Fix for Bug 19480 -- Adding a test case.

[lvoufo]

Summary

cf. Bug 19480

[lvoufo]

I pushed the previous patch in since it is a simple extension of existing template implementation logic for variable templates, which continues a trend that we started last summer.

Now, I am adding a test case.
I am not very experienced in writing linkage-level test cases yet. So, I could use additional pairs of eyes. Could someone please take a quick look and let me know if it's okay to go asap?

I imagine that it may be a bit overly verbose, but I'd rather be safer than sorrier.

[rsmith]

test/CodeGenCXX/cxx1y-variable-template-linkage.cpp

10

Instead of #ifdefs, can you merge together the two parts of this file into one? The small amount of the test that differs between the modes can be guarded by

#if __has_feature(cxx_exceptions)

[lvoufo]

Updated with respect to previous comments. Is it ready now?

[rsmith]

LGTM with one thing fixed.

test/CodeGenCXX/cxx1y-variable-template-linkage.cpp

2–3

Please add --check-prefix=CHECK to both of these FileCheck invocations. Otherwise, your CHECK-DAG: lines below will have no effect.

[lvoufo]

Ok. It's now perfect! Right?

[Eugene.Zelenko]

Committed in rL213987.

test/CodeGenCXX/cxx1y-variable-template-linkage.cpp

+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -std=c++1y -O1 -disable-llvm-optzns %s -o - | FileCheck %s -check-prefix=CHECKA -check-prefix=CHECK
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -emit-llvm -std=c++1y -O1 -disable-llvm-optzns -fcxx-exceptions %s -o - | FileCheck %s -check-prefix=CHECKB -check-prefix=CHECK
+// expected-no-diagnostics
+
+// The variable template specialization x<Foo> generated in each file
+// should be 'internal global' and not 'linkonce_odr global'.
+
+template <typename T> int x = 42;
+
+// CHECK-DAG: @_Z1xIZL3foovE3FooE = internal global
+
+// CHECK-DAG: define internal dereferenceable(4) i32* @_ZL3foov(
+static int &foo() {
+   struct Foo { };
+   
+   // CHECK-DAG: ret i32* @_Z1xIZL3foovE3FooE
+   return x<Foo>;
+}
+
+
+#if !__has_feature(cxx_exceptions) // File A
+// CHECKA-DAG: define dereferenceable(4) i32* @_Z3barv(
+int &bar() { 
+  // CHECKA-DAG: %call = call dereferenceable(4) i32* @_ZL3foov()
+  return foo();
+}
+
+#else // File B
+
+// CHECKB-DAG: declare dereferenceable(4) i32* @_Z3barv(
+int &bar();
+
+int main() {
+  // CHECKB-DAG: %call = call dereferenceable(4) i32* @_Z3barv()
+  // CHECKB-DAG: %call1 = call dereferenceable(4) i32* @_ZL3foov()
+  &bar() == &foo() ? throw 0 : (void)0; // Should not throw exception at runtime.
+}
+
+#endif // end of Files A and B
+