@matheusbsbs / matheus-bagliano / commits / fdae4114a6

breaking-changes: deprecate support for core.commentString=auto

When "core.commentString" is set to "auto" then "git commit" will automatically select the comment character ensuring that it is not the first character on any of the lines in the commit message. This was introduced by commit 84c9dc2c5a2 (commit: allow core.commentChar=auto for character auto selection, 2014-05-17). The motivation seems to be to avoid commenting out lines from the existing message when amending a commit that was created with a message from a file. Unfortunately this feature does not work with: * commit message templates that contain comments. * prepare-commit-msg hooks that introduce comments. * "git commit --cleanup=strip --edit -F <file>" which means that it is incompatible with - the "fixup" and "squash" commands of "git rebase -i" as the comments added by those commands are then treated as part of the commit message. - the conflict comments added to the commit message by "git cherry-pick", "git rebase" etc. as these comments are then treated as part of the commit message. It is also ignored by "git notes" when amending a note. The issues with comments coming from a template, hook or file are a consequence of the design of this feature and are therefore hard to fix. As the costs of this feature outweigh the benefits, deprecate it and remove it in Git 3.0. If someone comes up with some patches that fix all the issues in a maintainable way then I'd be happy to see this change reverted. The next commits will add a warning and some advice for users on how they can update their config settings. Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Phillip Wood committed Aug 26, 2025 at 14:35 UTC fdae4114a696014b6bf28ad9b1bc076bd8d7eec8

8 files changed +41 -8

Documentation/BreakingChanges.adoc

@@ -239,6 +239,11 @@ These features will be removed.

239 +

240 The command will be removed.

241

242 +* Support for `core.commentString=auto` has been deprecated and will

243 + be removed in Git 3.0.

244 ++

245 +cf. <xmqqa59i45wc.fsf@gitster.g>

246 +

247 == Superseded features that will not be deprecated

248

249 Some features have gained newer replacements that aim to improve the design in

Documentation/config/core.adoc

+18 -2

@@ -531,9 +531,25 @@ core.commentString::

531 commented, and removes them after the editor returns

532 (default '#').

533 +

534 -If set to "auto", `git-commit` would select a character that is not

534 +ifndef::with-breaking-changes[]

535 +If set to "auto", `git-commit` will select a character that is not

536 the beginning character of any line in existing commit messages.

536 -+

537 +Support for this value is deprecated and will be removed in Git 3.0

538 +due to the following limitations:

539 ++

540 +--

541 +* It is incompatible with adding comments in a commit message

542 + template. This includes the conflicts comments added to

543 + the commit message by `cherry-pick`, `merge`, `rebase` and

544 + `revert`.

545 +* It is incompatible with adding comments to the commit message

546 + in the `prepare-commit-msg` hook.

547 +* It is incompatible with the `fixup` and `squash` commands when

548 + rebasing,

549 +* It is not respected by `git notes`

550 +--

551 ++

552 +endif::with-breaking-changes[]

553 Note that these two variables are aliases of each other, and in modern

554 versions of Git you are free to use a string (e.g., `//` or `⁑⁕⁑`) with

555 `commentChar`. Versions of Git prior to v2.45.0 will ignore

builtin/commit.c

@@ -683,6 +683,7 @@ static int author_date_is_interesting(void)

683 return author_message || force_date;

684 }

685

686 +#ifndef WITH_BREAKING_CHANGES

687 static void adjust_comment_line_char(const struct strbuf *sb)

688 {

689 char candidates[] = "#;@!$%^&|:";

@@ -720,6 +721,7 @@ static void adjust_comment_line_char(const struct strbuf *sb)

721 free(comment_line_str_to_free);

722 comment_line_str = comment_line_str_to_free = xstrfmt("%c", *p);

723 }

724 +#endif /* !WITH_BREAKING_CHANGES */

725

726 static void prepare_amend_commit(struct commit *commit, struct strbuf *sb,

727 struct pretty_print_context *ctx)

@@ -916,8 +918,10 @@ static int prepare_to_commit(const char *index_file, const char *prefix,

918 if (fwrite(sb.buf, 1, sb.len, s->fp) < sb.len)

919 die_errno(_("could not write commit template"));

920

921 +#ifndef WITH_BREAKING_CHANGES

922 if (auto_comment_line_char)

923 adjust_comment_line_char(&sb);

924 +#endif /* !WITH_BREAKING_CHANGES */

925 strbuf_release(&sb);

926

927 /* This checks if committer ident is explicitly given */

environment.c

+8 -2

@@ -122,7 +122,9 @@ int protect_ntfs = PROTECT_NTFS_DEFAULT;

122 */

123 const char *comment_line_str = "#";

124 char *comment_line_str_to_free;

125 +#ifndef WITH_BREAKING_CHANGES

126 int auto_comment_line_char;

127 +#endif /* !WITH_BREAKING_CHANGES */

128

129 /* This is set by setup_git_directory_gently() and/or git_default_config() */

130 char *git_work_tree_cfg;

@@ -459,18 +461,22 @@ static int git_default_core_config(const char *var, const char *value,

461

462 if (!strcmp(var, "core.commentchar") ||

463 !strcmp(var, "core.commentstring")) {

462 - if (!value)

464 + if (!value) {

465 return config_error_nonbool(var);

464 - else if (!strcasecmp(value, "auto")) {

466 +#ifndef WITH_BREAKING_CHANGES

467 + } else if (!strcasecmp(value, "auto")) {

468 auto_comment_line_char = 1;

469 FREE_AND_NULL(comment_line_str_to_free);

470 comment_line_str = "#";

471 +#endif /* !WITH_BREAKING_CHANGES */

472 } else if (value[0]) {

473 if (strchr(value, '\n'))

474 return error(_("%s cannot contain newline"), var);

475 comment_line_str = value;

476 FREE_AND_NULL(comment_line_str_to_free);

477 +#ifndef WITH_BREAKING_CHANGES

478 auto_comment_line_char = 0;

479 +#endif /* !WITH_BREAKING_CHANGES */

480 } else

481 return error(_("%s must have at least one character"), var);

482 return 0;

environment.h

@@ -208,7 +208,9 @@ extern char *excludes_file;

208 */

209 extern const char *comment_line_str;

210 extern char *comment_line_str_to_free;

211 +#ifndef WITH_BREAKING_CHANGES

212 extern int auto_comment_line_char;

213 +#endif /* !WITH_BREAKING_CHANGES */

214

215 # endif /* USE_THE_REPOSITORY_VARIABLE */

216 #endif /* ENVIRONMENT_H */

t/t3404-rebase-interactive.sh

+1 -1

@@ -1176,7 +1176,7 @@ test_expect_success 'rebase -i respects core.commentchar' '

1176 test B = $(git cat-file commit HEAD^ | sed -ne \$p)

1177 '

1178

1179 -test_expect_success 'rebase -i respects core.commentchar=auto' '

1179 +test_expect_success !WITH_BREAKING_CHANGES 'rebase -i respects core.commentchar=auto' '

1180 test_config core.commentchar auto &&

1181 write_script copy-edit-script.sh <<-\EOF &&

1182 cp "$1" edit-script

t/t3418-rebase-continue.sh

+1 -1

@@ -328,7 +328,7 @@ test_expect_success 'there is no --no-reschedule-failed-exec in an ongoing rebas

328 test_expect_code 129 git rebase --edit-todo --no-reschedule-failed-exec

329 '

330

331 -test_expect_success 'no change in comment character due to conflicts markers with core.commentChar=auto' '

331 +test_expect_success !WITH_BREAKING_CHANGES 'no change in comment character due to conflicts markers with core.commentChar=auto' '

332 git checkout -b branch-a &&

333 test_commit A F1 &&

334 git checkout -b branch-b HEAD^ &&

t/t7502-commit-porcelain.sh

+2 -2

@@ -956,13 +956,13 @@ test_expect_success 'commit --status with custom comment character' '

956 test_grep "^; Changes to be committed:" .git/COMMIT_EDITMSG

957 '

958

959 -test_expect_success 'switch core.commentchar' '

959 +test_expect_success !WITH_BREAKING_CHANGES 'switch core.commentchar' '

960 test_commit "#foo" foo &&

961 GIT_EDITOR=.git/FAKE_EDITOR git -c core.commentChar=auto commit --amend &&

962 test_grep "^; Changes to be committed:" .git/COMMIT_EDITMSG

963 '

964

965 -test_expect_success 'switch core.commentchar but out of options' '

965 +test_expect_success !WITH_BREAKING_CHANGES 'switch core.commentchar but out of options' '

966 cat >text <<\EOF &&

967 # 1

968 ; 2