Do not lifetime-extend array/slice indices #147083
Open
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
When lowering non-overloaded indexing operations to MIR, this uses the temporary lifetime of the index expression for the index, rather than applying the temporary lifetime of the indexing operation as a whole to the index.
rustbot
added
S-waiting-on-review
traviscross
added
the
I-lang-radar
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Outdated suggestions cannot be applied.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.
When lowering non-overloaded indexing operations to MIR, this uses the temporary lifetime of the index expression for the index temporary, rather than applying the temporary lifetime of the indexing operation as a whole to the index.
For example, in
previously, the temporary containing the result of evaluating
iwould live until the end of the block due to the indexing operation being lifetime-extended. Under this PR, the temporary only lives to the end of theletstatement because it uses the more precise temporary lifetime of the index expression.I don't think this will affect semantics in an observable way, but it's consistent with the Reference specification (indices' lifetimes don't get extended) and the more precise
StorageDeadplacement may slightly improve analysis/codegen performance.r? mir