Commit graph

70 commits

Author SHA1 Message Date
lapla
88f0ac34dc
Fix const normalization for generic const items with trait assoc consts 2026-02-15 22:05:27 +09:00
León Orell Valerian Liehr
32e49a8b40
Reenable a GCI+mGCA+GCPT test case 2026-02-10 12:04:09 +01:00
Keith-Cancel
73a991fb9d Allow provisional mgca syntax of type const <IDENT> = <EXPR> to be reconized.
Revert, but without type const.

Update symbol for feature err, then update suggestion output, and lastly update tests that change because of those.

Update these new tests with the correct syntax, and few existing tests with the new outputs the merge with main added.

Fix for tidyfmt and some errors when manually resolving a merge conflicts.

Update these tests to use update error messages and type const syntax.

Update comments and error message to use new syntax instead of old type_const attribute.

Remove the type_const attribute

update some more tests to use the new syntax.

Update these test cases.

update feature gate test

Change gate logic for `mgca_type_const_syntax` to work also if `min_generic_const_args` is enabled.

Create a new feature gate that checks for the feature before expansion.

Make rustfmt handle the `type const` syntax correctly.

Add a convience method to check if a RhsKind is type const.

Rename `Const` discriminant to `Body` for `ConstItemRhsKind`

Give the `TraitItemKind` flag an enum instead of a simple bool to better describe what the flag is for.

Update formatting for these match statements.

Update clippy test to use type const syntax.

Update test to use type const syntax.

update rustfmt to match ast items.

Update clippy to match ast and hir items.

Few more test cases that used old attribute, instead of 'type const'

Update to match the output from the feature gate checks.

tidyfmt adjustments.

Update the is_type_const, so I can constrain record!(..) in encoder.rs

Update conditional compilation test.

Move the feature gate to after expansion to allow for cfg(...) to work.

Update some more tests to use the new syntax.

Update type const tests in associated-const-bindings to use new syntax.

Don't check based off the attribute, but the item here.

Update some tests outside of the const_generics folder that were using #[type_const]

update the tests in associated consts that use #[type_const] to use type const

Update these mgca tests with the type const syntax.

Add a flag to TraitItemKind for detecting type const for now. Maybe later change ItemConstRhs to have optional consts but that touches a lot more lines of code.

Don't need into for these now that it's a query.

Add is_type_const query to handle foreign def ids.

update this test to use type const syntax.

Fix logic here, we only want to lower if there is expression in this case.

Update built-in macros to use ConstItemRhsKind

Update more instance of the old ConstItemRhs.

Rename ConstItemKind to ConstItemRhsKind, I noticed there is a typed called ConstantItemKind, so add the Rhs to the name to avoid confusion.

Update lower to use ConstItemKind

Add an other helper method to check if the rhs kinda has an expr.

Update item parse to use ConstItemKind enum.

Felt the field name could a be little clear when editing a few other things.

Change the ConstItem struct see know if we have a type const or regular const.

Make sure this syntax is properly feature gated.
2026-02-09 07:59:24 -08:00
Noah Lev
9a30ec8149 Implement MVP for opaque generic const arguments
This is meant to be the interim successor to generic const expressions.
Essentially, const item RHS's will be allowed to do arbitrary const
operations using generics. The limitation is that these const items will
be treated opaquely, like ADTs in nominal typing, such that uses of them
will only be equal if the same const item is referenced. In other words,
two const items with the exact same RHS will not be considered equal.

I also added some logic to check feature gates that depend on others
being enabled (like oGCA depending on mGCA).

= Coherence =

During coherence, OGCA consts should be normalized ambiguously because
they are opaque but eventually resolved to a real value. We don't want
two OGCAs that have the same value to be treated as distinct for
coherence purposes. (Just like opaque types.)

This actually doesn't work yet because there are pre-existing
fundamental issues with equate relations involving consts that need to
be normalized. The problem is that we normalize only one layer of the
const item and don't actually process the resulting anon const. Normally
the created inference variable should be handled, which in this case
would cause us to hit the anon const, but that's not happening.
Specifically, `visit_const` on `Generalizer` should be updated to be
similar to `visit_ty`.
2026-02-08 18:15:11 +00:00
León Orell Valerian Liehr
baba337869
Introduce AssocTag::descr & refactor in the vicinity 2026-01-21 12:53:46 +01:00
León Orell Valerian Liehr
b144a11d2c
Replace more mentions of associated_const_equality 2026-01-09 00:32:37 +01:00
AprilNEA
4421270516
Merge associated_const_equality feature gate into MGCA
This removes `associated_const_equality` as a separate feature gate and makes it part of `min_generic_const_args` (mgca).

Key changes:
  - Remove `associated_const_equality` from unstable features, add to removed
  - Update all test files to use `min_generic_const_args` instead
  - Preserve the original "associated const equality is incomplete" error message by specially handling `sym::associated_const_equality` spans in `feature_gate.rs`
  - Rename FIXME(associated_const_equality) to FIXME(mgca)
2026-01-05 12:31:42 +08:00
Boxy Uwu
acc3a0e2da Syntactically distinguish anon const const args 2025-12-12 15:45:37 +00:00
Matthias Krüger
7e9b67d355
Rollup merge of #148716 - camelid:finish-type_const, r=BoxyUwU
mgca: Finish implementation of `#[type_const]`

tracking issue: rust-lang/rust#132980
fixes rust-lang/rust#140729
fixes rust-lang/rust#140860

- **Fix `#[type_const]` attribute placement validation**
- **Perform WF-checking on type_const RHS's**
- **Check type_const type is ConstParamTy_ and that RHS matches it**
- **Check that impls of `#[type_const]` consts also have the attr**

r? ```@BoxyUwU```
2025-11-09 17:37:07 +01:00
Matthias Krüger
e5a69bb215
Rollup merge of #148683 - fmease:rm-const_trait-attr, r=fee1-dead
Remove `#[const_trait]`

Remove `#[const_trait]` since we now have `const trait`. Update all structured diagnostics that still suggested the attribute.

r? ```@rust-lang/project-const-traits```
2025-11-09 17:37:05 +01:00
Noah Lev
9ba89327df Check type_const type is ConstParamTy_ and that RHS matches it 2025-11-08 23:05:08 -05:00
Noah Lev
c0939d4ec0 Perform WF-checking on type_const RHS's 2025-11-08 23:05:08 -05:00
bors
72b21e1a64 Auto merge of #139558 - camelid:mgca-const-items, r=oli-obk,BoxyUwU
mgca: Add ConstArg representation for const items

tracking issue: rust-lang/rust#132980
fixes rust-lang/rust#131046
fixes rust-lang/rust#134641

As part of implementing `min_generic_const_args`, we need to distinguish const items that can be used in the type system, such as in associated const equality projections, from const items containing arbitrary const code, which must be kept out of the type system. Specifically, all "type consts" must be either concrete (no generics) or generic with a trivial expression like `N` or a path to another type const item.

To syntactically distinguish these cases, we require, for now at least, that users annotate all type consts with the `#[type_const]` attribute. Then, we validate that the const's right-hand side is indeed eligible to be a type const and represent it differently in the HIR.

We accomplish this representation using a new `ConstItemRhs` enum in the HIR, and a similar but simpler enum in the AST. When `#[type_const]` is **not** applied to a const (e.g. on stable), we represent const item right-hand sides (rhs's) as HIR bodies, like before. However, when the attribute is applied, we instead lower to a `hir::ConstArg`. This syntactically distinguishes between trivial const args (paths) and arbitrary expressions, which are represented using `AnonConst`s. Then in `generics_of`, we can take advantage of the existing machinery to bar the `AnonConst` rhs's from using parent generics.
2025-11-08 22:31:33 +00:00
Boxy Uwu
0a355170c0 fix associated_const_equality tests 2025-11-08 13:50:48 -05:00
León Orell Valerian Liehr
c262920059
Remove #[const_trait] 2025-11-08 07:37:15 +01:00
Esteban Küber
1d860902f6 When a trait isn't implemented, but another similar impl is found, point at it:
```
error[E0277]: the trait bound `u32: Trait` is not satisfied
  --> $DIR/trait_objects_fail.rs:26:9
   |
LL |     foo(&10_u32);
   |         ^^^^^^^ the trait `Trait` is not implemented for `u32`
   |
help: the trait `Trait<12>` is not implemented for `u32`
      but trait `Trait<2>` is implemented for it
  --> $DIR/trait_objects_fail.rs:7:1
   |
LL | impl Trait<2> for u32 {}
   | ^^^^^^^^^^^^^^^^^^^^^
   = note: required for the cast from `&u32` to `&dyn Trait`
```

Pointing at the `impl` definition that *could* apply given a different self type is particularly useful when it has a blanket self type, as it might not be obvious and is not trivially greppable:

```
error[E0277]: the trait bound `RawImpl<_>: Raw<_>` is not satisfied
  --> $DIR/issue-62742.rs:4:5
   |
LL |     WrongImpl::foo(0i32);
   |     ^^^^^^^^^ unsatisfied trait bound
   |
help: the trait `Raw<_>` is not implemented for `RawImpl<_>`
      but trait `Raw<[_]>` is implemented for it
  --> $DIR/issue-62742.rs:29:1
   |
LL | impl<T> Raw<[T]> for RawImpl<T> {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: required by a bound in `SafeImpl`
  --> $DIR/issue-62742.rs:33:35
   |
LL | pub struct SafeImpl<T: ?Sized, A: Raw<T>>(PhantomData<(A, T)>);
   |                                   ^^^^^^ required by this bound in `SafeImpl`
```
2025-10-31 20:38:31 +00:00
León Orell Valerian Liehr
02ea38cfff
Fortify generic param default checks 2025-08-06 01:26:26 +02:00
Oli Scherer
6166cd6b50 Avoid looking at HIR for trait and impl items 2025-06-30 08:45:43 +00:00
León Orell Valerian Liehr
169e81cd59
Move an ACE test out of the GCI directory 2025-06-26 15:42:57 +02:00
Ralf Jung
17946c22b1 const-eval error: always say in which item the error occurred
also adjust the wording a little so that we don't say "the error occurred here" for two different spans
2025-06-07 13:42:30 +02:00
Oli Scherer
020216c31c Clarify why we are talking about a failed const eval at a random place 2025-06-02 15:37:15 +00:00
Oli Scherer
b331b8b96d Use the informative error as the main const eval error message 2025-06-02 15:37:15 +00:00
León Orell Valerian Liehr
9f12748086
GCI: Check where-clauses for well-formedness at the def site 2025-05-28 15:19:32 +02:00
León Orell Valerian Liehr
a83f8d02ea
Always evaluate free lifetime-generic constants
Co-authored-by: Michael Goulet <michael@errs.io>
2025-05-27 18:58:51 +02:00
Boxy
bfe3d54d81 User type annotations for free consts in pattern position 2025-05-01 13:14:53 +01:00
Nicholas Nethercote
7e8184fa2a Improve AssocItem::descr.
The commit adds "associated" to the description of associated types and
associated consts, to match the description of associated functions.
This increases error message precision and consistency with
`AssocKind::fmt`.

The commit also notes an imperfection in `AssocKind::fmt`; fixing this
imperfection is possible but beyond the scope of this PR.
2025-04-11 11:03:08 +10:00
Esteban Küber
f0b8e13b59 Do not suggest using -Zmacro-backtrace for builtin macros
For macros that are implemented on the compiler, we do *not* mention the `-Zmacro-backtrace` flag. This includes `derive`s and standard macros.
2025-03-14 19:50:03 +00:00
Matthias Krüger
415b207b7f
Rollup merge of #137617 - BoxyUwU:generic_const_parameter_types, r=lcnr
Introduce `feature(generic_const_parameter_types)`

Allows to define const generic parameters whose type depends on other generic parameters, e.g. `Foo<const N: usize, const ARR: [u8; N]>;`

Wasn't going to implement for this for a while until we could implement it with `bad_inference.rs` resolved but apparently the project simd folks would like to be able to use this for some intrinsics and the inference issue isn't really a huge problem there aiui. (cc ``@workingjubilee`` )
2025-03-01 11:33:58 +01:00
Boxy
df5b279ca9 Introduce feature(generic_const_parameter_types) 2025-02-28 20:43:15 +00:00
Esteban Küber
7d4d09eeeb Shorten span of panic failures in const context
Previously, we included a redundant prefix on the panic message and a postfix of the location of the panic. The prefix didn't carry any additional information beyond "something failed", and the location of the panic is redundant with the diagnostic's span, which gets printed out even if its code is not shown.

```
error[E0080]: evaluation of constant value failed
  --> $DIR/assert-type-intrinsics.rs:11:9
   |
LL |         MaybeUninit::<!>::uninit().assume_init();
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ evaluation panicked: aborted execution: attempted to instantiate uninhabited type `!`
```

```
error[E0080]: evaluation of `Fail::<i32>::C` failed
  --> $DIR/collect-in-dead-closure.rs:9:19
   |
LL |     const C: () = panic!();
   |                   ^^^^^^^^ evaluation panicked: explicit panic
   |
   = note: this error originates in the macro
`$crate::panic::panic_2015` which comes from the expansion of the macro
`panic` (in Nightly builds, run with -Z macro-backtrace for more info)
```

```
error[E0080]: evaluation of constant value failed
  --> $DIR/uninhabited.rs:41:9
   |
LL |         assert!(false);
   |         ^^^^^^^^^^^^^^ evaluation panicked: assertion failed: false
   |
   = note: this error originates in the macro `assert` (in Nightly builds, run with -Z macro-backtrace for more info)
```

---

When the primary span for a const error is the same as the first frame in the const error report, skip it.

```
error[E0080]: evaluation of constant value failed
  --> $DIR/issue-88434-removal-index-should-be-less.rs:3:24
   |
LL | const _CONST: &[u8] = &f(&[], |_| {});
   |                        ^^^^^^^^^^^^^^ evaluation panicked: explicit panic
   |
note: inside `f::<{closure@$DIR/issue-88434-removal-index-should-be-less.rs:3:31: 3:34}>`
  --> $DIR/issue-88434-removal-index-should-be-less.rs:10:5
   |
LL |     panic!()
   |     ^^^^^^^^ the failure occurred here
   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
```
instead of
```
error[E0080]: evaluation of constant value failed
  --> $DIR/issue-88434-removal-index-should-be-less.rs:10:5
   |
LL |     panic!()
   |     ^^^^^^^^ explicit panic
   |
note: inside `f::<{closure@$DIR/issue-88434-removal-index-should-be-less.rs:3:31: 3:34}>`
  --> $DIR/issue-88434-removal-index-should-be-less.rs:10:5
   |
LL |     panic!()
   |     ^^^^^^^^
note: inside `_CONST`
  --> $DIR/issue-88434-removal-index-should-be-less.rs:3:24
   |
LL | const _CONST: &[u8] = &f(&[], |_| {});
   |                        ^^^^^^^^^^^^^^
   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
```

---

Revert order of constant evaluation errors

Point at the code the user wrote first and std functions last.

```
error[E0080]: evaluation of constant value failed
  --> $DIR/const-errs-dont-conflict-103369.rs:5:25
   |
LL | impl ConstGenericTrait<{my_fn(1)}> for () {}
   |                         ^^^^^^^^ evaluation panicked: Some error occurred
   |
note: called from `my_fn`
  --> $DIR/const-errs-dont-conflict-103369.rs:10:5
   |
LL |     panic!("Some error occurred");
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
```
instead of
```
error[E0080]: evaluation of constant value failed
  --> $DIR/const-errs-dont-conflict-103369.rs:10:5
   |
LL |     panic!("Some error occurred");
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Some error occurred
   |
note: called from `<() as ConstGenericTrait<{my_fn(1)}>>::{constant#0}`
  --> $DIR/const-errs-dont-conflict-103369.rs:5:25
   |
LL | impl ConstGenericTrait<{my_fn(1)}> for () {}
   |                         ^^^^^^^^
   = note: this error originates in the macro `$crate::panic::panic_2015` which comes from the expansion of the macro `panic` (in Nightly builds, run with -Z macro-backtrace for more info)
```
2025-02-28 16:28:41 +00:00
Esteban Küber
f0845adb0c Show diff suggestion format on verbose replacement
```
error[E0610]: `{integer}` is a primitive type and therefore doesn't have fields
  --> $DIR/attempted-access-non-fatal.rs:7:15
   |
LL |     let _ = 2.l;
   |               ^
   |
help: if intended to be a floating point literal, consider adding a `0` after the period and a `f64` suffix
   |
LL -     let _ = 2.l;
LL +     let _ = 2.0f64;
   |
```
2025-02-10 20:21:39 +00:00
León Orell Valerian Liehr
e37b744bae
Rollup merge of #136168 - fmease:gci-fix-mono, r=compiler-errors
GCI: Don't try to eval / collect mono items inside overly generic free const items

Fixes #136156. Thanks for the pointers, errs!

There's one (preexisting) thing of note (maybe?). There's a difference between `const _: () = panic!();` and `const _<'a>: () = panic!();`: The former is a pre-mono error, the latter is a post-mono error. For comparison, both `fn _f() { const { panic!() } }` and `fn _f<'a: 'a>() { const { panic!() } }` are post-mono errors.

cc `@oli-obk`
r? compiler-errors or reassign
2025-01-29 06:03:23 +01:00
León Orell Valerian Liehr
0a9ee02d0a
GCI: Don't try to collect mono items inside overly generic free const items 2025-01-28 04:00:37 +01:00
León Orell Valerian Liehr
0b18b4fbbc
Remove all dead files inside tests/ui/ 2025-01-27 02:28:04 +01:00
Martin Zacho
38e10e5619 improve diagnostics for const eval query overflow 2025-01-06 09:43:05 +01:00
Michael Goulet
c529fe0475 Remove diagnostic_only_typeck and fix placeholder suggestion for const/static 2025-01-02 23:39:16 +00:00
Michael Goulet
0b5ddf30eb Yeet effects feature 2024-11-03 18:59:31 +00:00
Esteban Küber
b7fc1a7431 Add trait diff highlighting logic and use it in E0277
When a trait is not implemented for a type, but there *is* an `impl`
for another type or different trait params, we format the output to
use highlighting in the same way that E0308 does for types.

The logic accounts for 3 cases:
- When both the type and trait in the expected predicate and the candidate are different
- When only the types are different
- When only the trait generic params are different

For each case, we use slightly different formatting and wording.
2024-11-02 03:08:04 +00:00
Barrett Ray
c5598d6a9e fix(hir_analysis/wfcheck): don't leak {type error}
avoid `{type error}` being leaked in user-facing messages,
particularly when using the `adt_const_params` feature
2024-09-29 23:40:43 -05:00
Boxy
d0c11bf6e3 Split part of adt_const_params into unsized_const_params 2024-07-17 11:01:29 +01:00
Deadbeef
daff015314 Migrate tests to use -Znext-solver 2024-06-30 17:08:45 +00:00
León Orell Valerian Liehr
39d9b840bb
Handle trait/impl GAC mismatches when inferring missing/placeholder types 2024-05-24 00:42:32 +02:00
León Orell Valerian Liehr
24afa42a90
Properly deal with missing/placeholder types inside GACs 2024-05-24 00:36:32 +02:00
León Orell Valerian Liehr
dfbdce01e1
Check regions earlier when comparing impl with trait item def 2024-04-13 17:07:02 +02:00
Esteban Küber
796be88062 Use fn ptr signature instead of {closure@..} in infer error
When suggesting a type on inference error, do not use `{closure@..}`.
Instead, replace with an appropriate `fn` ptr.

On the error message, use `short_ty_string` and write long types to
disk.

```
error[E0284]: type annotations needed for `Select<{closure@lib.rs:2782:13}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: the full type name has been written to '/home/gh-estebank/iowo/target/debug/deps/lang-e2d6e25819442273.long-type-4587393693885174369.txt'
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<for<'a, 'b> fn(tokens::Token<'_>, &'a mut MapExtra<'_, 'b, _, _>) -> Option<Expression<'_>>, _, Expression<'_>, _> = select! {
   |                +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

instead of

```
error[E0284]: type annotations needed for `Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _>`
  --> crates/lang/src/parser.rs:41:13
   |
41 |         let lit = select! {
   |             ^^^
42 |             Token::Int(i) = e => Expression::new(Expr::Lit(ast::Lit::Int(i.parse().unwrap())), e.span()),
   |                                                                                                  ---- type must be known at this point
   |
   = note: cannot satisfy `<_ as chumsky::input::Input<'_>>::Span == SimpleSpan`
help: consider giving `lit` an explicit type, where the type for type parameter `I` is specified
   |
41 |         let lit: Select<{closure@/home/gh-estebank/.cargo/registry/src/index.crates.io-6f17d22bba15001f/chumsky-1.0.0-alpha.6/src/lib.rs:2782:13: 2782:28}, _, Expression<'_>, _> = select! {
   |                ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
```

Fix #123630.
2024-04-10 00:41:27 +00:00
Matthias Krüger
88aa71f108 add test for assertion failed: !value.has_infer() #115806
Fixes https://github.com/rust-lang/rust/issues/115806
2024-04-07 01:45:31 +02:00
bors
519d892f95 Auto merge of #121387 - oli-obk:eager_const_failures_regression, r=lcnr
Avoid some unnecessary query invocations.

Specifically this inlines `const_eval_poly` and avoids computing the generic params, the param env, normalizing the param env and erasing lifetimes on everything.

should fix the perf regression from https://github.com/rust-lang/rust/pull/121087
2024-03-26 10:52:11 +00:00
Matthias Krüger
877f29363d
Rollup merge of #122988 - matthiaskrgr:icetests, r=petrochenkov
add even more tests!

Fixes https://github.com/rust-lang/rust/issues/109869
Fixes https://github.com/rust-lang/rust/issues/110453
Fixes https://github.com/rust-lang/rust/issues/109020
Fixes https://github.com/rust-lang/rust/issues/108580
Fixes https://github.com/rust-lang/rust/issues/108220
Fixes https://github.com/rust-lang/rust/issues/113045
Fixes https://github.com/rust-lang/rust/issues/113133
Fixes https://github.com/rust-lang/rust/issues/114464
Fixes https://github.com/rust-lang/rust/issues/116599
Fixes https://github.com/rust-lang/rust/issues/119731
2024-03-25 17:05:34 +01:00
Matthias Krüger
6203ebe274 add test for ICE with associated_const_equality #108220
Fixes #108220
2024-03-24 10:28:25 +01:00
Esteban Küber
6b24fdf811 Provide structured suggestion for unconstrained generic constant
```
error: unconstrained generic constant
  --> $DIR/const-argument-if-length.rs:18:10
   |
LL |     pad: [u8; is_zst::<T>()],
   |          ^^^^^^^^^^^^^^^^^^^
   |
help: try adding a `where` bound
   |
LL | pub struct AtLeastByte<T: ?Sized> where [(); is_zst::<T>()]: {
   |                                   ++++++++++++++++++++++++++
```

Detect when the constant expression isn't `usize` and suggest casting:

```
error: unconstrained generic constant
 --> f300.rs:6:10
  |
6 |     bb::<{!N}>();
  |          ^^^^
-Ztrack-diagnostics: created at compiler/rustc_trait_selection/src/traits/error_reporting/type_err_ctxt_ext.rs:3539:36
  |
help: try adding a `where` bound
  |
5 | fn b<const N: bool>() where [(); {!N} as usize]: {
  |                       ++++++++++++++++++++++++++
```

Fix #122395.
2024-03-21 00:03:59 +00:00