fix(minifier): preserve catch binding with direct eval#22221
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Pull request overview
This PR fixes an unsafe minification case where the peephole optimization that removes an unused catch (e) binding could change runtime semantics when the catch scope contains a direct eval, since eval can reference the catch parameter dynamically even if static analysis reports it as unused.
Changes:
- Prevent
catchparameter removal when the catch scope is flagged as containing directeval. - Add regression tests covering direct
eval(including inside a nested function) vs. indirectevalvia optional chaining (eval?.(...)).
Reviewed changes
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| File | Description |
|---|---|
| crates/oxc_minifier/src/peephole/substitute_alternate_syntax.rs | Adds a safety guard to the optional catch binding optimization to preserve semantics in the presence of direct eval. |
| crates/oxc_minifier/tests/peephole/substitute_alternate_syntax.rs | Adds regression tests ensuring catch bindings are preserved for direct eval, while still allowing removal for indirect eval (eval?.). |
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Given:
```
try {
throw "error"
} catch (e) {
eval('console.log(e)')
}
```
The expected runtime behaviour is
```
"error"
```
instead, runtime behaviour is:
```
Uncaught ReferenceError: e is not defined
at eval (eval at <anonymous> (REPL5:4:3), <anonymous>:1:13)
```
This is because we remove the catch parameter, as we see no references to it, despite it being referenced in the `eval` call.
This PR adds a check to see if we are in a direct eval scope, and bails removing the catch parameter if this is the case.
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### 🚀 Features - 66c9b01 transformer/typescript: Debug_assert that `enum_eval` ran in semantic (#22252) (Dunqing) - ffe6475 minifier: Fold `Array` constructor with safe spreads (#22215) (camc314) ### 🐛 Bug Fixes - d3d0b18 traverse: Handle `ChainElement::TSNonNullExpression` in `GatherNodeParts` (#22247) (leaysgur) - 4e880de transformer/object-rest-spread: Declare temp vars for computed keys (#22284) (camc314) - a7c3e22 semantic: Clear member write target for computed keys (#22302) (camc314) - 6a8852d codegen: Emit newline after legal-comment orphan flush (#22304) (Dunqing) - 5da9fda transformer/explicit-resource-management: Preserve class names (#22306) (Dunqing) - b5d970f transformer/explicit-resource-management: Preserve class names (#22290) (camc314) - bc54fd4 minifier: Keep function / class names if direct eval is present in the scope (#22241) (sapphi-red) - 7a810c0 minifier: Refresh direct eval flags after DCE (#21787) (Dunqing) - dd88726 transformer/legacy-decorator: Preserve accessor type annotation for emitDecoratorMetadata (#21966) (Dunqing) - 29a3cd7 codegen: Swap mapping/indent order for top-level decls (#22206) (Dunqing) - 73b4f40 minifier: Preserve catch binding with direct eval (#22221) (camc314) - 0e13d17 minifier: Preserve optional chain base side effects (#22219) (camc314) - 0c7c01c transformer/typescript: Inline optional-chain enum member access (#21834) (Dunqing) - a6aff7e codegen: Emit block/array/object end mapping at close char (#22200) (Dunqing) - a099b03 codegen: Emit call end mapping at `)` position, not past it (#22199) (Dunqing) - 5753774 minifier: Cap if-return ternary collapse for firefox (#21841) (Gurupungav Narayanan) - 2493bdd codegen: Correct sourcemap end mappings for closing delimiters (#22001) (Mark Dalgleish) - 3b385e2 minifier: Bail optimizing `Array` with unknown arg count (#22188) (camc314) - 9fa2122 parser: Parse array computed class keys (#22159) (camc314) ### 📚 Documentation - a4a6892 napi/parser: Correct code comment (#22278) (overlookmotel) - 9305373 oxc: Update README (#22178) (camc314) Co-authored-by: Cameron <[email protected]>
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Given:
The expected runtime behaviour is
instead, runtime behaviour is:
This is because we remove the catch parameter, as we see no references to it, despite it being referenced in the
evalcall.This PR adds a check to see if we are in a direct eval scope, and bails removing the catch parameter if this is the case.