rebase --skip: fix commit message clean up when skipping squash

... The test is also updated to explicitly check
the commit messages rather than relying on grep to ensure they do not contain any stay commit headers.

To check the commit message the function test_commit_message() is moved from t3437-rebase-fixup-options.sh to test-lib.sh. As the function is now publicly available it is updated to provide better error detection and avoid overwriting the commonly used files "actual" and "expect". Support for reading the expected commit message from stdin is also added.

Signed-off-by Phillip Wood <[email protected]>

---
rebase --skip: fix commit message clean up when skipping squash

This patch is based on maint.
...

 sequencer.c                     | 26 +++++++++++----
 t/t3418-rebase-continue.sh      | 58 +++++++++++++++++++++++----------
 t/t3437-rebase-fixup-options.sh | 15 ---------
 t/test-lib-functions.sh         | 33 +++++++++++++++++++
 4 files changed, 93 insertions(+), 39 deletions(-)

sequencer.c +14 -5

index bceb6abcb6c..af271ab6fbd 100644
@@ -5038,19 +5038,31 @@ static int commit_staged_changes(struct repository *r,
 				 * We need to update the squash message to skip
 				 * the latest commit message.
 				 */
+				int res = 0;
 				struct commit *commit;
+				const char *msg;
 				const char *path = rebase_path_squash_msg();
 				const char *encoding = get_commit_output_encoding();
 
-				if (parse_head(r, &commit) ||
-				    !(p = repo_logmsg_reencode(r, commit, NULL, encoding)) ||
-				    write_message(p, strlen(p), path, 0)) {
-					repo_unuse_commit_buffer(r, commit, p);
-					return error(_("could not write file: "
+				if (parse_head(r, &commit))
+					return error(_("could not parse HEAD"));
+
+				p = repo_logmsg_reencode(r, commit, NULL, encoding);
+				if (!p)  {
+					res = error(_("could not parse commit %s"),
+						    oid_to_hex(&commit->object.oid));
+					goto unuse_commit_buffer;
+				}
+				find_commit_subject(p, &msg);
+				if (write_message(msg, strlen(msg), path, 0)) {
+					res = error(_("could not write file: "
 						       "'%s'"), path);

Quoted 3 lines · Phillip Wood via GitGitGadget

... The test is also updated to explicitly check
the commit messages rather than relying on grep to ensure they do not contain any stay commit headers.

"stay" -> "stray" presumably.

Quoted 6 lines

To check the commit message the function test_commit_message() is moved from t3437-rebase-fixup-options.sh to test-lib.sh. As the function is now publicly available it is updated to provide better error detection and avoid overwriting the commonly used files "actual" and "expect". Support for reading the expected commit message from stdin is also added.

It may make it cleaner to do the refactoring as a separate preparatory patch, but the end-result is not so large from the diffstat below, so it probably is OK.

I am not sure if deviating from expect vs actual is such a good idea. It is not like use of two temporary files are transparent to the caller of the new test helper---indeed, expect and actual are likely to be used by the caller in tests that comes before or after the ones that use test_commit_message, and by using a pair of files that are different, the caller will now see two extra untracked files left in the working tree.

The only case such a renaming could help callers is when they do

	cat >expect <<\-EOF &&
	here to prepare some outcome
	EOF
	git do-something-to-make-commit &&
	test_commit_message HEAD <<\-EOF &&
	here is what we expect to see in HEAD
	EOF
	git some-other-thing >actual &&
	test_cmp expect actual

as use of files other than expect/actual in test_commit_message will avoid stomping on the "expect" file that was already prepared.

I suspect that it would be rare, and something we can fix when need arises by allowing test_commit_message to accept an option to use non-standard filenames for its temporaries. The current callers, both the existing ones in t3437 and the new ones added by this patch, would not benefit. The only externally visible side effect is that the existing ones will have two extra untracked files in their working tree.

Quoted 11 lines

Signed-off-by Phillip Wood <[email protected]>

---
rebase --skip: fix commit message clean up when skipping squash

This patch is based on maint.
...

  sequencer.c                     | 26 +++++++++++----
  t/t3418-rebase-continue.sh      | 58 +++++++++++++++++++++++----------
  t/t3437-rebase-fixup-options.sh | 15 ---------
  t/test-lib-functions.sh         | 33 +++++++++++++++++++
  4 files changed, 93 insertions(+), 39 deletions(-)

OK.

Quoted 32 lines

sequencer.c +14 -5

index bceb6abcb6c..af271ab6fbd 100644
@@ -5038,19 +5038,31 @@ static int commit_staged_changes(struct repository *r,
  				 * We need to update the squash message to skip
  				 * the latest commit message.
  				 */
+				int res = 0;
  				struct commit *commit;
+				const char *msg;
  				const char *path = rebase_path_squash_msg();
  				const char *encoding = get_commit_output_encoding();
 
-				if (parse_head(r, &commit) ||
-				    !(p = repo_logmsg_reencode(r, commit, NULL, encoding)) ||
-				    write_message(p, strlen(p), path, 0)) {
-					repo_unuse_commit_buffer(r, commit, p);
-					return error(_("could not write file: "
+				if (parse_head(r, &commit))
+					return error(_("could not parse HEAD"));
+
+				p = repo_logmsg_reencode(r, commit, NULL, encoding);
+				if (!p)  {
+					res = error(_("could not parse commit %s"),
+						    oid_to_hex(&commit->object.oid));
+					goto unuse_commit_buffer;
+				}
+				find_commit_subject(p, &msg);
+				if (write_message(msg, strlen(msg), path, 0)) {
+					res = error(_("could not write file: "
  						       "'%s'"), path);

sequencer.c static int commit_staged_changes(struct repository *r, · line 5067

Quoted 10 lines

sequencer.c +5 -2

+					goto unuse_commit_buffer;
  				}
-				repo_unuse_commit_buffer(r,
-							 commit, p);
+			unuse_commit_buffer:
+				repo_unuse_commit_buffer(r, commit, p);
+				if (res)
+					return res;
  			}
  		}

Just as described in the proposed log message. Looking good.

Will queue. Thanks.

Quoted 7 lines

I am not sure if deviating from expect vs actual is such a good idea. It is not like use of two temporary files are transparent to the caller of the new test helper---indeed, expect and actual are likely to be used by the caller in tests that comes before or after the ones that use test_commit_message, and by using a pair of files that are different, the caller will now see two extra untracked files left in the working tree.

That's true, looking at test-lib-functions.sh it seems I unwittingly followed the example of test_cmp_config() which uses {actual,expect}.config when it calls test_cmp(). Anyway as this is in next I assume you're happy enough with the implementation as it stands.

From: Phillip Wood <[email protected]>

During a series of "fixup" and/or "squash" commands, the interactive rebase accumulates a commit message from all the commits that are being squashed together. If one of the commits has conflicts when it is picked and the user chooses to skip that commit then we need to remove that commit's message from accumulated messages. To do this 15ef69314d5 (rebase --skip: clean up commit message after a failed fixup/squash, 2018-04-27) updated commit_staged_changes() to reset the accumulated message to the commit message of HEAD (which does not contain the message from the skipped commit) when the last command was "fixup" or "squash" and there are no staged changes. Unfortunately the code to do this contains two bugs.

(1) If parse_head() fails we pass an invalid pointer to unuse_commit_buffer().

(2) The reconstructed message uses the entire commit buffer from HEAD including the headers, rather than just the commit message.

The fist issue is fixed by splitting up the "if" condition into several

Quoted 1 line

The fist issue is fixed by splitting up the "if" condition into several

s/fist/first/

(I'm not qualified to review anything else about this patch, but I like its intention...  :D )