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Rollup merge of rust-lang#100437 - compiler-errors:better-const-misma…
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…tch-err, r=oli-obk

Improve const mismatch `FulfillmentError`

Fixes rust-lang#100414
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Dylan-DPC authored Aug 26, 2022
2 parents 691a03c + 8189a45 commit d35938d
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Showing 16 changed files with 194 additions and 45 deletions.
5 changes: 5 additions & 0 deletions compiler/rustc_infer/src/infer/error_reporting/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1588,9 +1588,14 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
Mismatch::Variable(infer::ExpectedFound { expected, found }),
)
}
ValuePairs::Terms(infer::ExpectedFound {
expected: ty::Term::Const(_),
found: ty::Term::Const(_),
}) => (false, Mismatch::Fixed("constant")),
ValuePairs::TraitRefs(_) | ValuePairs::PolyTraitRefs(_) => {
(false, Mismatch::Fixed("trait"))
}
ValuePairs::Regions(_) => (false, Mismatch::Fixed("lifetime")),
_ => (false, Mismatch::Fixed("type")),
};
let vals = match self.values_str(values) {
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7 changes: 7 additions & 0 deletions compiler/rustc_middle/src/traits/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -469,6 +469,13 @@ impl<'tcx> ObligationCauseCode<'tcx> {
_ => None,
}
}

pub fn peel_match_impls(&self) -> &Self {
match self {
MatchImpl(cause, _) => cause.code(),
_ => self,
}
}
}

// `ObligationCauseCode` is used a lot. Make sure it doesn't unintentionally get bigger.
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21 changes: 18 additions & 3 deletions compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1506,13 +1506,28 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
.emit();
}
FulfillmentErrorCode::CodeConstEquateError(ref expected_found, ref err) => {
self.report_mismatched_consts(
let mut diag = self.report_mismatched_consts(
&error.obligation.cause,
expected_found.expected,
expected_found.found,
err.clone(),
)
.emit();
);
let code = error.obligation.cause.code().peel_derives().peel_match_impls();
if let ObligationCauseCode::BindingObligation(..)
| ObligationCauseCode::ItemObligation(..)
| ObligationCauseCode::ExprBindingObligation(..)
| ObligationCauseCode::ExprItemObligation(..) = code
{
self.note_obligation_cause_code(
&mut diag,
&error.obligation.predicate,
error.obligation.param_env,
code,
&mut vec![],
&mut Default::default(),
);
}
diag.emit();
}
}
}
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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,8 @@ error[E0308]: mismatched types
LL | Foo::<10, 12>
| ^^^^^^^^^^^^^ expected `11`, found `12`
|
= note: expected type `11`
found type `12`
= note: expected constant `11`
found constant `12`

error: aborting due to previous error

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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,8 @@ error[E0308]: mismatched types
LL | Foo::<N, { N + 2 }>
| ^^^^^^^^^^^^^^^^^^^ expected `{ N + 1 }`, found `{ N + 2 }`
|
= note: expected type `{ N + 1 }`
found type `{ N + 2 }`
= note: expected constant `{ N + 1 }`
found constant `{ N + 2 }`

error: aborting due to previous error

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Original file line number Diff line number Diff line change
Expand Up @@ -22,8 +22,13 @@ error[E0308]: mismatched types
LL | assert_impl::<HasCastInTraitImpl<{ N + 1 }, { N as u128 }>>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `{ N as u128 }`, found `{ O as u128 }`
|
= note: expected type `{ N as u128 }`
found type `{ O as u128 }`
= note: expected constant `{ N as u128 }`
found constant `{ O as u128 }`
note: required by a bound in `use_trait_impl::assert_impl`
--> $DIR/abstract-const-as-cast-3.rs:14:23
|
LL | fn assert_impl<T: Trait>() {}
| ^^^^^ required by this bound in `use_trait_impl::assert_impl`

error: unconstrained generic constant
--> $DIR/abstract-const-as-cast-3.rs:20:19
Expand All @@ -49,26 +54,41 @@ error[E0308]: mismatched types
LL | assert_impl::<HasCastInTraitImpl<{ N + 1 }, { N as _ }>>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `{ N as _ }`, found `{ O as u128 }`
|
= note: expected type `{ N as _ }`
found type `{ O as u128 }`
= note: expected constant `{ N as _ }`
found constant `{ O as u128 }`
note: required by a bound in `use_trait_impl::assert_impl`
--> $DIR/abstract-const-as-cast-3.rs:14:23
|
LL | fn assert_impl<T: Trait>() {}
| ^^^^^ required by this bound in `use_trait_impl::assert_impl`

error[E0308]: mismatched types
--> $DIR/abstract-const-as-cast-3.rs:23:5
|
LL | assert_impl::<HasCastInTraitImpl<13, { 12 as u128 }>>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `12`, found `13`
|
= note: expected type `12`
found type `13`
= note: expected constant `12`
found constant `13`
note: required by a bound in `use_trait_impl::assert_impl`
--> $DIR/abstract-const-as-cast-3.rs:14:23
|
LL | fn assert_impl<T: Trait>() {}
| ^^^^^ required by this bound in `use_trait_impl::assert_impl`

error[E0308]: mismatched types
--> $DIR/abstract-const-as-cast-3.rs:25:5
|
LL | assert_impl::<HasCastInTraitImpl<14, 13>>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `13`, found `14`
|
= note: expected type `13`
found type `14`
= note: expected constant `13`
found constant `14`
note: required by a bound in `use_trait_impl::assert_impl`
--> $DIR/abstract-const-as-cast-3.rs:14:23
|
LL | fn assert_impl<T: Trait>() {}
| ^^^^^ required by this bound in `use_trait_impl::assert_impl`

error: unconstrained generic constant
--> $DIR/abstract-const-as-cast-3.rs:35:19
Expand All @@ -94,8 +114,13 @@ error[E0308]: mismatched types
LL | assert_impl::<HasCastInTraitImpl<{ N + 1 }, { N as u128 }>>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `{ N as u128 }`, found `{ O as u128 }`
|
= note: expected type `{ N as u128 }`
found type `{ O as u128 }`
= note: expected constant `{ N as u128 }`
found constant `{ O as u128 }`
note: required by a bound in `use_trait_impl_2::assert_impl`
--> $DIR/abstract-const-as-cast-3.rs:32:23
|
LL | fn assert_impl<T: Trait>() {}
| ^^^^^ required by this bound in `use_trait_impl_2::assert_impl`

error: unconstrained generic constant
--> $DIR/abstract-const-as-cast-3.rs:38:19
Expand All @@ -121,26 +146,41 @@ error[E0308]: mismatched types
LL | assert_impl::<HasCastInTraitImpl<{ N + 1 }, { N as _ }>>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `{ N as _ }`, found `{ O as u128 }`
|
= note: expected type `{ N as _ }`
found type `{ O as u128 }`
= note: expected constant `{ N as _ }`
found constant `{ O as u128 }`
note: required by a bound in `use_trait_impl_2::assert_impl`
--> $DIR/abstract-const-as-cast-3.rs:32:23
|
LL | fn assert_impl<T: Trait>() {}
| ^^^^^ required by this bound in `use_trait_impl_2::assert_impl`

error[E0308]: mismatched types
--> $DIR/abstract-const-as-cast-3.rs:41:5
|
LL | assert_impl::<HasCastInTraitImpl<13, { 12 as u128 }>>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `12`, found `13`
|
= note: expected type `12`
found type `13`
= note: expected constant `12`
found constant `13`
note: required by a bound in `use_trait_impl_2::assert_impl`
--> $DIR/abstract-const-as-cast-3.rs:32:23
|
LL | fn assert_impl<T: Trait>() {}
| ^^^^^ required by this bound in `use_trait_impl_2::assert_impl`

error[E0308]: mismatched types
--> $DIR/abstract-const-as-cast-3.rs:43:5
|
LL | assert_impl::<HasCastInTraitImpl<14, 13>>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `13`, found `14`
|
= note: expected type `13`
found type `14`
= note: expected constant `13`
found constant `14`
note: required by a bound in `use_trait_impl_2::assert_impl`
--> $DIR/abstract-const-as-cast-3.rs:32:23
|
LL | fn assert_impl<T: Trait>() {}
| ^^^^^ required by this bound in `use_trait_impl_2::assert_impl`

error: aborting due to 12 previous errors

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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,8 @@ error[E0308]: mismatched types
LL | [0; size_of::<Foo<T>>()]
| ^^^^^^^^^^^^^^^^^^^^^^^^ expected `size_of::<T>()`, found `size_of::<Foo<T>>()`
|
= note: expected type `size_of::<T>()`
found type `size_of::<Foo<T>>()`
= note: expected constant `size_of::<T>()`
found constant `size_of::<Foo<T>>()`

error: unconstrained generic constant
--> $DIR/different-fn.rs:10:9
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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,8 @@ error[E0308]: mismatched types
LL | ArrayHolder([0; Self::SIZE])
| ^^^^^^^^^^^^^^^ expected `X`, found `Self::SIZE`
|
= note: expected type `X`
found type `Self::SIZE`
= note: expected constant `X`
found constant `Self::SIZE`

error: unconstrained generic constant
--> $DIR/issue-62504.rs:18:25
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Original file line number Diff line number Diff line change
Expand Up @@ -4,17 +4,31 @@ error[E0308]: mismatched types
LL | let x: Arr<{usize::MAX}> = Arr {};
| ^^^^^^^^^^^^^^^^^ expected `false`, found `true`
|
= note: expected type `false`
found type `true`
= note: expected constant `false`
found constant `true`
note: required by a bound in `Arr`
--> $DIR/issue-72819-generic-in-const-eval.rs:8:39
|
LL | struct Arr<const N: usize>
| --- required by a bound in this
LL | where Assert::<{N < usize::MAX / 2}>: IsTrue,
| ^^^^^^ required by this bound in `Arr`

error[E0308]: mismatched types
--> $DIR/issue-72819-generic-in-const-eval.rs:20:32
|
LL | let x: Arr<{usize::MAX}> = Arr {};
| ^^^ expected `false`, found `true`
|
= note: expected type `false`
found type `true`
= note: expected constant `false`
found constant `true`
note: required by a bound in `Arr`
--> $DIR/issue-72819-generic-in-const-eval.rs:8:39
|
LL | struct Arr<const N: usize>
| --- required by a bound in this
LL | where Assert::<{N < usize::MAX / 2}>: IsTrue,
| ^^^^^^ required by this bound in `Arr`

error: aborting due to 2 previous errors

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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,8 @@ error[E0308]: method not compatible with trait
LL | fn size(&self) -> [usize; DIM] {
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `Self::DIM`, found `DIM`
|
= note: expected type `Self::DIM`
found type `DIM`
= note: expected constant `Self::DIM`
found constant `DIM`

error: unconstrained generic constant
--> $DIR/issue-83765.rs:32:24
Expand All @@ -26,8 +26,8 @@ error[E0308]: mismatched types
LL | self.reference.size()
| ^^^^^^^^^^^^^^^^^^^^^ expected `DIM`, found `Self::DIM`
|
= note: expected type `DIM`
found type `Self::DIM`
= note: expected constant `DIM`
found constant `Self::DIM`

error: aborting due to 3 previous errors

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Original file line number Diff line number Diff line change
Expand Up @@ -54,8 +54,8 @@ error[E0308]: mismatched types
LL | writes_to_specific_path(&cap);
| ^^^^^^^^^^^^^^^^^^^^^^^ expected `true`, found `{ contains::<T, U>() }`
|
= note: expected type `true`
found type `{ contains::<T, U>() }`
= note: expected constant `true`
found constant `{ contains::<T, U>() }`

error: aborting due to 3 previous errors

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24 changes: 24 additions & 0 deletions src/test/ui/const-generics/generic_const_exprs/obligation-cause.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,24 @@
#![allow(incomplete_features)]
#![feature(generic_const_exprs)]

trait True {}

struct Is<const V: bool>;

impl True for Is<true> {}

fn g<T>()
//~^ NOTE required by a bound in this
where
Is<{ std::mem::size_of::<T>() == 0 }>: True,
//~^ NOTE required by a bound in `g`
//~| NOTE required by this bound in `g`
{
}

fn main() {
g::<usize>();
//~^ ERROR mismatched types
//~| NOTE expected `false`, found `true`
//~| NOTE expected constant `false`
}
Original file line number Diff line number Diff line change
@@ -0,0 +1,20 @@
error[E0308]: mismatched types
--> $DIR/obligation-cause.rs:20:5
|
LL | g::<usize>();
| ^^^^^^^^^^ expected `false`, found `true`
|
= note: expected constant `false`
found constant `true`
note: required by a bound in `g`
--> $DIR/obligation-cause.rs:13:44
|
LL | fn g<T>()
| - required by a bound in this
...
LL | Is<{ std::mem::size_of::<T>() == 0 }>: True,
| ^^^^ required by this bound in `g`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.
24 changes: 20 additions & 4 deletions src/test/ui/const-generics/issues/issue-73260.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -4,17 +4,33 @@ error[E0308]: mismatched types
LL | let x: Arr<{usize::MAX}> = Arr {};
| ^^^^^^^^^^^^^^^^^ expected `false`, found `true`
|
= note: expected type `false`
found type `true`
= note: expected constant `false`
found constant `true`
note: required by a bound in `Arr`
--> $DIR/issue-73260.rs:6:37
|
LL | struct Arr<const N: usize>
| --- required by a bound in this
LL | where
LL | Assert::<{N < usize::MAX / 2}>: IsTrue,
| ^^^^^^ required by this bound in `Arr`

error[E0308]: mismatched types
--> $DIR/issue-73260.rs:16:32
|
LL | let x: Arr<{usize::MAX}> = Arr {};
| ^^^ expected `false`, found `true`
|
= note: expected type `false`
found type `true`
= note: expected constant `false`
found constant `true`
note: required by a bound in `Arr`
--> $DIR/issue-73260.rs:6:37
|
LL | struct Arr<const N: usize>
| --- required by a bound in this
LL | where
LL | Assert::<{N < usize::MAX / 2}>: IsTrue,
| ^^^^^^ required by this bound in `Arr`

error: aborting due to 2 previous errors

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