Add overloaded slice operations to the prelude #17711
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The new overloaded slice operations have replaced the various `slice` methods on slice types. However, the relevant traits were not included in the prelude, meaning that you would have to manually import `std::ops::Slice` to get these operations -- an unintended regression. This commit adds the traits to the prelude, as is done with most other operator traits. Unfortunately, the trait `std::slice::Slice` (which defines an `as_slice` method) was already included in the prelude. This trait is renamed to `AsSlice`, which is a better name in any case. In addition, because of both `AsSlice` and `Str` traits being included in the prelude, both of which define `as_slice`, and both of which are used for generic programming, this commit renames `ops::Slice::as_slice` to `ops::Slice::as_slice_`. This is a stopgap solution; we'll need to figure out a long-term story here later on. Closes rust-lang#17710 Due to the renamings, this is a: [breaking-change]
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A few notes about this PR: ultimately it's not clear whether the Also, at the moment removing This PR therefore is the smallest delta that deals with the basic regression. After it lands, we'll need to figure out a real solution for these problems. |
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I've run into several additional problems, so I'm going to close this and instead revert #17620 |
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fix: Wrong BoundVar index when lowering impl trait parameter of parent generics Fixes rust-lang#17711 From the following test code; ```rust //- minicore: deref use core::ops::Deref; struct Struct<'a, T>(&'a T); trait Trait {} impl<'a, T: Deref<Target = impl Trait>> Struct<'a, T> { fn foo(&self) -> &Self { self } fn bar(&self) { let _ = self.foo(); } } ``` when we call `register_obligations_for_call` for `let _ = self.foo();`, https://github.com/rust-lang/rust-analyzer/blob/07659783fdfd4ec0a0bffa93017e33e31e567e42/crates/hir-ty/src/infer/expr.rs#L1939-L1952 we are querying `generic_predicates` and it has `T: Deref<Target = impl Trait>` predicate from the parent `impl Struct`; https://github.com/rust-lang/rust-analyzer/blob/07659783fdfd4ec0a0bffa93017e33e31e567e42/crates/hir-ty/src/lower.rs#L375-L399 but as we can see above, lowering `TypeRef = impl Trait` doesn't take into account the parent generic parameters, so the `BoundVar` index here is `0`, as `fn foo` has no generic args other than parent's, But this `BoundVar` is pointing at `'a` in `<'a, T: Deref<Target = impl Trait>>`. So, in the first code reference `register_obligations_for_call`'s L:1948 - `.substitute(Interner, parameters)`, we are substituting `'a` with `Ty`, not `Lifetime` and this makes panic inside the chalk. This PR fixes this wrong `BoundVar` index in such cases
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methods on slice types. However, the relevant traits were not included
in the prelude, meaning that you would have to manually import
std::ops::Sliceto get these operations -- an unintended regression.This commit adds the traits to the prelude, as is done with most other
operator traits.
Unfortunately, the trait
std::slice::Slice(which defines anas_slicemethod) was already included in the prelude. This trait isrenamed to
AsSlice, which is a better name in any case.In addition, because of both
AsSliceandStrtraits being includedin the prelude, both of which define
as_slice, and both of which areused for generic programming, this commit renames
ops::Slice::as_sliceto
ops::Slice::as_slice_. This is a stopgap solution; we'll need tofigure out a long-term story here later on.
Closes #17710
Due to the renamings, this is a:
[breaking-change]