fix(semantic): handle var hoisting in catch block with same catch parameter name #12313
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
Member
Author
How to use the Graphite Merge QueueAdd either label to this PR to merge it via the merge queue:
You must have a Graphite account in order to use the merge queue. Sign up using this link. An organization admin has enabled the Graphite Merge Queue in this repository. Please do not merge from GitHub as this will restart CI on PRs being processed by the merge queue. This stack of pull requests is managed by Graphite. Learn more about stacking. |
CodSpeed Instrumentation Performance ReportMerging #12313 will not alter performanceComparing Summary
|
Dunqing
force-pushed
the
07-16-fix_semantic_handle_hoisting_variable_binding_incorrectly
branch
from
ed829b5 to
5b32885
Compare
Boshen
changed the title
Boshen
changed the title
Dunqing
force-pushed
the
07-16-fix_semantic_handle_hoisting_variable_binding_incorrectly
branch
from
5b32885 to
beda069
Compare
Dunqing
commented
Jul 16, 2025
crates/oxc_minifier/src/peephole/substitute_alternate_syntax.rs
Outdated
Show resolved
Hide resolved
Dunqing
force-pushed
the
07-16-fix_semantic_handle_hoisting_variable_binding_incorrectly
branch
from
85f6477 to
5992963
Compare
Member
Merge activity
|
…ameter name (#12313) The root cause is that the variable was hoisted to a scope that has the same name binding ```js var a = 1; try { throw 2 } catch (a) { var a = 3; // ^ Shouldn't hoist to the top scope because there is a same name variable. } console.log(a); ``` Ref: https://tc39.es/ecma262/#sec-variablestatements-in-catch-blocks Note The [Block](https://tc39.es/ecma262/#prod-Block) of a [Catch](https://tc39.es/ecma262/#prod-Catch) clause may contain var declarations that bind a name that is also bound by the [CatchParameter](https://tc39.es/ecma262/#prod-CatchParameter). At runtime, such bindings are instantiated in the VariableDeclarationEnvironment. They do not shadow the same-named bindings introduced by the [CatchParameter](https://tc39.es/ecma262/#prod-CatchParameter) and hence the [Initializer](https://tc39.es/ecma262/#prod-Initializer) for such var declarations will assign to the corresponding catch parameter rather than the var binding.
graphite-app
bot
force-pushed
the
07-16-fix_semantic_handle_hoisting_variable_binding_incorrectly
branch
from
5992963 to
cd98426
Compare
graphite-app
bot
deleted the
07-16-fix_semantic_handle_hoisting_variable_binding_incorrectly
branch
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.
The root cause is that the variable was hoisted to a scope that has the same name binding
Ref: https://tc39.es/ecma262/#sec-variablestatements-in-catch-blocks
Note
The Block of a Catch clause may contain var declarations that bind a name that is also bound by the CatchParameter. At runtime, such bindings are instantiated in the VariableDeclarationEnvironment. They do not shadow the same-named bindings introduced by the CatchParameter and hence the Initializer for such var declarations will assign to the corresponding catch parameter rather than the var binding.