vector ABI check: reword so it makes more sense for non-obviously-vector types

compiler/rustc_monomorphize/src/diagnostics.rs

@@ -101,18 +101,23 @@ pub(crate) struct EncounteredErrorWhileInstantiatingGlobalAsm {
 pub(crate) struct StartNotFound;
 
 #[derive(Diagnostic)]
-#[diag("this function {$is_call ->
-    [true] call
-    *[false] definition
-} uses {$is_scalable ->
-    [true] scalable
-    *[false] SIMD
-} vector type `{$ty}` which (with the chosen ABI) requires the `{$required_feature}` target feature, which is not enabled{$is_call ->
-    [true] {\" \"}in the caller
-    *[false] {\"\"}
-}")]
+#[diag(
+    "this function {$is_call ->
+        [true] call
+        *[false] definition
+    } requires the `{$required_feature}` target feature, which is not enabled{$is_call ->
+        [true] {\" \"}in the caller
+        *[false] {\"\"}
+    }"
+)]
+#[note(
+    "the function has type `{$ty}` in its signature, which is passed in {$is_scalable ->
+        [true] scalable
+        *[false] SIMD
+    } vector registers under the \"{$abi}\" ABI"
+)]
 #[help(
-    "consider enabling it globally (`-C target-feature=+{$required_feature}`) or locally (`#[target_feature(enable=\"{$required_feature}\")]`)"
+    "consider enabling the missing target feature globally (`-C target-feature=+{$required_feature}`) or locally (`#[target_feature(enable=\"{$required_feature}\")]`)"
 )]
 pub(crate) struct AbiErrorDisabledVectorType<'a> {
     #[primary_span]
@@ -124,6 +129,7 @@ pub(crate) struct AbiErrorDisabledVectorType<'a> {
     )]
     pub span: Span,
     pub required_feature: &'a str,
+    pub abi: String,
     pub ty: Ty<'a>,
     /// Whether this is a problem at a call site or at a declaration.
     pub is_call: bool,

compiler/rustc_monomorphize/src/mono_checks/abi_check.rs

@@ -84,6 +84,7 @@ fn do_check_simd_vector_abi<'tcx>(
                     tcx.dcx().emit_err(diagnostics::AbiErrorDisabledVectorType {
                         span,
                         required_feature: feature,
+                        abi: abi.conv.to_string(),
                         ty: arg_abi.layout.ty,
                         is_call,
                         is_scalable: false,
@@ -101,6 +102,7 @@ fn do_check_simd_vector_abi<'tcx>(
                     tcx.dcx().emit_err(diagnostics::AbiErrorDisabledVectorType {
                         span,
                         required_feature,
+                        abi: abi.conv.to_string(),
                         ty: arg_abi.layout.ty,
                         is_call,
                         is_scalable: true,
@@ -170,12 +172,8 @@ fn check_instance_abi<'tcx>(tcx: TyCtxt<'tcx>, instance: Instance<'tcx>) {
         tcx.dcx().delayed_bug("ABI computation failure should lead to compilation failure");
         return;
     };
-    // Unlike the call-site check, we do also check "Rust" ABI functions here.
-    // This should never trigger, *except* if we start making use of vector registers
-    // for the "Rust" ABI and the user disables those vector registers (which should trigger a
-    // warning as that's clearly disabling a "required" target feature for this target).
-    // Using such a function is where disabling the vector register actually can start leading
-    // to soundness issues, so erroring here seems good.
+    // Unlike the call-site check, we do also check "Rust" ABI functions here. This can actually
+    // trigger due to scalable vectors being require for the "Rust" ABI for some types.
     let loc = || {
         let def_id = instance.def_id();
         (

tests/ui/abi/simd-abi-checks-avx.stderr

@@ -1,90 +1,101 @@
-error: this function call uses SIMD vector type `std::arch::x86_64::__m256` which (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
+error: this function call requires the `avx` target feature, which is not enabled in the caller
   --> $DIR/simd-abi-checks-avx.rs:59:11
    |
 LL |         f(g());
    |           ^^^ function called here
    |
-   = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
+   = note: the function has type `std::arch::x86_64::__m256` in its signature, which is passed in SIMD vector registers under the "C" ABI
+   = help: consider enabling the missing target feature globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
-error: this function call uses SIMD vector type `std::arch::x86_64::__m256` which (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
+error: this function call requires the `avx` target feature, which is not enabled in the caller
   --> $DIR/simd-abi-checks-avx.rs:59:9
    |
 LL |         f(g());
    |         ^^^^^^ function called here
    |
-   = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
+   = note: the function has type `std::arch::x86_64::__m256` in its signature, which is passed in SIMD vector registers under the "C" ABI
+   = help: consider enabling the missing target feature globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
-error: this function call uses SIMD vector type `std::arch::x86_64::__m256` which (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
+error: this function call requires the `avx` target feature, which is not enabled in the caller
   --> $DIR/simd-abi-checks-avx.rs:65:14
    |
 LL |         gavx(favx());
    |              ^^^^^^ function called here
    |
-   = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
+   = note: the function has type `std::arch::x86_64::__m256` in its signature, which is passed in SIMD vector registers under the "C" ABI
+   = help: consider enabling the missing target feature globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
-error: this function call uses SIMD vector type `std::arch::x86_64::__m256` which (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
+error: this function call requires the `avx` target feature, which is not enabled in the caller
   --> $DIR/simd-abi-checks-avx.rs:65:9
    |
 LL |         gavx(favx());
    |         ^^^^^^^^^^^^ function called here
    |
-   = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
+   = note: the function has type `std::arch::x86_64::__m256` in its signature, which is passed in SIMD vector registers under the "C" ABI
+   = help: consider enabling the missing target feature globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
-error: this function call uses SIMD vector type `std::arch::x86_64::__m256` which (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
+error: this function call requires the `avx` target feature, which is not enabled in the caller
   --> $DIR/simd-abi-checks-avx.rs:75:19
    |
 LL |         w(Wrapper(g()));
    |                   ^^^ function called here
    |
-   = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
+   = note: the function has type `std::arch::x86_64::__m256` in its signature, which is passed in SIMD vector registers under the "C" ABI
+   = help: consider enabling the missing target feature globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
-error: this function call uses SIMD vector type `Wrapper` which (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
+error: this function call requires the `avx` target feature, which is not enabled in the caller
   --> $DIR/simd-abi-checks-avx.rs:75:9
    |
 LL |         w(Wrapper(g()));
    |         ^^^^^^^^^^^^^^^ function called here
    |
-   = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
+   = note: the function has type `Wrapper` in its signature, which is passed in SIMD vector registers under the "C" ABI
+   = help: consider enabling the missing target feature globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
-error: this function call uses SIMD vector type `std::arch::x86_64::__m256` which (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
+error: this function call requires the `avx` target feature, which is not enabled in the caller
   --> $DIR/simd-abi-checks-avx.rs:89:9
    |
 LL |         some_extern();
    |         ^^^^^^^^^^^^^ function called here
    |
-   = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
+   = note: the function has type `std::arch::x86_64::__m256` in its signature, which is passed in SIMD vector registers under the "C" ABI
+   = help: consider enabling the missing target feature globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
-error: this function definition uses SIMD vector type `std::arch::x86_64::__m256` which (with the chosen ABI) requires the `avx` target feature, which is not enabled
+error: this function definition requires the `avx` target feature, which is not enabled
   --> $DIR/simd-abi-checks-avx.rs:24:1
    |
 LL | unsafe extern "C" fn g() -> __m256 {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
    |
-   = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
+   = note: the function has type `std::arch::x86_64::__m256` in its signature, which is passed in SIMD vector registers under the "C" ABI
+   = help: consider enabling the missing target feature globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
-error: this function definition uses SIMD vector type `std::arch::x86_64::__m256` which (with the chosen ABI) requires the `avx` target feature, which is not enabled
+error: this function definition requires the `avx` target feature, which is not enabled
   --> $DIR/simd-abi-checks-avx.rs:19:1
    |
 LL | unsafe extern "C" fn f(_: __m256) {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
    |
-   = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
+   = note: the function has type `std::arch::x86_64::__m256` in its signature, which is passed in SIMD vector registers under the "C" ABI
+   = help: consider enabling the missing target feature globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
-error: this function definition uses SIMD vector type `Wrapper` which (with the chosen ABI) requires the `avx` target feature, which is not enabled
+error: this function definition requires the `avx` target feature, which is not enabled
   --> $DIR/simd-abi-checks-avx.rs:14:1
    |
 LL | unsafe extern "C" fn w(_: Wrapper) {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ function defined here
    |
-   = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
+   = note: the function has type `Wrapper` in its signature, which is passed in SIMD vector registers under the "C" ABI
+   = help: consider enabling the missing target feature globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
-error: this function call uses SIMD vector type `std::arch::x86_64::__m256` which (with the chosen ABI) requires the `avx` target feature, which is not enabled in the caller
+error: this function call requires the `avx` target feature, which is not enabled in the caller
   --> $DIR/simd-abi-checks-avx.rs:53:8
    |
 LL |     || g()
    |        ^^^ function called here
    |
-   = help: consider enabling it globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
+   = note: the function has type `std::arch::x86_64::__m256` in its signature, which is passed in SIMD vector registers under the "C" ABI
+   = help: consider enabling the missing target feature globally (`-C target-feature=+avx`) or locally (`#[target_feature(enable="avx")]`)
 
 note: the above error was encountered while instantiating `fn in_closure::{closure#0}`
   --> $DIR/simd-abi-checks-avx.rs:81:9