Re: [PATCH 1/4] merge-tree: fail with a non-zero exit code on missing tree objects

Patrick Steinhardt
2024-02-07T07:42:36Z

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On Tue, Feb 06, 2024 at 09:49:38AM +0000, Johannes Schindelin via GitGitGadget wrote:
> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>
> When `git merge-tree` encounters a missing tree object, it should error
> out and not continue quietly as if nothing had happened.
>
> However, as of time of writing, `git merge-tree` _does_ continue, and
> then offers the empty tree as result.
>
> Let's fix this.
>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
> merge-ort.c | 7 ++++---
> t/t4301-merge-tree-write-tree.sh | 10 ++++++++++
> 2 files changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/merge-ort.c b/merge-ort.c
> index 6491070d965..c37fc035f13 100644
> --- a/merge-ort.c
> +++ b/merge-ort.c
> @@ -1659,9 +1659,10 @@ static int collect_merge_info(struct merge_options *opt,
> info.data = opt;
> info.show_all_errors = 1;
>
> - parse_tree(merge_base);
> - parse_tree(side1);
> - parse_tree(side2);
> + if (parse_tree(merge_base) < 0 ||
> + parse_tree(side1) < 0 ||
> + parse_tree(side2) < 0)
> + return -1;

I was wondering whether we also want to print an error in this case. But
`parse_tree()` calls `parse_tree_gently(tree, 0)`, where the second
parameter instructs the function to print an error message when the tree
is missing.

> init_tree_desc(t + 0, merge_base->buffer, merge_base->size);
> init_tree_desc(t + 1, side1->buffer, side1->size);
> init_tree_desc(t + 2, side2->buffer, side2->size);
> diff --git a/t/t4301-merge-tree-write-tree.sh b/t/t4301-merge-tree-write-tree.sh
> index 7d0fa74da74..4ea1b74445d 100755
> --- a/t/t4301-merge-tree-write-tree.sh
> +++ b/t/t4301-merge-tree-write-tree.sh
> @@ -950,5 +950,15 @@ test_expect_success '--merge-base with tree OIDs' '
> git merge-tree --merge-base=side1^^{tree} side1^{tree} side3^{tree} >with-trees &&
> test_cmp with-commits with-trees
> '

Nit: missing newline.

> +test_expect_success 'error out on missing tree objects' '
> + git init --bare missing-tree.git &&
> + (
> + git rev-list side3 &&
> + git rev-parse side3^:
> + ) | git pack-objects missing-tree.git/objects/pack/side3-tree-is-missing &&
> + side3=$(git rev-parse side3) &&
> + test_must_fail git --git-dir=missing-tree.git merge-tree $side3^ $side3 >actual &&
> + test_must_be_empty actual
> +'

Can't we avoid the subshell by using curly braces to pipe the outputs

Patrick

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