Support locally-declared external declarations in PCH files

llvm-svn: 69833

clang/include/clang/Frontend/PCHBitCodes.h

@@ -156,7 +156,11 @@ namespace clang {
       STATISTICS = 9,
 
       /// \brief Record code for the array of tentative definitions.
-      TENTATIVE_DEFINITIONS = 10
+      TENTATIVE_DEFINITIONS = 10,
+
+      /// \brief Record code for the array of locally-scoped external
+      /// declarations.
+      LOCALLY_SCOPED_EXTERNAL_DECLS = 11
     };
 
     /// \brief Record types used within a source manager block.

clang/include/clang/Frontend/PCHReader.h

@@ -153,6 +153,10 @@ private:
   /// file.
   llvm::SmallVector<uint64_t, 16> TentativeDefinitions;
 
+  /// \brief The set of locally-scoped external declarations stored in
+  /// the the PCH file.
+  llvm::SmallVector<uint64_t, 16> LocallyScopedExternalDecls;
+
   /// \brief Mapping from switch-case IDs in the PCH file to
   /// switch-case statements.
   std::map<unsigned, SwitchCase *> SwitchCaseStmts;

clang/lib/Frontend/PCHReader.cpp

@@ -1720,6 +1720,14 @@ PCHReader::ReadPCHBlock(uint64_t &PreprocessorBlockOffset) {
       }
       TentativeDefinitions.swap(Record);
       break;
+
+    case pch::LOCALLY_SCOPED_EXTERNAL_DECLS:
+      if (!LocallyScopedExternalDecls.empty()) {
+        Error("Duplicate LOCALLY_SCOPED_EXTERNAL_DECLS record in PCH file");
+        return Failure;
+      }
+      LocallyScopedExternalDecls.swap(Record);
+      break;
     }
   }
 
@@ -2537,6 +2545,14 @@ void PCHReader::InitializeSema(Sema &S) {
     VarDecl *Var = cast<VarDecl>(GetDecl(TentativeDefinitions[I]));
     SemaObj->TentativeDefinitions[Var->getDeclName()] = Var;
   }
+
+  // If there were any locally-scoped external declarations,
+  // deserialize them and add them to Sema's table of locally-scoped
+  // external declarations.
+  for (unsigned I = 0, N = LocallyScopedExternalDecls.size(); I != N; ++I) {
+    NamedDecl *D = cast<NamedDecl>(GetDecl(LocallyScopedExternalDecls[I]));
+    SemaObj->LocallyScopedExternalDecls[D->getDeclName()] = D;
+  }
 }
 
 IdentifierInfo* PCHReader::get(const char *NameStart, const char *NameEnd) {

clang/lib/Frontend/PCHWriter.cpp

@@ -2033,6 +2033,16 @@ void PCHWriter::WritePCH(Sema &SemaRef) {
        TD != TDEnd; ++TD)
     AddDeclRef(TD->second, TentativeDefinitions);
 
+  // Build a record containing all of the locally-scoped external
+  // declarations in this header file. Generally, this record will be
+  // empty.
+  RecordData LocallyScopedExternalDecls;
+  for (llvm::DenseMap<DeclarationName, NamedDecl *>::iterator 
+         TD = SemaRef.LocallyScopedExternalDecls.begin(),
+         TDEnd = SemaRef.LocallyScopedExternalDecls.end();
+       TD != TDEnd; ++TD)
+    AddDeclRef(TD->second, LocallyScopedExternalDecls);
+
   // Write the remaining PCH contents.
   RecordData Record;
   Stream.EnterSubblock(pch::PCH_BLOCK_ID, 3);
@@ -2058,6 +2068,11 @@ void PCHWriter::WritePCH(Sema &SemaRef) {
   // Write the record containing tentative definitions.
   if (!TentativeDefinitions.empty())
     Stream.EmitRecord(pch::TENTATIVE_DEFINITIONS, TentativeDefinitions);
+
+  // Write the record containing locally-scoped external definitions.
+  if (!LocallyScopedExternalDecls.empty())
+    Stream.EmitRecord(pch::LOCALLY_SCOPED_EXTERNAL_DECLS, 
+                      LocallyScopedExternalDecls);
   
   // Some simple statistics
   Record.clear();

clang/test/PCH/nonvisible-external-defs.c

@@ -0,0 +1,10 @@
+// Test this without pch.
+// RUN: clang-cc -include %S/nonvisible-external-defs.h -fsyntax-only -verify %s &&
+
+// Test with pch.
+// RUN: clang-cc -emit-pch -o %t %S/nonvisible-external-defs.h &&
+// RUN: clang-cc -include-pch %t -fsyntax-only -verify %s 
+
+int g(int, float); // expected-error{{conflicting types}}
+
+// expected-note{{previous declaration}}

clang/test/PCH/nonvisible-external-defs.h

@@ -0,0 +1,11 @@
+// Helper for PCH test nonvisible-external-defs.h
+
+
+
+
+
+
+
+void f() {
+  extern int g(int, int);
+}