diff --git a/compiler/rustc_hir_typeck/messages.ftl b/compiler/rustc_hir_typeck/messages.ftl index 220da19a29dc8..0ca958302f792 100644 --- a/compiler/rustc_hir_typeck/messages.ftl +++ b/compiler/rustc_hir_typeck/messages.ftl @@ -103,6 +103,8 @@ hir_typeck_no_associated_item = no {$item_kind} named `{$item_name}` found for { *[other] {" "}in the current scope } +hir_typeck_note_caller_chooses_ty_for_ty_param = the caller chooses a type for `{$ty_param_name}` which can be different from `{$found_ty}` + hir_typeck_note_edition_guide = for more on editions, read https://doc.rust-lang.org/edition-guide hir_typeck_option_result_asref = use `{$def_path}::as_ref` to convert `{$expected_ty}` to `{$expr_ty}` diff --git a/compiler/rustc_hir_typeck/src/errors.rs b/compiler/rustc_hir_typeck/src/errors.rs index df21b84f92ef3..eee4ac5ad23b5 100644 --- a/compiler/rustc_hir_typeck/src/errors.rs +++ b/compiler/rustc_hir_typeck/src/errors.rs @@ -11,7 +11,7 @@ use rustc_middle::ty::Ty; use rustc_span::{ edition::{Edition, LATEST_STABLE_EDITION}, symbol::Ident, - Span, + Span, Symbol, }; #[derive(Diagnostic)] @@ -614,3 +614,10 @@ pub struct SuggestConvertViaMethod<'tcx> { pub expected: Ty<'tcx>, pub found: Ty<'tcx>, } + +#[derive(Subdiagnostic)] +#[note(hir_typeck_note_caller_chooses_ty_for_ty_param)] +pub struct NoteCallerChoosesTyForTyParam<'tcx> { + pub ty_param_name: Symbol, + pub found_ty: Ty<'tcx>, +} diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs index 3f6f4cccba796..580976317302c 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs @@ -889,7 +889,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { self.dcx(), errors::ExpectedReturnTypeLabel::Other { span: hir_ty.span, expected }, ); - self.try_suggest_return_impl_trait(err, expected, ty, fn_id); + self.try_suggest_return_impl_trait(err, expected, found, fn_id); + self.note_caller_chooses_ty_for_ty_param(err, expected, found); return true; } } @@ -899,6 +900,23 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { false } + fn note_caller_chooses_ty_for_ty_param( + &self, + diag: &mut Diag<'_>, + expected: Ty<'tcx>, + found: Ty<'tcx>, + ) { + if let ty::Param(expected_ty_as_param) = expected.kind() { + diag.subdiagnostic( + self.dcx(), + errors::NoteCallerChoosesTyForTyParam { + ty_param_name: expected_ty_as_param.name, + found_ty: found, + }, + ); + } + } + /// check whether the return type is a generic type with a trait bound /// only suggest this if the generic param is not present in the arguments /// if this is true, hint them towards changing the return type to `impl Trait` diff --git a/src/tools/clippy/tests/ui/builtin_type_shadow.stderr b/src/tools/clippy/tests/ui/builtin_type_shadow.stderr index 1e15cdee772a2..033204af9255f 100644 --- a/src/tools/clippy/tests/ui/builtin_type_shadow.stderr +++ b/src/tools/clippy/tests/ui/builtin_type_shadow.stderr @@ -19,6 +19,7 @@ LL | 42 | = note: expected type parameter `u32` found type `{integer}` + = note: the caller chooses a type for `u32` which can be different from `i32` error: aborting due to 2 previous errors diff --git a/tests/ui/return/return-impl-trait-bad.stderr b/tests/ui/return/return-impl-trait-bad.stderr index a015b9f53affb..6277c5feb20e9 100644 --- a/tests/ui/return/return-impl-trait-bad.stderr +++ b/tests/ui/return/return-impl-trait-bad.stderr @@ -10,6 +10,7 @@ LL | "this should not suggest impl Trait" | = note: expected type parameter `T` found reference `&'static str` + = note: the caller chooses a type for `T` which can be different from `&'static str` error[E0308]: mismatched types --> $DIR/return-impl-trait-bad.rs:9:5 @@ -23,6 +24,7 @@ LL | "this will not suggest it, because that would probably be wrong" | = note: expected type parameter `T` found reference `&'static str` + = note: the caller chooses a type for `T` which can be different from `&'static str` error[E0308]: mismatched types --> $DIR/return-impl-trait-bad.rs:17:5 @@ -37,6 +39,7 @@ LL | "don't suggest this, because Option places additional constraints" | = note: expected type parameter `T` found reference `&'static str` + = note: the caller chooses a type for `T` which can be different from `&'static str` error[E0308]: mismatched types --> $DIR/return-impl-trait-bad.rs:28:5 @@ -53,6 +56,7 @@ LL | "don't suggest this, because the generic param is used in the bound." | = note: expected type parameter `T` found reference `&'static str` + = note: the caller chooses a type for `T` which can be different from `&'static str` error: aborting due to 4 previous errors diff --git a/tests/ui/return/return-impl-trait.stderr b/tests/ui/return/return-impl-trait.stderr index 707f014a16f9b..114ae0c244516 100644 --- a/tests/ui/return/return-impl-trait.stderr +++ b/tests/ui/return/return-impl-trait.stderr @@ -12,6 +12,7 @@ LL | () | = note: expected type parameter `T` found unit type `()` + = note: the caller chooses a type for `T` which can be different from `()` error[E0308]: mismatched types --> $DIR/return-impl-trait.rs:23:5 @@ -28,6 +29,7 @@ LL | () | = note: expected type parameter `T` found unit type `()` + = note: the caller chooses a type for `T` which can be different from `()` error: aborting due to 2 previous errors diff --git a/tests/ui/return/return-ty-mismatch-note.rs b/tests/ui/return/return-ty-mismatch-note.rs new file mode 100644 index 0000000000000..352bc2a163763 --- /dev/null +++ b/tests/ui/return/return-ty-mismatch-note.rs @@ -0,0 +1,21 @@ +// Checks existence of a note for "a caller chooses ty for ty param" upon return ty mismatch. + +fn f() -> (T,) { + (0,) //~ ERROR mismatched types +} + +fn g() -> (U, V) { + (0, "foo") + //~^ ERROR mismatched types + //~| ERROR mismatched types +} + +fn h() -> u8 { + 0u8 +} + +fn main() { + f::<()>(); + g::<(), ()>; + let _ = h(); +} diff --git a/tests/ui/return/return-ty-mismatch-note.stderr b/tests/ui/return/return-ty-mismatch-note.stderr new file mode 100644 index 0000000000000..135903da5c263 --- /dev/null +++ b/tests/ui/return/return-ty-mismatch-note.stderr @@ -0,0 +1,36 @@ +error[E0308]: mismatched types + --> $DIR/return-ty-mismatch-note.rs:4:6 + | +LL | fn f() -> (T,) { + | - expected this type parameter +LL | (0,) + | ^ expected type parameter `T`, found integer + | + = note: expected type parameter `T` + found type `{integer}` + +error[E0308]: mismatched types + --> $DIR/return-ty-mismatch-note.rs:8:6 + | +LL | fn g() -> (U, V) { + | - expected this type parameter +LL | (0, "foo") + | ^ expected type parameter `U`, found integer + | + = note: expected type parameter `U` + found type `{integer}` + +error[E0308]: mismatched types + --> $DIR/return-ty-mismatch-note.rs:8:9 + | +LL | fn g() -> (U, V) { + | - expected this type parameter +LL | (0, "foo") + | ^^^^^ expected type parameter `V`, found `&str` + | + = note: expected type parameter `V` + found reference `&'static str` + +error: aborting due to 3 previous errors + +For more information about this error, try `rustc --explain E0308`. diff --git a/tests/ui/suggestions/clone-on-unconstrained-borrowed-type-param.stderr b/tests/ui/suggestions/clone-on-unconstrained-borrowed-type-param.stderr index afbb9c32d516e..2c4be26a82b7b 100644 --- a/tests/ui/suggestions/clone-on-unconstrained-borrowed-type-param.stderr +++ b/tests/ui/suggestions/clone-on-unconstrained-borrowed-type-param.stderr @@ -10,6 +10,7 @@ LL | t.clone() | = note: expected type parameter `_` found reference `&_` + = note: the caller chooses a type for `T` which can be different from `&T` note: `T` does not implement `Clone`, so `&T` was cloned instead --> $DIR/clone-on-unconstrained-borrowed-type-param.rs:3:5 | diff --git a/tests/ui/trait-bounds/restrict-assoc-type-of-generic-bound.stderr b/tests/ui/trait-bounds/restrict-assoc-type-of-generic-bound.stderr index 5024ad21892a6..7aa32557af2de 100644 --- a/tests/ui/trait-bounds/restrict-assoc-type-of-generic-bound.stderr +++ b/tests/ui/trait-bounds/restrict-assoc-type-of-generic-bound.stderr @@ -10,6 +10,7 @@ LL | return a.bar(); | = note: expected type parameter `B` found associated type `::T` + = note: the caller chooses a type for `B` which can be different from `::T` help: consider further restricting this bound | LL | pub fn foo, B>(a: A) -> B { diff --git a/tests/ui/type/type-parameter-names.stderr b/tests/ui/type/type-parameter-names.stderr index 8e3e2388c6cba..be9000a99e44f 100644 --- a/tests/ui/type/type-parameter-names.stderr +++ b/tests/ui/type/type-parameter-names.stderr @@ -13,6 +13,7 @@ LL | x found type parameter `Foo` = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters + = note: the caller chooses a type for `Bar` which can be different from `Foo` error: aborting due to 1 previous error diff --git a/tests/ui/type/type-params-in-different-spaces-3.stderr b/tests/ui/type/type-params-in-different-spaces-3.stderr index 58783fe1ff008..3c0c022f1120a 100644 --- a/tests/ui/type/type-params-in-different-spaces-3.stderr +++ b/tests/ui/type/type-params-in-different-spaces-3.stderr @@ -14,6 +14,7 @@ LL | u found type parameter `X` = note: a type parameter was expected, but a different one was found; you might be missing a type parameter or trait bound = note: for more information, visit https://doc.rust-lang.org/book/ch10-02-traits.html#traits-as-parameters + = note: the caller chooses a type for `Self` which can be different from `X` error: aborting due to 1 previous error diff --git a/tests/ui/typeck/issue-13853.stderr b/tests/ui/typeck/issue-13853.stderr index 0683c782933af..45363c87d29df 100644 --- a/tests/ui/typeck/issue-13853.stderr +++ b/tests/ui/typeck/issue-13853.stderr @@ -9,6 +9,7 @@ LL | self.iter() | = note: expected type parameter `I` found struct `std::slice::Iter<'_, N>` + = note: the caller chooses a type for `I` which can be different from `std::slice::Iter<'_, N>` error[E0599]: no method named `iter` found for reference `&G` in the current scope --> $DIR/issue-13853.rs:27:23