add--interactive: fix missing file prompt for patch mode with "-i"

When invoked as "git add -i", each menu interactive menu
option prompts the user to select a list of files. This
includes the "patch" option, which gets the list before
starting the hunk-selection loop.

As "git add -p", it behaves differently, and jumps straight
to the hunk selection loop.

Since 0539d5e (i18n: add--interactive: mark patch prompt
for translation, 2016-12-14), the "add -i" case mistakenly
jumps to straight to the hunk-selection loop. Prior to that
commit the distinction between the two cases was managed by
the $patch_mode variable. That commit used $patch_mode for
something else, and moved the old meaning to the "$cmd"
variable.  But it forgot to update the $patch_mode check
inside patch_update_cmd() which controls the file-list
behavior.

The simplest fix would be to change that line to check $cmd.
But while we're here, let's use a less obscure name for this
flag: $patch_mode_only, a boolean which tells whether we are
in full-interactive mode or only in patch-mode.

Reported-by: Henrik Grubbström <grubba@grubba.org>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: peff

git-add--interactive.perl

@@ -92,7 +92,7 @@ sub colored {
 }
 
 # command line options
-my $cmd;
+my $patch_mode_only;
 my $patch_mode;
 my $patch_mode_revision;
 
@@ -1299,7 +1299,7 @@ sub patch_update_cmd {
 		}
 		return 0;
 	}
-	if ($patch_mode) {
+	if ($patch_mode_only) {
 		@them = @mods;
 	}
 	else {
@@ -1721,7 +1721,7 @@ sub process_args {
 		die sprintf(__("invalid argument %s, expecting --"),
 			       $arg) unless $arg eq "--";
 		%patch_mode_flavour = %{$patch_modes{$patch_mode}};
-		$cmd = 1;
+		$patch_mode_only = 1;
 	}
 	elsif ($arg ne "--") {
 		die sprintf(__("invalid argument %s, expecting --"), $arg);
@@ -1758,7 +1758,7 @@ sub main_loop {
 
 process_args();
 refresh();
-if ($cmd) {
+if ($patch_mode_only) {
 	patch_update_cmd();
 }
 else {

t/t3701-add-interactive.sh

@@ -394,4 +394,22 @@ test_expect_success 'diffs can be colorized' '
 	grep "$(printf "\\033")" output
 '
 
+test_expect_success 'patch-mode via -i prompts for files' '
+	git reset --hard &&
+
+	echo one >file &&
+	echo two >test &&
+	git add -i <<-\EOF &&
+	patch
+	test
+
+	y
+	quit
+	EOF
+
+	echo test >expect &&
+	git diff --cached --name-only >actual &&
+	test_cmp expect actual
+'
+
 test_done