[RFC 04/12] Add randomize_layout warning for unions

[Connor Kuehl via cfe-commits]

There is no technical advantage to randomizing the order
fields within unions as they all share the same offset.

Co-authored-by: Cole Nixon <nixontcole at gmail.com>
Co-authored-by: Connor Kuehl <cipkuehl at gmail.com>
Co-authored-by: James Foster <jafosterja at gmail.com>
Co-authored-by: Jeff Takahashi <jeffrey.takahashi at gmail.com>
Co-authored-by: Jordan Cantrell <jordan.cantrell at mail.com>
Co-authored-by: Nikk Forbus <nicholas.forbus at gmail.com>
Co-authored-by: Tim Pugh <nwtpugh at gmail.com>
---
 clang/include/clang/Basic/DiagnosticASTKinds.td | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/clang/include/clang/Basic/DiagnosticASTKinds.td b/clang/include/clang/Basic/DiagnosticASTKinds.td
index c2a390fa465..406325d3677 100644
--- a/clang/include/clang/Basic/DiagnosticASTKinds.td
+++ b/clang/include/clang/Basic/DiagnosticASTKinds.td
@@ -343,4 +343,6 @@ def warn_padded_struct_size : Warning<
   InGroup<Padded>, DefaultIgnore;
 def warn_unnecessary_packed : Warning<
   "packed attribute is unnecessary for %0">, InGroup<Packed>, DefaultIgnore;
+def warn_randomize_attr_union : Warning<
+  "union declared with 'randomize_layout' attribute">, InGroup<DiagGroup<"randomize-layout">>;
 }
-- 
2.17.1