[PATCH] D89013: [libcxx] Support per-target __config_site in per-target runtime build

[Petr Hosek via Phabricator via cfe-commits]

phosek added a comment.

In D89013#2662434 <https://reviews.llvm.org/D89013#2662434>, @ldionne wrote:

> I'm personally not so concerned with the Clang driver side of things, but primarily with adding more complexity to the libc++ build. Shouldn't we be driving things from the runtimes build and setting a different `CMAKE_INSTALL_PREFIX` to install stuff to the right location instead? Then you can run N builds of libc++ for N targets, each setting the appropriate install path.

We could do that but problem with the approach is that we would end up duplicating all headers across targets. Since all headers except `__config_site` should be the same, we only want to have per-target version of that header which is what this change is doing. The final directory layout you end up with:

  include/
    c++/
      v1/
        <headers except for __config_site>
    x86_64-linux-gnu/
      c++/
        v1/
          __config_site
    <other targets>

This is the most optimal layout but I don't think it's something we can achieve purely with `CMAKE_INSTALL_PREFIX` without additional build support.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D89013/new/

https://reviews.llvm.org/D89013