Some where clause lowering simplifications

[compiler-errors]

Rename PredicateFilter::SelfThatDefines to PredicateFilter::SelfTraitThatDefines to make it clear that it's only concerned with converting traits, and make it do a bit less work when converting bounds.

Also, make the predicate filter matching in probe_ty_param_bounds_in_generics explicit, and simply the args it receives a bit.

[rustbot]

r? @petrochenkov

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[rustbot]

HIR ty lowering was modified

cc @fmease

[petrochenkov]

Are there any observable effects from the second commit?
Or it's just a refactoring? (Due to the logic at the end of fn type_param_predicates?)
I'm not familiar with this code.

r=me after the explanation.
@rustbot author

[compiler-errors]

No, this should not have observable changes.

SelfTraitThatDefines is a filter that is concerned with gathering trait predicates of the form ParamTy: Trait for a given ParamTy. We did this previously somewhat haphazardly, both when lowering the bounds, and then re-filtering the bounds again after they've been collected, since the existing predicate filter handling was too lax.

Let me add a debug assertion back that I removed to validate that any further refactorings to the PredicateFilters doesn't accidentally reintroduce this behavior.

[compiler-errors]

forgot to flip back to ready:

@rustbot ready

[petrochenkov]

@bors r+

[bors]

📌 Commit 81dba07 has been approved by petrochenkov

It is now in the queue for this repository.

[bors]

⌛ Testing commit 81dba07 with merge 5ca0e9f...

[bors]

☀️ Test successful - checks-actions
Approved by: petrochenkov
Pushing 5ca0e9f to master...

[rust-timer]

Finished benchmarking commit (5ca0e9f): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

This benchmark run did not return any relevant results for this metric.

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 779.851s -> 780.79s (0.12%)
Artifact size: 334.92 MiB -> 334.96 MiB (0.01%)