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feat(minifier): remove unused assignments for vars #13231

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Merged
graphite-app merged 1 commit into from
Aug 24, 2025
Merged

feat(minifier): remove unused assignments for vars #13231

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12 changes: 6 additions & 6 deletions crates/oxc_minifier/src/peephole/inline.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -10,12 +10,12 @@ impl<'a> PeepholeOptimizations {
pub fn init_symbol_value(decl: &VariableDeclarator<'a>, ctx: &mut Ctx<'a, '_>) {
let BindingPatternKind::BindingIdentifier(ident) = &decl.id.kind else { return };
let Some(symbol_id) = ident.symbol_id.get() else { return };
// Skip for `var` declarations, due to TDZ problems.
if decl.kind.is_var() {
return;
}
let value =
decl.init.as_ref().map_or(Some(ConstantValue::Undefined), |e| e.evaluate_value(ctx));
let value = if decl.kind.is_var() {
// Skip constant value inlining for `var` declarations, due to TDZ problems.
None
} else {
decl.init.as_ref().map_or(Some(ConstantValue::Undefined), |e| e.evaluate_value(ctx))
};
ctx.init_value(symbol_id, value);
}

Expand Down
18 changes: 11 additions & 7 deletions crates/oxc_minifier/src/peephole/remove_unused_expression.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -733,8 +733,8 @@ mod test {
use crate::{
CompressOptions, TreeShakeOptions,
tester::{
default_options, test, test_options, test_same, test_same_options,
test_same_options_source_type,
default_options, test, test_options, test_options_source_type, test_same,
test_same_options, test_same_options_source_type,
},
};

Expand Down Expand Up @@ -1040,13 +1040,16 @@ mod test {
fn remove_unused_assignment_expression() {
use oxc_span::SourceType;
let options = CompressOptions::smallest();
// Vars are not handled yet due to TDZ.
test_same_options("var x = 1; x = 2;", &options);
test_same_options("var x = 1; x = foo();", &options);
test_options("var x = 1; x = 2;", "", &options);
test_options("var x = 1; x = foo();", "foo()", &options);
test_same_options("export var foo; foo = 0;", &options);
test_same_options("var x = 1; x = 2, foo(x)", &options);
test_same_options("function foo() { return t = x(); } foo();", &options);
test_same_options("function foo() { var t; return t = x(); } foo();", &options);
test_options(
"function foo() { var t; return t = x(); } foo();",
"function foo() { return x(); } foo();",
&options,
);
test_same_options("function foo(t) { return t = x(); } foo();", &options);

test_options("let x = 1; x = 2;", "", &options);
Expand Down Expand Up @@ -1081,8 +1084,9 @@ mod test {
let source_type = SourceType::cjs();
test_same_options_source_type("var x = 1; x = 2;", source_type, &options);
test_same_options_source_type("var x = 1; x = 2, foo(x)", source_type, &options);
test_same_options_source_type(
test_options_source_type(
"function foo() { var x = 1; x = 2, bar() } foo()",
"function foo() { bar() } foo()",
source_type,
&options,
);
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
@@ -1,7 +1,7 @@
| Oxc | ESBuild | Oxc | ESBuild |
Original | minified | minified | gzip | gzip | Iterations | File
-------------------------------------------------------------------------------------
72.14 kB | 23.38 kB | 23.70 kB | 8.45 kB | 8.54 kB | 2 | react.development.js
72.14 kB | 23.34 kB | 23.70 kB | 8.43 kB | 8.54 kB | 2 | react.development.js

173.90 kB | 59.48 kB | 59.82 kB | 19.18 kB | 19.33 kB | 2 | moment.js

Expand All @@ -19,9 +19,9 @@ Original | minified | minified | gzip | gzip | Iterations | Fi

2.14 MB | 715.37 kB | 724.14 kB | 161.66 kB | 181.07 kB | 2 | victory.js

3.20 MB | 1.01 MB | 1.01 MB | 323.98 kB | 331.56 kB | 2 | echarts.js
3.20 MB | 1.01 MB | 1.01 MB | 324.01 kB | 331.56 kB | 2 | echarts.js

6.69 MB | 2.23 MB | 2.31 MB | 461.69 kB | 488.28 kB | 3 | antd.js
6.69 MB | 2.23 MB | 2.31 MB | 461.08 kB | 488.28 kB | 4 | antd.js

10.95 MB | 3.35 MB | 3.49 MB | 860.58 kB | 915.50 kB | 2 | typescript.js
10.95 MB | 3.34 MB | 3.49 MB | 857.11 kB | 915.50 kB | 3 | typescript.js

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