Pass deployment target to cc linker with -m*-version-min=

[madsmtm]

Clang supports many ways of passing the deployment target, and prefers that you use the -target flag for doing so. This, however, works poorly work with Clang configuration files (at least before llvm/llvm-project#111387) and Zig CC.

To support GCC, we already passed the deployment target using the older, more widely supported -arch + -mmacosx-version-min= flag combination when compiling for macOS; let's do a similar thing for the other Apple targets too using -miphoneos-version-min=, -mtargetos= etc.

Note that when passing the target triple to the LLVM backend, we still have to merge the deployment target into that.

See also the similar fix in cc-rs where the problem is more prominent, exactly because we did not already do it for macOS.

@rustbot label O-apple
r? compiler
CC @thomcc @BlackHoleFox

[lcnr]

r? compiler

[briansmith]

See rust-lang/cc-rs#1339 (comment); the cc-rs change may need to be improved.

[madsmtm]

See rust-lang/cc-rs#1339 (comment); the cc-rs change may need to be improved.

Yeah, the cc-rs change was a bit wrong (have filed rust-lang/cc-rs#1384 to fix it), but that shouldn't affect rustc, since this PR also makes sure to not pass --target in the first place.

[madsmtm]

The related cc-rs change has seen a bit of breakage, so I'll wait let's say 3 weeks with this one until we're sure that part is sorted out.

@rustbot author

[LFS6502]

@madsmtm Any update on this PR? Thanks for your contribution.

[bors]

☔ The latest upstream changes (presumably #139037) made this pull request unmergeable. Please resolve the merge conflicts.

[madsmtm]

No update, I'll try to get back to it, but I need to think a bit to ensure that this is the right approach.