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[PATCH 1/2] diff: report copies and renames as changes in run_diff_cmd()

From
René Scharfe <l.s.r@web.de>
Date
Sep 8, 2024, 07:05 UTC
Message-ID
<130d4803-2818-4611-9258-951a18dd5717@web.de>

The diff machinery has two ways to detect changes to set the exit code: Just comparing hashes and comparing blob contents. The latter is needed if certain changes have to be ignored, e.g. with --ignore-space-change or --ignore-matching-lines. It's enabled by the diff_options flag diff_from_contents.

The slower mode has never considered copies and renames to be changes, which is inconsistent with the quicker one. Fix it. Even if we ignore the file contents (because it's empty or contains only ignored lines), there's still the meta data change of adding or changing a filename, so we need to report it in the exit code.

d7b97b7185 (diff: let external diffs report that changes are uninteresting, 2024-06-09) set diff_from_contents if external diff programs are allowed. This is the default e.g. for git diff, and so that change exposed the inconsistency much more widely.

Reported-by: Jorge Luis Martinez Gomez <jol@jol.dev>
Signed-off-by: René Scharfe <l.s.r@web.de>
---
 diff.c                 |  3 +++
 t/t4017-diff-retval.sh | 16 ++++++++++++++++
 2 files changed, 19 insertions(+)
diff --git a/diff.c b/diff.c
index 4035a9374d..1d2057d4cb 100644
--- a/diff.c
+++ b/diff.c
@@ -4587,6 +4587,9 @@ static void run_diff_cmd(const struct external_diff *pgm,
 		builtin_diff(name, other ? other : name,
 			     one, two, xfrm_msg, must_show_header,
 			     o, complete_rewrite);
+		if (p->status == DIFF_STATUS_COPIED ||
+		    p->status == DIFF_STATUS_RENAMED)
+			o->found_changes = 1;
 	} else {
 		fprintf(o->file, "* Unmerged path %s\n", name);
 		o->found_changes = 1;
diff --git a/t/t4017-diff-retval.sh b/t/t4017-diff-retval.sh
index f439f469bd..9a4f578614 100755
--- a/t/t4017-diff-retval.sh
+++ b/t/t4017-diff-retval.sh
@@ -143,4 +143,20 @@ test_expect_success 'option errors are not confused by --exit-code' '
 	grep '^usage:' err
 '

+for option in --exit-code --quiet
+do
+	test_expect_success "git diff $option returns 1 for copied file" "
+		git reset --hard &&
+		cp a copy &&
+		git add copy &&
+		test_expect_code 1 git diff $option --cached --find-copies-harder
+	"
+
+	test_expect_success "git diff $option returns 1 for renamed file" "
+		git reset --hard &&
+		git mv a renamed &&
+		test_expect_code 1 git diff $option --cached
+	"
+done
+
 test_done
--
2.46.0
Next: René Scharfe
Message 1 of 4 in “diff: report copies and renames as changes in run_diff_cmd()”
  1. 1/2 diff: report copies and renames as changes in run_diff_cmd()René Scharfe, Sep 8, 2024
  2. 2/2 diff: report dirty submodules as changes in builtin_diff()René Scharfe, Sep 8, 2024
  3. Phillip WoodSep 9, 2024
  4. Junio C HamanoSep 9, 2024

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