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feat(minifier): fold invalid typeof comparisons (#8550)

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camc314 2025-01-16 14:26:35 +00:00
parent c479a58718
commit 7cc81ef5ef
1 changed files with 51 additions and 2 deletions
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53
crates/oxc_minifier/src/ast_passes/peephole_fold_constants.rs
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@ -607,12 +607,12 @@ impl<'a, 'b> PeepholeFoldConstants {
))
}
// `typeof a === typeof b` -> `typeof a == typeof b`, `typeof a != typeof b` -> `typeof a != typeof b`,
// `typeof a == typeof a` -> `true`, `typeof a != typeof a` -> `false`
fn try_fold_binary_typeof_comparison(
bin_expr: &mut BinaryExpression<'a>,
ctx: Ctx<'a, 'b>,
) -> Option<Expression<'a>> {
// `typeof a === typeof b` -> `typeof a == typeof b`, `typeof a != typeof b` -> `typeof a != typeof b`,
// `typeof a == typeof a` -> `true`, `typeof a != typeof a` -> `false`
if bin_expr.operator.is_equality() {
if let (Expression::UnaryExpression(left), Expression::UnaryExpression(right)) =
(&bin_expr.left, &bin_expr.right)
@ -653,6 +653,41 @@ impl<'a, 'b> PeepholeFoldConstants {
}
}
// `typeof a === 'asd` -> `false``
// `typeof a !== 'b'` -> `true``
if let Expression::UnaryExpression(left) = &bin_expr.left {
if left.operator.is_typeof() && bin_expr.operator.is_equality() {
let right_ty = ValueType::from(&bin_expr.right);
if !right_ty.is_undetermined() && right_ty != ValueType::String {
return Some(ctx.ast.expression_boolean_literal(
bin_expr.span,
bin_expr.operator == BinaryOperator::Inequality
|| bin_expr.operator == BinaryOperator::StrictInequality,
));
}
if let Expression::StringLiteral(string_lit) = &bin_expr.right {
if !matches!(
string_lit.value.as_str(),
"string"
| "number"
| "bigint"
| "boolean"
| "symbol"
| "undefined"
| "object"
| "function"
) {
return Some(ctx.ast.expression_boolean_literal(
bin_expr.span,
bin_expr.operator == BinaryOperator::Inequality
|| bin_expr.operator == BinaryOperator::StrictInequality,
));
}
}
}
}
None
}
@ -1736,6 +1771,20 @@ mod test {
test("typeof foo.bar !== typeof foo.bar", "typeof foo.bar != typeof foo.bar");
}
#[test]
fn test_fold_invalid_typeof_comparison() {
test("typeof foo == 123", "false");
test("typeof foo == '123'", "false");
test("typeof foo === null", "false");
test("typeof foo === undefined", "false");
test("typeof foo !== 123", "true");
test("typeof foo !== '123'", "true");
test("typeof foo != null", "true");
test("typeof foo != undefined", "true");
test_same("typeof foo === 'string'");
test_same("typeof foo === 'number'");
}
// TODO: All big ints are rare and difficult to handle.
mod bigint {
use super::{