want_color: automatically fallback to color.ui

All of the "do we want color" flags default to -1 to
indicate that we don't have any color configured. This value
is handled in one of two ways:

  1. In porcelain, we check early on whether the value is
     still -1 after reading the config, and set it to the
     value of color.ui (which defaults to 0).

  2. In plumbing, it stays untouched as -1, and want_color
     defaults it to off.

This works fine, but means that every porcelain has to check
and reassign its color flag. Now that want_color gives us a
place to put this check in a single spot, we can do that,
simplifying the calling code.

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

builtin/branch.c

@@ -673,9 +673,6 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
 
 	git_config(git_branch_config, NULL);
 
-	if (branch_use_color == -1)
-		branch_use_color = git_use_color_default;
-
 	track = git_branch_track;
 
 	head = resolve_ref("HEAD", head_sha1, 0, NULL);

builtin/commit.c

@@ -1237,10 +1237,6 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 
 	if (s.relative_paths)
 		s.prefix = prefix;
-	if (s.use_color == -1)
-		s.use_color = git_use_color_default;
-	if (diff_use_color_default == -1)
-		diff_use_color_default = git_use_color_default;
 
 	switch (status_format) {
 	case STATUS_FORMAT_SHORT:
@@ -1394,15 +1390,10 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 	git_config(git_commit_config, &s);
 	determine_whence(&s);
 
-	if (s.use_color == -1)
-		s.use_color = git_use_color_default;
 	argc = parse_and_validate_options(argc, argv, builtin_commit_usage,
 					  prefix, &s);
-	if (dry_run) {
-		if (diff_use_color_default == -1)
-			diff_use_color_default = git_use_color_default;
+	if (dry_run)
 		return dry_run_commit(argc, argv, prefix, &s);
-	}
 	index_file = prepare_index(argc, argv, prefix, 0);
 
 	/* Set up everything for writing the commit object.  This includes

builtin/diff.c

@@ -277,9 +277,6 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
 	gitmodules_config();
 	git_config(git_diff_ui_config, NULL);
 
-	if (diff_use_color_default == -1)
-		diff_use_color_default = git_use_color_default;
-
 	init_revisions(&rev, prefix);
 
 	/* If this is a no-index diff, just run it and exit there. */

builtin/grep.c

@@ -883,8 +883,6 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 	strcpy(opt.color_sep, GIT_COLOR_CYAN);
 	opt.color = -1;
 	git_config(grep_config, &opt);
-	if (opt.color == -1)
-		opt.color = git_use_color_default;
 
 	/*
 	 * If there is no -- then the paths must exist in the working

builtin/log.c

@@ -359,9 +359,6 @@ int cmd_whatchanged(int argc, const char **argv, const char *prefix)
 
 	git_config(git_log_config, NULL);
 
-	if (diff_use_color_default == -1)
-		diff_use_color_default = git_use_color_default;
-
 	init_revisions(&rev, prefix);
 	rev.diff = 1;
 	rev.simplify_history = 0;
@@ -446,9 +443,6 @@ int cmd_show(int argc, const char **argv, const char *prefix)
 
 	git_config(git_log_config, NULL);
 
-	if (diff_use_color_default == -1)
-		diff_use_color_default = git_use_color_default;
-
 	init_pathspec(&match_all, NULL);
 	init_revisions(&rev, prefix);
 	rev.diff = 1;
@@ -524,9 +518,6 @@ int cmd_log_reflog(int argc, const char **argv, const char *prefix)
 
 	git_config(git_log_config, NULL);
 
-	if (diff_use_color_default == -1)
-		diff_use_color_default = git_use_color_default;
-
 	init_revisions(&rev, prefix);
 	init_reflog_walk(&rev.reflog_info);
 	rev.verbose_header = 1;
@@ -549,9 +540,6 @@ int cmd_log(int argc, const char **argv, const char *prefix)
 
 	git_config(git_log_config, NULL);
 
-	if (diff_use_color_default == -1)
-		diff_use_color_default = git_use_color_default;
-
 	init_revisions(&rev, prefix);
 	rev.always_show_header = 1;
 	memset(&opt, 0, sizeof(opt));

builtin/merge.c

@@ -1031,10 +1031,6 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 
 	git_config(git_merge_config, NULL);
 
-	/* for color.ui */
-	if (diff_use_color_default == -1)
-		diff_use_color_default = git_use_color_default;
-
 	if (branch_mergeoptions)
 		parse_branch_merge_options(branch_mergeoptions);
 	argc = parse_options(argc, argv, prefix, builtin_merge_options,

builtin/show-branch.c

@@ -685,9 +685,6 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 
 	git_config(git_show_branch_config, NULL);
 
-	if (showbranch_use_color == -1)
-		showbranch_use_color = git_use_color_default;
-
 	/* If nothing is specified, try the default first */
 	if (ac == 1 && default_num) {
 		ac = default_num;

color.c

@@ -1,7 +1,7 @@
 #include "cache.h"
 #include "color.h"
 
-int git_use_color_default = 0;
+static int git_use_color_default = 0;
 int color_stdout_is_tty = -1;
 
 /*
@@ -196,12 +196,15 @@ int want_color(int var)
 {
 	static int want_auto = -1;
 
+	if (var < 0)
+		var = git_use_color_default;
+
 	if (var == GIT_COLOR_AUTO) {
 		if (want_auto < 0)
 			want_auto = check_auto_color();
 		return want_auto;
 	}
-	return var > 0;
+	return var;
 }
 
 int git_color_config(const char *var, const char *value, void *cb)

color.h

@@ -58,11 +58,6 @@ struct strbuf;
 #define GIT_COLOR_ALWAYS 1
 #define GIT_COLOR_AUTO   2
 
-/*
- * This variable stores the value of color.ui
- */
-extern int git_use_color_default;
-
 /* A default list of colors to use for commit graphs and show-branch output */
 extern const char *column_colors_ansi[];
 extern const int column_colors_ansi_max;