organize and extend forbidden target feature tests

[RalfJung]

In particular this adds some loongarch tests for #135015, Cc @heiher

Seems like the tests change so much git does not detect the renames; a commit-by-commit review should help.

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[petrochenkov]

r=me with tidy fixed.
@rustbot author

[rustbot]

Reminder, once the PR becomes ready for a review, use @rustbot ready.

[rust-log-analyzer]

The job x86_64-gnu-llvm-19 failed! Check out the build log: (web) (plain)

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

#18 exporting to docker image format
#18 sending tarball 19.6s done
#18 DONE 27.6s
##[endgroup]
Setting extra environment values for docker:  --env ENABLE_GCC_CODEGEN=1 --env GCC_EXEC_PREFIX=/usr/lib/gcc/
[CI_JOB_NAME=x86_64-gnu-llvm-19]
[CI_JOB_NAME=x86_64-gnu-llvm-19]
debug: `DISABLE_CI_RUSTC_IF_INCOMPATIBLE` configured.
---
sccache: Listening on address 127.0.0.1:4226
##[group]Configure the build
configure: processing command line
configure: 
configure: build.configure-args := ['--build=x86_64-unknown-linux-gnu', '--llvm-root=/usr/lib/llvm-19', '--enable-llvm-link-shared', '--set', 'rust.randomize-layout=true', '--set', 'rust.thin-lto-import-instr-limit=10', '--set', 'build.print-step-timings', '--enable-verbose-tests', '--set', 'build.metrics', '--enable-verbose-configure', '--enable-sccache', '--disable-manage-submodules', '--enable-locked-deps', '--enable-cargo-native-static', '--set', 'rust.codegen-units-std=1', '--set', 'dist.compression-profile=balanced', '--dist-compression-formats=xz', '--set', 'rust.lld=false', '--disable-dist-src', '--release-channel=nightly', '--enable-debug-assertions', '--enable-overflow-checks', '--enable-llvm-assertions', '--set', 'rust.verify-llvm-ir', '--set', 'rust.codegen-backends=llvm,cranelift,gcc', '--set', 'llvm.static-libstdcpp', '--set', 'gcc.download-ci-gcc=true', '--enable-new-symbol-mangling']
configure: build.build          := x86_64-unknown-linux-gnu
configure: target.x86_64-unknown-linux-gnu.llvm-config := /usr/lib/llvm-19/bin/llvm-config
configure: llvm.link-shared     := True
configure: rust.randomize-layout := True
configure: rust.thin-lto-import-instr-limit := 10
---
---- [ui] tests/ui/target-feature/abi-required-target-feature-flag-disable.rs#loongarch stdout ----
Saved the actual stderr to "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/target-feature/abi-required-target-feature-flag-disable.loongarch/abi-required-target-feature-flag-disable.loongarch.stderr"
diff of stderr:

+ '+div32' is not a recognized feature for this target (ignoring feature)
+ '+div32' is not a recognized feature for this target (ignoring feature)
+ '+lam-bh' is not a recognized feature for this target (ignoring feature)
+ '+lam-bh' is not a recognized feature for this target (ignoring feature)
+ '+lamcas' is not a recognized feature for this target (ignoring feature)
+ '+lamcas' is not a recognized feature for this target (ignoring feature)
+ '+ld-seq-sa' is not a recognized feature for this target (ignoring feature)
+ '+ld-seq-sa' is not a recognized feature for this target (ignoring feature)
+ '+scq' is not a recognized feature for this target (ignoring feature)
+ '+scq' is not a recognized feature for this target (ignoring feature)
1 warning: target feature `d` must be enabled to ensure that the ABI of the current target can be implemented correctly
2    |
3    = note: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!


The actual stderr differed from the expected stderr.
To update references, rerun the tests and pass the `--bless` flag
To only update this specific test, also pass `--test-args target-feature/abi-required-target-feature-flag-disable.rs`

error in revision `loongarch`: 1 errors occurred comparing output.
status: exit status: 0
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/target-feature/abi-required-target-feature-flag-disable.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2" "--cfg" "loongarch" "--check-cfg" "cfg(test,FALSE,x86,x86_implied,aarch64,riscv,loongarch)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/target-feature/abi-required-target-feature-flag-disable.loongarch" "-A" "unused" "-A" "internal_features" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--crate-type=lib" "--target=loongarch64-unknown-none" "-Ctarget-feature=-d"
stdout: none
--- stderr -------------------------------
'+div32' is not a recognized feature for this target (ignoring feature)
'+div32' is not a recognized feature for this target (ignoring feature)
'+lam-bh' is not a recognized feature for this target (ignoring feature)
'+lam-bh' is not a recognized feature for this target (ignoring feature)
'+lamcas' is not a recognized feature for this target (ignoring feature)
'+lamcas' is not a recognized feature for this target (ignoring feature)
'+ld-seq-sa' is not a recognized feature for this target (ignoring feature)
'+ld-seq-sa' is not a recognized feature for this target (ignoring feature)
'+scq' is not a recognized feature for this target (ignoring feature)
'+scq' is not a recognized feature for this target (ignoring feature)
warning: target feature `d` must be enabled to ensure that the ABI of the current target can be implemented correctly
   |
   = note: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
   = note: for more information, see issue #116344 <https://github.com/rust-lang/rust/issues/116344>

warning: unstable feature specified for `-Ctarget-feature`: `d`
   |
   = note: this feature is not stably supported; its behavior can change in the future

warning: both target-abi and the triple-implied ABI are invalid, ignoring and using feature-implied ABI
warning: 'lp64f' has not been standardized
warning: 2 warnings emitted
------------------------------------------

[RalfJung]

@heiher any idea what this warning is about? Does it come from LLVM?

For riscv it says

Hard-float 'd' ABI can't be used for a target that doesn't support the D instruction set extension (ignoring target-abi)

which is a lot more clear. Is this trying to say the same thing?

[RalfJung]

So somehow on CI we get a bunch of extra warnings:

2025-04-28T14:35:22.9208959Z '+div32' is not a recognized feature for this target (ignoring feature)
2025-04-28T14:35:22.9209370Z '+div32' is not a recognized feature for this target (ignoring feature)
2025-04-28T14:35:22.9209778Z '+lam-bh' is not a recognized feature for this target (ignoring feature)
2025-04-28T14:35:22.9210178Z '+lam-bh' is not a recognized feature for this target (ignoring feature)
2025-04-28T14:35:22.9210688Z '+lamcas' is not a recognized feature for this target (ignoring feature)
2025-04-28T14:35:22.9211099Z '+lamcas' is not a recognized feature for this target (ignoring feature)
2025-04-28T14:35:22.9211515Z '+ld-seq-sa' is not a recognized feature for this target (ignoring feature)
2025-04-28T14:35:22.9211932Z '+ld-seq-sa' is not a recognized feature for this target (ignoring feature)
2025-04-28T14:35:22.9212335Z '+scq' is not a recognized feature for this target (ignoring feature)
2025-04-28T14:35:22.9212721Z '+scq' is not a recognized feature for this target (ignoring feature)

I don't get those when running the test locally. Is that an LLVM version thing? Does loongarch64-unknown-none not work on older LLVM versions (not without a bunch of warnings, anyway)? How would one write a test for that target then...? And what even enables those target features?!?