Reinstate r185229, reverted in r185256, with a tweak: further ignore the

standard's rule that an extern "C" declaration conflicts with any entity in the
global scope with the same name. Now we only care if the global scope entity is
a variable declaration (and so might have the same mangled name as the extern
"C" declaration). This has been reported as a standard defect.

Original commit message:

PR7927, PR16247: Reimplement handling of matching extern "C" declarations
across scopes.

When we declare an extern "C" name that is not a redeclaration of an entity in
the same scope, check whether it redeclares some extern "C" entity from another
scope, and if not, check whether it conflicts with a (non-extern-"C") entity in
the translation unit.

When we declare a name in the translation unit that is not a redeclaration,
check whether it conflicts with any extern "C" entities (possibly from other
scopes).

llvm-svn: 185281

1 files changed, 15 insertions, 0 deletions

diff --git a/clang/test/Sema/overloadable.c b/clang/test/Sema/overloadable.c
index 5d39f15ec81..ad021898f2a 100644
--- a/clang/test/Sema/overloadable.c
+++ b/clang/test/Sema/overloadable.c
@@ -69,3 +69,18 @@ void test() {
   f0();
   f1();
 }
+
+void before_local_1(int) __attribute__((overloadable)); // expected-note {{here}}
+void before_local_2(int); // expected-note {{here}}
+void before_local_3(int) __attribute__((overloadable));
+void local() {
+  void before_local_1(char); // expected-error {{must have the 'overloadable' attribute}}
+  void before_local_2(char) __attribute__((overloadable)); // expected-error {{conflicting types}}
+  void before_local_3(char) __attribute__((overloadable));
+  void after_local_1(char); // expected-note {{here}}
+  void after_local_2(char) __attribute__((overloadable)); // expected-note {{here}}
+  void after_local_3(char) __attribute__((overloadable));
+}
+void after_local_1(int) __attribute__((overloadable)); // expected-error {{conflicting types}}
+void after_local_2(int); // expected-error {{must have the 'overloadable' attribute}}
+void after_local_3(int) __attribute__((overloadable));