<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/65880>65880</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            "libstdc++ version must be at least" assertion when building with libc++
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            libc++,
            new issue
      </td>
    </tr>

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

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

<pre>
    Hi!

I
1. cloned/built/installed llvm 
2. rebuilding llvm with the latest llvm trunk. 

First time it worked, but when I am building with trunk, the configuration fails.

Please help?

history of commands

```
 2017 CC=clang CXX=clang++ cmake -G Ninja -DCMAKE_CXX_FLAGS="--stdlib=libc++ -march=native" -DLLVM_ENABLE_RUNTIMES=all -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra;cross-project-tests;libc;libclc;lld;lldb;openmp;polly;pstl" -DCMAKE_BUILD_TYPE=Release  ../llvm
 2018  clear
 2019  time ninja
 2020  sudo ninja install
 2021  rm -rf *
 2022  CC=clang CXX=clang++ cmake -G Ninja -DCMAKE_CXX_FLAGS="--stdlib=libc++ -march=native" -DLLVM_ENABLE_RUNTIMES=all -DLLVM_ENABLE_PROJECTS="clang;clang-tools-extra;cross-project-tests;libc;libclc;lld;lldb;openmp;polly;pstl" -DCMAKE_BUILD_TYPE=Release  ../llvm
```

Now fails with

```
CMake Error at cmake/modules/CheckCompilerVersion.cmake:88 (message):
  libstdc++ version must be at least 7.4.
Call Stack (most recent call first):
  cmake/config-ix.cmake:16 (include)
 CMakeLists.txt:872 (include)
```

Versions:

```
clang --version
clang version 18.0.0 (git@github.com:llvm/llvm-project.git 444abb396c340e52a8a4db5778b7d6b3b6195070)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin

clang++ --version
clang version 18.0.0 (git@github.com:llvm/llvm-project.git 444abb396c340e52a8a4db5778b7d6b3b6195070)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/bin
```
</pre>
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