Augment the interface of ExternalASTSource::FindExternalLexicalDecls()

to allow clients to specify that they've already (correctly) loaded
declarations, and that no further action is needed. 

Also, make sure that we clear the "has external lexical declarations"
bit before calling FindExternalLexicalDecls(), to avoid infinite
recursion.

llvm-svn: 135306

8 files changed, 44 insertions, 22 deletions

diff --git a/clang/include/clang/AST/ExternalASTSource.h b/clang/include/clang/AST/ExternalASTSource.h
index 846813adf7c..ef1f1618ba1 100644
--- a/clang/include/clang/AST/ExternalASTSource.h
+++ b/clang/include/clang/AST/ExternalASTSource.h
@@ -32,6 +32,20 @@ class Selector;
 class Stmt;
 class TagDecl;
 
+/// \brief Enumeration describing the result of loading information from
+/// an external source.
+enum ExternalLoadResult {
+  /// \brief Loading the external information has succeeded.
+  ELR_Success,
+  
+  /// \brief Loading the external information has failed.
+  ELR_Failure,
+  
+  /// \brief The external information has already been loaded, and therefore
+  /// no additional processing is required.
+  ELR_AlreadyLoaded
+};
+  
 /// \brief Abstract interface for external sources of AST nodes.
 ///
 /// External AST sources provide AST nodes constructed from some
@@ -132,10 +146,10 @@ public:
   /// declaration kind is one we are looking for. If NULL, all declarations
   /// are returned.
   ///
-  /// \return true if an error occurred
+  /// \return an indication of whether the load succeeded or failed.
   ///
   /// The default implementation of this method is a no-op.
-  virtual bool FindExternalLexicalDecls(const DeclContext *DC,
+  virtual ExternalLoadResult FindExternalLexicalDecls(const DeclContext *DC,
                                         bool (*isKindWeWant)(Decl::Kind),
                                         llvm::SmallVectorImpl<Decl*> &Result);
 
@@ -143,14 +157,14 @@ public:
   /// DeclContext.
   ///
   /// \return true if an error occurred
-  bool FindExternalLexicalDecls(const DeclContext *DC,
+  ExternalLoadResult FindExternalLexicalDecls(const DeclContext *DC,
                                 llvm::SmallVectorImpl<Decl*> &Result) {
     return FindExternalLexicalDecls(DC, 0, Result);
   }
 
   template <typename DeclTy>
-  bool FindExternalLexicalDeclsBy(const DeclContext *DC,
-                                llvm::SmallVectorImpl<Decl*> &Result) {
+  ExternalLoadResult FindExternalLexicalDeclsBy(const DeclContext *DC,
+                                  llvm::SmallVectorImpl<Decl*> &Result) {
     return FindExternalLexicalDecls(DC, DeclTy::classofKind, Result);
   }
 
diff --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h
index a6c32aafd33..9e210c3db28 100644
--- a/clang/include/clang/Serialization/ASTReader.h
+++ b/clang/include/clang/Serialization/ASTReader.h
@@ -1070,7 +1070,7 @@ public:
   ///
   /// \returns true if there was an error while reading the
   /// declarations for this declaration context.
-  virtual bool FindExternalLexicalDecls(const DeclContext *DC,
+  virtual ExternalLoadResult FindExternalLexicalDecls(const DeclContext *DC,
                                         bool (*isKindWeWant)(Decl::Kind),
                                         llvm::SmallVectorImpl<Decl*> &Decls);
 
diff --git a/clang/include/clang/Serialization/ChainedIncludesSource.h b/clang/include/clang/Serialization/ChainedIncludesSource.h
index 0c3e86faf41..f547902ef0e 100644
--- a/clang/include/clang/Serialization/ChainedIncludesSource.h
+++ b/clang/include/clang/Serialization/ChainedIncludesSource.h
@@ -47,7 +47,7 @@ protected:
   virtual DeclContextLookupResult
   FindExternalVisibleDeclsByName(const DeclContext *DC, DeclarationName Name);
   virtual void MaterializeVisibleDecls(const DeclContext *DC);
-  virtual bool FindExternalLexicalDecls(const DeclContext *DC,
+  virtual ExternalLoadResult FindExternalLexicalDecls(const DeclContext *DC,
                                         bool (*isKindWeWant)(Decl::Kind),
                                         llvm::SmallVectorImpl<Decl*> &Result);
   virtual void CompleteType(TagDecl *Tag);
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 9b507cfc5e2..4c323da7eee 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -2361,8 +2361,15 @@ void RecordDecl::LoadFieldsFromExternalStorage() const {
   ExternalASTSource::Deserializing TheFields(Source);
 
   llvm::SmallVector<Decl*, 64> Decls;
-  if (Source->FindExternalLexicalDeclsBy<FieldDecl>(this, Decls))
+  LoadedFieldsFromExternalStorage = true;  
+  switch (Source->FindExternalLexicalDeclsBy<FieldDecl>(this, Decls)) {
+  case ELR_Success:
+    break;
+    
+  case ELR_AlreadyLoaded:
+  case ELR_Failure:
     return;
+  }
 
 #ifndef NDEBUG
   // Check that all decls we got were FieldDecls.
@@ -2370,8 +2377,6 @@ void RecordDecl::LoadFieldsFromExternalStorage() const {
     assert(isa<FieldDecl>(Decls[i]));
 #endif
 
-  LoadedFieldsFromExternalStorage = true;
-
   if (Decls.empty())
     return;
 
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 7d146572bf6..b2806f092cb 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -839,12 +839,17 @@ DeclContext::LoadLexicalDeclsFromExternalStorage() const {
   // Notify that we have a DeclContext that is initializing.
   ExternalASTSource::Deserializing ADeclContext(Source);
 
+  // Load the external declarations, if any.
   llvm::SmallVector<Decl*, 64> Decls;
-  if (Source->FindExternalLexicalDecls(this, Decls))
-    return;
-
-  // There is no longer any lexical storage in this context
   ExternalLexicalStorage = false;
+  switch (Source->FindExternalLexicalDecls(this, Decls)) {
+  case ELR_Success:
+    break;
+    
+  case ELR_Failure:
+  case ELR_AlreadyLoaded:
+    return;
+  }
 
   if (Decls.empty())
     return;
diff --git a/clang/lib/AST/ExternalASTSource.cpp b/clang/lib/AST/ExternalASTSource.cpp
index f428318a21e..b96d65a729c 100644
--- a/clang/lib/AST/ExternalASTSource.cpp
+++ b/clang/lib/AST/ExternalASTSource.cpp
@@ -51,11 +51,11 @@ ExternalASTSource::FindExternalVisibleDeclsByName(const DeclContext *DC,
 
 void ExternalASTSource::MaterializeVisibleDecls(const DeclContext *DC) { }
 
-bool 
+ExternalLoadResult 
 ExternalASTSource::FindExternalLexicalDecls(const DeclContext *DC,
                                             bool (*isKindWeWant)(Decl::Kind),
                                          llvm::SmallVectorImpl<Decl*> &Result) {
-  return true;
+  return ELR_AlreadyLoaded;
 }
 
 void ExternalASTSource::getMemoryBufferSizes(MemoryBufferSizes &sizes) const { }
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 13933b3eb3f..a4ed5f4da48 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -4008,12 +4008,9 @@ Stmt *ASTReader::GetExternalDeclStmt(uint64_t Offset) {
   llvm_unreachable("Broken chain");
 }
 
-bool ASTReader::FindExternalLexicalDecls(const DeclContext *DC,
+ExternalLoadResult ASTReader::FindExternalLexicalDecls(const DeclContext *DC,
                                          bool (*isKindWeWant)(Decl::Kind),
                                          llvm::SmallVectorImpl<Decl*> &Decls) {
-  assert(DC->hasExternalLexicalStorage() &&
-         "DeclContext has no lexical decls in storage");
-
   // There might be lexical decls in multiple parts of the chain, for the TU
   // at least.
   // DeclContextOffsets might reallocate as we load additional decls below,
@@ -4038,7 +4035,7 @@ bool ASTReader::FindExternalLexicalDecls(const DeclContext *DC,
   }
 
   ++NumLexicalDeclContextsRead;
-  return false;
+  return ELR_Success;
 }
 
 DeclContext::lookup_result
diff --git a/clang/lib/Serialization/ChainedIncludesSource.cpp b/clang/lib/Serialization/ChainedIncludesSource.cpp
index da5be957a53..3b7cd23b92a 100644
--- a/clang/lib/Serialization/ChainedIncludesSource.cpp
+++ b/clang/lib/Serialization/ChainedIncludesSource.cpp
@@ -185,7 +185,8 @@ ChainedIncludesSource::FindExternalVisibleDeclsByName(const DeclContext *DC,
 void ChainedIncludesSource::MaterializeVisibleDecls(const DeclContext *DC) {
   return getFinalReader().MaterializeVisibleDecls(DC);
 }
-bool ChainedIncludesSource::FindExternalLexicalDecls(const DeclContext *DC,
+ExternalLoadResult 
+ChainedIncludesSource::FindExternalLexicalDecls(const DeclContext *DC,
                                       bool (*isKindWeWant)(Decl::Kind),
                                       llvm::SmallVectorImpl<Decl*> &Result) {
   return getFinalReader().FindExternalLexicalDecls(DC, isKindWeWant, Result);