emit StorageLive and schedule StorageDead for let-else's bindings after matching
#143028
+36
−69
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
rustbot
added
S-waiting-on-review
|
Some changes occurred in match lowering cc @Nadrieril |
workingjubilee
added
the
needs-crater
|
Building for crater: |
rust-bors bot
added a commit
that referenced
this pull request
Jun 25, 2025
emit `StorageLive` and schedule `StorageDead` for `let`-`else`'s bindings after matching This PR removes special handling of `let`-`else`, so that `StorageLive`s are emitted and `StorageDead`s are scheduled only after pattern-matching has succeeded. This means `StorageDead`s will no longer appear for all of its bindings on the `else` branch (because they're not live yet) and its drops&`StorageDead`s will happen together like they do elsewhere, rather than having all drops first, then all `StorageDead`s. This fixes #142056, and is therefore a breaking change. I believe it'll need a crater run and a T-lang nomination/fcp thereafter. Specifically, this makes drop-checking slightly more restrictive for `let`-`else` to match the behavior of other variable binding forms. An alternative approach could be to change the relative order of drops and `StorageDead`s for other binding forms to make drop-checking more permissive, but making that consistent would be a significantly more involved change. r? mir cc `@dingxiangfei2009` `@rustbot` label +T-lang +needs-crater
|
@craterbot check |
|
👌 Experiment ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more |
craterbot
added
S-waiting-on-crater
|
🚧 Experiment ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This PR removes special handling of
let-else, so thatStorageLives are emitted andStorageDeads are scheduled only after pattern-matching has succeeded. This meansStorageDeads will no longer appear for all of its bindings on theelsebranch (because they're not live yet) and its drops&StorageDeads will happen together like they do elsewhere, rather than having all drops first, then allStorageDeads.This fixes #142056, and is therefore a breaking change. I believe it'll need a crater run and a T-lang nomination/fcp thereafter. Specifically, this makes drop-checking slightly more restrictive for
let-elseto match the behavior of other variable binding forms. An alternative approach could be to change the relative order of drops andStorageDeads for other binding forms to make drop-checking more permissive, but making that consistent would be a significantly more involved change.r? mir
cc @dingxiangfei2009
@rustbot label +T-lang +needs-crater