diff --git a/src/const-generics.md b/src/const-generics.md index 9e26a174d8..e8aa118337 100644 --- a/src/const-generics.md +++ b/src/const-generics.md @@ -5,7 +5,7 @@ Most of the kinds of `ty::Const` that exist have direct parallels to kinds of types that exist, for example `ConstKind::Param` is equivalent to `TyKind::Param`. The main interesting points here are: -- [`ConstKind::Unevaluated`], which is equivalent to `TyKind::Alias` and in the long term should be renamed (as well as introducing an `AliasConstKind` to parallel `ty::AliasKind`). +- [`ConstKind::Alias`], which is equivalent to `TyKind::Alias`. - [`ConstKind::Value`], which is the final value of a `ty::Const` after monomorphization. This is somewhat similar to fully concrete things like `TyKind::Str` or `TyKind::ADT`. @@ -35,7 +35,7 @@ const ANON: usize = 1 + 1; type Alias = [u8; ANON]; ``` -Where the array length in `[u8; ANON]` isn't itself an anon const containing a usage of `ANON`, but a kind of "direct" usage of the `ANON` const item ([`ConstKind::Unevaluated`]). +Where the array length in `[u8; ANON]` isn't itself an anon const containing a usage of `ANON`, but a kind of "direct" usage of the `ANON` const item ([`ConstKind::Alias`]). Anon consts do not inherit any generic parameters of the item they are inside of: ```rust @@ -81,7 +81,7 @@ type Alias = [u8; ANON]; When we go through HIR ty lowering for the array type in `Alias`, we will lower the array length too, and feed `type_of(ANON) -> usize`. This will effectively set the type of the `ANON` const item during some later part of the compiler rather than when constructing the HIR. -After all of this desugaring has taken place the final representation in the type system (ie as a `ty::Const`) is a `ConstKind::Unevaluated` with the `DefId` of the `AnonConst`. This is equivalent to how we would representa a usage of an actual const item if we were to represent them without going through an anon const (e.g. when `min_generic_const_args` is enabled). +After all of this desugaring has taken place the final representation in the type system (ie as a `ty::Const`) is a `ConstKind::Alias` with the `DefId` of the `AnonConst`. This is equivalent to how we would representa a usage of an actual const item if we were to represent them without going through an anon const (e.g. when `min_generic_const_args` is enabled). This allows the representation for const "aliases" to be the same as the representation of `TyKind::Alias`. Having a proper HIR body also allows for a *lot* of code re-use, e.g. we can reuse HIR typechecking and all of the lowering steps to MIR where we can then reuse const eval. @@ -215,7 +215,7 @@ Proving `ConstArgHasType` goals is implemented by first computing the type of th A rough outline of how the type of a Const Argument may be computed: - [`ConstKind::Param(N)`][`ConstKind::Param`] can be looked up in the [`ParamEnv`] to find a `ConstArgHasType(N, ty)` clause - [`ConstKind::Value`] stores the type of the value inside itself so can trivially be accessed -- [`ConstKind::Unevaluated`] can have its type computed by calling the `type_of` query +- [`ConstKind::Alias`] can have its type computed by calling the `type_of` query - See the implementation of proving `ConstArgHasType` goals for more detailed information `ConstArgHasType` is *the* soundness critical way that we check Const Arguments have the correct type. @@ -238,11 +238,11 @@ what actually happens is a *type checking* error when type checking the anon con Looking at the above example, this corresponds to `[u8; ANON]` being a well formed type because `ANON` has type `usize`, but the *body* of `ANON` being illformed and resulting in a type checking error because `true` can't be returned from a const item of type `usize`. [ambig-unambig-ty-and-consts]: ./ambig-unambig-ty-and-consts.md -[`ConstKind`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.ConstKind.html -[`ConstKind::Infer`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.ConstKind.html#variant.Infer -[`ConstKind::Param`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.ConstKind.html#variant.Param -[`ConstKind::Unevaluated`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.ConstKind.html#variant.Unevaluated -[`ConstKind::Value`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.ConstKind.html#variant.Value +[`ConstKind`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/consts/type.ConstKind.html +[`ConstKind::Infer`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/consts/type.ConstKind.html#variant.Infer +[`ConstKind::Param`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/consts/type.ConstKind.html#variant.Param +[`ConstKind::Alias`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/consts/type.ConstKind.html#variant.Alias +[`ConstKind::Value`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/consts/type.ConstKind.html#variant.Value [const_arg_has_type]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/type.ClauseKind.html#variant.ConstArgHasType [`ParamEnv`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.ParamEnv.html [`generics_of`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/ty/struct.TyCtxt.html#impl-TyCtxt%3C'tcx%3E/method.generics_of