[all-commits] [llvm/llvm-project] c640a1: [lldb] Explicitly set libcxx paths when USE_SYSTEM...

[Felipe de Azevedo Piovezan via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c640a146c4caa3cca559e308e2e7ecc78c45140d
      https://github.com/llvm/llvm-project/commit/c640a146c4caa3cca559e308e2e7ecc78c45140d
  Author: Felipe de Azevedo Piovezan <fpiovezan at apple.com>
  Date:   2023-03-23 (Thu, 23 Mar 2023)

  Changed paths:
    M lldb/packages/Python/lldbsuite/test/make/Makefile.rules

  Log Message:
  -----------
  [lldb] Explicitly set libcxx paths when USE_SYSTEM_STDLIB is provided

For tests marked as "USE_SYSTEM_STDLIB", the expectation is that the
system's standard library should be used. However, the implementation of
this flag is such that we simply don't pass _any_ libcxxx-related flags
to Clang; in turn, Clang will use its defaults.

For a Clang/Libcxx pair compiled together, Clang defaults to:
1. The headers of the sibling libcxx.
2. The libraries of the system.

This mismatch is actually a bug in the driver; once fixed, however, (2)
would point to the sibling libcxx as well, which is _not_ what test
authors intended with the USE_SYSTEM_STDLIB flag.

As such, this patch explicitly sets a path to the system's libraries.
This change is done only in Apple platforms so that we can test this
works in this case first.

Differential Revision: https://reviews.llvm.org/D146714