[Lldb-commits] [libcxx] [libcxxabi] [lldb] [libc++] Stop copying headers to the build directory (PR #115380)

[Alexander Richardson via lldb-commits]

arichardson wrote:

> IIUC, the build that encountered issues in this patch ([in the comment above](https://github.com/llvm/llvm-project/pull/115380#issuecomment-2590801533)) is a flavour of (2), right? That seems surprising to me though since we also use the same flags when configuring libc++: https://github.com/llvm/llvm-project/blob/main/libcxx/CMakeLists.txt#L596
> 
> So the difference would be that you folks are building libc++ instrumented via the bootstrapping build instead of the "runtimes" build that we use for the rest of libc++ CI. I also fail to understand why our own bootstrapping build pre-commit CI didn't trip this wire.

I think the problem is that some of the buildbots use the compiler from the stage1 build directory as the compiler for the stage2 build. This happens to pick up the correct libc++ if the headers are in the build directory, but without the symlinks it would need to be installed first to another directory and then use the stage1 install as the compiler for stage 2.

https://github.com/llvm/llvm-project/pull/115380