Re: [PATCH] meson: Check whether git is new enough to support ls-files --deduplicate

From: Martin Storsjö <martin@martin.st>
Date: Aug 1, 2025, 07:55 UTC
Message-ID: <69faab5-43d4-812c-90f-c518ff7f618@martin.st>
In-Reply-To: <aIxQWSrnMOuEmfHo@pks.im>

Hi Patrick,

On Fri, 1 Aug 2025, Patrick Steinhardt wrote:

> Our commit messages are described so that we first describe the error
> and then we describe how this is fixed, and typically they are written
> in such a way that they can be read without requiring you to also read
> the subject line.

Thanks for the commit message rewrite!

Show 13 quoted lines

> So something like:
>
>    When using the Meson build system with an old-enough Git version
>    that does not yet know the `git ls-files --deduplicate` option one
>    can observe the following error:
>
>        ../meson.build:697:19: ERROR: Command `/usr/bin/git -C /home/martin/code/git ls-files --deduplicate '*.h' ':!contrib' ':!compat/inet_ntop.c' ':!compat/inet_pton.c' ':!compat/nedmalloc' ':!compat/obstack.*' ':!compat/poll' ':!compat/regex' ':!sha1collisiondetection' ':!sha1dc' ':!t/unit-tests/clar' ':!t/t[0-9][0-9][0-9][0-9]*' ':!xdiff'` failed with status 129.
>
>    The failing command is used to find all header files in our code
>    base, which is required for static analysis.
>
>    Static analysis is an entirely optional feature that distributors
>    typically don't care, and about we already know to skip running the

I presume this is a typo, and this should be "typically don't care about, and we already know to ..." - I've amended your suggestion in this way locally.

Show 12 quoted lines

>>  headers_to_check = []
>> -if git.found() and fs.exists(meson.project_source_root() / '.git')
>> +if meson.version().version_compare('>=0.62')
>> +  new_enough_git = git.found() and git.version().version_compare('>=2.31')
>> +else
>> +  # On Meson 0.61, we can't check git.version(), so we just have to
>> +  # assume that the found git is new enough.
>> +  new_enough_git = git.found()
>
> I'd rather call this `git_supports_file_deduplication`. It's a bit of a
> mouthful, but `new_enough_git` raises the question of what it is new
> enough for.

Fair enough, good suggestion. Although based on your other suggestion below, we don't end up needing this part at all.

Show 7 quoted lines

>> +endif
>> +if new_enough_git and fs.exists(meson.project_source_root() / '.git')
>>    foreach header : run_command(git, '-C', meson.project_source_root(), 'ls-files', '--deduplicate', '*.h', third_party_excludes, check: true).stdout().split()
>
> I wonder whether we could avoid the whole version check machinery and
> just change this command to `check: false`. If so we accept in case the
> command fails, which we can check by calling `.returncode()`.

Thanks, this sounds like a much neater way of avoiding the whole issue!

// Martin