[modules] If we reach a definition of a class for which we already have a

non-visible definition, skip the new definition and make the old one visible
instead of trying to parse it again and failing horribly. C++'s ODR allows
us to assume that the two definitions are identical.

llvm-svn: 233250

4 files changed, 27 insertions, 1 deletions

diff --git a/clang/include/clang/AST/ASTMutationListener.h b/clang/include/clang/AST/ASTMutationListener.h
index 27fdeac6b1f..d2b0a8b0c7e 100644
--- a/clang/include/clang/AST/ASTMutationListener.h
+++ b/clang/include/clang/AST/ASTMutationListener.h
@@ -24,6 +24,7 @@ namespace clang {
   class DeclContext;
   class FunctionDecl;
   class FunctionTemplateDecl;
+  class NamedDecl;
   class ObjCCategoryDecl;
   class ObjCContainerDecl;
   class ObjCInterfaceDecl;
@@ -113,6 +114,12 @@ public:
   /// \param D the declaration marked OpenMP threadprivate.
   virtual void DeclarationMarkedOpenMPThreadPrivate(const Decl *D) {}
 
+  /// \brief A definition has been made visible by being redefined locally.
+  ///
+  /// \param D The definition that was previously not visible.
+  virtual void RedefinedHiddenDefinition(const NamedDecl *D,
+                                         SourceLocation Loc) {}
+
   // NOTE: If new methods are added they should also be added to
   // MultiplexASTMutationListener.
 };
diff --git a/clang/include/clang/Parse/Parser.h b/clang/include/clang/Parse/Parser.h
index 179bc038d5e..0352c649fc3 100644
--- a/clang/include/clang/Parse/Parser.h
+++ b/clang/include/clang/Parse/Parser.h
@@ -2284,6 +2284,10 @@ private:
                            AccessSpecifier AS, bool EnteringContext,
                            DeclSpecContext DSC, 
                            ParsedAttributesWithRange &Attributes);
+  void SkipCXXMemberSpecification(SourceLocation StartLoc,
+                                  SourceLocation AttrFixitLoc,
+                                  unsigned TagType,
+                                  Decl *TagDecl);
   void ParseCXXMemberSpecification(SourceLocation StartLoc,
                                    SourceLocation AttrFixitLoc,
                                    ParsedAttributesWithRange &Attrs,
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 92d3b735e51..9e07ad533f1 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -1279,6 +1279,10 @@ private:
   bool RequireCompleteTypeImpl(SourceLocation Loc, QualType T,
                            TypeDiagnoser &Diagnoser);
 public:
+  /// Determine if \p D has a visible definition. If not, suggest a declaration
+  /// that should be made visible to expose the definition.
+  bool hasVisibleDefinition(NamedDecl *D, NamedDecl **Suggested);
+
   bool RequireCompleteType(SourceLocation Loc, QualType T,
                            TypeDiagnoser &Diagnoser);
   bool RequireCompleteType(SourceLocation Loc, QualType T,
@@ -1725,7 +1729,7 @@ public:
                  bool &OwnedDecl, bool &IsDependent,
                  SourceLocation ScopedEnumKWLoc,
                  bool ScopedEnumUsesClassTag, TypeResult UnderlyingType,
-                 bool IsTypeSpecifier);
+                 bool IsTypeSpecifier, bool *SkipBody = nullptr);
 
   Decl *ActOnTemplatedFriendTag(Scope *S, SourceLocation FriendLoc,
                                 unsigned TagSpec, SourceLocation TagLoc,
@@ -1790,6 +1794,11 @@ public:
   /// struct, or union).
   void ActOnTagStartDefinition(Scope *S, Decl *TagDecl);
 
+  /// \brief Invoked when we enter a tag definition that we're skipping.
+  void ActOnTagStartSkippedDefinition(Scope *S, Decl *TD) {
+    PushDeclContext(S, cast<DeclContext>(TD));
+  }
+
   Decl *ActOnObjCContainerStartDefinition(Decl *IDecl);
 
   /// ActOnStartCXXMemberDeclarations - Invoked when we have parsed a
@@ -1805,6 +1814,10 @@ public:
   void ActOnTagFinishDefinition(Scope *S, Decl *TagDecl,
                                 SourceLocation RBraceLoc);
 
+  void ActOnTagFinishSkippedDefinition() {
+    PopDeclContext();
+  }
+
   void ActOnObjCContainerFinishDefinition();
 
   /// \brief Invoked when we must temporarily exit the objective-c container
diff --git a/clang/include/clang/Serialization/ASTWriter.h b/clang/include/clang/Serialization/ASTWriter.h
index 5f702223ac6..068815ee90f 100644
--- a/clang/include/clang/Serialization/ASTWriter.h
+++ b/clang/include/clang/Serialization/ASTWriter.h
@@ -861,6 +861,8 @@ public:
                                     const ObjCCategoryDecl *ClassExt) override;
   void DeclarationMarkedUsed(const Decl *D) override;
   void DeclarationMarkedOpenMPThreadPrivate(const Decl *D) override;
+  void RedefinedHiddenDefinition(const NamedDecl *D,
+                                 SourceLocation Loc) override;
 };
 
 /// \brief AST and semantic-analysis consumer that generates a