Re: [PATCH v5 5/6] meson: add support for 'hdr-check'

> Hi Karthik
>
> On 23/04/2025 09:15, 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. This also skips the folder
>> from the 'coccinelle' checks, this is okay, since this code is an
>> external dependency.
>
> The xdiff code is in a kind of limbo as the upstream project is dead and
> so people who want a standalone copy take the code from our repository.
> The Makefile does run coccinelle on it but not hdr-check as that fails.
> Looking at the filenames in contrib/coccinelle they are almost all quite
> git specific so it probably makes sense to skip the xdiff files.
>

> Best Wishes
>
> Phillip
>
>> Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
>> ---
>>   meson.build | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 63 insertions(+)
>>
>> diff --git a/meson.build b/meson.build
>> index 4618804c7a..22fc65ec80 100644
>> --- a/meson.build
>> +++ b/meson.build
>> @@ -645,6 +645,7 @@ third_party_excludes = [
>>     ':!sha1dc',
>>     ':!t/unit-tests/clar',
>>     ':!t/t[0-9][0-9][0-9][0-9]*',
>> +  ':!xdiff',
>>   ]
>>
>>   headers_to_check = []
>> @@ -1994,6 +1995,68 @@ endif
>>
>>   subdir('contrib')
>>
>> +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 != 'gcrypt'
>> +  exclude_from_check_headers += 'sha256/gcrypt.h'
>> +endif
>> +
>> +if headers_to_check.length() != 0 and compiler.get_argument_syntax() == 'gcc'
>> +  hco_targets = []
>> +  foreach h : headers_to_check
>> +    skip_header = false
>> +    foreach exclude : exclude_from_check_headers
>> +      if h.startswith(exclude)
>> +        skip_header = true
>> +        break
>> +      endif
>> +    endforeach
>> +
>> +    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(),
>>