[clang] [clang][driver] Use TheDriver.ClangExecutable in SetInstallDir to point to the actual install folder (PR #68091)

[Liviu Ionescu via cfe-commits]

ilg-ul wrote:

@jansvoboda11, since the Apple clang already fixed this bug, could you suggest how to proceed? Could you backport the Apple patch to upstream?

Please also take a look at the original bug report #66704, since it is related to macOS.


https://github.com/llvm/llvm-project/pull/68091