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fix(minifier): remove more unused assignment expressions #12364

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Merged
merged 1 commit into from
Jul 17, 2025
Merged

fix(minifier): remove more unused assignment expressions #12364

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4 changes: 4 additions & 0 deletions crates/oxc_minifier/src/peephole/remove_dead_code.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,10 @@ impl<'a> PeepholeOptimizations {
self.try_fold_conditional_expression(e, state, ctx)
}
Expression::SequenceExpression(e) => self.try_fold_sequence_expression(e, state, ctx),
Expression::AssignmentExpression(_) => {
self.remove_unused_assignment_expression(expr, state, ctx);
None
}
_ => None,
} {
*expr = folded_expr;
Expand Down
21 changes: 13 additions & 8 deletions crates/oxc_minifier/src/peephole/remove_unused_variable_declaration.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,5 @@
use oxc_allocator::TakeIn;
use oxc_ast::ast::*;
use oxc_ecmascript::side_effects::MayHaveSideEffects;

use crate::{CompressOptionsUnused, ctx::Ctx};

Expand Down Expand Up @@ -79,13 +78,9 @@ impl<'a> PeepholeOptimizations {
if !ctx.scoping().get_resolved_references(symbol_id).all(|r| !r.flags().is_read()) {
return false;
}
*e = assign_expr.right.take_in(ctx.ast);
state.changed = true;
if assign_expr.right.may_have_side_effects(ctx) {
*e = assign_expr.right.take_in(ctx.ast);
false
} else {
true
}
false
}

/// Do remove top level vars in script mode.
Expand Down Expand Up @@ -132,7 +127,17 @@ mod test {
test_options("var x = 1; x = 2;", "", &options);
test_options("var x = 1; x = foo();", "foo()", &options);
test_same_options("var x = 1; x = 2, foo(x)", &options);
test_same_options("function foo() { var t; return t = x(); } foo();", &options);
test_same_options("function foo() { return t = x(); } foo();", &options);
test_options(
"function foo() { var t; return t = x(); } foo();",
"function foo() { return x(); } foo();",
&options,
);
test_options(
"function foo(t) { return t = x(); } foo();",
"function foo(t) { return x(); } foo();",
&options,
);
}

#[test]
Expand Down
8 changes: 4 additions & 4 deletions tasks/minsize/minsize.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -11,17 +11,17 @@ Original | minified | minified | gzip | gzip | Fixture

544.10 kB | 71.38 kB | 72.48 kB | 25.85 kB | 26.20 kB | lodash.js

555.77 kB | 270.82 kB | 270.13 kB | 88.25 kB | 90.80 kB | d3.js
555.77 kB | 270.80 kB | 270.13 kB | 88.24 kB | 90.80 kB | d3.js

1.01 MB | 440.17 kB | 458.89 kB | 122.37 kB | 126.71 kB | bundle.min.js

1.25 MB | 647 kB | 646.76 kB | 160.28 kB | 163.73 kB | three.js

2.14 MB | 716.11 kB | 724.14 kB | 161.77 kB | 181.07 kB | victory.js
2.14 MB | 716.10 kB | 724.14 kB | 161.76 kB | 181.07 kB | victory.js

3.20 MB | 1.01 MB | 1.01 MB | 324.08 kB | 331.56 kB | echarts.js

6.69 MB | 2.25 MB | 2.31 MB | 463.06 kB | 488.28 kB | antd.js
6.69 MB | 2.24 MB | 2.31 MB | 462.45 kB | 488.28 kB | antd.js

10.95 MB | 3.35 MB | 3.49 MB | 860.92 kB | 915.50 kB | typescript.js
10.95 MB | 3.34 MB | 3.49 MB | 856.90 kB | 915.50 kB | typescript.js

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