As Paul Eggert says in the PR, we shouldn't warn for enum bit-fields
in C99/C11 mode. C11 6.7.2.1 (5) says "A bit-field shall have a type
that is a qualified or unqualified version of _Bool, signed int,
unsigned int, or some other implementation-defined type.", so ISTM
that enum bit-fields should be fine. OTOH, I would warn in ISO C
mode. It's true that no constraint is violated, but in C89 in 3.5.2.1
Semantics there's: "A bit-field may have type int, unsigned int, or
signed int." so it seems desirable to warn in this case.
Regtested/bootstrapped on x86_64-linux, ok for trunk?
2014-01-03 Marek Polacek <pola...@redhat.com>
PR c/57773
c/
* c-decl.c (check_bitfield_type_and_width): Warn for enum bit-fields
only in ISO C.
testsuite/
* gcc.dg/pr57773.c: New test.
--- gcc/c/c-decl.c.mp 2014-01-03 13:50:37.041997222 +0100
+++ gcc/c/c-decl.c 2014-01-03 14:46:29.115816235 +0100
@@ -4840,7 +4840,8 @@ check_bitfield_type_and_width (tree *typ
if (!in_system_header_at (input_location)
&& type_mv != integer_type_node
&& type_mv != unsigned_type_node
- && type_mv != boolean_type_node)
+ && type_mv != boolean_type_node
+ && !flag_isoc99)
pedwarn (input_location, OPT_Wpedantic,
"type of bit-field %qs is a GCC extension", name);
--- gcc/testsuite/gcc.dg/pr57773.c.mp 2014-01-03 14:50:51.097902818 +0100
+++ gcc/testsuite/gcc.dg/pr57773.c 2014-01-03 14:49:05.727462306 +0100
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+/* { dg-options "-std=c99 -Wpedantic" } */
+
+enum e { zero };
+struct { enum e field: 2; } s;
Marek
