Emit -Wfortify-source using DiagRuntimeBehaviour

This fixes a false positive on the following, where st is configured to have
different sizes based on some preprocessor logic:

  if (sizeof(buf) == sizeof(*st))
    memcpy(&buf, st, sizeof(*st));

llvm-svn: 357041

1 files changed, 3 insertions, 0 deletions

diff --git a/clang/test/Sema/warn-fortify-source.c b/clang/test/Sema/warn-fortify-source.c
index 208ff6909f1..3cd939a2d99 100644
--- a/clang/test/Sema/warn-fortify-source.c
+++ b/clang/test/Sema/warn-fortify-source.c
@@ -20,6 +20,9 @@ void call_memcpy() {
   char dst[10];
   char src[20];
   memcpy(dst, src, 20); // expected-warning {{memcpy' will always overflow; destination buffer has size 10, but size argument is 20}}
+
+  if (sizeof(dst) == sizeof(src))
+    memcpy(dst, src, 20); // no warning, unreachable
 }
 
 void call_memcpy_type() {