no longer mark x86 soft-float as a forbidden feature

Author: RalfJung

compiler/rustc_target/src/target_features.rs

@@ -419,7 +419,6 @@ const X86_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
     ("sha512", Unstable(sym::sha512_sm_x86), &["avx2"]),
     ("sm3", Unstable(sym::sha512_sm_x86), &["avx"]),
     ("sm4", Unstable(sym::sha512_sm_x86), &["avx2"]),
-    ("soft-float", Stability::Forbidden { reason: "unsound because it changes float ABI" }, &[]),
     ("sse", Stable, &[]),
     ("sse2", Stable, &["sse"]),
     ("sse3", Stable, &["sse2"]),

tests/ui/target-feature/forbidden-target-feature-attribute.rs

@@ -1,11 +1,11 @@
-//@ compile-flags: --target=x86_64-unknown-linux-gnu --crate-type=lib
-//@ needs-llvm-components: x86
+//@ compile-flags: --target=riscv32i-unknown-none-elf --crate-type=lib
+//@ needs-llvm-components: riscv
 #![feature(no_core, lang_items)]
 #![no_core]
 
 #[lang = "sized"]
 pub trait Sized {}
 
-#[target_feature(enable = "soft-float")]
+#[target_feature(enable = "forced-atomics")]
 //~^ERROR: cannot be enabled with
 pub unsafe fn my_fun() {}

tests/ui/target-feature/forbidden-target-feature-attribute.stderr

@@ -1,8 +1,8 @@
-error: target feature `soft-float` cannot be enabled with `#[target_feature]`: unsound because it changes float ABI
+error: target feature `forced-atomics` cannot be enabled with `#[target_feature]`: unsound because it changes the ABI of atomic operations
   --> $DIR/forbidden-target-feature-attribute.rs:9:18
    |
-LL | #[target_feature(enable = "soft-float")]
-   |                  ^^^^^^^^^^^^^^^^^^^^^
+LL | #[target_feature(enable = "forced-atomics")]
+   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to 1 previous error
 

tests/ui/target-feature/forbidden-target-feature-flag-disable.stderr

@@ -1,7 +1,7 @@
-warning: target feature `soft-float` cannot be disabled with `-Ctarget-feature`: unsound because it changes float ABI
+warning: unknown and unstable feature specified for `-Ctarget-feature`: `soft-float`
    |
-   = 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>
+   = note: it is still passed through to the codegen backend, but use of this feature might be unsound and the behavior of this feature can change in the future
+   = help: consider filing a feature request
 
 warning: 1 warning emitted
 

tests/ui/target-feature/forbidden-target-feature-flag.stderr

@@ -1,7 +1,12 @@
-warning: target feature `soft-float` cannot be enabled with `-Ctarget-feature`: unsound because it changes float ABI
+warning: unknown and unstable feature specified for `-Ctarget-feature`: `soft-float`
+   |
+   = note: it is still passed through to the codegen backend, but use of this feature might be unsound and the behavior of this feature can change in the future
+   = help: consider filing a feature request
+
+warning: target feature `soft-float` cannot be enabled with `-Ctarget-feature`: this feature is incompatible with the target ABI
    |
    = 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: 1 warning emitted
+warning: 2 warnings emitted