Subject: Re: [PATCH v3 3/4] meson: add support for 'hdr-check'

From: [email-masked]
Date: Tue, 15 Apr 2025 14:28:40 +0100

Hi Karthik

On 14/04/2025 22:16, Karthik Nayak wrote:
> The Makefile supports a target called 'hdr-check', which checks if
> individual header files can be independently compiled. Let's port this
> functionality to Meson, our new build system too. The implementation
> resembles that of the Makefile and provides the same check.
> 
> Since meson builds are out-of-tree, header dependencies are not
> automatically met. So unlike the Makefile version, we also need to add
> the required dependencies.
> 
> Also add the 'xdiff/' dir to the list of 'third_party_sources' as those
> headers must be skipped from the checks too!

Doesn't this mean we'll skip all the xdiff files when running coccinelle 
as well? If so the commit message should point that out and explain why 
that is an improvement.

> +exclude_from_check_headers = generated_headers

I'm not sure this is necessary. The list of headers that we filter is 
generated with "git ls-files" and so wont contain generated headers in 
the first place.

> +exclude_from_check_headers += [
> +  'compat/',
> +  'unicode-width.h',
> +]
> +
> +if sha1_backend != 'openssl'
> +  exclude_from_check_headers += 'sha1/openssl.h'
> +endif
> +if sha256_backend != 'openssl'
> +  exclude_from_check_headers += 'sha256/openssl.h'
> +endif
> +if sha256_backend != 'nettle'
> +  exclude_from_check_headers += 'sha256/nettle.h'
> +endif
> +if sha256_backend != 'gcrpyt'
> +  exclude_from_check_headers += 'sha256/gcrypt.h'
> +endif
> +
> +if git.found() and compiler.get_argument_syntax() == 'gcc'
> +  hco_targets = []
> +  foreach h : headers
> +    skip_header = false
> +    foreach exclude : exclude_from_check_headers
> +      if h.startswith(exclude)
> +        skip_header = true
> +        break
> +      endif
> +    endforeach

This part looks much more maintainable than than the previous version

Thanks

Phillip

> +    if skip_header
> +      continue
> +    endif
> +
> +    hcc = custom_target(
> +      input: h,
> +      output: h.underscorify() + 'cc',
> +      command: [
> +        shell,
> +        '-c',
> +        'echo \'#include "git-compat-util.h"\' > @OUTPUT@ && echo \'#include "' + h + '"\' >> @OUTPUT@'
> +      ]
> +    )
> +
> +    hco = custom_target(
> +      input: hcc,
> +      output: fs.replace_suffix(h.underscorify(), '.hco'),
> +      command: [
> +        compiler.cmd_array(),
> +        libgit_c_args,
> +        '-I', meson.project_source_root(),
> +        '-I', meson.project_source_root() / 't/unit-tests',
> +        '-o', '/dev/null',
> +        '-c', '-xc',
> +        '@INPUT@'
> +      ]
> +    )
> +    hco_targets += hco
> +  endforeach
> +
> +  alias_target('hdr-check', hco_targets)
> +endif
> +
>   foreach key, value : {
>     'DIFF': diff.full_path(),
>     'GIT_SOURCE_DIR': meson.project_source_root(),