diff --git a/compiler/rustc_typeck/src/check/compare_method.rs b/compiler/rustc_typeck/src/check/compare_method.rs index 3a337dadc88e..964aa8426ea9 100644 --- a/compiler/rustc_typeck/src/check/compare_method.rs +++ b/compiler/rustc_typeck/src/check/compare_method.rs @@ -290,18 +290,55 @@ fn compare_predicate_entailment<'tcx>( "method `{}` has an incompatible type for trait", trait_m.ident ); - if let TypeError::ArgumentMutability(_) = terr { - if let Some(trait_err_span) = trait_err_span { - if let Ok(trait_err_str) = tcx.sess.source_map().span_to_snippet(trait_err_span) + match &terr { + TypeError::ArgumentMutability(0) | TypeError::ArgumentSorts(_, 0) + if trait_m.fn_has_self_parameter => + { + let ty = trait_sig.inputs()[0]; + let sugg = match ExplicitSelf::determine(ty, |_| ty == impl_trait_ref.self_ty()) { + ExplicitSelf::ByValue => "self".to_owned(), + ExplicitSelf::ByReference(_, hir::Mutability::Not) => "&self".to_owned(), + ExplicitSelf::ByReference(_, hir::Mutability::Mut) => { + "&mut self".to_owned() + } + _ => format!("self: {}", ty), + }; + + // When the `impl` receiver is an arbitrary self type, like `self: Box`, the + // span points only at the type `Box, but we want to cover the whole + // argument pattern and type. + let impl_m_hir_id = + tcx.hir().local_def_id_to_hir_id(impl_m.def_id.expect_local()); + let span = match tcx.hir().expect_impl_item(impl_m_hir_id).kind { + ImplItemKind::Fn(ref sig, body) => tcx + .hir() + .body_param_names(body) + .zip(sig.decl.inputs.iter()) + .map(|(param, ty)| param.span.to(ty.span)) + .next() + .unwrap_or(impl_err_span), + _ => bug!("{:?} is not a method", impl_m), + }; + + diag.span_suggestion( + span, + "change the self-receiver type to match the trait", + sugg, + Applicability::MachineApplicable, + ); + } + TypeError::ArgumentMutability(i) | TypeError::ArgumentSorts(_, i) => { + if let Some(trait_ty) = trait_sig.inputs().get(*i) { diag.span_suggestion( impl_err_span, - "consider changing the mutability to match the trait", - trait_err_str, + "change the parameter type to match the trait", + trait_ty.to_string(), Applicability::MachineApplicable, ); } } + _ => {} } infcx.note_type_err( @@ -482,8 +519,7 @@ fn compare_self_type<'tcx>( tcx.sess, impl_m_span, E0186, - "method `{}` has a `{}` declaration in the trait, but \ - not in the impl", + "method `{}` has a `{}` declaration in the trait, but not in the impl", trait_m.ident, self_descr ); diff --git a/src/test/ui/compare-method/bad-self-type.rs b/src/test/ui/compare-method/bad-self-type.rs new file mode 100644 index 000000000000..9eb978664bff --- /dev/null +++ b/src/test/ui/compare-method/bad-self-type.rs @@ -0,0 +1,23 @@ +use std::future::Future; +use std::task::{Context, Poll}; + +fn main() {} + +struct MyFuture {} + +impl Future for MyFuture { + type Output = (); + fn poll(self, _: &mut Context<'_>) -> Poll<()> { + //~^ ERROR method `poll` has an incompatible type for trait + todo!() + } +} + +trait T { + fn foo(self); +} + +impl T for MyFuture { + fn foo(self: Box) {} + //~^ ERROR method `foo` has an incompatible type for trait +} diff --git a/src/test/ui/compare-method/bad-self-type.stderr b/src/test/ui/compare-method/bad-self-type.stderr new file mode 100644 index 000000000000..4d85ff86df5d --- /dev/null +++ b/src/test/ui/compare-method/bad-self-type.stderr @@ -0,0 +1,30 @@ +error[E0053]: method `poll` has an incompatible type for trait + --> $DIR/bad-self-type.rs:10:13 + | +LL | fn poll(self, _: &mut Context<'_>) -> Poll<()> { + | ^^^^ + | | + | expected struct `Pin`, found struct `MyFuture` + | help: change the self-receiver type to match the trait: `self: Pin<&mut MyFuture>` + | + = note: expected fn pointer `fn(Pin<&mut MyFuture>, &mut Context<'_>) -> Poll<_>` + found fn pointer `fn(MyFuture, &mut Context<'_>) -> Poll<_>` + +error[E0053]: method `foo` has an incompatible type for trait + --> $DIR/bad-self-type.rs:21:18 + | +LL | fn foo(self); + | ---- type in trait +... +LL | fn foo(self: Box) {} + | ------^^^^^^^^^ + | | | + | | expected struct `MyFuture`, found struct `Box` + | help: change the self-receiver type to match the trait: `self` + | + = note: expected fn pointer `fn(MyFuture)` + found fn pointer `fn(Box)` + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0053`. diff --git a/src/test/ui/compare-method/reordered-type-param.stderr b/src/test/ui/compare-method/reordered-type-param.stderr index f1f8a663f212..d581628ea48a 100644 --- a/src/test/ui/compare-method/reordered-type-param.stderr +++ b/src/test/ui/compare-method/reordered-type-param.stderr @@ -5,8 +5,10 @@ LL | fn b(&self, x: C) -> C; | - type in trait ... LL | fn b(&self, _x: G) -> G { panic!() } - | - - ^ expected type parameter `F`, found type parameter `G` - | | | + | - - ^ + | | | | + | | | expected type parameter `F`, found type parameter `G` + | | | help: change the parameter type to match the trait: `F` | | found type parameter | expected type parameter | diff --git a/src/test/ui/impl-trait/impl-generic-mismatch-ab.stderr b/src/test/ui/impl-trait/impl-generic-mismatch-ab.stderr index 638a0093fb21..d37670db0853 100644 --- a/src/test/ui/impl-trait/impl-generic-mismatch-ab.stderr +++ b/src/test/ui/impl-trait/impl-generic-mismatch-ab.stderr @@ -5,8 +5,10 @@ LL | fn foo(&self, a: &A, b: &impl Debug); | -- type in trait ... LL | fn foo(&self, a: &impl Debug, b: &B) { } - | - ^^^^^^^^^^^ expected type parameter `B`, found type parameter `impl Debug` - | | + | - ^^^^^^^^^^^ + | | | + | | expected type parameter `B`, found type parameter `impl Debug` + | | help: change the parameter type to match the trait: `&B` | expected type parameter | = note: expected fn pointer `fn(&(), &B, &impl Debug)` diff --git a/src/test/ui/impl-trait/trait_type.stderr b/src/test/ui/impl-trait/trait_type.stderr index 0bf43a65aa07..bea24339837a 100644 --- a/src/test/ui/impl-trait/trait_type.stderr +++ b/src/test/ui/impl-trait/trait_type.stderr @@ -2,7 +2,10 @@ error[E0053]: method `fmt` has an incompatible type for trait --> $DIR/trait_type.rs:7:21 | LL | fn fmt(&self, x: &str) -> () { } - | ^^^^ types differ in mutability + | ^^^^ + | | + | types differ in mutability + | help: change the parameter type to match the trait: `&mut Formatter<'_>` | = note: expected fn pointer `fn(&MyType, &mut Formatter<'_>) -> Result<(), std::fmt::Error>` found fn pointer `fn(&MyType, &str)` diff --git a/src/test/ui/issues/issue-13033.stderr b/src/test/ui/issues/issue-13033.stderr index 57447fa48aac..6c3651ff1217 100644 --- a/src/test/ui/issues/issue-13033.stderr +++ b/src/test/ui/issues/issue-13033.stderr @@ -8,7 +8,7 @@ LL | fn bar(&mut self, other: &dyn Foo) {} | ^^^^^^^^ | | | types differ in mutability - | help: consider changing the mutability to match the trait: `&mut dyn Foo` + | help: change the parameter type to match the trait: `&mut dyn Foo` | = note: expected fn pointer `fn(&mut Baz, &mut dyn Foo)` found fn pointer `fn(&mut Baz, &dyn Foo)` diff --git a/src/test/ui/issues/issue-20225.stderr b/src/test/ui/issues/issue-20225.stderr index 756301de17c2..6f4813ca6235 100644 --- a/src/test/ui/issues/issue-20225.stderr +++ b/src/test/ui/issues/issue-20225.stderr @@ -4,7 +4,10 @@ error[E0053]: method `call` has an incompatible type for trait LL | impl<'a, T> Fn<(&'a T,)> for Foo { | - this type parameter LL | extern "rust-call" fn call(&self, (_,): (T,)) {} - | ^^^^ expected `&T`, found type parameter `T` + | ^^^^ + | | + | expected `&T`, found type parameter `T` + | help: change the parameter type to match the trait: `(&'a T,)` | = note: expected fn pointer `extern "rust-call" fn(&Foo, (&'a T,))` found fn pointer `extern "rust-call" fn(&Foo, (T,))` @@ -15,7 +18,10 @@ error[E0053]: method `call_mut` has an incompatible type for trait LL | impl<'a, T> FnMut<(&'a T,)> for Foo { | - this type parameter LL | extern "rust-call" fn call_mut(&mut self, (_,): (T,)) {} - | ^^^^ expected `&T`, found type parameter `T` + | ^^^^ + | | + | expected `&T`, found type parameter `T` + | help: change the parameter type to match the trait: `(&'a T,)` | = note: expected fn pointer `extern "rust-call" fn(&mut Foo, (&'a T,))` found fn pointer `extern "rust-call" fn(&mut Foo, (T,))` @@ -27,7 +33,10 @@ LL | impl<'a, T> FnOnce<(&'a T,)> for Foo { | - this type parameter ... LL | extern "rust-call" fn call_once(self, (_,): (T,)) {} - | ^^^^ expected `&T`, found type parameter `T` + | ^^^^ + | | + | expected `&T`, found type parameter `T` + | help: change the parameter type to match the trait: `(&'a T,)` | = note: expected fn pointer `extern "rust-call" fn(Foo, (&'a T,))` found fn pointer `extern "rust-call" fn(Foo, (T,))` diff --git a/src/test/ui/issues/issue-35869.stderr b/src/test/ui/issues/issue-35869.stderr index f80561bf6be8..c104aa30cb03 100644 --- a/src/test/ui/issues/issue-35869.stderr +++ b/src/test/ui/issues/issue-35869.stderr @@ -5,7 +5,10 @@ LL | fn foo(_: fn(u8) -> ()); | ------------ type in trait ... LL | fn foo(_: fn(u16) -> ()) {} - | ^^^^^^^^^^^^^ expected `u8`, found `u16` + | ^^^^^^^^^^^^^ + | | + | expected `u8`, found `u16` + | help: change the parameter type to match the trait: `fn(u8)` | = note: expected fn pointer `fn(fn(u8))` found fn pointer `fn(fn(u16))` @@ -17,7 +20,10 @@ LL | fn bar(_: Option); | ---------- type in trait ... LL | fn bar(_: Option) {} - | ^^^^^^^^^^^ expected `u8`, found `u16` + | ^^^^^^^^^^^ + | | + | expected `u8`, found `u16` + | help: change the parameter type to match the trait: `Option` | = note: expected fn pointer `fn(Option)` found fn pointer `fn(Option)` @@ -29,7 +35,10 @@ LL | fn baz(_: (u8, u16)); | --------- type in trait ... LL | fn baz(_: (u16, u16)) {} - | ^^^^^^^^^^ expected `u8`, found `u16` + | ^^^^^^^^^^ + | | + | expected `u8`, found `u16` + | help: change the parameter type to match the trait: `(u8, u16)` | = note: expected fn pointer `fn((u8, _))` found fn pointer `fn((u16, _))` diff --git a/src/test/ui/mismatched_types/E0053.stderr b/src/test/ui/mismatched_types/E0053.stderr index e0a3ce922b97..6ce8126b9f97 100644 --- a/src/test/ui/mismatched_types/E0053.stderr +++ b/src/test/ui/mismatched_types/E0053.stderr @@ -5,7 +5,10 @@ LL | fn foo(x: u16); | --- type in trait ... LL | fn foo(x: i16) { } - | ^^^ expected `u16`, found `i16` + | ^^^ + | | + | expected `u16`, found `i16` + | help: change the parameter type to match the trait: `u16` | = note: expected fn pointer `fn(u16)` found fn pointer `fn(i16)` @@ -20,7 +23,7 @@ LL | fn bar(&mut self) { } | ^^^^^^^^^ | | | types differ in mutability - | help: consider changing the mutability to match the trait: `&self` + | help: change the self-receiver type to match the trait: `self: &Bar` | = note: expected fn pointer `fn(&Bar)` found fn pointer `fn(&mut Bar)` diff --git a/src/test/ui/mismatched_types/trait-impl-fn-incompatibility.stderr b/src/test/ui/mismatched_types/trait-impl-fn-incompatibility.stderr index 161843473b6c..2ac4d1c33a9b 100644 --- a/src/test/ui/mismatched_types/trait-impl-fn-incompatibility.stderr +++ b/src/test/ui/mismatched_types/trait-impl-fn-incompatibility.stderr @@ -5,7 +5,10 @@ LL | fn foo(x: u16); | --- type in trait ... LL | fn foo(x: i16) { } - | ^^^ expected `u16`, found `i16` + | ^^^ + | | + | expected `u16`, found `i16` + | help: change the parameter type to match the trait: `u16` | = note: expected fn pointer `fn(u16)` found fn pointer `fn(i16)` @@ -20,7 +23,7 @@ LL | fn bar(&mut self, bar: &Bar) { } | ^^^^ | | | types differ in mutability - | help: consider changing the mutability to match the trait: `&mut Bar` + | help: change the parameter type to match the trait: `&mut Bar` | = note: expected fn pointer `fn(&mut Bar, &mut Bar)` found fn pointer `fn(&mut Bar, &Bar)` diff --git a/src/test/ui/wrong-mul-method-signature.stderr b/src/test/ui/wrong-mul-method-signature.stderr index ce3528dcc9c0..9be07cb1a74a 100644 --- a/src/test/ui/wrong-mul-method-signature.stderr +++ b/src/test/ui/wrong-mul-method-signature.stderr @@ -2,7 +2,10 @@ error[E0053]: method `mul` has an incompatible type for trait --> $DIR/wrong-mul-method-signature.rs:16:21 | LL | fn mul(self, s: &f64) -> Vec1 { - | ^^^^ expected `f64`, found `&f64` + | ^^^^ + | | + | expected `f64`, found `&f64` + | help: change the parameter type to match the trait: `f64` | = note: expected fn pointer `fn(Vec1, f64) -> Vec1` found fn pointer `fn(Vec1, &f64) -> Vec1` @@ -11,7 +14,10 @@ error[E0053]: method `mul` has an incompatible type for trait --> $DIR/wrong-mul-method-signature.rs:33:21 | LL | fn mul(self, s: f64) -> Vec2 { - | ^^^ expected struct `Vec2`, found `f64` + | ^^^ + | | + | expected struct `Vec2`, found `f64` + | help: change the parameter type to match the trait: `Vec2` | = note: expected fn pointer `fn(Vec2, Vec2) -> f64` found fn pointer `fn(Vec2, f64) -> Vec2`