c++: support gcc's application of weak attribute on

class declaration which forces any such class and any 
class that inherits from such a class to have their 
typeinfo symbols be marked as weak.
// rdar://10246395
A    test/CodeGenCXX/weak-extern-typeinfo.cpp
M    lib/Sema/SemaDeclCXX.cpp
M    lib/Sema/SemaDeclAttr.cpp
M    lib/CodeGen/CGRTTI.cpp


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@142693 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 0 deletions

diff --git a/lib/CodeGen/CGRTTI.cpp b/lib/CodeGen/CGRTTI.cpp
index 1b3cb08284..d9790d0b9e 100644
--- a/lib/CodeGen/CGRTTI.cpp
+++ b/lib/CodeGen/CGRTTI.cpp
@@ -336,6 +336,8 @@ getTypeInfoLinkage(CodeGenModule &CGM, QualType Ty) {
 
     if (const RecordType *Record = dyn_cast<RecordType>(Ty)) {
       const CXXRecordDecl *RD = cast<CXXRecordDecl>(Record->getDecl());
+      if (RD->hasAttr<WeakAttr>())
+        return llvm::GlobalValue::WeakODRLinkage;
       if (RD->isDynamicClass())
         return CGM.getVTableLinkage(RD);
     }