From: jsg <jsg@openbsd.org>
Date: Wed, 7 Oct 2015 10:26:23 +0000 (+0000)
Subject: Correct handling of enum attributes with g++
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=26cf605ac021cb49566b375e773978e4ad305ae6;p=openbsd

Correct handling of enum attributes with g++

gcc and g++ can currently have different ideas on the size of a
packed enum type:

enum __attribute__((packed)) foo { a = 0, b};

gcc: 1
g++: 4

enum foo { a = 0, b} __attribute__((packed));

gcc: 1
g++: 1

The first format is actually the preferred one according to the
documentation.
https://gcc.gnu.org/onlinedocs/gcc-4.2.1/gcc/Type-Attributes.html
g++ will accept the first format and silently not actually choose a
smaller size.

This was responsible for memory corruption with recent versions
of Mesa where c and c++ code share a header with a packed enum type.

The problem was reported in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=39219
and fixed in gcc >= 4.3.6 in rev 144284.
This was after the switch from gplv2 but it's a trivial one line change.

ok guenther@ deraadt@ kettenis@
---

diff --git a/gnu/gcc/gcc/cp/parser.c b/gnu/gcc/gcc/cp/parser.c
index e060d49c343..11685688fdf 100644
--- a/gnu/gcc/gcc/cp/parser.c
+++ b/gnu/gcc/gcc/cp/parser.c
@@ -10482,6 +10482,7 @@ cp_parser_enum_specifier (cp_parser* parser)
   if (cp_parser_allow_gnu_extensions_p (parser))
     {
       tree trailing_attr = cp_parser_attributes_opt (parser);
+      trailing_attr = chainon (trailing_attr, attributes);
       cplus_decl_attributes (&type,
 			     trailing_attr,
 			     (int) ATTR_FLAG_TYPE_IN_PLACE);