[-fms-extensions] Allow missing exception specifications in redeclarations as an extension

Microsoft's ATL headers make use of this MSVC extension, add support for
it and issue a diagnostic under -Wmicrosoft-exception-spec.

This fixes PR25265.

llvm-svn: 250854

1 files changed, 8 insertions, 0 deletions

diff --git a/clang/test/SemaCXX/MicrosoftExtensions.cpp b/clang/test/SemaCXX/MicrosoftExtensions.cpp
index 11f4f195562..3d11c20148a 100644
--- a/clang/test/SemaCXX/MicrosoftExtensions.cpp
+++ b/clang/test/SemaCXX/MicrosoftExtensions.cpp
@@ -422,3 +422,11 @@ template <typename TX> struct A {
   };
 };
 }
+
+namespace PR25265 {
+struct S {
+  int fn() throw(); // expected-note {{previous declaration is here}}
+};
+
+int S::fn() { return 0; } // expected-warning {{is missing exception specification}}
+}