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feat(minifier): minify var x; void x -> void 0 (#8466)

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This commit is contained in:
Boshen 2025-01-13 16:07:59 +00:00
parent 2be1e82964
commit 8accfefa74
2 changed files with 26 additions and 3 deletions
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27
crates/oxc_minifier/src/ast_passes/normalize.rs
View file

@ -1,4 +1,5 @@
use oxc_ast::ast::*;
use oxc_ecmascript::constant_evaluation::ConstantEvaluation;
use oxc_span::GetSpan;
use oxc_syntax::scope::ScopeFlags;
use oxc_traverse::{traverse_mut_with_ctx, ReusableTraverseCtx, Traverse, TraverseCtx};
@ -12,6 +13,7 @@ use crate::{ctx::Ctx, CompressorPass};
/// * convert whiles to fors
/// * convert `Infinity` to `f64::INFINITY`
/// * convert `NaN` to `f64::NaN`
/// * convert `var x; void x` to `void 0`
///
/// <https://github.com/google/closure-compiler/blob/v20240609/src/com/google/javascript/jscomp/Normalize.java>
pub struct Normalize;
@ -34,8 +36,14 @@ impl<'a> Traverse<'a> for Normalize {
}
fn exit_expression(&mut self, expr: &mut Expression<'a>, ctx: &mut TraverseCtx<'a>) {
if let Expression::Identifier(_) = expr {
Self::convert_infinity_or_nan_into_number(expr, ctx);
match expr {
Expression::Identifier(_) => {
Self::convert_infinity_or_nan_into_number(expr, ctx);
}
Expression::UnaryExpression(e) if e.operator.is_void() => {
Self::convert_void_ident(e, ctx);
}
_ => {}
}
}
}
@ -89,6 +97,15 @@ impl<'a> Normalize {
}
}
}
fn convert_void_ident(e: &mut UnaryExpression<'a>, ctx: &mut TraverseCtx<'a>) {
debug_assert!(e.operator.is_void());
let Expression::Identifier(ident) = &e.argument else { return };
if Ctx(ctx).is_global_reference(ident) {
return;
}
e.argument = ctx.ast.expression_numeric_literal(ident.span, 0.0, None, NumberBase::Decimal);
}
}
#[cfg(test)]
@ -108,4 +125,10 @@ mod test {
// Verify while loops are converted to FOR loops.
test("while(c < b) foo()", "for(; c < b;) foo()");
}
#[test]
fn test_void_ident() {
test("var x; void x", "var x; void 0");
test("void x", "void x"); // reference error
}
}

2
tasks/minsize/minsize.snap
View file

@ -13,7 +13,7 @@ Original | minified | minified | gzip | gzip | Fixture
555.77 kB | 273.15 kB | 270.13 kB | 90.92 kB | 90.80 kB | d3.js
1.01 MB | 460.18 kB | 458.89 kB | 126.77 kB | 126.71 kB | bundle.min.js
1.01 MB | 460.17 kB | 458.89 kB | 126.76 kB | 126.71 kB | bundle.min.js
1.25 MB | 652.84 kB | 646.76 kB | 163.54 kB | 163.73 kB | three.js