Subject: Re: [PATCH v2] meson: Tolerate errors from git ls-files --deduplicate

From: Patrick Steinhardt <[email-masked]>
Date: Fri, 1 Aug 2025 11:23:44 +0200

On Fri, Aug 01, 2025 at 10:56:22AM +0300, Martin Storsjö wrote:
> 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 about, and we already know to skip running the
> command when we are not in a Git repository. But we do not handle
> the above failure gracefully, even though we could.
> 
> Fix this by passing `check: false` to `run_command`, which makes it
> tolerate failures. Then check `returncode()` manually to decide
> whether to inspect the output.
> 
> Signed-off-by: Martin Storsjö <[email-masked]>
> ---
>  meson.build | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/meson.build b/meson.build
> index 9bc1826cb6..9b519e6eed 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -694,9 +694,12 @@ third_party_excludes = [
>  
>  headers_to_check = []
>  if git.found() 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()
> -    headers_to_check += header
> -  endforeach
> +  ls_headers = run_command(git, '-C', meson.project_source_root(), 'ls-files', '--deduplicate', '*.h', third_party_excludes, check: false)
> +  if ls_headers.returncode() == 0
> +    foreach header : ls_headers.stdout().split()
> +      headers_to_check += header
> +    endforeach
> +  endif
>  endif

Yup, this looks reasonable to me. We could have an `else` branch that
warns about the command failing, for example like this:

    warning("could not find headers: " + ls_headers.stderr())

But other than that I'm happy.

Thanks!

Patrick