<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/137704>137704</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            libc++ headers vs GCC 15 type traits builtins
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            libc++
      </td>
    </tr>

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

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

<pre>
    Between GCC 14 and GCC 15, a bunch of new C++ traits builtins were added that Clang already has:
```
1b7cfa715c6 c++: introduce __builtin_is_virtual_base_of 
3dab8f8a542 c++: Implement __is_nothrow_invocable built-in trait                
7bd33955970 c++: Implement __is_invocable built-in trait                        
37fad797ade c++: Implement __array_rank built-in trait                          
142d1d8e057 c++: Implement __decay built-in trait                               
85c2ba42441 c++: Implement __add_rvalue_reference built-in trait 
c08d1afbf53 c++: Implement __add_lvalue_reference built-in trait 
86812be98a1 c++: Implement __remove_all_extents built-in trait 
e1ca1fa1c7a c++: Implement __remove_extent built-in trait 
2763f81e0b9 c++: Implement __add_pointer built-in trait 
06d64eb96cd c++: Implement __is_unbounded_array built-in trait                  
cb5d904c775 c++: Implement __is_pointer built-in trait                          
9b51b3e79e4 c++: Implement __is_volatile built-in trait                         
7dd8c905219 c++: Implement __is_const built-in trait                            
```

Unlike Clang, GCC gets upset if these are used via template aliases rather than only via the standard `...::type` type aliases.
PR #81386 addressed the same issue earlier for `__remove_cv` and `__remove_cvref`.
Equivalent changes are needed for all the other ones where `__has_builtin(...)` has become true in GCC 15.

</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJyMlV2P6jYQhn-NuRkd5DgJcS5ywW67Ve-qSr2OxvaEuMfY1HbY8u8rB7bnE3YRUhDKPPPh1-9gSvbgiQbWPrH2lw0ueQ5xmGJQmfS8UcFchifKr0Qefnt-hqoB9Ob6s2XiGRDU4vUMYQJPr_DMxBMTT5Aj2pxALdZl6xO8UiRAY8hAnjHDs0N_AHSR0FxgxsTqPeN7tuO3L99XqtMTdlWrd6CvWFbvwfocg1k0wTje8KNN49nGvKAbFSYawwSM72uDSk4S20Z8Dfj9eHJ0JJ9hLIE-5DmG19H6c9CoHF2L_mT9tQn47sP4vlOmrvu27Tv-APxR4FfgupvQdH2Hhu6BMUa8jBH95w9iV3DVCFMZSbzt7oENabx8mPkGlq0WChvRNNXdio0Z4xndQmOkiSJ5_cNIGN9rLk2Fk5ra-hHJvU-SO1kJRb3EuzVFOoYzjejcSP9m8m9S_YZDlcZqwkp3-A7nyvgJQnS7epIVcdU_auoUrM8UfwLgO7NrSPU7bR5IbfEqLN6Qucrj3VMs41at6Xmju659AL5T2CNF9KqtVE1dT80D8Dk4zPbDd2O9dcZI3fNWVHdnadOog08_nMRjDX9tOozv__LOfqarQxWHK153oJxgOSXKYCfIMyUCjARLIgNni5DpeHKYCdBZTJQgYp4pFrPzELy7XN-aCVJGbzAaYDu-3W6L79X7fDkR23EozzfElvH9H38CE7Wsarkr7hkppdVBCRIeCWxKCwFhdJYiTCEW6P-q1OeCLHb97b-RppKb8f2v_yz2jK4MT8_oD5TWrjxRMerCQ-fWdGHtJnhK8DoXL1-RM6Y3D2ZClm5EX3LOmECRDkeCHBcCe1sebUm6MUNt-rrHDQ1V17Syq3jTbOah74zWk5xq1aDSu6rinVS8kagbpfmEGzsILlreCCl4idlKqTs9yVpWups4TqzhdETrts6dj9sQD5t1QkNVdx1vNg4VubTuOiGcVW8qEqLsvjiUqE9qOSTWcGdTTl842WZHw5cYmAkNxQTndGvtenbf7b3NEt0w53xa95t4YeLlYPO8qK0ORyZeCv_2-HSK4W_SmYmXtejExMut7vMg_gsAAP__t-5elw">