[PATCH STABLE] tags: fix typo in fast path detection of fnode resolution (issue6673)

[Raphaël Gomès]

Queued, that was fast, thanks a lot!

On 3/29/22 12:10, Yuya Nishihara wrote:
> # HG changeset patch
> # User Yuya Nishihara <yuya at tcha.org>
> # Date 1648545349 -32400
> #      Tue Mar 29 18:15:49 2022 +0900
> # Branch stable
> # Node ID 1da3259a1a38ed0ba6607c0830bb1aec461ec784
> # Parent  9bb700223f000be88912382adee80b8a7afe5fcb
> tags: fix typo in fast path detection of fnode resolution (issue6673)
>
> If I understand it, mctx.readfast() is unreliable here if p1/p2 .hgtags
> nodes differ, and tags on that branch would be randomly discarded
> depending on which parent were picked.
>
> The test case added by this patch would fail only on zstd-compressed
> repository. I didn't try hard to stabilize the failure case.
>
> diff --git a/mercurial/tags.py b/mercurial/tags.py
> --- a/mercurial/tags.py
> +++ b/mercurial/tags.py
> @@ -808,7 +808,7 @@ class hgtagsfnodescache(object):
>               # There is some no-merge changeset where p1 is null and p2 is set
>               # Processing them as merge is just slower, but still gives a good
>               # result.
> -            p2node = cl.node(p1rev)
> +            p2node = cl.node(p2rev)
>               p2fnode = self.getfnode(p2node, computemissing=False)
>               if p1fnode != p2fnode:
>                   # we cannot rely on readfast because we don't know against what
> diff --git a/tests/test-tags.t b/tests/test-tags.t
> --- a/tests/test-tags.t
> +++ b/tests/test-tags.t
> @@ -933,3 +933,58 @@ Avoid writing logs on trying to delete a
>     a8a82d372bb35b42ff736e74f07c23bcd99c371f a
>     a8a82d372bb35b42ff736e74f07c23bcd99c371f a
>     0000000000000000000000000000000000000000 a
> +
> +  $ cd ..
> +
> +.hgtags fnode should be properly resolved at merge revision (issue6673)
> +
> +  $ hg init issue6673
> +  $ cd issue6673
> +
> +  $ touch a
> +  $ hg ci -qAm a
> +  $ hg branch -q stable
> +  $ hg ci -m branch
> +
> +  $ hg up -q default
> +  $ hg merge -q stable
> +  $ hg ci -m merge
> +
> + add tag to stable branch:
> +
> +  $ hg up -q stable
> +  $ echo a >> a
> +  $ hg ci -m a
> +  $ hg tag whatever
> +  $ hg log -GT'{rev} {tags}\n'
> +  @  4 tip
> +  |
> +  o  3 whatever
> +  |
> +  | o  2
> +  |/|
> +  o |  1
> +  |/
> +  o  0
> +
> +
> + merge tagged stable into default:
> +
> +  $ hg up -q default
> +  $ hg merge -q  stable
> +  $ hg ci -m merge
> +  $ hg log -GT'{rev} {tags}\n'
> +  @    5 tip
> +  |\
> +  | o  4
> +  | |
> +  | o  3 whatever
> +  | |
> +  o |  2
> +  |\|
> +  | o  1
> +  |/
> +  o  0
> +
> +
> +  $ cd ..
>
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