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Merged
merged 1 commit into from
Aug 14, 2025
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feat(minifier): mark more global constructors as side-effect free #13082

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1 change: 1 addition & 0 deletions Cargo.lock
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26 changes: 26 additions & 0 deletions crates/oxc_ecmascript/src/side_effects/may_have_side_effects.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -540,6 +540,32 @@ impl<'a> MayHaveSideEffects<'a> for NewExpression<'a> {
if (self.pure && ctx.annotations()) || ctx.manual_pure_functions(&self.callee) {
return self.arguments.iter().any(|e| e.may_have_side_effects(ctx));
}
if let Expression::Identifier(ident) = &self.callee
&& ctx.is_global_reference(ident)
&& matches!(
ident.name.as_str(),
"Set"
| "Map"
| "WeakSet"
| "WeakMap"
| "ArrayBuffer"
| "Date"
| "Boolean"
| "Error"
| "EvalError"
| "RangeError"
| "ReferenceError"
| "RegExp"
| "SyntaxError"
| "TypeError"
| "URIError"
| "Number"
| "Object"
| "String"
)
{
return self.arguments.iter().any(|e| e.may_have_side_effects(ctx));
}
true
}
}
Expand Down
1 change: 1 addition & 0 deletions crates/oxc_minifier/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -41,4 +41,5 @@ oxc_parser = { workspace = true }

base64 = { workspace = true }
insta = { workspace = true }
javascript-globals = { workspace = true }
pico-args = { workspace = true }
189 changes: 103 additions & 86 deletions crates/oxc_minifier/tests/ecmascript/may_have_side_effects.rs
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Original file line number Diff line number Diff line change
@@ -1,3 +1,7 @@
use javascript_globals::GLOBALS;

use rustc_hash::FxHashSet;

use oxc_allocator::Allocator;
use oxc_ast::ast::{Expression, IdentifierReference, Statement};
use oxc_ecmascript::{
Expand All @@ -8,28 +12,31 @@ use oxc_parser::Parser;
use oxc_span::SourceType;

struct Ctx {
global_variable_names: Vec<String>,
global_variable_names: FxHashSet<&'static str>,
annotation: bool,
pure_function_names: Vec<String>,
property_read_side_effects: PropertyReadSideEffects,
unknown_global_side_effects: bool,
}

impl Default for Ctx {
fn default() -> Self {
Self {
global_variable_names: vec![],
global_variable_names: GLOBALS["builtin"].keys().copied().collect::<FxHashSet<_>>(),
annotation: true,
pure_function_names: vec![],
property_read_side_effects: PropertyReadSideEffects::All,
unknown_global_side_effects: true,
}
}
}

impl<'a> GlobalContext<'a> for Ctx {
fn is_global_reference(&self, ident: &IdentifierReference<'a>) -> bool {
self.global_variable_names.iter().any(|name| name == ident.name.as_str())
self.global_variable_names.contains(ident.name.as_str())
}
}

impl MayHaveSideEffectsContext<'_> for Ctx {
fn annotations(&self) -> bool {
self.annotation
Expand All @@ -52,20 +59,26 @@ impl MayHaveSideEffectsContext<'_> for Ctx {
}
}

#[track_caller]
fn test(source_text: &str, expected: bool) {
let ctx = Ctx::default();
test_with_ctx(source_text, &ctx, expected);
}

#[track_caller]
fn test_with_global_variables(
source_text: &str,
global_variable_names: Vec<String>,
global_variable_names: &[&'static str],
expected: bool,
) {
let ctx = Ctx { global_variable_names, ..Default::default() };
let ctx = Ctx {
global_variable_names: global_variable_names.iter().copied().collect(),
..Default::default()
};
test_with_ctx(source_text, &ctx, expected);
}

#[track_caller]
fn test_with_ctx(source_text: &str, ctx: &Ctx, expected: bool) {
let allocator = Allocator::default();
let ret = Parser::new(&allocator, source_text, SourceType::mjs()).parse();
Expand Down Expand Up @@ -159,9 +172,9 @@ fn closure_compiler_tests() {
test("undefined", false);
test("void 0", false);
test("void foo()", true);
test_with_global_variables("-Infinity", vec!["Infinity".to_string()], false);
test_with_global_variables("Infinity", vec!["Infinity".to_string()], false);
test_with_global_variables("NaN", vec!["NaN".to_string()], false);
test("-Infinity", false);
test("Infinity", false);
test("NaN", false);
// test("({}||[]).foo = 2;", false);
// test("(true ? {} : []).foo = 2;", false);
// test("({},[]).foo = 2;", false);
Expand Down Expand Up @@ -367,9 +380,9 @@ fn closure_compiler_tests() {
#[test]
fn test_identifier_reference() {
// accessing global variables may have a side effect
test_with_global_variables("a", vec!["a".to_string()], true);
test_with_global_variables("a", &["a"], true);
// accessing known globals are side-effect free
test_with_global_variables("NaN", vec!["NaN".to_string()], false);
test("NaN", false);
}

#[test]
Expand Down Expand Up @@ -407,8 +420,8 @@ fn test_unary_expressions() {
test("!foo()", true);

test("typeof 'foo'", false);
test_with_global_variables("typeof a", vec!["a".to_string()], false);
test_with_global_variables("typeof (0, a)", vec!["a".to_string()], true);
test_with_global_variables("typeof a", &["a"], false);
test_with_global_variables("typeof (0, a)", &["a"], true);
test("typeof foo()", true);

test("+0", false);
Expand All @@ -418,9 +431,9 @@ fn test_unary_expressions() {
test("+'foo'", false); // NaN
test("+`foo`", false); // NaN
test("+/foo/", false); // NaN
test_with_global_variables("+Infinity", vec!["Infinity".to_string()], false);
test_with_global_variables("+NaN", vec!["NaN".to_string()], false);
test_with_global_variables("+undefined", vec!["undefined".to_string()], false); // NaN
test("+Infinity", false);
test("+NaN", false);
test("+undefined", false); // NaN
test("+[]", false); // 0
test("+[foo()]", true);
test("+foo()", true);
Expand All @@ -436,9 +449,9 @@ fn test_unary_expressions() {
test("-'foo'", false); // -NaN
test("-`foo`", false); // NaN
test("-/foo/", false); // NaN
test_with_global_variables("-Infinity", vec!["Infinity".to_string()], false);
test_with_global_variables("-NaN", vec!["NaN".to_string()], false);
test_with_global_variables("-undefined", vec!["undefined".to_string()], false); // NaN
test("-Infinity", false);
test("-NaN", false);
test("-undefined", false); // NaN
test("-[]", false); // -0
test("-[foo()]", true);
test("-foo()", true);
Expand Down Expand Up @@ -516,9 +529,9 @@ fn test_binary_expressions() {
test("'' + []", false);
test("'' + [foo()]", true);
test("'' + Symbol()", true);
test_with_global_variables("'' + Infinity", vec!["Infinity".to_string()], false);
test_with_global_variables("'' + NaN", vec!["NaN".to_string()], false);
test_with_global_variables("'' + undefined", vec!["undefined".to_string()], false);
test("'' + Infinity", false);
test("'' + NaN", false);
test("'' + undefined", false);
test("'' + s", true); // assuming s is Symbol
test("Symbol() + ''", true);
test("'' + {}", false);
Expand Down Expand Up @@ -549,10 +562,10 @@ fn test_binary_expressions() {
test("0 - /a/", false); // NaN
test("0 - []", false); // 0
test("0 - [foo()]", true);
test_with_global_variables("0 - Infinity", vec!["Infinity".to_string()], false); // -Infinity
test_with_global_variables("0 - NaN", vec!["NaN".to_string()], false); // NaN
test_with_global_variables("0 - undefined", vec!["undefined".to_string()], false); // NaN
test_with_global_variables("null - Infinity", vec!["Infinity".to_string()], false); // -Infinity
test("0 - Infinity", false); // -Infinity
test("0 - NaN", false); // NaN
test("0 - undefined", false); // NaN
test("null - Infinity", false); // -Infinity
test("0 - {}", false); // NaN
test("'' - { toString() { return Symbol() } }", true);
test("'' - { valueOf() { return Symbol() } }", true);
Expand Down Expand Up @@ -583,8 +596,8 @@ fn test_binary_expressions() {

test("[] instanceof 1", true); // throws an error
test("[] instanceof { [Symbol.hasInstance]() { throw 'foo' } }", true);
test_with_global_variables("[] instanceof Object", vec!["Object".to_string()], false);
test_with_global_variables("a instanceof Object", vec!["Object".to_string()], true); // a maybe a proxy that has a side effectful "getPrototypeOf" trap
test("[] instanceof Object", false);
test("a instanceof Object", true); // a maybe a proxy that has a side effectful "getPrototypeOf" trap

// b maybe not a object
// b maybe a proxy that has a side effectful "has" trap
Expand Down Expand Up @@ -710,6 +723,30 @@ fn test_property_access() {
test("[...a, 1][0]", true); // "...a" may have a sideeffect
}

#[test]
fn test_new_expressions() {
test("new AggregateError", true);
test("new DataView", true);
test("new Set", false);
test("new Map", false);
test("new WeakSet", false);
test("new WeakMap", false);
test("new ArrayBuffer", false);
test("new Date", false);
test("new Boolean", false);
test("new Error", false);
test("new EvalError", false);
test("new RangeError", false);
test("new ReferenceError", false);
test("new RegExp", false);
test("new SyntaxError", false);
test("new TypeError", false);
test("new URIError", false);
test("new Number", false);
test("new Object", false);
test("new String", false);
}

#[test]
fn test_call_like_expressions() {
test("foo()", true);
Expand Down Expand Up @@ -796,12 +833,12 @@ fn test_property_read_side_effects_support() {
fn test_unknown_global_side_effects_support() {
let true_ctx = Ctx {
unknown_global_side_effects: true,
global_variable_names: vec!["foo".to_string()],
global_variable_names: FxHashSet::from_iter(["foo"]),
..Default::default()
};
let false_ctx = Ctx {
unknown_global_side_effects: false,
global_variable_names: vec!["foo".to_string()],
global_variable_names: FxHashSet::from_iter(["foo"]),
..Default::default()
};
test_with_ctx("foo", &true_ctx, true);
Expand Down Expand Up @@ -835,70 +872,50 @@ fn test_object_with_to_primitive_related_properties_overridden() {

#[test]
fn test_typeof_guard_patterns() {
test_with_global_variables("typeof x !== 'undefined' && x", vec!["x".to_string()], false);
test_with_global_variables("typeof x != 'undefined' && x", vec!["x".to_string()], false);
test_with_global_variables("'undefined' !== typeof x && x", vec!["x".to_string()], false);
test_with_global_variables("'undefined' != typeof x && x", vec!["x".to_string()], false);
test_with_global_variables("typeof x === 'undefined' || x", vec!["x".to_string()], false);
test_with_global_variables("typeof x == 'undefined' || x", vec!["x".to_string()], false);
test_with_global_variables("'undefined' === typeof x || x", vec!["x".to_string()], false);
test_with_global_variables("'undefined' == typeof x || x", vec!["x".to_string()], false);
test_with_global_variables("typeof x < 'u' && x", vec!["x".to_string()], false);
test_with_global_variables("typeof x <= 'u' && x", vec!["x".to_string()], false);
test_with_global_variables("'u' > typeof x && x", vec!["x".to_string()], false);
test_with_global_variables("'u' >= typeof x && x", vec!["x".to_string()], false);
test_with_global_variables("typeof x > 'u' || x", vec!["x".to_string()], false);
test_with_global_variables("typeof x >= 'u' || x", vec!["x".to_string()], false);
test_with_global_variables("'u' < typeof x || x", vec!["x".to_string()], false);
test_with_global_variables("'u' <= typeof x || x", vec!["x".to_string()], false);

test_with_global_variables("typeof x === 'undefined' ? 0 : x", vec!["x".to_string()], false);
test_with_global_variables("typeof x == 'undefined' ? 0 : x", vec!["x".to_string()], false);
test_with_global_variables("'undefined' === typeof x ? 0 : x", vec!["x".to_string()], false);
test_with_global_variables("'undefined' == typeof x ? 0 : x", vec!["x".to_string()], false);
test_with_global_variables("typeof x !== 'undefined' ? x : 0", vec!["x".to_string()], false);
test_with_global_variables("typeof x != 'undefined' ? x : 0", vec!["x".to_string()], false);
test_with_global_variables("'undefined' !== typeof x ? x : 0", vec!["x".to_string()], false);
test_with_global_variables("'undefined' != typeof x ? x : 0", vec!["x".to_string()], false);

test_with_global_variables(
"typeof x !== 'undefined' && (x + foo())",
vec!["x".to_string()],
true,
);
test_with_global_variables(
"typeof x === 'undefined' || (x + foo())",
vec!["x".to_string()],
true,
);
test_with_global_variables("typeof x === 'undefined' ? foo() : x", vec!["x".to_string()], true);
test_with_global_variables("typeof x !== 'undefined' ? x : foo()", vec!["x".to_string()], true);
test_with_global_variables("typeof foo() !== 'undefined' && x", vec!["x".to_string()], true);
test_with_global_variables("typeof foo() === 'undefined' || x", vec!["x".to_string()], true);
test_with_global_variables("typeof foo() === 'undefined' ? 0 : x", vec!["x".to_string()], true);
test_with_global_variables(
"typeof y !== 'undefined' && x",
vec!["x".to_string(), "y".to_string()],
true,
);
test_with_global_variables(
"typeof y === 'undefined' || x",
vec!["x".to_string(), "y".to_string()],
true,
);
test_with_global_variables(
"typeof y === 'undefined' ? 0 : x",
vec!["x".to_string(), "y".to_string()],
true,
);
test_with_global_variables("typeof x !== 'undefined' && x", &["x"], false);
test_with_global_variables("typeof x != 'undefined' && x", &["x"], false);
test_with_global_variables("'undefined' !== typeof x && x", &["x"], false);
test_with_global_variables("'undefined' != typeof x && x", &["x"], false);
test_with_global_variables("typeof x === 'undefined' || x", &["x"], false);
test_with_global_variables("typeof x == 'undefined' || x", &["x"], false);
test_with_global_variables("'undefined' === typeof x || x", &["x"], false);
test_with_global_variables("'undefined' == typeof x || x", &["x"], false);
test_with_global_variables("typeof x < 'u' && x", &["x"], false);
test_with_global_variables("typeof x <= 'u' && x", &["x"], false);
test_with_global_variables("'u' > typeof x && x", &["x"], false);
test_with_global_variables("'u' >= typeof x && x", &["x"], false);
test_with_global_variables("typeof x > 'u' || x", &["x"], false);
test_with_global_variables("typeof x >= 'u' || x", &["x"], false);
test_with_global_variables("'u' < typeof x || x", &["x"], false);
test_with_global_variables("'u' <= typeof x || x", &["x"], false);

test_with_global_variables("typeof x === 'undefined' ? 0 : x", &["x"], false);
test_with_global_variables("typeof x == 'undefined' ? 0 : x", &["x"], false);
test_with_global_variables("'undefined' === typeof x ? 0 : x", &["x"], false);
test_with_global_variables("'undefined' == typeof x ? 0 : x", &["x"], false);
test_with_global_variables("typeof x !== 'undefined' ? x : 0", &["x"], false);
test_with_global_variables("typeof x != 'undefined' ? x : 0", &["x"], false);
test_with_global_variables("'undefined' !== typeof x ? x : 0", &["x"], false);
test_with_global_variables("'undefined' != typeof x ? x : 0", &["x"], false);

test_with_global_variables("typeof x !== 'undefined' && (x + foo())", &["x"], true);
test_with_global_variables("typeof x === 'undefined' || (x + foo())", &["x"], true);
test_with_global_variables("typeof x === 'undefined' ? foo() : x", &["x"], true);
test_with_global_variables("typeof x !== 'undefined' ? x : foo()", &["x"], true);
test_with_global_variables("typeof foo() !== 'undefined' && x", &["x"], true);
test_with_global_variables("typeof foo() === 'undefined' || x", &["x"], true);
test_with_global_variables("typeof foo() === 'undefined' ? 0 : x", &["x"], true);
test_with_global_variables("typeof y !== 'undefined' && x", &["x", "y"], true);
test_with_global_variables("typeof y === 'undefined' || x", &["x", "y"], true);
test_with_global_variables("typeof y === 'undefined' ? 0 : x", &["x", "y"], true);

test("typeof localVar !== 'undefined' && localVar", false);
test("typeof localVar === 'undefined' || localVar", false);
test("typeof localVar === 'undefined' ? 0 : localVar", false);

test_with_global_variables(
"typeof x !== 'undefined' && typeof y !== 'undefined' && x && y",
vec!["x".to_string(), "y".to_string()],
&["x", "y"],
true, // This can be improved
);
}
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