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>

11 files changed, 26 insertions, 28 deletions

diff --git a/builtin/branch.c b/builtin/branch.c
index b2e1895ca9..0a8ed9d22a 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -93,8 +93,7 @@ static int git_branch_config(const char *var, const char *value, void *cb)
 			return 0;
 		if (!value)
 			return config_error_nonbool(var);
-		color_parse(value, var, branch_colors[slot]);
-		return 0;
+		return color_parse(value, branch_colors[slot]);
 	}
 	return git_color_default_config(var, value, cb);
 }
diff --git a/builtin/clean.c b/builtin/clean.c
index 1032563e5f..035ea391a2 100644
--- a/builtin/clean.c
+++ b/builtin/clean.c
@@ -116,8 +116,7 @@ static int git_clean_config(const char *var, const char *value, void *cb)
 			return 0;
 		if (!value)
 			return config_error_nonbool(var);
-		color_parse(value, var, clean_colors[slot]);
-		return 0;
+		return color_parse(value, clean_colors[slot]);
 	}
 
 	if (!strcmp(var, "clean.requireforce")) {
diff --git a/builtin/commit.c b/builtin/commit.c
index 5a8a29e075..8dab44d933 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1295,8 +1295,7 @@ static int git_status_config(const char *k, const char *v, void *cb)
 			return 0;
 		if (!v)
 			return config_error_nonbool(k);
-		color_parse(v, k, s->color_palette[slot]);
-		return 0;
+		return color_parse(v, s->color_palette[slot]);
 	}
 	if (!strcmp(k, "status.relativepaths")) {
 		s->relative_paths = git_config_bool(k, v);
diff --git a/builtin/config.c b/builtin/config.c
index 7bba516383..842809b0b3 100644
--- a/builtin/config.c
+++ b/builtin/config.c
@@ -296,7 +296,8 @@ static int git_get_color_config(const char *var, const char *value, void *cb)
 	if (!strcmp(var, get_color_slot)) {
 		if (!value)
 			config_error_nonbool(var);
-		color_parse(value, var, parsed_color);
+		if (color_parse(value, parsed_color) < 0)
+			return -1;
 		get_color_found = 1;
 	}
 	return 0;
@@ -309,8 +310,10 @@ static void get_color(const char *def_color)
 	git_config_with_options(git_get_color_config, NULL,
 				&given_config_source, respect_includes);
 
-	if (!get_color_found && def_color)
-		color_parse(def_color, "command line", parsed_color);
+	if (!get_color_found && def_color) {
+		if (color_parse(def_color, parsed_color) < 0)
+			die(_("unable to parse default color value"));
+	}
 
 	fputs(parsed_color, stdout);
 }
diff --git a/builtin/for-each-ref.c b/builtin/for-each-ref.c
index 47bd624696..d41920d382 100644
--- a/builtin/for-each-ref.c
+++ b/builtin/for-each-ref.c
@@ -673,7 +673,8 @@ static void populate_value(struct refinfo *ref)
 		} else if (starts_with(name, "color:")) {
 			char color[COLOR_MAXLEN] = "";
 
-			color_parse(name + 6, "--format", color);
+			if (color_parse(name + 6, color) < 0)
+				die(_("unable to parse format"));
 			v->s = xstrdup(color);
 			continue;
 		} else if (!strcmp(name, "flag")) {
@@ -1007,7 +1008,8 @@ static void show_ref(struct refinfo *info, const char *format, int quote_style)
 		struct atom_value resetv;
 		char color[COLOR_MAXLEN] = "";
 
-		color_parse("reset", "--format", color);
+		if (color_parse("reset", color) < 0)
+			die("BUG: couldn't parse 'reset' as a color");
 		resetv.s = color;
 		print_value(&resetv, quote_style);
 	}
diff --git a/color.c b/color.c
index f672885b71..7941e932d2 100644
--- a/color.c
+++ b/color.c
@@ -60,13 +60,12 @@ static int parse_attr(const char *name, int len)
 	return -1;
 }
 
-void color_parse(const char *value, const char *var, char *dst)
+int color_parse(const char *value, char *dst)
 {
-	color_parse_mem(value, strlen(value), var, dst);
+	return color_parse_mem(value, strlen(value), dst);
 }
 
-void color_parse_mem(const char *value, int value_len, const char *var,
-		char *dst)
+int color_parse_mem(const char *value, int value_len, char *dst)
 {
 	const char *ptr = value;
 	int len = value_len;
@@ -76,7 +75,7 @@ void color_parse_mem(const char *value, int value_len, const char *var,
 
 	if (!strncasecmp(value, "reset", len)) {
 		strcpy(dst, GIT_COLOR_RESET);
-		return;
+		return 0;
 	}
 
 	/* [fg [bg]] [attr]... */
@@ -153,9 +152,9 @@ void color_parse_mem(const char *value, int value_len, const char *var,
 		*dst++ = 'm';
 	}
 	*dst = 0;
-	return;
+	return 0;
 bad:
-	die("bad color value '%.*s' for variable '%s'", value_len, value, var);
+	return error(_("invalid color value: %.*s"), value_len, value);
 }
 
 int git_config_colorbool(const char *var, const char *value)
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)))
diff --git a/diff.c b/diff.c
index 867f034b8f..4493dde749 100644
--- a/diff.c
+++ b/diff.c
@@ -248,8 +248,7 @@ int git_diff_basic_config(const char *var, const char *value, void *cb)
 			return 0;
 		if (!value)
 			return config_error_nonbool(var);
-		color_parse(value, var, diff_colors[slot]);
-		return 0;
+		return color_parse(value, diff_colors[slot]);
 	}
 
 	/* like GNU diff's --suppress-blank-empty option  */
diff --git a/grep.c b/grep.c
index 99217dc04f..4dc31ea386 100644
--- a/grep.c
+++ b/grep.c
@@ -111,7 +111,7 @@ int grep_config(const char *var, const char *value, void *cb)
 	if (color) {
 		if (!value)
 			return config_error_nonbool(var);
-		color_parse(value, var, color);
+		return color_parse(value, color);
 	}
 	return 0;
 }
diff --git a/log-tree.c b/log-tree.c
index 479b1d2a5b..a21ef30d0c 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -73,8 +73,7 @@ int parse_decorate_color_config(const char *var, const char *slot_name, const ch
 		return 0;
 	if (!value)
 		return config_error_nonbool(var);
-	color_parse(value, var, decoration_colors[slot]);
-	return 0;
+	return color_parse(value, decoration_colors[slot]);
 }
 
 /*
diff --git a/pretty.c b/pretty.c
index 31fc76b2fd..6182ca9aed 100644
--- a/pretty.c
+++ b/pretty.c
@@ -979,9 +979,8 @@ static size_t parse_color(struct strbuf *sb, /* in UTF-8 */
 				return end - placeholder + 1;
 			begin += 5;
 		}
-		color_parse_mem(begin,
-				end - begin,
-				"--pretty format", color);
+		if (color_parse_mem(begin, end - begin, color) < 0)
+			die(_("unable to parse --pretty format"));
 		strbuf_addstr(sb, color);
 		return end - placeholder + 1;
 	}