[Lldb-commits] [PATCH] D156270: [lldb][NFCI] Change logic to find clang resource dir in standalone builds

Thu Aug 17 20:28:27 PDT 2023

paperchalice added a comment.

When I made D141907 <https://reviews.llvm.org/D141907>, I want `get_clang_resource_dir` in cmake and GetResourcesPath <https://clang.llvm.org/doxygen/CompilerInvocation_8cpp_source.html#l02913> in clang to have the same behavior and it also respects the doc string of `CLANG_RESOURCE_DIR`, but the behavior of `GetResourcesPath` itself is unintuitive when custom resource path is empty.

In D156270#4557902 <https://reviews.llvm.org/D156270#4557902>, @mgorny wrote:

> I'm not sure if it was really intended but the new API is kinda horrible, at least for us in Gentoo.
>
> Our install prefix is `/usr/lib/llvm/NN`, whereas clang resource dir is `/usr/lib/clang/NN`.
>
> If I don't override `CLANG_RESOURCE_DIR`, it infers the wrong directory:
> `/usr/lib/llvm/18/lib64/cmake/clang/../../..//lib64/clang/18`.

IIUC, the resource dir should be `/usr/lib/llvm/18/lib64/clang/18` when `CLANG_RESOURCE_DIR` is empty.

> To get the correct directory, I need to pass:
> `-DCLANG_RESOURCE_DIR="../../../clang/${LLVM_MAJOR}"`
> which is absolutely counterintuitive (the path gets appended to:
> `/usr/lib/llvm/18/lib64/cmake/clang/../../../bin`
> ).
>
> Not saying it's not workable but I'd hardly call that an improvement over the previous API.
>
> CC @tstellar, @paperchalice.

The API here is indeed user unfriendly, a possible improvement is to let `CLANG_RESOURCE_DIR` aslo accept absolute path.
Also, `CLANG_RESOURCE_DIR` doesn't seem to work in standalone mode, some extra variables should be exported to `ClangConfig.cmake` e.g. the install prefix and bin dir of clang.

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D156270/new/

https://reviews.llvm.org/D156270