<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/133193>133193</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang-tidy] `readability-avoid-const-params-in-decls` does not work in header files
        </td>
    </tr>

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

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

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

<pre>
    As the title suggests, `readability-avoid-const-params-in-decls` does not work in header files.

It can be demonstrated using this CMake project:

[readability-avoid-const-params-in-decls.zip](https://github.com/user-attachments/files/19477828/readability-avoid-const-params-in-decls.zip)

It contains 2 functions:
- `void print(int const)`: Declared in header, defined in source file.
- `void print2(int const)`: Declared and defined in source file.

If you try to build it, you'll notice that `readability-avoid-const-params-in-decls` only warns about `print2()`, but I expect it to warn about both `print()` and `print2()`.

P.S. I wish I can demonstrate this on Godbolt, but seems like running clang-tidy with a CMake project is not possible there.

<details>
<summary>Here are my detailed reproduce steps</summary>

Only relevant command output are shown.

#### In host machine

```console
$ docker run -it fedora:41 bash
$ docker cp readability-avoid-const-params-in-decls/ <CONTAINER>:/root
```

#### In Docker container

```console
# cd
# dnf update
# dnf install @c-development cmake git ninja-build
# git clone https://github.com/llvm/llvm-project.git
# cd llvm-project/
# cmake -S llvm -B build -G Ninja -DLLVM_ENABLE_PROJECTS='clang;lld;clang-tools-extra' -DCMAKE_BUILD_TYPE=Release
# cd build/
# cmake --build .
# cmake --install .
# clang --version
clang version 21.0.0git (https://github.com/llvm/llvm-project.git a629b505757a1853e6083290e5d8d7b82f4f4d4a)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
# cd ~/readability-avoid-const-params-in-decls/
# CC=clang CXX=clang++ cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
-- The C compiler identification is Clang 21.0.0
-- The CXX compiler identification is Clang 21.0.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/local/bin/clang - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/local/bin/clang++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Looking for clang-tidy
-- Looking for clang-tidy - found
'/usr/local/bin/clang-tidy' '--version'
LLVM (http://llvm.org/):
 LLVM version 21.0.0git
  Optimized build.
-- Configuring done (0.3s)
-- Generating done (0.0s)
-- Build files have been written to: /root/readability-avoid-const-params-in-decls/build
# cd build/
# cmake --build .
[2/3] Building CXX object CMakeFiles/readability_avoid_const_params_in_decls.dir/main.cpp.o
/root/readability-avoid-const-params-in-decls/main.cpp:5:17: warning: parameter 'i' is const-qualified in the function declaration; const-qualification of parameters only has an effect in function definitio
ns [readability-avoid-const-params-in-decls]
    5 | void print2(int const i);
      |                 ^~~~~
[3/3] Linking CXX executable readability_avoid_const_params_in_decls
```

</details>
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJysV0lv4zoS_jX0pSBDJi3LPvjgtScz6QXdmUHPyaDEksUXmtSQVBK_Q377gJQcO6-TdAK8wEBsspavFn4scufkXiPOSbYk2XrAW18bO_fIbdXaQWHEcb5w4GsEL71CcO1-j847QldAJqlFLnghlfTHhN8ZKZLSaOeThlt-cInUicBSOTJJQRh0oI2He2NvQWqokQu0UEmFbkjSBUkXVx5KrqFAEHgIhiz3KKB1Uu_B19LB6jO_RWis-QNLT9ii0yPZ8p1Ihn_KhmRrQqe1940LFuiW0O1e-rothqU5ELptHdqEe8_L-oA6BLuNKAndjmbjPJ_SKaHbj3iks3OARnsutQMKVatLL412XSBJyGgwBI2V2hM6lTrKOx8MTFLCFrDGUnGL4pzBUAqBldTdojOtLTGmdfirUfobq1yLN4yFCCo4mha8PYI3ULRSCZA-YDialtBcqVBkWSL4mvsP9ojR6gj33GoHvDBtVH-C3aOlKyhaD1eADw2WHqQPQIJSr1MYXz8pPunFyH4110f1bfhjCFdwL10NV7EHLxqw6zyj4ZMRhVH-BMEhHhwoeYtgW61Dj5aK633ipTjCvfQ18OcNC7I7Ao1xThYqWEZ7yixhK4GeS-UI23S_XXs4cHskbPMPtAjcIhyO0EmhAIuNNaItEZzH0MwrQrdnnc7s15BTiwrveKz74RAyYVrftD5adLW51ycMlD194EpDbZyHAy9rqbGXmKTdJxTRqLhKxyBMeYs25AES6aFCYSwnbDEeQcFd_VyqbOC9TUG3QNhq9fXLzeLqy-Z7iCoeWWuMv0TzMvx17687cmjfCIFBKfovQlfQNoJ7vFiQ2nmuFJBxWiYC71CZJpADlIdQ4L30oKX-gyfxSPSKYbVURiO8wTZK3Z3-JX2fDPfSP6GCy52g329Ev8mPuA3Jsj-LySf4EnBAsr6-_s_n3ebLYnm92X37_vWfm9XND8LWhOaxTQlbKiUIW_ZNa4xyCT54ywnNIVmvPi_-tdkt_311vd7d_PfbhrD1d1TI3Tlhnc9fMHU5gOFfVk8pfFoPfiFJ7tA6aTRJF91K_xvoaJgO05DDt-n6lQQCn9BZkaVZnuV8NM0YTtIpo7MUMzEVeTGl1bgaizHv2PmG2z2GKwUeppPdZJy0-labe50oqduHZK_bIFSHxoWDEaiCaGOcfAis2IWGYi1tWI-XiA2gTMkVodtC6nPWHt9_e5xzu1oRtu4StPr58_Sd0CWhy1OKX2iCN6uYJHBTI6wCLTRSoQUpUHtZyZKHiynw1Sq67GpxofLz58eU1uix9IEjL7wtllcgdWXeIQIJCKN70Ksay1uojI3DxHONV9NPt33DgbuVTYPiVa9QIfetRfd7iWewLgQv0_NqlC8J_S7OC53fRdr3xuvxnm29HvELMs8gXhsTgQWQ59vvrT1IoDKt7jgyfyuAzhTNgdD8TBM0J-kicNuJFp5YITDA0Nh9_DXrhiqIkr9QStiBr42XB_kn9jw27JNudCX3rQ3IQ5zBTTpkrqOJJIFPqNFy_3w_Pe8v4xmMEyPU_A6hQNRwb6X3qMGbvm7xCvsIEVzeLO_i3mxJCd0ykq07TKeCmiIOI3E02faD7QWMXYSxizB2HYyd1LtumhUyFOvApR6WTTM00fvHYzkZIGyREbYY5SEpYYiT4WJaQNRAjzbUXoYekK4bWpP_tVzJSnYDaniZnMZoEHGKjSRE2PK5eM9Npjqbdt28WXMHXANWVZzQ9KW9SmrpZQhSO3j_KyO8MEKDAWRA8hW8Mn-DjG267GUhyv71j2Sbx8fHx66e7FTPa6mf-AAfsGw9D_PkO6v4wuQUZ8fz_DkQcyZmbMYHOB_lY5aO0zGjg3rOOS_Gk2qUMkYnZTqZ5VWejlgxzcYln-Y4kHOa0ixlNE9HGcvosJiMuaiqKi-nyBhHMk7xwKUano7rQDrX4nzE2GjGBooXqFx8kFJ6SQM0PFDtPF7zRbt3ZJwq6bw724lP1KB5oZat_8536qC1av6xUYTQbYwvvh67EO_m9P8BAAD__64TAHE">