(EXPERIMENT) compiletest: Don't set TARGET for non-run-make tests

[Zalathar]

There seem to be a few UI tests that use environment variable TARGET to avoid problems on i586, but we should probably just permit and use //@ ignore-i586 instead.

The run-make runner explicitly sets TARGET on its own, so run-make tests shouldn't be affected.

This PR is currently just for running try jobs; it's not intended for merging (yet).

r? ghost

[rustbot]

Some changes occurred in src/tools/compiletest

cc @jieyouxu

[Zalathar]

@bors try jobs=dist-i586-gnu-i586-i686-musl

[rust-bors]

☀️ Try build successful (CI)
Build commit: 0bf5ba8 (0bf5ba8b452dcbef660253c1594cbd22ffffeaf1, parent: f04e3dfc87d7e2b6ad53e7a52253812cd62eba50)

[rustbot]

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[Zalathar]

@bors try jobs=dist-i586-gnu-i586-i686-musl

[Zalathar]

@bors try cancel

[rust-bors]

Try build cancelled. Cancelled workflows:

• https://github.com/rust-lang/rust/actions/runs/18642218467

[Zalathar]

@bors try jobs=dist-i586-gnu-i586-i686-musl

[rust-bors]

💔 Test for 1f51c82 failed: CI. Failed jobs:

• try - dist-i586-gnu-i586-i686-musl (web logs, extended logs)

[Zalathar]

OK, this confirms that i586 still requires special treatment to avoid breaking CI.

But we should be able to just use //@ ignore-i586 for that.

[rustbot]

compiletest directives have been modified. Please add or update docs for the
new or modified directive in src/doc/rustc-dev-guide/.

[rust-log-analyzer]

The job aarch64-gnu-llvm-20-1 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

##[group]Building test helpers for aarch64-unknown-linux-gnu
##[endgroup]
[TIMING:end] test::TestHelpers { target: aarch64-unknown-linux-gnu } -- 0.059
##[group]Testing stage2 with compiletest suite=ui mode=ui (aarch64-unknown-linux-gnu)
2025-10-20T07:27:53.060061Z ERROR compiletest::directives: /checkout/tests/ui/abi/homogenous-floats-target-feature-mixup.rs:10: invalid line: ignore-i586 (no SSE2)
2025-10-20T07:27:53.169400Z ERROR compiletest::directives: /checkout/tests/ui/target-feature/target-feature-detection.rs:5: invalid line: ignore-i586 (no SSE2)


thread 'main' (24437) panicked at src/tools/compiletest/src/lib.rs:650:9:
there are errors in tests
stack backtrace:

[Zalathar]

@bors try jobs=dist-i586-gnu-i586-i686-musl

[rust-bors]

⌛ Trying commit 9347126 with merge 4bedb6d…

To cancel the try build, run the command @bors try cancel.

Workflow: https://github.com/rust-lang/rust/actions/runs/18646956085