[win][arm64ec] Fix finding assembler and setting is_arm for Arm64EC

[dpaoliello]

No description provided.

[NobodyXu]

Thanks!

Just one refactor required

[NobodyXu]

Thank you!

[NobodyXu]

Seems like it break the ci on main

https://github.com/rust-lang/cc-rs/actions/runs/16855945795/job/47749185799#step:6:1

[dpaoliello]

clang: error: unknown argument: '-?'

Errr... doesn't seem related to my change. It shouldn't have affected non-MSVC targets...

[dpaoliello]

Hmm... This is for build-std with nightly, did something break in the Rust project?

[NobodyXu]

Maybe? i was thinking if there's some
new commits on main, combine with this PR, cause the failure

[NobodyXu]

Took another look, you are right, it's probably a nightly issue

[dpaoliello]

Looks like those compiler warnings were red herrings, the real error is:

note: ld: building for 'visionOS-simulator', but linking in object file (/Users/runner/work/cc-rs/cc-rs/target/aarch64-apple-visionos-sim/debug/build/cc-test-55b62b3e97617bab/out/libOptLinkage.a[2](ea708c7824d36062-opt_linkage.o)) built for 'visionOS'

[dpaoliello]

I believe the root cause is rust-lang/rust#139451 (cc @madsmtm)

Looking at: https://github.com/rust-lang/rust/pull/139451/files#diff-e8d43d302ad15ae5c24ca635b7a9abd544a4bac8b12b086b3f71c8da49e68538

Seems that sim was changed from an abi to env, which breaks the checks in cc:

cc-rs/src/target/apple.rs

Lines 33 to 47 in ca81dcc

	match (self.os, self.abi) {
	("macos", "") => format!("-mmacosx-version-min={min_version}"),
	("ios", "") => format!("-miphoneos-version-min={min_version}"),
	("ios", "sim") => format!("-mios-simulator-version-min={min_version}"),
	("ios", "macabi") => format!("-mtargetos=ios{min_version}-macabi"),
	("tvos", "") => format!("-mappletvos-version-min={min_version}"),
	("tvos", "sim") => format!("-mappletvsimulator-version-min={min_version}"),
	("watchos", "") => format!("-mwatchos-version-min={min_version}"),
	("watchos", "sim") => format!("-mwatchsimulator-version-min={min_version}"),
	// `-mxros-version-min` does not exist
	// https://github.com/llvm/llvm-project/issues/88271
	("visionos", "") => format!("-mtargetos=xros{min_version}"),
	("visionos", "sim") => format!("-mtargetos=xros{min_version}-simulator"),
	(os, _) => panic!("invalid Apple target OS {}", os),
	}

@wesleywiser can we do a crater run with nightly? Seems like this is a breaking change...

Guessing the fix in cc is to check both abi AND env?

[NobodyXu]

Fixed in #1517

[NobodyXu]

Thank you for finding the rust PR for me!

[wesleywiser]

I don't think a crater run will really find anything as it effectively can only test {i686,x86_64}-unknown-linux-{gnu,musl}. Even the breakage detected in CI here would not have been uncovered by crater as far as I can tell.

I agree there's a compatibility concern here but that was disclosed on rust-lang/rust#139451 and the compiler team FCP'd the change. I'll make sure we have a release note for that.