fix: flatten nested HRTB predicate binders - #23139
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Now, lifetime search is changed to preferentially match the last name added in the same binder, correctly handle nested lifetime shadowing, and remove the previously incorrect index offset. |
ChayimFriedman2
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Aug 27, 2026
| if let LifetimeRef::Named(lt_name) = &self.store[lifetime] { | ||
| self.bound_vars.iter().rev().enumerate().find_map(|(debruijn, (binder, _))| { | ||
| binder.iter().enumerate().find_map(|(index, l)| { | ||
| binder.iter().enumerate().rev().find_map(|(index, l)| { |
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This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
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两个issue的问题都在于关联类型 bound 递归 lowering 时，clause binder 只记录最内层 lifetime，引用的外层 lifetime 以 ^1/^2 形式逃逸。因此我修复了lower.rs中将 overarching 和内层 HRTB 变量合并到同一个 predicate binder，同时保留dyn Trait了作为真正独立的existential binder。
<The problem is that when the associated type bound is recursively lowering, the clause binder only records the innermost lifetime, and the outer lifetime of the reference escapes in the form of ^1/^2.
So I fix merging overarching and inner HRTB variables into the same predicate binder in lower.rs while retaining the dyn Trait's truly independent existential binder.>
In simpler terms: Outer lifetimes in nested binders are not flattened/renumbered correctly
Fix: #23063 and Fix #23064