PATCH RFC: Fix enum comparisons

[Richard Guenther]

On Thu, Sep 4, 2008 at 1:26 AM, Joseph S. Myers <joseph@codesourcery.com> wrote:
> On Wed, 3 Sep 2008, Ian Lance Taylor wrote:
>
>> The first attachment below is the -Wenum-compare support.  I don't
>> propose to apply that patch now, but I would be interested in any
>> comments from the C frontend maintainers.  I have not yet updated the
>> documentation; basically, -Wenum-compare is the default in C++, and in
>> C it is enabled by -Wall or -Wc++-compat.
>
> The C patch seems fine (for stage 1) to me.

Note that I think -Wenum-compare should _not_ be enabled with -Wall.
That is, I suppose -Wenum-compare will warn about comparing against
integer constants as well, which is commonly used in C code that
defines bitmask members as enums like

enum C { bit1 = 1, bit2 = 2, bit3 = 4 };

and then do

enum C x;
if (x == bit1 | bit2)

Richard.