[c++1z] P0003R5: Removing dynamic exception specifications.

We continue to support dynamic exception specifications in C++1z as an
extension, but produce an error-by-default warning when we encounter one. This
allows users to opt back into the feature with a warning flag, and implicitly
opts system headers back into the feature should they happen to use it.

There is one semantic change implied by P0003R5 but not implemented here:
violating a throw() exception specification should now call std::terminate
directly instead of calling std::unexpected(), but since P0003R5 also removes
std::unexpected() and std::set_unexpected, and the default unexpected handler
calls std::terminate(), a conforming C++1z program cannot tell that we are
still calling it. The upside of this strategy is perfect backwards
compatibility; the downside is that we don't get the more efficient 'noexcept'
codegen for 'throw()'.

llvm-svn: 289019

1 files changed, 5 insertions, 1 deletions

diff --git a/clang/lib/Parse/ParseDeclCXX.cpp b/clang/lib/Parse/ParseDeclCXX.cpp
index e353c79f4cb..332735a1619 100644
--- a/clang/lib/Parse/ParseDeclCXX.cpp
+++ b/clang/lib/Parse/ParseDeclCXX.cpp
@@ -3513,7 +3513,11 @@ static void diagnoseDynamicExceptionSpecification(
     Parser &P, SourceRange Range, bool IsNoexcept) {
   if (P.getLangOpts().CPlusPlus11) {
     const char *Replacement = IsNoexcept ? "noexcept" : "noexcept(false)";
-    P.Diag(Range.getBegin(), diag::warn_exception_spec_deprecated) << Range;
+    P.Diag(Range.getBegin(),
+           P.getLangOpts().CPlusPlus1z && !IsNoexcept
+               ? diag::ext_dynamic_exception_spec
+               : diag::warn_exception_spec_deprecated)
+        << Range;
     P.Diag(Range.getBegin(), diag::note_exception_spec_deprecated)
       << Replacement << FixItHint::CreateReplacement(Range, Replacement);
   }