Tentative declarations are supposed to have common linkage, not weak.  
This change makes clang generate the same thing as llvm-gcc.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@51674 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 525c13f..0b7d30a 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -500,7 +500,7 @@
       assert(0 && "Can't have auto or register globals");
     case VarDecl::None:
       if (!D->getInit())
-        GV->setLinkage(llvm::GlobalVariable::WeakLinkage);
+        GV->setLinkage(llvm::GlobalVariable::CommonLinkage);
       break;
     case VarDecl::Extern:
     case VarDecl::PrivateExtern: