difftool: Fix '--gui' when diff.guitool is unconfigured

When diff.guitool is unconfigured and "--gui" is specified
git-difftool dies with the following error message:

	config diff.guitool: command returned error: 1

Catch the error so that the "--gui" flag is a no-op when
diff.guitool is unconfigured.

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-difftool.perl b/git-difftool.perl
index d975d072dbf0fab36266c3f3a71a69875206e4d8..adc42de8752fd395707f1e395c61991b3146cebb 100755 (executable)
--- a/git-difftool.perl
+++ b/git-difftool.perl
@@ -78,11 +78,13 @@ sub generate_command
                        next;
                }
                if ($arg eq '-g' || $arg eq '--gui') {
-                       my $tool = Git::command_oneline('config',
-                                                       'diff.guitool');
-                       if (length($tool)) {
-                               $ENV{GIT_DIFF_TOOL} = $tool;
-                       }
+                       eval {
+                               my $tool = Git::command_oneline('config',
+                                                               'diff.guitool');
+                               if (length($tool)) {
+                                       $ENV{GIT_DIFF_TOOL} = $tool;
+                               }
+                       };
                        next;
                }
                if ($arg eq '-y' || $arg eq '--no-prompt') {

diff --git a/t/t7800-difftool.sh b/t/t7800-difftool.sh
index 19c72f55bf60c746f72e640e24043b2d83e00fe3..1de83ef98fdcbfd63469e66ba4886c2477b983ff 100755 (executable)
--- a/t/t7800-difftool.sh
+++ b/t/t7800-difftool.sh
@@ -92,6 +92,15 @@ test_expect_success 'difftool honors --gui' '
        restore_test_defaults
 '
 
+test_expect_success 'difftool --gui works without configured diff.guitool' '
+       git config diff.tool test-tool &&
+
+       diff=$(git difftool --no-prompt --gui branch) &&
+       test "$diff" = "branch" &&
+
+       restore_test_defaults
+'
+
 # Specify the diff tool using $GIT_DIFF_TOOL
 test_expect_success 'GIT_DIFF_TOOL variable' '
        git config --unset diff.tool