[GCC] Support for __final specifier

As reported in bug 28473, GCC supports "final" functionality in pre-C++11 code using the __final keyword. Clang currently supports the "final" keyword in accordance with the C++11 specification, however it ALSO supports it in pre-C++11 mode, with a warning.

This patch adds the "__final" keyword for compatibility with GCC in GCC Keywords mode (so it is enabled with existing flags), and issues a warning on its usage (suggesting switching to the C++11 keyword). This patch also adds a regression test for the functionality described. I believe this patch has minimal impact, as it simply adds a new keyword for existing behavior.

This has been validated with check-clang to avoid regressions. Patch is created in reference to revisions 276665.

Patch by Erich Keane.

Differential Revision: https://reviews.llvm.org/D22919

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@277134 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 0 deletions

diff --git a/lib/Sema/DeclSpec.cpp b/lib/Sema/DeclSpec.cpp
index c294658c03..42d4633dd8 100644
--- a/lib/Sema/DeclSpec.cpp
+++ b/lib/Sema/DeclSpec.cpp
@@ -1299,6 +1299,7 @@ bool VirtSpecifiers::SetSpecifier(Specifier VS, SourceLocation Loc,
   switch (VS) {
   default: llvm_unreachable("Unknown specifier!");
   case VS_Override: VS_overrideLoc = Loc; break;
+  case VS_GNU_Final:
   case VS_Sealed:
   case VS_Final:    VS_finalLoc = Loc; break;
   }
@@ -1311,6 +1312,7 @@ const char *VirtSpecifiers::getSpecifierName(Specifier VS) {
   default: llvm_unreachable("Unknown specifier");
   case VS_Override: return "override";
   case VS_Final: return "final";
+  case VS_GNU_Final: return "__final";
   case VS_Sealed: return "sealed";
   }
 }