Fix PCH deserialization bug with local static symbols being treated as local extern.

This triggered a miscompilation of code using Boost's function_template.hpp
when it was included inside a PCH file.  A local static within
that header would be treated as local extern, resulting in the wrong
mangling.  This only occurred during PCH deserialization.

Fixes <rdar://problem/15975816> and <rdar://problem/15926311>.

llvm-svn: 201130

3 files changed, 28 insertions, 1 deletions

diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 943328b9cdc..18dbb053b99 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -973,7 +973,7 @@ ASTDeclReader::RedeclarableResult ASTDeclReader::VisitVarDeclImpl(VarDecl *VD) {
   VD->setCachedLinkage(VarLinkage);
 
   // Reconstruct the one piece of the IdentifierNamespace that we need.
-  if (VarLinkage != NoLinkage &&
+  if (VD->getStorageClass() == SC_Extern && VarLinkage != NoLinkage &&
       VD->getLexicalDeclContext()->isFunctionOrMethod())
     VD->setLocalExternDecl();
 
diff --git a/clang/test/PCH/local_static.cpp b/clang/test/PCH/local_static.cpp
new file mode 100644
index 00000000000..1085d81d317
--- /dev/null
+++ b/clang/test/PCH/local_static.cpp
@@ -0,0 +1,20 @@
+// Test this without PCH.
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.9.0 -include %S/local_static.h -fsyntax-only %s -emit-llvm -o %t.no_pch.ll %s
+// RUN: FileCheck --input-file %t.no_pch.ll %s
+
+// Test with PCH.
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.9.0 -x c++-header -emit-pch -o %t.pch %S/local_static.h
+// RUN: %clang_cc1 -triple x86_64-apple-macosx10.9.0 -include-pch %t.pch -emit-llvm -o %t.pch.ll %s
+// RUN: FileCheck --input-file %t.pch.ll %s
+
+void test(Bar &b) {
+  b.f<int>();
+  static int s;
+}
+
+// Check if the mangling of static and local extern variables
+// are correct and preserved by PCH.
+
+// CHECK: @_ZZ4testR3BarE1s = internal global i32 0, align 4
+// CHECK: @_ZZN3Bar1fIiEEvvE1y = linkonce_odr constant i32 0, align 4
+
diff --git a/clang/test/PCH/local_static.h b/clang/test/PCH/local_static.h
new file mode 100644
index 00000000000..a69382adf83
--- /dev/null
+++ b/clang/test/PCH/local_static.h
@@ -0,0 +1,7 @@
+class Bar {
+public:
+  template<typename T>
+  void f() {
+    static const T y = 0;
+  }
+};