 3214b653b9..9ce589ba80 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -1178,7 +1178,8 @@ public:
 class TypedefDecl;
   
 /// TagDecl - Represents the declaration of a struct/union/class/enum.
-class TagDecl : public TypeDecl, public DeclContext {
+class TagDecl 
+  : public TypeDecl, public DeclContext, public Redeclarable<TagDecl> {
 public:
   enum TagKind {
     TK_struct,
@@ -1205,15 +1206,28 @@ private:
 
 protected:
   TagDecl(Kind DK, TagKind TK, DeclContext *DC, SourceLocation L,
-          IdentifierInfo *Id, SourceLocation TKL = SourceLocation())
+          IdentifierInfo *Id, TagDecl *PrevDecl,
+          SourceLocation TKL = SourceLocation())
     : TypeDecl(DK, DC, L, Id), DeclContext(DK), TypedefForAnonDecl(0),
       TagKeywordLoc(TKL) {
     assert((DK != Enum || TK == TK_enum) &&"EnumDecl not matched with TK_enum");
     TagDeclKind = TK;
     IsDefinition = false;
+    setPreviousDeclaration(PrevDecl);
   }
+    
+  typedef Redeclarable<TagDecl> redeclarable_base;
+  virtual TagDecl *getNextRedeclaration() { return RedeclLink.getNext(); }
+    
 public:
-  
+  typedef redeclarable_base::redecl_iterator redecl_iterator;
+  redecl_iterator redecls_begin() const {
+    return redeclarable_base::redecls_begin();
+  } 
+  redecl_iterator redecls_end() const {
+    return redeclarable_base::redecls_end();
+  }
+    
   SourceLocation getRBraceLoc() const { return RBraceLoc; }
   void setRBraceLoc(SourceLocation L) { RBraceLoc = L; }
 
@@ -1307,8 +1321,8 @@ class EnumDecl : public TagDecl {
   EnumDecl *InstantiatedFrom;
 
   EnumDecl(DeclContext *DC, SourceLocation L,
-           IdentifierInfo *Id, SourceLocation TKL)
-    : TagDecl(Enum, TK_enum, DC, L, Id, TKL), InstantiatedFrom(0) {
+           IdentifierInfo *Id, EnumDecl *PrevDecl, SourceLocation TKL)
+    : TagDecl(Enum, TK_enum, DC, L, Id, PrevDecl, TKL), InstantiatedFrom(0) {
       IntegerType = QualType();
     }
 public:
@@ -1380,7 +1394,8 @@ class RecordDecl : public TagDecl {
 
 protected:
   RecordDecl(Kind DK, TagKind TK, DeclContext *DC,
-             SourceLocation L, IdentifierInfo *Id, SourceLocation TKL);
+             SourceLocation L, IdentifierInfo *Id, 
+             RecordDecl *PrevDecl, SourceLocation TKL);
   virtual ~RecordDecl();
 
 public:
diff --git a/include/clang/AST/DeclCXX.h b/include/clang/AST/DeclCXX.h
index 8ad8aede60..3da7230ab0 100644
--- a/include/clang/AST/DeclCXX.h
+++ b/include/clang/AST/DeclCXX.h
@@ -376,6 +376,7 @@ class CXXRecordDecl : public RecordDecl {
 protected:
   CXXRecordDecl(Kind K, TagKind TK, DeclContext *DC,
                 SourceLocation L, IdentifierInfo *Id,
+                CXXRecordDecl *PrevDecl,
                 SourceLocation TKL = SourceLocation());
 
   ~CXXRecordDecl();
diff --git a/include/clang/AST/DeclTemplate.h b/include/clang/AST/DeclTemplate.h
index 17c8bc877d..7cf8bfdecf 100644
--- a/include/clang/AST/DeclTemplate.h
+++ b/include/clang/AST/DeclTemplate.h
@@ -883,7 +883,8 @@ protected:
   ClassTemplateSpecializationDecl(ASTContext &Context, Kind DK,
                                   DeclContext *DC, SourceLocation L,
                                   ClassTemplateDecl *SpecializedTemplate,
-                                  TemplateArgumentListBuilder &Builder);
+                                  TemplateArgumentListBuilder &Builder,
+                                  ClassTemplateSpecializationDecl *PrevDecl);
                                   
 public:
   static ClassTemplateSpecializationDecl *
@@ -954,9 +955,12 @@ class ClassTemplatePartialSpecializationDecl
                                          DeclContext *DC, SourceLocation L,
                                          TemplateParameterList *Params,
                                          ClassTemplateDecl *SpecializedTemplate,
-                                         TemplateArgumentListBuilder &Builder)
-    : ClassTemplateSpecializationDecl(Context, ClassTemplatePartialSpecialization,
-                                      DC, L, SpecializedTemplate, Builder),
+                                         TemplateArgumentListBuilder &Builder,
+                               ClassTemplatePartialSpecializationDecl *PrevDecl)
+    : ClassTemplateSpecializationDecl(Context, 
+                                      ClassTemplatePartialSpecialization,
+                                      DC, L, SpecializedTemplate, Builder,
+                                      PrevDecl),
       TemplateParams(Params) { }
 
 public: