Re: [PATCH v2 02/25] isxdigit: cast input to unsigned char

> Otherwise, callers must do so or risk triggering warnings
> -Wchar-subscript (and rightfully so; a signed char might
> cause us to use a bogus negative index into the
> hexval_table).
>
> While we are dropping the now-unnecessary casts from the
> caller in urlmatch.c, we can get rid of similar casts in
> actually parsing the hex by using the hexval() helper, which
> implicitly casts to unsigned (but note that we cannot
> implement isxdigit in terms of hexval(), as it also casts
> its return value to unsigned).
>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
> The patch that added more calls to isxdigit later in the series actually
> got reworked. So this is purely a cleanup and can be dropped if need be,
> though I still think it is an improvement.

>
>  git-compat-util.h | 2 +-
>  urlmatch.c        | 8 ++++----
>  2 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/git-compat-util.h b/git-compat-util.h
> index fb41118..44890d5 100644
> --- a/git-compat-util.h
> +++ b/git-compat-util.h
> @@ -677,7 +677,7 @@ extern const unsigned char sane_ctype[256];
>  #define iscntrl(x) (sane_istest(x,GIT_CNTRL))
>  #define ispunct(x) sane_istest(x, GIT_PUNCT | GIT_REGEX_SPECIAL | \
>  		GIT_GLOB_SPECIAL | GIT_PATHSPEC_MAGIC)
> -#define isxdigit(x) (hexval_table[x] != -1)
> +#define isxdigit(x) (hexval_table[(unsigned char)(x)] != -1)
>  #define tolower(x) sane_case((unsigned char)(x), 0x20)
>  #define toupper(x) sane_case((unsigned char)(x), 0)
>  #define is_pathspec_magic(x) sane_istest(x,GIT_PATHSPEC_MAGIC)
> diff --git a/urlmatch.c b/urlmatch.c
> index 3d4c54b..618d216 100644
> --- a/urlmatch.c
> +++ b/urlmatch.c
> @@ -43,11 +43,11 @@ static int append_normalized_escapes(struct strbuf *buf,
>  		from_len--;
>  		if (ch == '%') {
>  			if (from_len < 2 ||
> -			    !isxdigit((unsigned char)from[0]) ||
> -			    !isxdigit((unsigned char)from[1]))
> +			    !isxdigit(from[0]) ||
> +			    !isxdigit(from[1]))
>  				return 0;
> -			ch = hexval_table[(unsigned char)*from++] << 4;
> -			ch |= hexval_table[(unsigned char)*from++];
> +			ch = hexval(*from++) << 4;
> +			ch |= hexval(*from++);
>  			from_len -= 2;
>  			was_esc = 1;
>  		}