add a normalizes-to fast path by lcnr · Pull Request #125334 · rust-lang/rust

lcnr · 2024-05-20T17:55:36Z

Fixes the minimization in rust-lang/trait-system-refactor-initiative#109. It does not fix rayon as rayon has a blanket impl of ParallelIterator.

r? @compiler-errors

compiler/rustc_trait_selection/src/solve/normalizes_to/fast_reject.rs

compiler-errors

also squash

compiler/rustc_trait_selection/src/solve/normalizes_to/fast_reject.rs

rustbot · 2024-05-21T19:09:26Z

Some changes occurred to the core trait solver

cc @rust-lang/initiative-trait-system-refactor

compiler-errors · 2024-05-22T15:07:59Z

compiler/rustc_trait_selection/src/solve/normalizes_to/fast_reject.rs

+#[instrument(level = "trace", skip(tcx), ret)]
+fn no_applicable_blanket_impls<'tcx>(tcx: TyCtxt<'tcx>, trait_def_id: DefId) -> bool {
+    // FIXME(ptr_metadata): There's currently a builtin impl for `Pointee` which
+    // applies for all `T` as long as `T: Sized` holds. THis impl should


Suggested change

// applies for all `T` as long as `T: Sized` holds. THis impl should

// applies for all `T` as long as `T: Sized` holds. This impl should

compiler-errors · 2024-05-22T15:15:05Z

compiler/rustc_middle/src/ty/fast_reject.rs

+            // Start by checking whether the type in the candidate may unify with
            // pretty much everything. Just return `true` in that case.
-            ty::Param(_) | ty::Error(_) | ty::Alias(..) => return true,
+            ty::Param(_) | ty::Error(_) | ty::Alias(..) | ty::Infer(_) | ty::Placeholder(..) => {


This treats params always as bound vars (which is true for unsubstituted impl headers), vs when they come from the environment they should be treated as placeholders (param-env candidate matching).

I think drcx should be reworked to make this distinction, so we don't return true more than we need to.

Ideally this could then be used when matching param-env candidates in the new and old solvers, so we can avoid instantiating binders and doing type equality when it's useless.

compiler-errors · 2024-05-25T01:33:03Z

@rustbot author

bors · 2024-05-28T20:34:41Z

☔ The latest upstream changes (presumably #125665) made this pull request unmergeable. Please resolve the merge conflicts.

lolbinarycat · 2024-09-01T20:54:33Z

@lcnr still interested in working on this?

compiler-errors · 2024-09-01T20:55:40Z

This PR should stay open for now

[DO NOT MERGE] bootstrap with `-Znext-solver=globally` A revival of rust-lang#124812. Current status, we're failing in: - failing in `rustc_next_trait_solver` with 126 instances of the following error ``` error[E0311]: the parameter type `I` may not live long enough | help: consider adding an explicit lifetime bound --> compiler/rustc_next_trait_solver/src/solve/trait_goals.rs:624:53 | 624 ~ fn consider_structural_builtin_unsize_candidates<'a>( 625 ~ ecx: &mut EvalCtxt<'a, D>, 626 | goal: Goal<I, Self>, 627 ~ ) -> Vec<Candidate<I>> where I: 'a { ``` - `itertools` hangs, we're already encountered this hang in our previous attempt due to large type sizes. I believe that it's simply caused by a missing cache somewhere, potentially in `wf.rs`, but other visitors may also be responsible. See rust-itertools/itertools#945 for more details ### commits - rust-lang#133501 - rust-lang#133493 - 9456bfe and b21b116 reimplement candidate preference based on rust-lang#132325, not yet a separate PR - c3ef9cd is a rebased version of rust-lang#125334, unsure whether I actually want to land this PR for now r? `@ghost`

[DO NOT MERGE] bootstrap with `-Znext-solver=globally` A revival of rust-lang#124812. Current status: `./x.py b --stage 2` passes 🎉 ### commits - rust-lang#133501 - rust-lang#133493 - 9456bfe and b21b116 reimplement candidate preference based on rust-lang#132325, not yet a separate PR - c3ef9cd is a rebased version of rust-lang#125334, unsure whether I actually want to land this PR for now - rust-lang#133517 * rust-lang#133518 * rust-lang#133519 * rust-lang#133520 * rust-lang#133521 * rust-lang#133524 r? `@ghost`

[DO NOT MERGE] bootstrap with `-Znext-solver=globally` A revival of rust-lang#124812. Current status: ~~`./x.py b --stage 2` passes 🎉~~ `try` builds succeed 🎉 🎉 🎉 ### commits - rust-lang#133643 - ce66d92 is a rebased version of rust-lang#125334, unsure whether I actually want to land this PR for now * rust-lang#133559 * rust-lang#133558 r? `@ghost`

[DO NOT MERGE] bootstrap with `-Znext-solver=globally` A revival of rust-lang#124812. Current status: ~~`./x.py b --stage 2` passes 🎉~~ `try` builds succeed 🎉 🎉 🎉 [first perf run](rust-lang#133502 (comment)) 👻 ### in-flight changes - ce66d92 is a rebased version of rust-lang#125334, unsure whether I actually want to land this PR for now - rust-lang#135445 - https://github.com/lcnr/rust/tree/opaque-type-method-call support method calls on not-yet defined opaque types in their defining scope ☠️ r? `@ghost`

[DO NOT MERGE] bootstrap with `-Znext-solver=globally` A revival of rust-lang#124812. Current status: ~~`./x.py b --stage 2` passes 🎉~~ `try` builds succeed 🎉 🎉 🎉 [first perf run](rust-lang#133502 (comment)) 👻 ### in-flight changes - ce66d92 is a rebased version of rust-lang#125334, unsure whether I actually want to land this PR for now - rust-lang#136824 r? `@ghost`

rustbot assigned compiler-errors May 20, 2024

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. WG-trait-system-refactor The Rustc Trait System Refactor Initiative (-Znext-solver) labels May 20, 2024

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lcnr added 2 commits May 21, 2024 19:06

add a normalizes-to fast path

cff9321

add fixme :(

2322dff

rust-cloud-vms bot force-pushed the normalizes-to-rigid-fastpath branch from b416190 to 2322dff Compare May 21, 2024 19:06

lcnr marked this pull request as ready for review May 21, 2024 19:09

compiler-errors reviewed May 22, 2024

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 25, 2024

alex-semenyuk added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Oct 25, 2024

lcnr mentioned this pull request Nov 26, 2024

[DO NOT MERGE] -Znext-solver=globally experiments #133502

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JohnCSimon removed the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Feb 5, 2025

JohnCSimon added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Feb 5, 2025

lcnr closed this May 2, 2025

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add a normalizes-to fast path#125334

add a normalizes-to fast path#125334
lcnr wants to merge 2 commits intorust-lang:masterfrom
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	// applies for all `T` as long as `T: Sized` holds. THis impl should
	// applies for all `T` as long as `T: Sized` holds. This impl should

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