add a test for target-feature-ABI warnings in closures

Author: RalfJung

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -576,9 +576,9 @@ fn codegen_fn_attrs(tcx: TyCtxt<'_>, did: LocalDefId) -> CodegenFnAttrs {
     // If this closure is marked `#[inline(always)]`, simply skip adding `#[target_feature]`.
     //
     // At this point, `unsafe` has already been checked and `#[target_feature]` only affects codegen.
-    // Emitting both `#[inline(always)]` and `#[target_feature]` can potentially result in an
-    // ICE, because LLVM errors when the function fails to be inlined due to a target feature
-    // mismatch.
+    // Due to LLVM limitations, emitting both `#[inline(always)]` and `#[target_feature]` is *unsound*:
+    // the function may be inlined into a caller with fewer target features. Also see
+    // <https://github.com/rust-lang/rust/issues/116573>.
     //
     // Using `#[inline(always)]` implies that this closure will most likely be inlined into
     // its parent function, which effectively inherits the features anyway. Boxing this closure

tests/ui/simd-abi-checks.rs

@@ -4,6 +4,7 @@
 
 #![feature(avx512_target_feature)]
 #![feature(portable_simd)]
+#![feature(target_feature_11)]
 #![allow(improper_ctypes_definitions)]
 
 use std::arch::x86_64::*;
@@ -50,6 +51,14 @@ unsafe fn test() {
     as_f64x8(arg);
 }
 
+#[target_feature(enable = "avx")]
+unsafe fn in_closure() -> impl FnOnce() -> __m256 {
+    #[inline(always)] // this disables target-feature inheritance
+    || g()
+    //~^ WARNING this function call uses a SIMD vector type that (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
+    //~| WARNING this was previously accepted by the compiler
+}
+
 fn main() {
     unsafe {
         f(g());
@@ -78,4 +87,8 @@ fn main() {
         //~| WARNING this was previously accepted by the compiler
         //~| WARNING this was previously accepted by the compiler
     }
+
+    unsafe {
+        in_closure()();
+    }
 }

tests/ui/simd-abi-checks.stderr

@@ -1,5 +1,5 @@
 warning: this function call uses a SIMD vector type that (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
-  --> $DIR/simd-abi-checks.rs:55:11
+  --> $DIR/simd-abi-checks.rs:64:11
    |
 LL |         f(g());
    |           ^^^ function called here
@@ -10,7 +10,7 @@ LL |         f(g());
    = note: `#[warn(abi_unsupported_vector_types)]` on by default
 
 warning: this function call uses a SIMD vector type that (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
-  --> $DIR/simd-abi-checks.rs:55:9
+  --> $DIR/simd-abi-checks.rs:64:9
    |
 LL |         f(g());
    |         ^^^^^^ function called here
@@ -20,7 +20,7 @@ LL |         f(g());
    = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
 warning: this function call uses a SIMD vector type that (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
-  --> $DIR/simd-abi-checks.rs:63:14
+  --> $DIR/simd-abi-checks.rs:72:14
    |
 LL |         gavx(favx());
    |              ^^^^^^ function called here
@@ -30,7 +30,7 @@ LL |         gavx(favx());
    = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
 warning: this function call uses a SIMD vector type that (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
-  --> $DIR/simd-abi-checks.rs:63:9
+  --> $DIR/simd-abi-checks.rs:72:9
    |
 LL |         gavx(favx());
    |         ^^^^^^^^^^^^ function called here
@@ -40,7 +40,7 @@ LL |         gavx(favx());
    = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
 warning: this function call uses a SIMD vector type that (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
-  --> $DIR/simd-abi-checks.rs:75:19
+  --> $DIR/simd-abi-checks.rs:84:19
    |
 LL |         w(Wrapper(g()));
    |                   ^^^ function called here
@@ -50,7 +50,7 @@ LL |         w(Wrapper(g()));
    = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
 warning: this function call uses a SIMD vector type that (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
-  --> $DIR/simd-abi-checks.rs:75:9
+  --> $DIR/simd-abi-checks.rs:84:9
    |
 LL |         w(Wrapper(g()));
    |         ^^^^^^^^^^^^^^^ function called here
@@ -60,7 +60,7 @@ LL |         w(Wrapper(g()));
    = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
 warning: this function definition uses a SIMD vector type that (with the chosen ABI) requires the `avx` target feature, which is not enabled
-  --> $DIR/simd-abi-checks.rs:26:1
+  --> $DIR/simd-abi-checks.rs:27:1
    |
 LL | unsafe extern "C" fn g() -> __m256 {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
@@ -70,7 +70,7 @@ LL | unsafe extern "C" fn g() -> __m256 {
    = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
 warning: this function definition uses a SIMD vector type that (with the chosen ABI) requires the `avx` target feature, which is not enabled
-  --> $DIR/simd-abi-checks.rs:20:1
+  --> $DIR/simd-abi-checks.rs:21:1
    |
 LL | unsafe extern "C" fn f(_: __m256) {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
@@ -80,7 +80,7 @@ LL | unsafe extern "C" fn f(_: __m256) {
    = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
 warning: this function definition uses a SIMD vector type that (with the chosen ABI) requires the `avx` target feature, which is not enabled
-  --> $DIR/simd-abi-checks.rs:14:1
+  --> $DIR/simd-abi-checks.rs:15:1
    |
 LL | unsafe extern "C" fn w(_: Wrapper) {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
@@ -89,7 +89,17 @@ LL | unsafe extern "C" fn w(_: Wrapper) {
    = note: for more information, see issue #116558 <https://github.com/rust-lang/rust/issues/116558>
    = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
-warning: 9 warnings emitted
+warning: this function call uses a SIMD vector type that (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
+  --> $DIR/simd-abi-checks.rs:57:8
+   |
+LL |     || g()
+   |        ^^^ function called here
+   |
+   = warning: 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 #116558 <https://github.com/rust-lang/rust/issues/116558>
+   = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
+
+warning: 10 warnings emitted
 
 Future incompatibility report: Future breakage diagnostic:
 warning: this function call uses a SIMD vector type that (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller