Auto merge of #64360 - varkor:foreign-items-diagnostic-const-generics, r=cramertj
Correct the polymorphic extern fn error for const parameters Before, any polymorphism on extern functions was assumed to be type polymorphism.
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commit
a5e3de3437
@ -1511,21 +1511,34 @@ pub fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, it: &'tcx hir::Item) {
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} else {
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for item in &m.items {
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let generics = tcx.generics_of(tcx.hir().local_def_id(item.hir_id));
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if generics.params.len() - generics.own_counts().lifetimes != 0 {
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let mut err = struct_span_err!(
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let own_counts = generics.own_counts();
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if generics.params.len() - own_counts.lifetimes != 0 {
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let (kinds, kinds_pl, egs) = match (own_counts.types, own_counts.consts) {
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(_, 0) => ("type", "types", Some("u32")),
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// We don't specify an example value, because we can't generate
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// a valid value for any type.
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(0, _) => ("const", "consts", None),
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_ => ("type or const", "types or consts", None),
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};
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struct_span_err!(
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tcx.sess,
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item.span,
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E0044,
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"foreign items may not have type parameters"
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);
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err.span_label(item.span, "can't have type parameters");
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// FIXME: once we start storing spans for type arguments, turn this into a
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// suggestion.
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err.help(
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"use specialization instead of type parameters by replacing them \
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with concrete types like `u32`",
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);
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err.emit();
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"foreign items may not have {} parameters",
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kinds,
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).span_label(
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item.span,
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&format!("can't have {} parameters", kinds),
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).help(
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// FIXME: once we start storing spans for type arguments, turn this
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// into a suggestion.
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&format!(
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"replace the {} parameters with concrete {}{}",
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kinds,
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kinds_pl,
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egs.map(|egs| format!(" like `{}`", egs)).unwrap_or_default(),
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),
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).emit();
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}
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if let hir::ForeignItemKind::Fn(ref fn_decl, _, _) = item.node {
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10
src/test/ui/const-generics/foreign-item-const-parameter.rs
Normal file
10
src/test/ui/const-generics/foreign-item-const-parameter.rs
Normal file
@ -0,0 +1,10 @@
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#![feature(const_generics)]
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//~^ WARN the feature `const_generics` is incomplete and may cause the compiler to crash
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extern "C" {
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fn foo<const X: usize>(); //~ ERROR foreign items may not have const parameters
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fn bar<T, const X: usize>(_: T); //~ ERROR foreign items may not have type or const parameters
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}
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fn main() {}
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@ -0,0 +1,27 @@
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warning: the feature `const_generics` is incomplete and may cause the compiler to crash
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--> $DIR/foreign-item-const-parameter.rs:1:12
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LL | #![feature(const_generics)]
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| ^^^^^^^^^^^^^^
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= note: `#[warn(incomplete_features)]` on by default
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error[E0044]: foreign items may not have const parameters
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--> $DIR/foreign-item-const-parameter.rs:5:5
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LL | fn foo<const X: usize>();
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| ^^^^^^^^^^^^^^^^^^^^^^^^^ can't have const parameters
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= help: replace the const parameters with concrete consts
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error[E0044]: foreign items may not have type or const parameters
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--> $DIR/foreign-item-const-parameter.rs:7:5
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LL | fn bar<T, const X: usize>(_: T);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ can't have type or const parameters
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= help: replace the type or const parameters with concrete types or consts
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0044`.
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@ -1,7 +1,7 @@
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extern {
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fn sqrt<T>(f: T) -> T;
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//~^ ERROR foreign items may not have type parameters [E0044]
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//~| HELP use specialization instead of type parameters by replacing them with concrete types
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//~| HELP replace the type parameters with concrete types
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//~| NOTE can't have type parameters
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}
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@ -4,7 +4,7 @@ error[E0044]: foreign items may not have type parameters
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LL | fn sqrt<T>(f: T) -> T;
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| ^^^^^^^^^^^^^^^^^^^^^^ can't have type parameters
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= help: use specialization instead of type parameters by replacing them with concrete types like `u32`
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= help: replace the type parameters with concrete types like `u32`
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error: aborting due to previous error
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@ -4,7 +4,7 @@ error[E0044]: foreign items may not have type parameters
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LL | fn foo<T>();
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| ^^^^^^^^^^^^ can't have type parameters
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= help: use specialization instead of type parameters by replacing them with concrete types like `u32`
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= help: replace the type parameters with concrete types like `u32`
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error: aborting due to previous error
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