Re: [PATCH] sequencer: ensure labels that are object IDs are rewritten

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Brian,

On Tue, 29 May 2018, brian m. carlson wrote:

> When writing the todo script for --rebase-merges, we try to find a label
> for certain commits.  If the label ends up being a valid object ID, such
> as when we merge a detached commit, we want to rewrite it so it is no
> longer a valid object ID.
> 
> However, the code path that does this checks for its length to be
> equivalent to GIT_SHA1_RAWSZ, which isn't correct, since what we are
> reading is a hex object ID.  Instead, check for the length being
> equivalent to that of a hex object ID.  Use the_hash_algo so this code
> works regardless of the hash size.

D'oh. Thank you so much for this fix.

> I noticed this while cleaning up a few instances of GIT_SHA1_* constants
> and thought I'd send a patch.

You thought well!

> diff --git a/sequencer.c b/sequencer.c
> index 1ce63261a3..75ed86a94e 100644
> --- a/sequencer.c
> +++ b/sequencer.c
> @@ -3636,7 +3636,7 @@ static const char *label_oid(struct object_id *oid, const char *label,
>  				p[i] = save;
>  			}
>  		}
> -	} else if (((len = strlen(label)) == GIT_SHA1_RAWSZ &&
> +	} else if (((len = strlen(label)) == the_hash_algo->hexsz &&

Obviously good!

>  		    !get_oid_hex(label, &dummy)) ||
>  		   (len == 1 && *label == '#') ||
>  		   hashmap_get_from_hash(&state->labels,
> diff --git a/t/t3430-rebase-merges.sh b/t/t3430-rebase-merges.sh
> index 3d4dfdf7be..472ad9463c 100755
> --- a/t/t3430-rebase-merges.sh
> +++ b/t/t3430-rebase-merges.sh
> @@ -70,6 +70,7 @@ test_expect_success 'create completely different structure' '
>  	merge -C H second
>  	merge onebranch # Merge the topic branch '\''onebranch'\''
>  	EOF
> +	cp script-from-scratch script-from-scratch-orig &&
>  	test_config sequence.editor \""$PWD"/replace-editor.sh\" &&
>  	test_tick &&
>  	git rebase -i -r A &&
> @@ -241,4 +242,20 @@ test_expect_success 'refuse to merge ancestors of HEAD' '
>  	test_cmp_rev HEAD $before
>  '
>  
> +test_expect_success 'labels that are object IDs are rewritten' '

Thanks for writing a test, I had been meaning to, but it slipped from my
mind.

> +	git checkout -b third B &&
> +	test_tick &&
> +	test_commit I &&

The test_tick before test_commit is unnecessary.

> +	third=$(git rev-parse HEAD) &&
> +	git checkout -b labels master &&
> +	git merge --no-commit third &&
> +	test_tick &&
> +	git commit -m "Merge commit '\''$third'\'' into labels" &&

Here, the test_tick is required because we commit via `git commit`.

BTW another thing that I had been meaning to address but totally forgot is
this '\'' ugliness. I had been meaning to define SQ="'" before all test
cases and then use $SQ everywhere. Not your problem, though.

> +	cp script-from-scratch-orig script-from-scratch &&

There is nothing in that script that you need. Why not simply

	echo noop >script-from-scratch

or if you care about the branch,

	echo reset $third >script-from-scratch

> +	test_config sequence.editor \""$PWD"/replace-editor.sh\" &&
> +	test_tick &&
> +	git rebase -i -r A &&
> +	! grep "^label $third$" .git/ORIGINAL-TODO

I would like to verify in addition that /^label $third-/ is present in
ORIGINAL-TODO, what do you think?

Thank you,
Dscho