[PATCH] D101479: [Driver] Support libc++ in MSVC

[Petr Hosek via Phabricator via cfe-commits]

phosek added a comment.

In D101479#2813724 <https://reviews.llvm.org/D101479#2813724>, @mstorsjo wrote:

> Couldn’t this commit have been kept in, and just reverting the one for using it in the fuchsia cmake cache? (I’m not using this particular commit myself, just observing.)

The problem is that there's no way to configure the default libc++ on a per-target basis. We want to use libc++ as a default for all targets that support it, so for example even if you're compiling on Windows but targeting Fuchsia or Linux. Unfortunately, with this change that triggers D103947 <https://reviews.llvm.org/D103947> when compiling compiler-rt and I don't know how to work around it.

I'd point out that we have the same problem for other defaults, for example if you set lld as the default linker on Darwin, it causes issues because Clang tries to use `lld.ld64` which is not yet usable. We still want to use lld for all other targets, but there's no way to specify that in CMake today which is something we may want to address.


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https://reviews.llvm.org/D101479