color_parse: do not mention variable name in error message

Originally the color-parsing function was used only for
config variables. It made sense to pass the variable name so
that the die() message could be something like:

  $ git -c color.branch.plain=bogus branch
  fatal: bad color value 'bogus' for variable 'color.branch.plain'

These days we call it in other contexts, and the resulting
error messages are a little confusing:

  $ git log --pretty='%C(bogus)'
  fatal: bad color value 'bogus' for variable '--pretty format'

  $ git config --get-color foo.bar bogus
  fatal: bad color value 'bogus' for variable 'command line'

This patch teaches color_parse to complain only about the
value, and then return an error code. Config callers can
then propagate that up to the config parser, which mentions
the variable name. Other callers can provide a custom
message. After this patch these three cases now look like:

  $ git -c color.branch.plain=bogus branch
  error: invalid color value: bogus
  fatal: unable to parse 'color.branch.plain' from command-line config

  $ git log --pretty='%C(bogus)'
  error: invalid color value: bogus
  fatal: unable to parse --pretty format

  $ git config --get-color foo.bar bogus
  error: invalid color value: bogus
  fatal: unable to parse default color value

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/color.h b/color.h
index 9a8495bb7f..f5beab1ed7 100644
--- a/color.h
+++ b/color.h
@@ -77,8 +77,8 @@ int git_color_default_config(const char *var, const char *value, void *cb);
 
 int git_config_colorbool(const char *var, const char *value);
 int want_color(int var);
-void color_parse(const char *value, const char *var, char *dst);
-void color_parse_mem(const char *value, int len, const char *var, char *dst);
+int color_parse(const char *value, char *dst);
+int color_parse_mem(const char *value, int len, char *dst);
 __attribute__((format (printf, 3, 4)))
 int color_fprintf(FILE *fp, const char *color, const char *fmt, ...);
 __attribute__((format (printf, 3, 4)))