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matthiaskrgrmatthiaskrgr
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Rollup merge of rust-lang#119703 - compiler-errors:impl-trait-tweaks, r=fmease
Impl trait diagnostic tweaks 1. Tweak some names for `impl Trait` being used in the wrong position 2. Remove two helper functions that are no longer needed since RPITIT is stable, and which causes matches to be a bit obtuse. 3. Split and fix the part where the error notes that it's "only allowed in XX" Fixes rust-lang#119629
2 parents a9b6908 + 7e38b70 commit 0207e24

39 files changed

+292
-182
lines changed

‎compiler/rustc_ast_lowering/messages.ftl‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -106,7 +106,8 @@ ast_lowering_misplaced_double_dot =
106106
.note = only allowed in tuple, tuple struct, and slice patterns
107107
108108
ast_lowering_misplaced_impl_trait =
109-
`impl Trait` only allowed in function and inherent method argument and return types, not in {$position}
109+
`impl Trait` is not allowed in {$position}
110+
.note = `impl Trait` is only allowed in arguments and return types of functions and methods
110111
111112
ast_lowering_misplaced_relax_trait_bound =
112113
`?Trait` bounds are only permitted at the point where a type parameter is declared

‎compiler/rustc_ast_lowering/src/errors.rs‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -90,6 +90,7 @@ pub enum AssocTyParenthesesSub {
9090

9191
#[derive(Diagnostic)]
9292
#[diag(ast_lowering_misplaced_impl_trait, code = "E0562")]
93+
#[note]
9394
pub struct MisplacedImplTrait<'a> {
9495
#[primary_span]
9596
pub span: Span,

‎compiler/rustc_ast_lowering/src/item.rs‎

Lines changed: 7 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -182,7 +182,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
182182
self.lower_use_tree(use_tree, &prefix, id, vis_span, ident, attrs)
183183
}
184184
ItemKind::Static(box ast::StaticItem { ty: t, mutability: m, expr: e }) => {
185-
let (ty, body_id) = self.lower_const_item(t, span, e.as_deref());
185+
let (ty, body_id) =
186+
self.lower_const_item(t, span, e.as_deref(), ImplTraitPosition::StaticTy);
186187
hir::ItemKind::Static(ty, *m, body_id)
187188
}
188189
ItemKind::Const(box ast::ConstItem { generics, ty, expr, .. }) => {
@@ -191,7 +192,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
191192
Const::No,
192193
id,
193194
&ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
194-
|this| this.lower_const_item(ty, span, expr.as_deref()),
195+
|this| {
196+
this.lower_const_item(ty, span, expr.as_deref(), ImplTraitPosition::ConstTy)
197+
},
195198
);
196199
hir::ItemKind::Const(ty, generics, body_id)
197200
}
@@ -448,8 +451,9 @@ impl<'hir> LoweringContext<'_, 'hir> {
448451
ty: &Ty,
449452
span: Span,
450453
body: Option<&Expr>,
454+
impl_trait_position: ImplTraitPosition,
451455
) -> (&'hir hir::Ty<'hir>, hir::BodyId) {
452-
let ty = self.lower_ty(ty, &ImplTraitContext::Disallowed(ImplTraitPosition::ConstTy));
456+
let ty = self.lower_ty(ty, &ImplTraitContext::Disallowed(impl_trait_position));
453457
(ty, self.lower_const_body(span, body))
454458
}
455459

‎compiler/rustc_ast_lowering/src/lib.rs‎

Lines changed: 37 additions & 55 deletions
Original file line numberDiff line numberDiff line change
@@ -304,8 +304,6 @@ enum ImplTraitPosition {
304304
ClosureParam,
305305
PointerParam,
306306
FnTraitParam,
307-
TraitParam,
308-
ImplParam,
309307
ExternFnReturn,
310308
ClosureReturn,
311309
PointerReturn,
@@ -324,29 +322,27 @@ impl std::fmt::Display for ImplTraitPosition {
324322
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
325323
let name = match self {
326324
ImplTraitPosition::Path => "paths",
327-
ImplTraitPosition::Variable => "variable bindings",
325+
ImplTraitPosition::Variable => "the type of variable bindings",
328326
ImplTraitPosition::Trait => "traits",
329327
ImplTraitPosition::AsyncBlock => "async blocks",
330328
ImplTraitPosition::Bound => "bounds",
331329
ImplTraitPosition::Generic => "generics",
332-
ImplTraitPosition::ExternFnParam => "`extern fn` params",
333-
ImplTraitPosition::ClosureParam => "closure params",
334-
ImplTraitPosition::PointerParam => "`fn` pointer params",
335-
ImplTraitPosition::FnTraitParam => "`Fn` trait params",
336-
ImplTraitPosition::TraitParam => "trait method params",
337-
ImplTraitPosition::ImplParam => "`impl` method params",
330+
ImplTraitPosition::ExternFnParam => "`extern fn` parameters",
331+
ImplTraitPosition::ClosureParam => "closure parameters",
332+
ImplTraitPosition::PointerParam => "`fn` pointer parameters",
333+
ImplTraitPosition::FnTraitParam => "the parameters of `Fn` trait bounds",
338334
ImplTraitPosition::ExternFnReturn => "`extern fn` return types",
339335
ImplTraitPosition::ClosureReturn => "closure return types",
340336
ImplTraitPosition::PointerReturn => "`fn` pointer return types",
341-
ImplTraitPosition::FnTraitReturn => "`Fn` trait return types",
337+
ImplTraitPosition::FnTraitReturn => "the return type of `Fn` trait bounds",
342338
ImplTraitPosition::GenericDefault => "generic parameter defaults",
343339
ImplTraitPosition::ConstTy => "const types",
344340
ImplTraitPosition::StaticTy => "static types",
345341
ImplTraitPosition::AssocTy => "associated types",
346342
ImplTraitPosition::FieldTy => "field types",
347-
ImplTraitPosition::Cast => "cast types",
343+
ImplTraitPosition::Cast => "cast expression types",
348344
ImplTraitPosition::ImplSelf => "impl headers",
349-
ImplTraitPosition::OffsetOf => "`offset_of!` params",
345+
ImplTraitPosition::OffsetOf => "`offset_of!` parameters",
350346
};
351347

352348
write!(f, "{name}")
@@ -364,19 +360,6 @@ enum FnDeclKind {
364360
Impl,
365361
}
366362

367-
impl FnDeclKind {
368-
fn param_impl_trait_allowed(&self) -> bool {
369-
matches!(self, FnDeclKind::Fn | FnDeclKind::Inherent | FnDeclKind::Impl | FnDeclKind::Trait)
370-
}
371-
372-
fn return_impl_trait_allowed(&self) -> bool {
373-
match self {
374-
FnDeclKind::Fn | FnDeclKind::Inherent | FnDeclKind::Impl | FnDeclKind::Trait => true,
375-
_ => false,
376-
}
377-
}
378-
}
379-
380363
#[derive(Copy, Clone)]
381364
enum AstOwner<'a> {
382365
NonOwner,
@@ -1842,19 +1825,19 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
18421825
inputs = &inputs[..inputs.len() - 1];
18431826
}
18441827
let inputs = self.arena.alloc_from_iter(inputs.iter().map(|param| {
1845-
let itctx = if kind.param_impl_trait_allowed() {
1846-
ImplTraitContext::Universal
1847-
} else {
1848-
ImplTraitContext::Disallowed(match kind {
1849-
FnDeclKind::Fn | FnDeclKind::Inherent => {
1850-
unreachable!("fn should allow APIT")
1851-
}
1852-
FnDeclKind::ExternFn => ImplTraitPosition::ExternFnParam,
1853-
FnDeclKind::Closure => ImplTraitPosition::ClosureParam,
1854-
FnDeclKind::Pointer => ImplTraitPosition::PointerParam,
1855-
FnDeclKind::Trait => ImplTraitPosition::TraitParam,
1856-
FnDeclKind::Impl => ImplTraitPosition::ImplParam,
1857-
})
1828+
let itctx = match kind {
1829+
FnDeclKind::Fn | FnDeclKind::Inherent | FnDeclKind::Impl | FnDeclKind::Trait => {
1830+
ImplTraitContext::Universal
1831+
}
1832+
FnDeclKind::ExternFn => {
1833+
ImplTraitContext::Disallowed(ImplTraitPosition::ExternFnParam)
1834+
}
1835+
FnDeclKind::Closure => {
1836+
ImplTraitContext::Disallowed(ImplTraitPosition::ClosureParam)
1837+
}
1838+
FnDeclKind::Pointer => {
1839+
ImplTraitContext::Disallowed(ImplTraitPosition::PointerParam)
1840+
}
18581841
};
18591842
self.lower_ty_direct(&param.ty, &itctx)
18601843
}));
@@ -1866,26 +1849,25 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
18661849
}
18671850
None => match &decl.output {
18681851
FnRetTy::Ty(ty) => {
1869-
let context = if kind.return_impl_trait_allowed() {
1870-
let fn_def_id = self.local_def_id(fn_node_id);
1871-
ImplTraitContext::ReturnPositionOpaqueTy {
1872-
origin: hir::OpaqueTyOrigin::FnReturn(fn_def_id),
1852+
let itctx = match kind {
1853+
FnDeclKind::Fn
1854+
| FnDeclKind::Inherent
1855+
| FnDeclKind::Trait
1856+
| FnDeclKind::Impl => ImplTraitContext::ReturnPositionOpaqueTy {
1857+
origin: hir::OpaqueTyOrigin::FnReturn(self.local_def_id(fn_node_id)),
18731858
fn_kind: kind,
1859+
},
1860+
FnDeclKind::ExternFn => {
1861+
ImplTraitContext::Disallowed(ImplTraitPosition::ExternFnReturn)
1862+
}
1863+
FnDeclKind::Closure => {
1864+
ImplTraitContext::Disallowed(ImplTraitPosition::ClosureReturn)
1865+
}
1866+
FnDeclKind::Pointer => {
1867+
ImplTraitContext::Disallowed(ImplTraitPosition::PointerReturn)
18741868
}
1875-
} else {
1876-
ImplTraitContext::Disallowed(match kind {
1877-
FnDeclKind::Fn
1878-
| FnDeclKind::Inherent
1879-
| FnDeclKind::Trait
1880-
| FnDeclKind::Impl => {
1881-
unreachable!("fn should allow return-position impl trait in traits")
1882-
}
1883-
FnDeclKind::ExternFn => ImplTraitPosition::ExternFnReturn,
1884-
FnDeclKind::Closure => ImplTraitPosition::ClosureReturn,
1885-
FnDeclKind::Pointer => ImplTraitPosition::PointerReturn,
1886-
})
18871869
};
1888-
hir::FnRetTy::Return(self.lower_ty(ty, &context))
1870+
hir::FnRetTy::Return(self.lower_ty(ty, &itctx))
18891871
}
18901872
FnRetTy::Default(span) => hir::FnRetTy::DefaultReturn(self.lower_span(*span)),
18911873
},

‎tests/ui/associated-consts/issue-105330.stderr‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -33,11 +33,13 @@ LL | fn main<A: TraitWAssocConst<A=32>>() {
3333
= note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
3434
= help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
3535

36-
error[E0562]: `impl Trait` only allowed in function and inherent method argument and return types, not in impl headers
36+
error[E0562]: `impl Trait` is not allowed in impl headers
3737
--> $DIR/issue-105330.rs:6:27
3838
|
3939
LL | impl TraitWAssocConst for impl Demo {
4040
| ^^^^^^^^^
41+
|
42+
= note: `impl Trait` is only allowed in arguments and return types of functions and methods
4143

4244
error[E0131]: `main` function is not allowed to have generic parameters
4345
--> $DIR/issue-105330.rs:15:8

‎tests/ui/feature-gates/feature-gate-associated_type_bounds.rs‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -54,20 +54,20 @@ fn _rpit_dyn() -> Box<dyn Tr1<As1: Copy>> { Box::new(S1) }
5454

5555
const _cdef: impl Tr1<As1: Copy> = S1;
5656
//~^ ERROR associated type bounds are unstable
57-
//~| ERROR `impl Trait` only allowed in function and inherent method argument and return types
57+
//~| ERROR `impl Trait` is not allowed in const types
5858
// FIXME: uncomment when `impl_trait_in_bindings` feature is fixed.
5959
// const _cdef_dyn: &dyn Tr1<As1: Copy> = &S1;
6060

6161
static _sdef: impl Tr1<As1: Copy> = S1;
6262
//~^ ERROR associated type bounds are unstable
63-
//~| ERROR `impl Trait` only allowed in function and inherent method argument and return types
63+
//~| ERROR `impl Trait` is not allowed in static types
6464
// FIXME: uncomment when `impl_trait_in_bindings` feature is fixed.
6565
// static _sdef_dyn: &dyn Tr1<As1: Copy> = &S1;
6666

6767
fn main() {
6868
let _: impl Tr1<As1: Copy> = S1;
6969
//~^ ERROR associated type bounds are unstable
70-
//~| ERROR `impl Trait` only allowed in function and inherent method argument and return types
70+
//~| ERROR `impl Trait` is not allowed in the type of variable bindings
7171
// FIXME: uncomment when `impl_trait_in_bindings` feature is fixed.
7272
// let _: &dyn Tr1<As1: Copy> = &S1;
7373
}

‎tests/ui/feature-gates/feature-gate-associated_type_bounds.stderr‎

Lines changed: 9 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -115,23 +115,29 @@ LL | let _: impl Tr1<As1: Copy> = S1;
115115
= note: see issue #52662 <https://github.com/rust-lang/rust/issues/52662> for more information
116116
= help: add `#![feature(associated_type_bounds)]` to the crate attributes to enable
117117

118-
error[E0562]: `impl Trait` only allowed in function and inherent method argument and return types, not in const types
118+
error[E0562]: `impl Trait` is not allowed in const types
119119
--> $DIR/feature-gate-associated_type_bounds.rs:55:14
120120
|
121121
LL | const _cdef: impl Tr1<As1: Copy> = S1;
122122
| ^^^^^^^^^^^^^^^^^^^
123+
|
124+
= note: `impl Trait` is only allowed in arguments and return types of functions and methods
123125

124-
error[E0562]: `impl Trait` only allowed in function and inherent method argument and return types, not in const types
126+
error[E0562]: `impl Trait` is not allowed in static types
125127
--> $DIR/feature-gate-associated_type_bounds.rs:61:15
126128
|
127129
LL | static _sdef: impl Tr1<As1: Copy> = S1;
128130
| ^^^^^^^^^^^^^^^^^^^
131+
|
132+
= note: `impl Trait` is only allowed in arguments and return types of functions and methods
129133

130-
error[E0562]: `impl Trait` only allowed in function and inherent method argument and return types, not in variable bindings
134+
error[E0562]: `impl Trait` is not allowed in the type of variable bindings
131135
--> $DIR/feature-gate-associated_type_bounds.rs:68:12
132136
|
133137
LL | let _: impl Tr1<As1: Copy> = S1;
134138
| ^^^^^^^^^^^^^^^^^^^
139+
|
140+
= note: `impl Trait` is only allowed in arguments and return types of functions and methods
135141

136142
error[E0277]: the trait bound `<<Self as _Tr3>::A as Iterator>::Item: Copy` is not satisfied
137143
--> $DIR/feature-gate-associated_type_bounds.rs:12:28

‎tests/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.rs‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,6 @@
11
fn f() -> impl Fn() -> impl Sized { || () }
2-
//~^ ERROR `impl Trait` only allowed in function and inherent method argument and return types, not in `Fn` trait return
2+
//~^ ERROR `impl Trait` is not allowed in the return type of `Fn` trait bounds
33
fn g() -> &'static dyn Fn() -> impl Sized { &|| () }
4-
//~^ ERROR `impl Trait` only allowed in function and inherent method argument and return types, not in `Fn` trait return
4+
//~^ ERROR `impl Trait` is not allowed in the return type of `Fn` trait bounds
55

66
fn main() {}

‎tests/ui/feature-gates/feature-gate-impl_trait_in_fn_trait_return.stderr‎

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,18 +1,20 @@
1-
error[E0562]: `impl Trait` only allowed in function and inherent method argument and return types, not in `Fn` trait return types
1+
error[E0562]: `impl Trait` is not allowed in the return type of `Fn` trait bounds
22
--> $DIR/feature-gate-impl_trait_in_fn_trait_return.rs:1:24
33
|
44
LL | fn f() -> impl Fn() -> impl Sized { || () }
55
| ^^^^^^^^^^
66
|
7+
= note: `impl Trait` is only allowed in arguments and return types of functions and methods
78
= note: see issue #99697 <https://github.com/rust-lang/rust/issues/99697> for more information
89
= help: add `#![feature(impl_trait_in_fn_trait_return)]` to the crate attributes to enable
910

10-
error[E0562]: `impl Trait` only allowed in function and inherent method argument and return types, not in `Fn` trait return types
11+
error[E0562]: `impl Trait` is not allowed in the return type of `Fn` trait bounds
1112
--> $DIR/feature-gate-impl_trait_in_fn_trait_return.rs:3:32
1213
|
1314
LL | fn g() -> &'static dyn Fn() -> impl Sized { &|| () }
1415
| ^^^^^^^^^^
1516
|
17+
= note: `impl Trait` is only allowed in arguments and return types of functions and methods
1618
= note: see issue #99697 <https://github.com/rust-lang/rust/issues/99697> for more information
1719
= help: add `#![feature(impl_trait_in_fn_trait_return)]` to the crate attributes to enable
1820

‎tests/ui/impl-trait/issues/issue-54600.rs‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2,6 +2,6 @@ use std::fmt::Debug;
22

33
fn main() {
44
let x: Option<impl Debug> = Some(44_u32);
5-
//~^ `impl Trait` only allowed in function and inherent method argument and return types
5+
//~^ `impl Trait` is not allowed in the type of variable bindings
66
println!("{:?}", x);
77
}

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