<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/142119>142119</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang-tidy does not respect clang++.cfg
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang,
            clang-tidy
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          smuzaffar
      </td>
    </tr>
</table>

<pre>
    Hi,
 In order to use gcc headers from our custom gcc installation we create `llvm/bin/clang++.cfg` file with contents like [a] in it. This allows us to use `clang++` with explicitly setting `--gcc-toolchain` via command line. Looks like `clang-tidy` does not respect  `llvm/bin/clang++.cfg` and fails with errors like [b]. 

  `clang-tidy` works if I pass `--extra-arg="--gcc-toolchain=/path/to/custon/gcc". I tried creating `llvm/bin/clang-tidy.cfg` hoping that  `clang-tidy` might read it but this did not work.

  Is it on purpose that `clang-tidy` does not respect `clang++.cfg` file? 

[a]
```
> cat bin/clang++.cfg
--gcc-toolchain=/path/el8_amd64_gcc12/external/gcc/12.3.1-40d504be6370b5a30e3947a6e575ca28
--target=x86_64-redhat-linux-gnu
```

[b]
```
Error while processing .../src/TestSubsystem/TestDQMAnalyzerStream/plugins/TestDQMAnalyzerStream.cc.
.../el8_amd64_gcc12/lcg/root/6.32.13-4719c3acec5bf7dbc47dbafce0eb285d/include/TString.h:39:12: error: 'compare' file not found [clang-diagnostic-error]
   39 | #  include <compare>
```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJyMVEtv4zgT_DX0pSGBIvWwDjo44xG-AN8eFpl7QJEtiRuKFEgqj_n1C9oykk1mH4APEt0qVlVXtwhBTxaxI9Udqc4HscXZ-S4s208xjsIfBqfeuv9pwr4ReoJ7C84r9BAdbAFhkhJmFAp9gNG7BdzmQW4huuXyn7YhCmNE1M7CC4L0KCICqakxzwth_aAtYb00wk6E3RF2l8txIjWFURuEFx1nkM5GtDGA0U8IpLoTpDqDtqBjDj9mHUAY414CbOFGi9T0A2SCuyDh62q01NG8QcAYtZ1SZZZNUmbROSNnoW2qftYCpFsWYRUYbTGH_zv3dGOwg2dRq7dUrRwGsC6Cx7CijPBf9CXoUWgTdmreO_8ucSDVOQdCT8n0rze-OP8UQI9wD6sI4aoCX6MXmfAT4WfC2GdZ6bBfRZwJ66NLpFKbErtJSsJYDvcQvUZ1bdJuzlcZFxI3FbNbU2GcRfwFzUVPc3JFKNARhi1CTO1SWl3sSirym8b7kGqchXXzqwt4xfx3r__a6o_pIbzfHdwzk55quv_oifDvIEWEX7eInv7JQDTHR7GounycpCxYOnmN6K0wNz_7guU8L7KSqoqWA9a8oUMlOEXelo2osWoqKdjxclEUfsJI-Pn1WD_WZeZRzSJmRtvtNZvs9pn5RdLwVdL3lCJ4mdPsrN5JDCG1J89zwvrgE60fGOLDNoS3EHHZ38-__3aywrz9RP8QPYp0vppt0jb8XUUuZWrdFfmrG0ZOhPXeuUhYX-ec5QXPyqZoJRcSZTWMjRpk2ahBjBIpDuxYKcJ6baXZFKZbH6LXdspnwk-8JfxUMMJP1zlJD4Q10i2r8EhYc90WKRaj26xKE3SNjdJisi5ELbPrlxfLAIC3QJpvQBgH2C8Fwr_dIPn3j84eVMdVy1txwK5oymNNi6bkh7mjR9EoJXhZ0LZoqRqbYixbOjZcsHFQ7UF3jLKKVpwWtGSM51I0YmBcVHXR8qJpSElxEdrkadBy56eDDmHDrihZUbQHIwY04bKcGdsjytIu3t-uc8FYWt2-SxjZsE2BlNToEMM7atTRYPf-zddB-jQAh82bbo5xDYSfCOtTrnWctyGXLuVjXwyXK1fv_kCZWn0hn0Kz83_u2J8BAAD__0zf_3w">