<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/59267>59267</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Target "cxx_static" requires the language dialect "CXX20" Occurs in version 15.0.4
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

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

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

<pre>
    **The error log is below:**

CMake Error in /build/llvm-project-llvmorg-15.0.4/libcxx/src/CMakeLists.txt:
  Target "cxx_experimental" requires the language dialect "CXX20" , but CMake
  does not know the compile flags to use to enable it.

CMake Error in /build/llvm-project-llvmorg-15.0.4/libcxx/src/CMakeLists.txt:
  Target "cxx_static" requires the language dialect "CXX20" , but CMake does
  not know the compile flags to use to enable it.


-- Generating done
CMake Generate step failed.  Build files cannot be regenerated correctly.

**The following are the commands for building**
```shell
cmake -S ../llvm-project-llvmorg-15.0.4/llvm -G Ninja -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/build/target/llvm-15.0.1 -DLLVM_ENABLE_PROJECTS="clang" -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi" -DLLVM_INSTALL_UTILS=ON

ninja -j8 & ninja install

cmake ../llvm-project-llvmorg-15.0.4/compiler-rt -G Ninja -DLLVM_CONFIG_PATH=/build/target/llvm-15.0.1/bin/llvm-config -DCMAKE_INSTALL_PREFIX=/build/llvm-15.0.1-compile-rt/ -DLLVM_DIR=/build/build/ -DClang_DIR=/build/build/

ninja -j8 & ninja install
```


**Also, I tried the 12.0.1 build on my environment, and the results were good.**



</pre>
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