<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/131466>131466</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang-tidy.cert-dcl58-cpp false positive
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
      </td>
    </tr>

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

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

<pre>
    When I use `CMAKE_CXX_FLAGS=--gcc-install-dir=/usr/lib/gcc/x86_64-linux-gnu/13`, no clang-tidy issues found.
But with `CMAKE_CXX_FLAGS=--gcc-install-dir=/usr/lib/gcc/x86_64-linux-gnu/14` i get:
```
FAILED: CMakeFiles/pso_metr.dir/lib/metrology/pso_metr.cpp.o 
/usr/bin/cmake -E __run_co_compile --tidy="/usr/bin/clang-tidy-20;--warnings-as-errors=*;--config-file=tidycfg.yaml;--extra-arg-before=--driver-mode=g++" --source=test.cpp -- /usr/bin/clang++-20 -DONLY_C_LOCALE=0 -DUSE_OS_TZDB=1 --gcc-install-dir=/usr/lib/gcc/x86_64-linux-gnu/14 -O3 -DNDEBUG -gline-tables-only -std=gnu++20 -fPIC -Wall -Wextra -Werror -Wno-unknown-pragmas -Wno-unknown-warning-option -Wno-unknown-attributes -Wno-unknown-sanitizers -ftabstop=4 -ferror-limit=100 -Winvalid-pch -Xclang -include-pch -Xclang cmake_pch.hxx.pch -Xclang -include -Xclang cmake_pch.hxx -MD -MT test.cpp.o -MF test.cpp.o.d -o test.cpp.o -c test.cpp
error: modification of 'std' namespace can result in undefined behavior [cert-dcl58-cpp,-warnings-as-errors]
/usr/lib/gcc/x86_64-linux-gnu/14/../../../../include/c++/14/type_traits:65:11: note: 'std' namespace opened here
   65 | namespace std _GLIBCXX_VISIBILITY(default)
      |           ^
```
I suppose there is something wrong with "is system header" check - 14th folder by some reason is not "system".
tidycfg.yaml contains:
```
HeaderFilterRegex: '(/cxxpr/.+\.hxx$)|((Opc|[^bk]/core/|/drivers/).+\.(h|hpp|hxx)$)'
SystemHeaders: false
```
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJy0VV-P4yYQ_zTkZYRl4z9JHvLgxPE1ava26t517_piYYxtuhgswNmkn77C2dzt3q3Uh6qRBQHmz29-MDPUWtEpzjco3aK0WNDJ9dpsJmN16xa1bi6bx54rOMBkOaAs3N3lv-6r3ZcvVXnMPzyguMC4YwwLZR2VEjfCoLhApJysQaSUokak7BhDpDyvsipLsBRqOuNOTYiUUYyyEJEdKA1MUtVhJ5oLCGsnbqHVk2oCFObbycGzcP3_ACBBWQgCOu5QnKMw93iuX5iX-eG4L1Ccw-6OPvFSSG4RKUerq4E7E3hXNw9-Q0vdXV4LsHEMNHirNzi1UIiUbKBPHPAeqspMqmK6YnoYheSAZwLmAMiPSt_4wSRE8RbjZ2qUUJ3F1GJujDZ2VsznQ6ZVKzrcCslRXHg11nbBhQ5yPuZnZyimpsM1b7XhM4-NESdu8KAbv-4Q2c4fAYytngybLXHrfGCAMbyH8KqESQi4uP94_FrtquP9Lj_uUVz4vc8P--r-ofr0Z7FFcRHBf7s9wPcx4OJjsd9-_gC4k0Jx7GgtucVayQtg6xofi5f3wDyu9rfDDvAjlRLw40yEnz2BgB-VxpN6UvpZ4dHQbqD27eYL6ViPTmj19ow6Z0Q9Of6DjqVKOPE3NxZw62htnR5RXCSA29ktlmIQztMRhoAfhTpRKRo8sh7wl5lVwEIxOTX8zeb8jqqR9UF_Pgfvib8vCviuAHz3CW6XGWjAd-WrZdAA1m-O2bcVCvMZtU-MQTeiFYzOXOgWEFl6wskSFB24HSnjwKgCw-0kHQgFk2p4KxRvoOY9PQltAKVbxo3DDZPpCnsPZPfe406L16n075lNyiD4eXhhxr_X2wO_CrvLyCtnqHAWxXmWojiPIh-k0o77-b3g9Mh9LD03HIU5AGQpoOXulYR1DVQfjoetr1l_HB4O28Px8OkrIquGt3SSDpH1VRVgVv3-Q-n-h5J0ADuNo7YcnHcJwoLVA3e9UB08G-3HuVAS4o8u1vEBek4bbnwes56zJ8AQJa6HVsuGG6gvswkwnFqtvEWlnTdw1UaE-BL8uoAA08pRoezPJfOX2VUppOPmd97x8wtviKw84efz6K8u8KynO_8UEUl8_MvdLLG6H5n_75vRvn7yN05K5ssTKWeZ8lqifBlGZH2zg8iqR8tdP45-9EbXL3bJEoX5wxzIFZrHDC2Vlr9Gvmg2cbOO13TBN9EyIWGWrJNk0W-a5ZJkYULbqGZtuFquSNu2Ubau46Spl1m0EBsSkjSMozRapWmSBEmapCSL47SJIlInNUpCPlAhAylPQ6BNt5i72yaKoyTLFpLWXNpb-zUbL4XrqbMoCaWwzn7Xc8JJvvneBoK3SXONCkZthRMnvpiM3PTOjfMtebrKTrh-qgOmB58-8nSb8Gj0X5w5nxxz55078wzvtCH_BAAA__94OYtz">