Fix linker detection for clang with prefix

[taiki-e]

#106489 removed check for clang with prefix. It says:

Also remove the check for -clang, since there are no architecture specific variants of clang (to my knowledge).

However, when doing cross-compilation, a wrapper script for clang with the target name as a prefix is sometimes used.

rust/src/ci/docker/host-x86_64/dist-various-2/Dockerfile

Line 62 in 1716932

CC_i686_unknown_freebsd=i686-unknown-freebsd12-clang \

rust/src/ci/docker/scripts/freebsd-toolchain.sh

Lines 76 to 80 in 1716932

	for tool in clang clang++; do
	tool_path=/usr/local/bin/${triple}-${tool}
	cat > "$tool_path" <<EOF
	#!/bin/sh
	exec $tool --sysroot=$sysroot --prefix=${sysroot}/bin "\$@" --target=$triple

rust/src/ci/docker/host-x86_64/dist-various-2/Dockerfile

Line 40 in 1716932

CC_aarch64_unknown_fuchsia=aarch64-unknown-fuchsia-clang \

rust/compiler/rustc_target/src/spec/aarch64_pc_windows_gnullvm.rs

Line 7 in 1716932

base.linker = Some("aarch64-w64-mingw32-clang".into());

It seems the regression did not occur on the targets mentioned above because the default linker flavor is gcc, but it did occur on targets where the default linker flavor is not gcc (taiki-e/setup-cross-toolchain-action@fd352f3).

r? @petrochenkov

[jonhoo]

I'm also running into this with Rust 1.68.0 as I have an instance where the build is pointed at x86_64-unknown-linux-gnu-clang. This should probably be tagged with regression-from-stable-to-stable.

[petrochenkov]

Thanks!
In #106489 I wanted to suggest always treating gcc and clang identically, but the PR already went through too many rounds of tweaks, so I just merged it in hope that if *-clang versions exist then someone reports it, likely a mistake in retrospect.

[petrochenkov]

This needs to be backported, but not important enough for a stable backport unless there will be a point release for other reasons.

[petrochenkov]

@bors r+ rollup

[bors]

📌 Commit 86a5e36 has been approved by petrochenkov

It is now in the queue for this repository.

[apiraino]

Beta backport accepted as per compiler team on Zulip

@rustbot label +beta-accepted