remove duplicate error in check_rustc_legacy_const_generics

Author: Edvin Bryntesson

compiler/rustc_passes/src/check_attr.rs

@@ -213,7 +213,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     self.check_macro_export(hir_id, *span, target)
                 },
                 Attribute::Parsed(AttributeKind::RustcLegacyConstGenerics{attr_span, fn_indexes}) => {
-                    self.check_rustc_legacy_const_generics(hir_id, span, target, item, *attr_span, fn_indexes)
+                    self.check_rustc_legacy_const_generics(item, *attr_span, fn_indexes)
                 },
                 Attribute::Parsed(AttributeKind::Doc(attr)) => self.check_doc_attrs(attr, hir_id, target),
                 Attribute::Parsed(AttributeKind::EiiImpls(impls)) => {
@@ -1218,29 +1218,17 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
     /// Checks if `#[rustc_legacy_const_generics]` is applied to a function and has a valid argument.
     fn check_rustc_legacy_const_generics(
         &self,
-        hir_id: HirId,
-        span: Span,
-        target: Target,
         item: Option<ItemLike<'_>>,
         attr_span: Span,
         index_list: &ThinVec<(u128, Span)>,
     ) {
-        let is_function = matches!(target, Target::Fn);
-        if !is_function {
-            self.dcx().emit_err(errors::AttrShouldBeAppliedToFn {
-                attr_span,
-                defn_span: span,
-                on_crate: hir_id == CRATE_HIR_ID,
-            });
-            return;
-        }
-
         let Some(ItemLike::Item(Item {
             kind: ItemKind::Fn { sig: FnSig { decl, .. }, generics, .. },
             ..
         })) = item
         else {
-            bug!("should be a function item");
+            // No error here, since it's already given by the parser
+            return;
         };
 
         for param in generics.params {

tests/ui/invalid/invalid-rustc_legacy_const_generics-arguments.rs

@@ -16,7 +16,6 @@ fn foo4<const X: usize>() {}
 fn foo5<const X: usize, const Y: usize, const Z: usize, const W: usize>() {}
 
 #[rustc_legacy_const_generics(0)] //~ ERROR `#[rustc_legacy_const_generics]` attribute cannot be used on structs
-//~^ ERROR attribute should be applied to a function definition
 struct S;
 
 #[rustc_legacy_const_generics(0usize)]
@@ -26,7 +25,6 @@ fn foo6<const X: usize>() {}
 
 extern "C" {
     #[rustc_legacy_const_generics(1)] //~ ERROR `#[rustc_legacy_const_generics]` attribute cannot be used on foreign functions
-    //~^ ERROR attribute should be applied to a function definition
     fn foo7<const X: usize>(); //~ ERROR foreign items may not have const parameters
 }
 
@@ -35,7 +33,6 @@ fn foo8<X>() {}
 
 impl S {
     #[rustc_legacy_const_generics(0)] //~ ERROR `#[rustc_legacy_const_generics]` attribute cannot be used on inherent methods
-    //~^ ERROR attribute should be applied to a function definition
     fn foo9<const X: usize>() {}
 }
 

tests/ui/invalid/invalid-rustc_legacy_const_generics-arguments.stderr

@@ -25,15 +25,15 @@ LL | #[rustc_legacy_const_generics(0)]
    = help: `#[rustc_legacy_const_generics]` can only be applied to functions
 
 error: suffixed literals are not allowed in attributes
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:22:31
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:21:31
    |
 LL | #[rustc_legacy_const_generics(0usize)]
    |                               ^^^^^^
    |
    = help: instead of using a suffixed literal (`1u8`, `1.0f32`, etc.), use an unsuffixed version (`1`, `1.0`, etc.)
 
 error[E0539]: malformed `rustc_legacy_const_generics` attribute input
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:22:1
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:21:1
    |
 LL | #[rustc_legacy_const_generics(0usize)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^------^^
@@ -42,23 +42,23 @@ LL | #[rustc_legacy_const_generics(0usize)]
    | help: must be of the form: `#[rustc_legacy_const_generics(N)]`
 
 error: `#[rustc_legacy_const_generics]` attribute cannot be used on foreign functions
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:28:5
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:27:5
    |
 LL |     #[rustc_legacy_const_generics(1)]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: `#[rustc_legacy_const_generics]` can only be applied to functions
 
 error: `#[rustc_legacy_const_generics]` attribute cannot be used on inherent methods
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:37:5
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:35:5
    |
 LL |     #[rustc_legacy_const_generics(0)]
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: `#[rustc_legacy_const_generics]` can only be applied to functions
 
 error[E0539]: malformed `rustc_legacy_const_generics` attribute input
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:42:1
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:39:1
    |
 LL | #[rustc_legacy_const_generics]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -67,7 +67,7 @@ LL | #[rustc_legacy_const_generics]
    | help: must be of the form: `#[rustc_legacy_const_generics(N)]`
 
 error[E0539]: malformed `rustc_legacy_const_generics` attribute input
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:45:1
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:42:1
    |
 LL | #[rustc_legacy_const_generics = 1]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^---^
@@ -95,50 +95,23 @@ error: index exceeds number of arguments
 LL | #[rustc_legacy_const_generics(2)]
    |                               ^ there are only 2 arguments
 
-error: attribute should be applied to a function definition
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:18:1
-   |
-LL | #[rustc_legacy_const_generics(0)]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-LL |
-LL | struct S;
-   | --------- not a function definition
-
 error: #[rustc_legacy_const_generics] functions must only have const generics
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:33:1
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:31:1
    |
 LL | #[rustc_legacy_const_generics(0)]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 LL | fn foo8<X>() {}
    |         - non-const generic parameter
 
-error: attribute should be applied to a function definition
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:37:5
-   |
-LL |     #[rustc_legacy_const_generics(0)]
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-LL |
-LL |     fn foo9<const X: usize>() {}
-   |     ---------------------------- not a function definition
-
-error: attribute should be applied to a function definition
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:28:5
-   |
-LL |     #[rustc_legacy_const_generics(1)]
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-LL |
-LL |     fn foo7<const X: usize>();
-   |     -------------------------- not a function definition
-
 error[E0044]: foreign items may not have const parameters
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:30:5
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:28:5
    |
 LL |     fn foo7<const X: usize>();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^ can't have const parameters
    |
    = help: replace the const parameters with concrete consts
 
-error: aborting due to 17 previous errors
+error: aborting due to 14 previous errors
 
 Some errors have detailed explanations: E0044, E0539.
 For more information about an error, try `rustc --explain E0044`.