[PATCH] D110663: [Driver] Support Debian multiarch style lib/clang/14.0.0/x86_64-linux-gnu runtime path and include/x86_64-linux-gnu/c++/v1 libc++ path

[Fangrui Song via Phabricator via cfe-commits]

MaskRay added a comment.

In D110663#3055813 <https://reviews.llvm.org/D110663#3055813>, @phosek wrote:

> I'm still worried that this solution as implemented is going to break existing users, including major one like Rust.

Well, it's better than calling the Project build deprecated (in favor of Runtime build) and making the situation unfortunate for major distributions like Debian/Ubuntu.

For downstream packages like Rust, there is currently no evidence for the breakage.

Moreover, llvm-project has always had the attitude: "downstream projects are on their own".
In reality we seldom exercise this right but if there are quirky things we reserve the right to ask them to fix.
(I have patched packages like Julia/Rust/ldc, so I understand that for each major version, some adaptation is unavoidable.)

> I'm not also not a fan of special casing individual targets like Fuchsia directly inside `Driver`, I believe that any per-target logic should live in the corresponding `ToolChain` subclass.

I add the code more as a workaround. I hope Fuchsia can move away from the mix of `x86_64-unknown-fuchsia` and `x86_64-fuchsia`.
At the point when the mix is fixed, we can simply remove the special case.
The special case is for providing a transition period. Using subclasses adds more complexity to the driver code.


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https://reviews.llvm.org/D110663