feat(minifier): prune empty case before trailing default#17994
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graphite-app[bot] merged 1 commit intomainfrom Jan 14, 2026
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feat(minifier): prune empty case before trailing default#17994graphite-app[bot] merged 1 commit intomainfrom
case before trailing default#17994graphite-app[bot] merged 1 commit intomainfrom
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Pull request overview
This PR adds a minification optimization that removes empty case clauses containing only primitive literals when they immediately precede a trailing default clause in switch statements. This is a port from esbuild that reduces code size without changing behavior.
Changes:
- Added optimization logic to prune empty literal cases before trailing defaults
- Added comprehensive test coverage for various literal types and edge cases
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| crates/oxc_minifier/src/peephole/minimize_statements.rs | Implements the optimization to remove empty literal cases before trailing default |
| crates/oxc_minifier/tests/peephole/esbuild.rs | Adds comprehensive test cases covering literals, non-literals, and edge cases |
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## Summary - Adds minification optimization to remove empty `case` clauses that precede a trailing `default` clause when those cases contain only primitive literals - Port of evanw/esbuild@add452e ### Example ```javascript // Before: switch (x) { case 0: foo(); break; case 1: default: bar() } // After: switch (x) { case 0: foo(); break; default: bar() } ``` ## Test plan - [x] Added tests for basic case with empty literal before default - [x] Added tests for multiple empty literal cases - [x] Added tests for non-literal identifiers (should NOT be removed) - [x] Added tests for default not at end (preserved) - [x] Added tests for string, null, and BigInt literals - [x] All existing minifier tests pass 🤖 Generated with [Claude Code](https://claude.com/claude-code)
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## Summary - Adds minification optimization to remove empty `case` clauses that precede a trailing `default` clause when those cases contain only primitive literals - Port of evanw/esbuild@add452e ### Example ```javascript // Before: switch (x) { case 0: foo(); break; case 1: default: bar() } // After: switch (x) { case 0: foo(); break; default: bar() } ``` ## Test plan - [x] Added tests for basic case with empty literal before default - [x] Added tests for multiple empty literal cases - [x] Added tests for non-literal identifiers (should NOT be removed) - [x] Added tests for default not at end (preserved) - [x] Added tests for string, null, and BigInt literals - [x] All existing minifier tests pass 🤖 Generated with [Claude Code](https://claude.com/claude-code)
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Jan 15, 2026
| if first_empty_idx < default_idx { | ||
| let default_case = switch_stmt.cases.pop().unwrap(); | ||
| switch_stmt.cases.truncate(first_empty_idx); | ||
| switch_stmt.cases.push(default_case); |
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default case should be ommited when its empty, either empty block or no stmt
armano2
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Jan 15, 2026
| while first_empty_idx > 0 { | ||
| let case = &switch_stmt.cases[first_empty_idx - 1]; | ||
| // Only remove empty cases with primitive literal tests | ||
| if case.consequent.is_empty() |
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case that contains only break without label, block stmt, block with break could be also be considered empty
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Summary
caseclauses that precede a trailingdefaultclause when those cases contain only primitive literalsExample
Test plan
🤖 Generated with Claude Code