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narrow: fix commits of empty files
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Authored by valentin.gatienbaron on Sep 10 2021, 3:13 PM.

Details

Summary

The problem is that when committing a new file with empty contents (or
in general empty file with filelog p1 = -1), hg commit with narrow
doesn't create a filelog revision at all, which causes failures in
further commands.

The problem seems to be that:

  • hg thinks that instead of creating a new filelog revision, it can use the filelog's p1 (the nullrev)
  • because it thinks the file contents is the same in that revision and in p1
  • because narrowfilelog.cmp(nullrev, b'') is True (unlike with filelog.cmp)

It's not clear to me which cmp behaves better. But I think it makes
sense to change the commit code to not to "reuse" the null rev when
adding an empty file with filelog p1 == filelog p2 == -1. This is
consistent with never writing the null rev in the manifest, which `hg
verify` claims is an invariant:

inside/c@4: manifest refers to unknown revision 000000000000

Diff Detail

Repository
rHG Mercurial
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

Alphare requested changes to this revision.Sep 13 2021, 6:07 AM
Alphare added a subscriber: Alphare.

Other than my request in the test, the change seems like a good idea to me.

tests/test-narrow-commit.t
110–111

I would add a check that the file has actually been added by the commit and not just silently creating an empty commit somehow.

This revision now requires changes to proceed.Sep 13 2021, 6:07 AM
valentin.gatienbaron marked an inline comment as done.Sep 13 2021, 9:22 AM
Alphare accepted this revision.Sep 13 2021, 9:23 AM

Thanks. I'll queue this on stable.

This revision is now accepted and ready to land.Sep 13 2021, 9:23 AM
Alphare updated this revision to Diff 30216.Sep 13 2021, 11:35 AM
This revision was automatically updated to reflect the committed changes.