diff: mode-only change should be noticed by "--patch -w --exit-code"

The codepath to notice the content-level changes, taking certain
no-op changes like "ignore whitespace" into account, forgot that
a mode-only change is still a change.  This resulted in

    $ git diff --patch --exit-code -w

to exit with status 0 even when there is such a mode-only change,
breaking both "--patch" and "--quiet" output formats.

Teach the builtin_diff() codepath that creation and deletion as well
as mode changes are all interesting changes.

Note that the test specifically checks removal of an empty file,
because if there is anything in the preimage (i.e. the removed file
is not empty), the removal would still trigger textual patch output
and the codepath for that does update .found_changes bit to report
that it found an interesting change.  We need to make sure that the
.found_changes bit is set even without triggering textual patch
output.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/diff.c b/diff.c
index 0ce678fc06e796e6f2f63ca1967c4263b4f3966a..998d7ae20ca874e2d4cdd2dbe2d6b39c435be6a0 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -3497,18 +3497,21 @@ static void builtin_diff(const char *name_a,
                strbuf_addf(&header, "%s%snew file mode %06o%s\n", line_prefix, meta, two->mode, reset);
                if (xfrm_msg)
                        strbuf_addstr(&header, xfrm_msg);
+               o->found_changes = 1;
                must_show_header = 1;
        }
        else if (lbl[1][0] == '/') {
                strbuf_addf(&header, "%s%sdeleted file mode %06o%s\n", line_prefix, meta, one->mode, reset);
                if (xfrm_msg)
                        strbuf_addstr(&header, xfrm_msg);
+               o->found_changes = 1;
                must_show_header = 1;
        }
        else {
                if (one->mode != two->mode) {
                        strbuf_addf(&header, "%s%sold mode %06o%s\n", line_prefix, meta, one->mode, reset);
                        strbuf_addf(&header, "%s%snew mode %06o%s\n", line_prefix, meta, two->mode, reset);
+                       o->found_changes = 1;
                        must_show_header = 1;
                }
                if (xfrm_msg)

diff --git a/t/t4015-diff-whitespace.sh b/t/t4015-diff-whitespace.sh
index f3e20dd5bba202ba5d5589e897d753672096b866..02731dccb9741e625a9e263e4f158298681c92c2 100755 (executable)
--- a/t/t4015-diff-whitespace.sh
+++ b/t/t4015-diff-whitespace.sh
@@ -1,7 +1,7 @@
 #!/bin/sh
 #
 # Copyright (c) 2006 Johannes E. Schindelin
-#
+# Copyright (c) 2023 Google LLC
 
 test_description='Test special whitespace in diff engine.
 
@@ -11,6 +11,39 @@ TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 . "$TEST_DIRECTORY"/lib-diff.sh
 
+for opts in --patch --quiet -s
+do
+
+       test_expect_success "status with $opts (different)" '
+               echo foo >x &&
+               git add x &&
+               echo bar >x &&
+               test_expect_code 1 git diff -w $opts --exit-code x
+       '
+
+       test_expect_success POSIXPERM "status with $opts (mode differs)" '
+               test_when_finished "git update-index --chmod=-x x" &&
+               echo foo >x &&
+               git add x &&
+               git update-index --chmod=+x x &&
+               test_expect_code 1 git diff -w $opts --exit-code x
+       '
+
+       test_expect_success "status with $opts (removing an empty file)" '
+               : >x &&
+               git add x &&
+               rm x &&
+               test_expect_code 1 git diff -w $opts --exit-code -- x
+       '
+
+       test_expect_success "status with $opts (different but equivalent)" '
+               echo foo >x &&
+               git add x &&
+               echo " foo" >x &&
+               git diff -w $opts --exit-code x
+       '
+done
+
 test_expect_success "Ray Lehtiniemi's example" '
        cat <<-\EOF >x &&
        do {