Handle generic reborrow in expression-use adjustment walking#156795
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Handle generic reborrow in expression-use adjustment walking#156795P8L1 wants to merge 1 commit into
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rustbot has assigned @nikomatsakis. Use Why was this reviewer chosen?The reviewer was selected based on:
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aapoalas
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May 21, 2026
| // assignment. This is a contradiction. | ||
| unreachable!("Reborrow trait usage during adjustment walk"); | ||
| adjustment::Adjust::GenericReborrow(mutability) => { | ||
| let bk = ty::BorrowKind::from_mutbl(mutability); |
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thought: I don't have in-depth understanding about what this exactly doing and if that matches my understanding but... probably it does :) Definitely it's better than an ICE.
The interesting corner-case would probably be something like this:
fn id_with_closure<'a>(x: CustomMut<'a>) -> CustomMut<'a> {
let cb = || x;
cb()
}Right now due to a mistake/complication in the implementation this wouldn't even work with just returning x, but once that's fixed then the closure version should also work.
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Does this fix #156339 ? |
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Fixes an ICE in expression-use adjustment walking where
Adjust::GenericReborrowcould reach a match arm that assumed generic reborrow was unreachable.GenericReborrowis already emitted by typeck and classified as rvalue-producing elsewhere inexpr_use_visitor.rs, so the adjustment walker must handle it explicitly instead of panicking.This PR models
GenericReborrowas a borrow-like use of the source expression:Mutability::Mutis treated like an exclusive/mutable reborrow use.Mutability::Notis treated like a shared/coerce-shared borrow-like use.cc @aapoalas