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: 185229

1 files changed, 12 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/linkage2.cpp b/clang/test/SemaCXX/linkage2.cpp
index a811575c612..c97a2f4ba74 100644
--- a/clang/test/SemaCXX/linkage2.cpp
+++ b/clang/test/SemaCXX/linkage2.cpp
@@ -201,3 +201,15 @@ namespace test18 {
   }
   void *h() { return f(); }
 }
+
+extern "C" void pr16247_foo(int); // expected-note {{here}}
+static void pr16247_foo(double); // expected-error {{conflicts with declaration with C language linkage}}
+void pr16247_foo(int) {}
+void pr16247_foo(double) {}
+
+namespace PR16247 {
+  extern "C" void pr16247_bar(int);
+  static void pr16247_bar(double);
+  void pr16247_bar(int) {}
+  void pr16247_bar(double) {}
+}