[clang][driver] Add <executable>/../include/c++/v1 to include path on Darwin (#70817)

On macOS, when clang is invoked via a symlink, since the InstalledDir is
where the link is located, the C++ headers are not identified and the
default system headers from the SDK are used.

This can be undesirable if a toolchain is created by symlinking clang
into a directory and placing libc++ headers in that directory with the
intent of those headers overriding the SDK headers. This change solves
that problem by also looking for libc++ headers in the toolchain-relative
location of the executable symlink, if any.

0 files changed, 0 insertions, 0 deletions