Implement C++ [basic.link]p8.

If a function or variable has a type with no linkage (and is not extern "C"),
any use of it requires a definition within the same translation unit; the idea
is that it is not possible to define the entity elsewhere, so any such use is
necessarily an error.

There is an exception, though: some types formally have no linkage but
nonetheless can be referenced from other translation units (for example, this
happens to anonymous structures defined within inline functions). For entities
with those types, we suppress the diagnostic except under -pedantic.

llvm-svn: 313729

1 files changed, 5 insertions, 2 deletions

diff --git a/clang/test/CodeGenCXX/mangle-ms-cxx11.cpp b/clang/test/CodeGenCXX/mangle-ms-cxx11.cpp
index 819b0d9c9d0..b22c04698ea 100644
--- a/clang/test/CodeGenCXX/mangle-ms-cxx11.cpp
+++ b/clang/test/CodeGenCXX/mangle-ms-cxx11.cpp
@@ -160,6 +160,8 @@ struct { } a;
 decltype(a) fun(decltype(a) x, decltype(a)) { return x; }
 // CHECK-DAG: @"\01?fun@PR18022@@YA?AU<unnamed-type-a>@1@U21@0@Z"
 
+void use_fun() { fun(a, a); }
+
 }
 
 inline int define_lambda() {
@@ -280,7 +282,7 @@ void g() {
 
 namespace PR18204 {
 template <typename T>
-int f(T *);
+int f(T *) { return 0; }
 static union {
   int n = f(this);
 };
@@ -346,4 +348,5 @@ int call_it = (A::default_args(), 1);
 
 enum { enumerator };
 void f(decltype(enumerator)) {}
-// CHECK-DAG: define void @"\01?f@@YAXW4<unnamed-enum-enumerator>@@@Z"(
+// CHECK-DAG: define internal void @"\01?f@@YAXW4<unnamed-enum-enumerator>@@@Z"(
+void use_f() { f(enumerator); }