[all-commits] [llvm/llvm-project] 515afe: [libc++] Change workaround for init_priority((100)...

[Louis Dionne via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 515afe8b13a659a7a979280ed87891e74cc7915c
      https://github.com/llvm/llvm-project/commit/515afe8b13a659a7a979280ed87891e74cc7915c
  Author: Louis Dionne <ldionne.2 at gmail.com>
  Date:   2021-12-13 (Mon, 13 Dec 2021)

  Changed paths:
    M libcxx/src/chrono.cpp
    A libcxx/src/chrono_system_time_init.h
    M libcxx/src/experimental/memory_resource.cpp
    A libcxx/src/experimental/memory_resource_init_helper.h
    M libcxx/src/iostream.cpp
    A libcxx/src/iostream_init.h

  Log Message:
  -----------
  [libc++] Change workaround for init_priority((100)) outside of system headers

We had previously been using a different workaround for pretending that
we were inside a system header, however it had some undesirable effects
on dependency parsing for build systems, as explained in [1].

This patch changes the workaround to use `#pragma GCC system_header`,
which shouldn't suffer from the same issue. Unfortunately, it is a lot
more verbose. The issue is that `#pragma GCC system_header` is ignored
when we are inside a source file, so we have to create a header just for
the sake of using it. IMO this seems like an artificial restriction
without much benefit, but investigating that is a different story.
For now, this should at least solve build system problems at the
cost of some readability.

[1]: https://reviews.llvm.org/D95972#3178968

Differential Revision: https://reviews.llvm.org/D115334