feat(minifier): convert switch with one case to if statement#24611
feat(minifier): convert switch with one case to if statement#24611armano2 wants to merge 15 commits into
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Merging this PR will not alter performance
Comparing 
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| impl<'a> VisitJs<'a> for FindNestedBreak { |
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similar check is going to be required for loops, as currently we do not inline/remove them, tho in that case we also have to check for continue
eg. while(true) break;
I'm also not sure where to put this visitor
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@codex review |
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| SPAN, | ||
| switch_stmt.discriminant.take_in(ctx), | ||
| BinaryOperator::StrictEquality, | ||
| test, |
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When a single-case switch contains a lexical declaration that shadows the case expression, switch evaluates the case test inside the switch's case-block scope, but this if condition is built outside the new block_stmt scope. For let x = 1; switch (0) { case x: let x = 2; }, the original reads the switch-scoped x and throws a TDZ ReferenceError, while the transformed if (0 === x) { let x = 2; } reads the outer x and continues, so this inlining changes runtime behavior.
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Minifier assumes that the input has not TDZ violations so this isn't supported at this point.
oxc/crates/oxc_minifier/docs/ASSUMPTIONS.md
Lines 59 to 67 in 6ce51d3
| vec.pop().unwrap() | ||
| } else { | ||
| Statement::new_block_statement_with_scope_id( | ||
| SPAN, |
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maybe we should take switch case span in here
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Inline switch with 1 case to if statement or in case of default to statement expressions + block statement
https://github.com/oxc-project/oxc/actions/runs/29759622291#summary-88410679091
change extracted from #17523
ref #17544