Handle the edge case of a weak function with incomplete type correctly.

Found by code inspection; I haven't seen this in real-world code.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@72408 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CodeGenModule.cpp

@@ -373,7 +373,9 @@ void CodeGenModule::SetInternalFunctionAttributes(const Decl *D,
 }
 
 void CodeGenModule::SetFunctionAttributes(const FunctionDecl *FD,
-                                          llvm::Function *F) {
+                                          llvm::Function *F,
+                                          bool IsIncompleteFunction) {
+  if (!IsIncompleteFunction)
     SetLLVMFunctionAttributes(FD, getTypes().getFunctionInfo(FD), F);
   
   // Only a few attributes are set on declarations; these may later be
@@ -625,18 +627,19 @@ llvm::Constant *CodeGenModule::GetOrCreateLLVMFunction(const char *MangledName,
   // This function doesn't have a complete type (for example, the return
   // type is an incomplete struct). Use a fake type instead, and make
   // sure not to try to set attributes.
-  bool ShouldSetAttributes = true;
+  bool IsIncompleteFunction = false;
   if (!isa<llvm::FunctionType>(Ty)) {
     Ty = llvm::FunctionType::get(llvm::Type::VoidTy,
                                  std::vector<const llvm::Type*>(), false);
-    ShouldSetAttributes = false;
+    IsIncompleteFunction = true;
   }
   llvm::Function *F = llvm::Function::Create(cast<llvm::FunctionType>(Ty), 
                                              llvm::Function::ExternalLinkage,
                                              "", &getModule());
   F->setName(MangledName);
-  if (D.getDecl() && ShouldSetAttributes)
-    SetFunctionAttributes(cast<FunctionDecl>(D.getDecl()), F);
+  if (D.getDecl())
+    SetFunctionAttributes(cast<FunctionDecl>(D.getDecl()), F,
+                          IsIncompleteFunction);
   Entry = F;
   return F;
 }

lib/CodeGen/CodeGenModule.h

@@ -402,7 +402,8 @@ private:
   /// SetFunctionAttributes - Set function attributes for a function
   /// declaration.
   void SetFunctionAttributes(const FunctionDecl *FD,
-                             llvm::Function *F);
+                             llvm::Function *F,
+                             bool IsIncompleteFunction);
 
   /// EmitGlobal - Emit code for a singal global function or var decl. Forward
   /// declarations are emitted lazily.

test/CodeGen/weak-incomplete.c

@@ -0,0 +1,5 @@
+// RUN: clang-cc -emit-llvm < %s | grep 'extern_weak' | count 1
+
+struct S;
+void __attribute__((weak)) foo1(struct S);
+void (*foo2)(struct S) = foo1;