Don't build `ParamEnv` and do trait solving in `ItemCtxt`s when lowering IATs #140247

BoxyUwU · 2025-04-24T10:15:25Z

Fixes #125879
This was due to updating inhabited predicate stuff which I had to do to make constructing ADTs with IATs in fields not ICE

Fixes #136678 (but no test added, I don't rly care about weird IAT edge cases under GCE)
Fixes #138131

Avoids doing "fully correct" candidate selection for IATs during hir ty lowering when in item signatures as it almost always leads to a query cycle from trying to build a ParamEnv. I replaced it with a use DeepRejectCtxt which should be able to handle this kind of conservative "could these types unify" while in a context where we don't want to do type equality.

This is a relatively simple scheme and should be forwards compatible with doing something more complex/powerful.

I'm not really sure how this interacts with #126651, though I'm also not really sure its super important to support projecting IATs from IAT self types given we don't even support T::Assoc::Other for trait-associated types so didn't give much thought to how this might fit in with that.

r? @compiler-errors
cc @fmease

rustbot · 2025-04-24T10:15:31Z

This PR changes a file inside tests/crashes. If a crash was fixed, please move into the corresponding ui subdir and add 'Fixes #' to the PR description to autoclose the issue upon merge.

HIR ty lowering was modified

cc @fmease

compiler/rustc_hir_analysis/src/collect.rs

bors · 2025-04-28T21:32:11Z

☔ The latest upstream changes (presumably #140388) made this pull request unmergeable. Please resolve the merge conflicts.

compiler-errors · 2025-05-22T09:49:10Z

@bors r+

bors · 2025-05-22T09:49:13Z

📌 Commit 34ce403 has been approved by compiler-errors

It is now in the queue for this repository.

…iaskrgr Rollup of 7 pull requests Successful merges: - rust-lang#135562 (Add ignore value suggestion in closure body) - rust-lang#139635 (Finalize repeat expr inference behaviour with inferred repeat counts) - rust-lang#139668 (Handle regions equivalent to 'static in non_local_bounds) - rust-lang#140218 (HIR ty lowering: Clean up & refactor the lowering of type-relative paths) - rust-lang#140435 (use uX::from instead of _ as uX in non - const contexts) - rust-lang#141130 (rustc_on_unimplemented cleanups) - rust-lang#141286 (Querify `coroutine_hidden_types`) Failed merges: - rust-lang#140247 (Don't build `ParamEnv` and do trait solving in `ItemCtxt`s when lowering IATs) r? `@ghost` `@rustbot` modify labels: rollup

bors · 2025-05-23T01:02:00Z

☔ The latest upstream changes (presumably #141396) made this pull request unmergeable. Please resolve the merge conflicts.

BoxyUwU · 2025-05-23T14:28:28Z

I should probably update this to use DeepRejectCtxt and handle LTAs correctly like discussed at the all hands 🤔 I was just gonna do it in a followup PR but if I'm having to rebase and figure out new crashes tests then I may aswell just do it all now

compiler/rustc_hir_analysis/src/collect.rs

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

…iaskrgr Rollup of 7 pull requests Successful merges: - rust-lang#135562 (Add ignore value suggestion in closure body) - rust-lang#139635 (Finalize repeat expr inference behaviour with inferred repeat counts) - rust-lang#139668 (Handle regions equivalent to 'static in non_local_bounds) - rust-lang#140218 (HIR ty lowering: Clean up & refactor the lowering of type-relative paths) - rust-lang#140435 (use uX::from instead of _ as uX in non - const contexts) - rust-lang#141130 (rustc_on_unimplemented cleanups) - rust-lang#141286 (Querify `coroutine_hidden_types`) Failed merges: - rust-lang#140247 (Don't build `ParamEnv` and do trait solving in `ItemCtxt`s when lowering IATs) r? `@ghost` `@rustbot` modify labels: rollup

tests/ui/associated-inherent-types/impl_params_are_infers.rs

bors · 2025-05-27T19:39:03Z

☔ The latest upstream changes (presumably #141644) made this pull request unmergeable. Please resolve the merge conflicts.

BoxyUwU · 2025-05-27T19:44:38Z

oh come on lol

compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs

lcnr · 2025-06-11T10:07:57Z

compiler/rustc_type_ir/src/fast_reject.rs

+        if lhs == rhs {
+            return true;
+        }


this fast path should be in types_may_unify_inner

please remove

bors · 2025-06-14T08:37:02Z

☔ The latest upstream changes (presumably #142483) made this pull request unmergeable. Please resolve the merge conflicts.

lcnr · 2025-06-17T14:26:49Z

tests/ui/associated-inherent-types/bound_vars_in_args.rs

+// Test that we can resolve to the right IAT when the self type
+// contains a bound type.


Suggested change

// Test that we can resolve to the right IAT when the self type

// contains a bound type.

// Test whether we can resolve to the right IAT when the self type

// contains a bound type. This should ideally use the second impl.

lcnr · 2025-06-17T14:28:04Z

tests/ui/associated-inherent-types/candidate-with-alias-2.rs

@@ -0,0 +1,26 @@
+#![feature(inherent_associated_types)]
+#![expect(incomplete_features)]
+


Suggested change

// A behavior test showcasing that we do not normalize associated types when

// assembling IAT candidates.

lcnr · 2025-06-17T14:28:23Z

tests/ui/associated-inherent-types/candidate-with-alias.rs

+
+#![feature(inherent_associated_types)]
+#![expect(incomplete_features)]
+


lcnr · 2025-06-17T14:29:37Z

tests/ui/associated-inherent-types/multiple-candidates-in-adt-field-2.rs

+#![expect(incomplete_features)]
+
+// Test that when we have an unnormalized projection we don't normalize it
+// to determine which IAT to resolve to.


difference between this test and tests/ui/associated-inherent-types/candidate-with-alias-2.rs?

lcnr

nits, then r=me

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Tracking Issue for RFC 3591: useing a function from a trait #134691

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Rollup of 7 pull requests #141396

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fmease added the F-inherent_associated_types `#![feature(inherent_associated_types)]` label Jun 3, 2025

fmease added this to Inherent Associated Types (IAT) Jun 3, 2025

fmease moved this to In Progress in Inherent Associated Types (IAT) Jun 3, 2025

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If inherent associated type selection fails, we should still consider trait associated type candidates as a fallback #142006

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BoxyUwU added 3 commits June 17, 2025 14:18

Don't build ParamEnv and do trait solving in ItemCtxts

442862b

Test whether we use DeepRejectCtxt

2a950b5

rebase

9961747

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Dont replace escaping bound vars in item sigs

ae65625

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		// Test that we can resolve to the right IAT when the self type
		// contains a bound type.

		@@ -0,0 +1,26 @@
		#![feature(inherent_associated_types)]
		#![expect(incomplete_features)]



	// A behavior test showcasing that we do not normalize associated types when
	// assembling IAT candidates.

Don't build ParamEnv and do trait solving in ItemCtxts when lowering IATs #140247

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Don't build ParamEnv and do trait solving in ItemCtxts when lowering IATs #140247

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Don't build `ParamEnv` and do trait solving in `ItemCtxt`s when lowering IATs #140247

Don't build `ParamEnv` and do trait solving in `ItemCtxt`s when lowering IATs #140247

BoxyUwU commented Apr 24, 2025 •

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