Re: [PATCH 2/2] fix clang -Wtautological-compare with unsigned enum

> Create a GREP_HEADER_FIELD_MIN so we can check that the field value is
> sane and silent the clang warning.
>
> Clang warning happens because the enum is unsigned (this is
> implementation-defined, and there is no negative fields) and the check
> is then tautological.
>
> Signed-off-by: Antoine Pelisse <apelisse@gmail.com>
> ---
> I tried to consider discussion [1] and this [2] discussion on clang's list
>
> With these two patches and the patch from Max Horne, I'm finally able to
> compile with CC=clang CFLAGS=-Werror.
>
>  [1]: http://thread.gmane.org/gmane.comp.version-control.git/184908
>  [2]: http://clang-developers.42468.n3.nabble.com/Possibly-invalid-enum-tautology-warning-td3233140.html
>
>  grep.c | 3 ++-
>  grep.h | 3 ++-
>  2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/grep.c b/grep.c
> index 4bd1b8b..bb548ca 100644
> --- a/grep.c
> +++ b/grep.c
> @@ -625,7 +625,8 @@ static struct grep_expr *prep_header_patterns(struct grep_opt *opt)
>         for (p = opt->header_list; p; p = p->next) {
>                 if (p->token != GREP_PATTERN_HEAD)
>                         die("bug: a non-header pattern in grep header list.");
> -               if (p->field < 0 || GREP_HEADER_FIELD_MAX <= p->field)
> +               if (p->field < GREP_HEADER_FIELD_MIN ||
> +                   GREP_HEADER_FIELD_MAX <= p->field)
>                         die("bug: unknown header field %d", p->field);
>                 compile_regexp(p, opt);
>         }
> diff --git a/grep.h b/grep.h
> index 8fc854f..e4a1df5 100644
> --- a/grep.h
> +++ b/grep.h
> @@ -28,7 +28,8 @@ enum grep_context {
>  };
>
>  enum grep_header_field {
> -       GREP_HEADER_AUTHOR = 0,
> +       GREP_HEADER_FIELD_MIN = 0,
> +       GREP_HEADER_AUTHOR = GREP_HEADER_FIELD_MIN,
>         GREP_HEADER_COMMITTER,
>         GREP_HEADER_REFLOG,
>
> --
> 1.8.1.1.435.g20d29be.dirty
>