color: downgrade "always" to "auto" only for on-disk configuration

An earlier patch downgraded "always" that comes via the ui.color
configuration variable to "auto", in order to work around an
unfortunate regression to "git add -i".

That "fix" however regressed other third-party tools that depend on
"git -c color.ui=always cmd" as the way to defeat any end-user
configuration and force coloured output from git subcommand, even
when the output does not go to a terminal.

It is a bit ugly to treat "-c color.ui=always" from the command line
differently from a definition that comes from on-disk configuration
files, but it is a moral equivalent of "--color=always" option given
to the subcommand from the command line, i.e. a signal that tells us
that the script writer knows what s/he is doing.  So let's take that
route to unbreak this case while defeating a (now declared to be)
misguided color.ui that is set to always in the configuration file.

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

2 files changed, 26 insertions, 2 deletions

diff --git a/color.c b/color.c
index 17e2713f96..5b06c76bdc 100644
--- a/color.c
+++ b/color.c
@@ -307,8 +307,21 @@ int git_config_colorbool(const char *var, const char *value)
 	if (value) {
 		if (!strcasecmp(value, "never"))
 			return 0;
-		if (!strcasecmp(value, "always"))
-			return var ? GIT_COLOR_AUTO : 1;
+		if (!strcasecmp(value, "always")) {
+			/*
+			 * Command-line options always respect "always".
+			 * Likewise for "-c" config on the command-line.
+			 */
+			if (!var ||
+			    current_config_scope() == CONFIG_SCOPE_CMDLINE)
+				return 1;
+
+			/*
+			 * Otherwise, we're looking at on-disk config;
+			 * downgrade to auto.
+			 */
+			return GIT_COLOR_AUTO;
+		}
 		if (!strcasecmp(value, "auto"))
 			return GIT_COLOR_AUTO;
 	}
diff --git a/t/t6006-rev-list-format.sh b/t/t6006-rev-list-format.sh
index 25a9c65dc5..582cab5c8a 100755
--- a/t/t6006-rev-list-format.sh
+++ b/t/t6006-rev-list-format.sh
@@ -261,6 +261,17 @@ test_expect_success 'rev-list %C(auto,...) respects --color' '
 	test_cmp expect actual
 '
 
+test_expect_success "color.ui=always in config file same as auto" '
+	test_config color.ui always &&
+	git log --format=$COLOR -1 >actual &&
+	has_no_color actual
+'
+
+test_expect_success "color.ui=always on command-line is always" '
+	git -c color.ui=always log --format=$COLOR -1 >actual &&
+	has_color actual
+'
+
 iconv -f utf-8 -t $test_encoding > commit-msg <<EOF
 Test printing of complex bodies