Re: [PATCH 8/8] commit-graph: drop COMMIT_GRAPH_WRITE_CHECK_OIDS flag

[Derrick Stolee <stolee@gmail.com>]

On 5/4/2020 9:14 PM, Taylor Blau wrote:
> Since 7c5c9b9c57 (commit-graph: error out on invalid commit oids in
> 'write --stdin-commits', 2019-08-05), the commit-graph builtin dies on
> receiving non-commit OIDs as input to '--stdin-commits'.
> 
> This behavior can be cumbersome to work around in, say, the case of
> piping 'git for-each-ref' to 'git commit-graph write --stdin-commits' if
> the caller does not want to cull out non-commits themselves. In this
> situation, it would be ideal if 'git commit-graph write' wrote the graph
> containing the inputs that did pertain to commits, and silently ignored
> the remainder of the input.
> 
> Some options have been proposed to the effect of '--[no-]check-oids'
> which would allow callers to have the commit-graph builtin do just that.
> After some discussion, it is difficult to imagine a caller who wouldn't
> want to pass '--no-check-oids', suggesting that we should get rid of the
> behavior of complaining about non-commit inputs altogether.
> 
> If callers do wish to retain this behavior, they can easily work around
> this change by doing the following:
> 
>     git for-each-ref --format='%(objectname) %(objecttype) %(*objecttype)' |
>     awk '/commit/ { print $1 }' |
>     git commit-graph write --stdin-commits

I appreciate that you included the workaround here for posterity. That
allows anyone complaining to bisect to these instructions.

> To make it so that valid OIDs that refer to non-existent objects are
> indeed an error after loosening the error handling, perform an extra
> lookup to make sure that object indeed exists before sending it to the
> commit-graph internals.
> 
> Signed-off-by: Taylor Blau <me@ttaylorr.com>
> ---
>  Documentation/git-commit-graph.txt |  6 ++++--
>  builtin/commit-graph.c             | 10 +++++-----
>  commit-graph.c                     |  2 --
>  commit-graph.h                     | 10 ++++------
>  t/t5318-commit-graph.sh            | 15 +++++++++++----
>  5 files changed, 24 insertions(+), 19 deletions(-)
> 
> diff --git a/Documentation/git-commit-graph.txt b/Documentation/git-commit-graph.txt
> index 53a650225a..fcac7d12e1 100644
> --- a/Documentation/git-commit-graph.txt
> +++ b/Documentation/git-commit-graph.txt
> @@ -47,8 +47,10 @@ with `--stdin-commits` or `--reachable`.)
>  +
>  With the `--stdin-commits` option, generate the new commit graph by
>  walking commits starting at the commits specified in stdin as a list
> -of OIDs in hex, one OID per line. (Cannot be combined with
> -`--stdin-packs` or `--reachable`.)
> +of OIDs in hex, one OID per line. OIDs that resolve to non-commits
> +(either directly, or by peeling tags) are silently ignored. OIDs that
> +are malformed, or do not exist generate an error. (Cannot be combined
> +with `--stdin-packs` or `--reachable`.)
>  +
>  With the `--reachable` option, generate the new commit graph by walking
>  commits starting at all refs. (Cannot be combined with `--stdin-commits`
> diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
> index 9eec68572f..3637d079fb 100644
> --- a/builtin/commit-graph.c
> +++ b/builtin/commit-graph.c
> @@ -153,13 +153,14 @@ static int read_one_commit(struct oidset *commits, struct progress *progress,
>  
>  	display_progress(progress, oidset_size(commits) + 1);
>  
> +	if (oid_object_info(the_repository, &oid, NULL) < 0) {
> +		error(_("object %s does not exist"), hash);
> +		return 1;
> +	}
> +

If we get a non-existent object, then this will cause us to fail
the command, right?

> diff --git a/t/t5318-commit-graph.sh b/t/t5318-commit-graph.sh
> index 89020d3d44..74f93f0a17 100755
> --- a/t/t5318-commit-graph.sh
> +++ b/t/t5318-commit-graph.sh
> @@ -84,11 +84,18 @@ graph_read_expect() {
>  
>  test_expect_success 'exit with correct error on bad input to --stdin-commits' '
>  	cd "$TRASH_DIRECTORY/full" &&
> -	echo HEAD | test_expect_code 1 git commit-graph write --stdin-commits 2>stderr &&
> +	# invalid, non-hex OID
> +	echo HEAD >in &&
> +	test_expect_code 1 git commit-graph write --stdin-commits <in 2>stderr &&
>  	test_i18ngrep "unexpected non-hex object ID: HEAD" stderr &&
> -	# valid tree OID, but not a commit OID
> -	git rev-parse HEAD^{tree} | test_expect_code 1 git commit-graph write --stdin-commits 2>stderr &&
> -	test_i18ngrep "invalid commit object id" stderr
> +	# non-existent OID
> +	echo $ZERO_OID >in &&
> +	test_expect_code 1 git commit-graph write --stdin-commits <in 2>stderr &&
> +	test_i18ngrep "does not exist" stderr &&

And here you verify that it fails at that point. Excellent!

> +	# valid commit and tree OID
> +	git rev-parse HEAD HEAD^{tree} >in &&
> +	git commit-graph write --stdin-commits <in &&
> +	graph_read_expect 3
>  '

This is an excellent series! Thanks.

Reviewed-by: Derrick Stolee <dstolee@microsoft.com>