rustc_target: route LayoutOf through TyAbiInterface.
#88338
Closed
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
Some changes occured to rustc_codegen_cranelift cc @bjorn3 Some changes occurred in src/tools/clippy. cc @rust-lang/clippy Some changes occured to the CTFE / Miri engine cc @rust-lang/miri |
|
r? @cjgillot (rust-highfive has picked a reviewer for you, use r? to override) |
rust-highfive
added
the
S-waiting-on-review
bjorn3
reviewed
Aug 25, 2021
eddyb
referenced
this pull request
in eddyb/rust
Aug 25, 2021
|
r? @nagisa |
This comment has been minimized.
This comment has been minimized.
eddyb
force-pushed
the
layout-of-rerouting
branch
2 times, most recently
from
a87e3c2 to
4cbc291
Compare
eddyb
force-pushed
the
layout-of-rerouting
branch
from
4cbc291 to
8211ebe
Compare
|
Closing as superseded by #88499, which doesn't have the ergonomic downsides. |
bors
added a commit
to rust-lang-ci/rust
that referenced
this pull request
Sep 5, 2021
Provide `layout_of` automatically (given tcx + param_env + error handling). After rust-lang#88337, there's no longer any uses of `LayoutOf` within `rustc_target` itself, so I realized I could move the trait to `rustc_middle::ty::layout` and redesign it a bit. This is similar to rust-lang#88338 (and supersedes it), but at no ergonomic loss, since there's no funky `C: LayoutOf<Ty = Ty>` -> `Ty: TyAbiInterface<C>` generic `impl` chain, and each `LayoutOf` still corresponds to one `impl` (of `LayoutOfHelpers`) for the specific context. After this PR, this is what's needed to get `trait LayoutOf` (with the `layout_of` method) implemented on some context type: * `TyCtxt`, via `HasTyCtxt` * `ParamEnv`, via `HasParamEnv` * a way to transform `LayoutError`s into the desired error type * an error type of `!` can be paired with having `cx.layout_of(...)` return `TyAndLayout` *without* `Result<...>` around it, such as used by codegen * this is done through a new `LayoutOfHelpers` trait (and so is specifying the type of `cx.layout_of(...)`) When going through this path (and not bypassing it with a manual `impl` of `LayoutOf`), the end result is that only the error case can be customized, the query itself and the success paths are guaranteed to be uniform. (**EDIT**: just noticed that because of the supertrait relationship, you cannot actually implement `LayoutOf` yourself, the blanket `impl` fully covers all possible context types that could ever implement it) Part of the motivation for this shape of API is that I've been working on querifying `FnAbi::of_*`, and what I want/need to introduce for that looks a lot like the setup in this PR - in particular, it's harder to express the `FnAbi` methods in `rustc_target`, since they're much more tied to `rustc` concepts. r? `@nagisa` cc `@oli-obk` `@bjorn3`
flip1995
pushed a commit
to flip1995/rust
that referenced
this pull request
Sep 8, 2021
Provide `layout_of` automatically (given tcx + param_env + error handling). After rust-lang#88337, there's no longer any uses of `LayoutOf` within `rustc_target` itself, so I realized I could move the trait to `rustc_middle::ty::layout` and redesign it a bit. This is similar to rust-lang#88338 (and supersedes it), but at no ergonomic loss, since there's no funky `C: LayoutOf<Ty = Ty>` -> `Ty: TyAbiInterface<C>` generic `impl` chain, and each `LayoutOf` still corresponds to one `impl` (of `LayoutOfHelpers`) for the specific context. After this PR, this is what's needed to get `trait LayoutOf` (with the `layout_of` method) implemented on some context type: * `TyCtxt`, via `HasTyCtxt` * `ParamEnv`, via `HasParamEnv` * a way to transform `LayoutError`s into the desired error type * an error type of `!` can be paired with having `cx.layout_of(...)` return `TyAndLayout` *without* `Result<...>` around it, such as used by codegen * this is done through a new `LayoutOfHelpers` trait (and so is specifying the type of `cx.layout_of(...)`) When going through this path (and not bypassing it with a manual `impl` of `LayoutOf`), the end result is that only the error case can be customized, the query itself and the success paths are guaranteed to be uniform. (**EDIT**: just noticed that because of the supertrait relationship, you cannot actually implement `LayoutOf` yourself, the blanket `impl` fully covers all possible context types that could ever implement it) Part of the motivation for this shape of API is that I've been working on querifying `FnAbi::of_*`, and what I want/need to introduce for that looks a lot like the setup in this PR - in particular, it's harder to express the `FnAbi` methods in `rustc_target`, since they're much more tied to `rustc` concepts. r? `@nagisa` cc `@oli-obk` `@bjorn3`
bjorn3
pushed a commit
to bjorn3/rust
that referenced
this pull request
Sep 19, 2021
Provide `layout_of` automatically (given tcx + param_env + error handling). After rust-lang#88337, there's no longer any uses of `LayoutOf` within `rustc_target` itself, so I realized I could move the trait to `rustc_middle::ty::layout` and redesign it a bit. This is similar to rust-lang#88338 (and supersedes it), but at no ergonomic loss, since there's no funky `C: LayoutOf<Ty = Ty>` -> `Ty: TyAbiInterface<C>` generic `impl` chain, and each `LayoutOf` still corresponds to one `impl` (of `LayoutOfHelpers`) for the specific context. After this PR, this is what's needed to get `trait LayoutOf` (with the `layout_of` method) implemented on some context type: * `TyCtxt`, via `HasTyCtxt` * `ParamEnv`, via `HasParamEnv` * a way to transform `LayoutError`s into the desired error type * an error type of `!` can be paired with having `cx.layout_of(...)` return `TyAndLayout` *without* `Result<...>` around it, such as used by codegen * this is done through a new `LayoutOfHelpers` trait (and so is specifying the type of `cx.layout_of(...)`) When going through this path (and not bypassing it with a manual `impl` of `LayoutOf`), the end result is that only the error case can be customized, the query itself and the success paths are guaranteed to be uniform. (**EDIT**: just noticed that because of the supertrait relationship, you cannot actually implement `LayoutOf` yourself, the blanket `impl` fully covers all possible context types that could ever implement it) Part of the motivation for this shape of API is that I've been working on querifying `FnAbi::of_*`, and what I want/need to introduce for that looks a lot like the setup in this PR - in particular, it's harder to express the `FnAbi` methods in `rustc_target`, since they're much more tied to `rustc` concepts. r? `@nagisa` cc `@oli-obk` `@bjorn3`
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This is a bit strange (potentially an ergonomic disaster, especially around errors, see below), but I decided to try and use the
trait TyAbiInterfacefrom #88337 to provide a single implementation oflayout_of, tied toTy<'tcx>, and usable with any context that provides:TyCtxt, viaHasTyCtxtParamEnv, viaHasParamEnvLayoutErrors into the desired error type!can be paired with havingcx.layout_of(...)returnTyAndLayoutwithoutResult<...>around it, such as used by codegenIsLayoutCxtrait (and so is specifying the type ofcx.layout_of(...))Sadly, because of the generics involved, and Rust type-checking/inference limitations (mostly around autoderef and coercions), certain things that we took for granted change:
cx: &mut Cdoesn't autoderef incx.layout_of(...), if onlyC: LayoutOfimpls of the relevant traits on&mut _cx.layout_of(ty: &Ty)doesn't coerce&TytoTyTyAbiInterfaceon&Ty, but I decided to fix the callsites insteadI doubt this change can be landed in its initial state (or at all), but since I did get it to work, I wanted to put it up.