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When `#![feature(min_generic_const_args)]` is enabled, we now lower all const paths in generic arg position to `hir::ConstArgKind::Path`. We then lower assoc const paths to `ty::ConstKind::Unevaluated` since we can no longer use the anon const expression lowering machinery. In the process of implementing this, I factored out `hir_ty_lowering` code that is now shared between lowering assoc types and assoc consts. This PR also introduces a `#[type_const]` attribute for trait assoc consts that are allowed as const args. However, we still need to implement code to check that assoc const definitions satisfy `#[type_const]` if present (basically is it a const path or a monomorphic anon const).
23 lines
980 B
Plaintext
23 lines
980 B
Plaintext
error: generic parameters may not be used in const operations
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--> $DIR/feature-gate-min-generic-const-args.rs:8:29
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LL | fn foo<T: Trait>() -> [u8; <T as Trait>::ASSOC] {
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| ^ cannot perform const operation using `T`
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= note: type parameters may not be used in const expressions
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= help: add `#![feature(generic_const_exprs)]` to allow generic const expressions
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error[E0658]: the `#[type_const]` attribute is an experimental feature
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--> $DIR/feature-gate-min-generic-const-args.rs:2:5
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LL | #[type_const]
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| ^^^^^^^^^^^^^
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= note: see issue #132980 <https://github.com/rust-lang/rust/issues/132980> for more information
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= help: add `#![feature(min_generic_const_args)]` to the crate attributes to enable
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= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
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error: aborting due to 2 previous errors
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For more information about this error, try `rustc --explain E0658`.
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