range-diff: avoid compiler warning when char is unsigned

Commit Message

René Scharfe Feb. 28, 2023, 4:13 p.m. UTC

Since 2b15969f61 (range-diff: let '--abbrev' option takes effect,
2023-02-20), GCC 11.3 on Ubuntu 22.04 on aarch64 warns (and errors
out if the make variable DEVELOPER is set):

range-diff.c: In function ‘output_pair_header’:
range-diff.c:388:20: error: comparison is always false due to limited range of data type [-Werror=type-limits]
  388 |         if (abbrev < 0)
      |                    ^
cc1: all warnings being treated as errors

That's because char is unsigned on that platform.  Use int instead, just
like in struct diff_options, to copy the value faithfully.

Signed-off-by: René Scharfe <[e-mail]>
---
 range-diff.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--
2.34.1

Comments

Junio C Hamano Feb. 28, 2023, 11:44 p.m. UTC | #1

René Scharfe <[e-mail]> writes:

> Since 2b15969f61 (range-diff: let '--abbrev' option takes effect,
> 2023-02-20), GCC 11.3 on Ubuntu 22.04 on aarch64 warns (and errors
> out if the make variable DEVELOPER is set):
>
> range-diff.c: In function ‘output_pair_header’:
> range-diff.c:388:20: error: comparison is always false due to limited range of data type [-Werror=type-limits]
>   388 |         if (abbrev < 0)
>       |                    ^
> cc1: all warnings being treated as errors
>
> That's because char is unsigned on that platform.  Use int instead, just
> like in struct diff_options, to copy the value faithfully.
>
> Signed-off-by: René Scharfe <[e-mail]>
> ---
>  range-diff.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Very clearly explained.  The patch does make sense.

Thanks.

> diff --git a/range-diff.c b/range-diff.c
> index 086365dffb..4bd65ab749 100644
> --- a/range-diff.c
> +++ b/range-diff.c
> @@ -383,7 +383,7 @@ static void output_pair_header(struct diff_options *diffopt,
>  	const char *color_new = diff_get_color_opt(diffopt, DIFF_FILE_NEW);
>  	const char *color_commit = diff_get_color_opt(diffopt, DIFF_COMMIT);
>  	const char *color;
> -	char abbrev = diffopt->abbrev;
> +	int abbrev = diffopt->abbrev;
>
>  	if (abbrev < 0)
>  		abbrev = DEFAULT_ABBREV;
> --
> 2.34.1

Patch

diff --git a/range-diff.c b/range-diff.c
index 086365dffb..4bd65ab749 100644
--- a/range-diff.c
+++ b/range-diff.c
@@ -383,7 +383,7 @@  static void output_pair_header(struct diff_options *diffopt,
 	const char *color_new = diff_get_color_opt(diffopt, DIFF_FILE_NEW);
 	const char *color_commit = diff_get_color_opt(diffopt, DIFF_COMMIT);
 	const char *color;
-	char abbrev = diffopt->abbrev;
+	int abbrev = diffopt->abbrev;

 	if (abbrev < 0)
 		abbrev = DEFAULT_ABBREV;