Add better diagnostic for unbounded Abst. Const
~~In the case where a generic abst. const requires a trivial where bound: `where TypeWithConst<const_fn(N)>: ,`,
instead of requiring a where bound, just check that only consts are being substituted in to skip over where check.~~
~~This is pretty sketchy, but I think it works. Presumably, if there is checking for type bounds added later, it can first check nested requirements, and see if they're satisfied by the current `ParamEnv`.~~
Changed the diagnostic to add a better example, which is more practical than what was previously proposed.
r? ```@lcnr```
Add error message for private fn
Attempts to add a more detailed error when a `const_evaluatable` fn from another scope is used inside of a scope which cannot access it.
r? ````@lcnr````
Add a test for #71202Closes#71202
---
Note that the test normally generates this warning:
```
warning: cannot use constants which depend on generic parameters in types
--> test.rs:10:5
|
10 | / const ITEM_IS_COPY: [(); 1 - {
11 | | trait NotCopy {
12 | | const VALUE: bool = false;
13 | | }
... |
26 | | <IsCopy<T>>::VALUE
27 | | } as usize] = [];
| |_____________________^
|
= note: `#[warn(const_evaluatable_unchecked)]` on by default
= warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
= note: for more information, see issue #76200 <https://github.com/rust-lang/rust/issues/76200>
```
I added `allow(const_evaluatable_unchecked)`, but maybe we just don't want to add a test for this as the program is not really valid?
Stabilize by-value `[T; N]` iterator `core::array::IntoIter`
Tracking issue: https://github.com/rust-lang/rust/issues/65798
This is unblocked now that `min_const_generics` has been stabilized in https://github.com/rust-lang/rust/pull/79135.
This PR does *not* include the corresponding `IntoIterator` impl, which is https://github.com/rust-lang/rust/pull/65819. Instead, an iterator can be constructed through the `new` method.
`new` would become unnecessary when `IntoIterator` is implemented and might be deprecated then, although it will stay stable.
correctly deal with late-bound lifetimes in anon consts
adds support for using late bound lifetimes of the parent context in anon consts.
```rust
#![feature(const_generics)]
const fn inner<'a>() -> usize where &'a (): Sized { 3 }
fn test<'a>() {
let _: [u8; inner::<'a>()];
}
```
The lifetime `'a` is late bound in `test` so it's not included in its generics but is instead dealt with separately in borrowck.
This didn't previously work for anon consts as they have to use the late bound lifetimes of their parent which has
to be explicitly handled.
r? ```@matthewjasper``` cc ```@varkor``` ```@eddyb```
Add check for `[T;N]`/`usize` mismatch in astconv
Helps clarify the issue in #80506
by adding a specific check for mismatches between [T;N] and usize.
r? `@lcnr`
const_evaluatable_checked: fix occurs check
fixes#79615
this is kind of a hack because we use `TypeRelation` for both the `Generalizer` and the `ConstInferUnifier` but i am not sure if there is a useful way to disentangle this without unnecessarily duplicating some code.
The error in the added test is kind of unavoidable until we erase the unused substs of `ConstKind::Unevaluated`. We talked a bit about this in the cg lazy norm meeting (https://rust-lang.zulipchat.com/#narrow/stream/260443-project-const-generics/topic/lazy_normalization_consts)
Part of #68490.
Care has been taken to leave the old consts where appropriate, for testing backcompat regressions, module shadowing, etc. The intrinsics docs were accidentally referring to some methods on f64 as std::f64, which I changed due to being contrary with how we normally disambiguate the shadow module from the primitive. In one other place I changed std::u8 to std::ops since it was just testing path handling in macros.
For places which have legitimate uses of the old consts, deprecated attributes have been optimistically inserted. Although currently unnecessary, they exist to emphasize to any future deprecation effort the necessity of these specific symbols and prevent them from being accidentally removed.
As `Cell` won't receive an allocator parameter, it is used. Otherwise a `#![feature(allocator_api)]` could have been added, but for the purpose of this test, changing the type is more clear.
