read-cache: disable renames in add_files_to_cache

add_files_to_cache() refreshes the index from worktree changes and does not need rename detection. When unmerged entries and a deleted stage-0 path are present together, rename detection can pair them and rewrite an unmerged diff pair to point at the deleted path. That later makes "git commit -a" and "git add -u" try to stat the deleted path and die with "unable to stat". Disable rename detection in this callback-driven staging path and add a regression test covering the crash. Signed-off-by: Nick Golden <blindmansion@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Nick Golden committed Apr 1, 2026 at 15:00 UTC c0ce43376b178d876bce2073b81737ce49657def
2 files changed +39
read-cache.c
+1
@@ -3975,6 +3975,7 @@ int add_files_to_cache(struct repository *repo, const char *prefix,
3975 rev.diffopt.format_callback = update_callback;
3976 rev.diffopt.format_callback_data = &data;
3977 rev.diffopt.flags.override_submodule_config = 1;
3978 + rev.diffopt.detect_rename = 0; /* staging worktree changes does not need renames */
3979 rev.max_count = 0; /* do not compare unmerged paths with stage #2 */
3980
3981 /*
t/t2200-add-update.sh
+38
@@ -200,6 +200,44 @@ test_expect_success 'add -u resolves unmerged paths' '
200 test_cmp expect actual
201 '
202
203 +test_expect_success 'add -u avoids rename pairing on unmerged paths' '
204 + test_create_repo rename-crash &&
205 + (
206 + cd rename-crash &&
207 + test_seq 1 100 |
208 + sed "s/.*/line &: same text/" >conflict.txt &&
209 + cp conflict.txt bystander.txt &&
210 + git add conflict.txt bystander.txt &&
211 + git commit -m "initial: two files with identical content" &&
212 + main_branch=$(git symbolic-ref --short HEAD) &&
213 + git checkout -b feature &&
214 + sed "s/^line 50:.*/line 50: FEATURE/" \
215 + conflict.txt >conflict.txt.tmp &&
216 + mv conflict.txt.tmp conflict.txt &&
217 + git add conflict.txt &&
218 + git commit -m "feature: modify line 50" &&
219 + git checkout "$main_branch" &&
220 + sed "s/^line 50:.*/line 50: MAIN/" \
221 + conflict.txt >conflict.txt.tmp &&
222 + mv conflict.txt.tmp conflict.txt &&
223 + git add conflict.txt &&
224 + git commit -m "main: modify line 50 differently" &&
225 + test_must_fail git merge feature &&
226 + rm bystander.txt &&
227 + git add -u >out &&
228 + test_must_be_empty out &&
229 + git ls-files -u >actual &&
230 + test_must_be_empty actual &&
231 + git ls-files bystander.txt conflict.txt >actual &&
232 + cat >expect <<-\EOF &&
233 + conflict.txt
234 + EOF
235 + test_cmp expect actual &&
236 + git diff-files --name-only >actual &&
237 + test_must_be_empty actual
238 + )
239 +'
240 +
241 test_expect_success '"add -u non-existent" should fail' '
242 test_must_fail git add -u non-existent &&
243 git ls-files >actual &&