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Inline env vars through optional chaining and globalThis in bundler #28693

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074654b
Inline env vars through optional chaining and globalThis in bundler
robobun Jun 28, 2026
9d7bdc4
Trim define-loop comments to what the code does not already say
robobun Sep 8, 2026
09f4f45
Drop define-loop comment; the best_*_len names already say longest wins
robobun Sep 8, 2026
507be7e
Share the unbound-identifier check between is_global_this and is_dot_…
robobun Sep 8, 2026
814c91f
Shorten is_unbound_identifier_named doc to one line
robobun Sep 8, 2026
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73 changes: 43 additions & 30 deletions src/js_parser/p.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7183,14 +7183,16 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
match expr.data {
js_ast::ExprData::EDot(ex) => {
if parts.len() > 1 {
if ex.optional_chain.is_some() {
return false;
}
// Intermediates must be dot expressions
let last = parts.len() - 1;
let is_tail_match = strings::eql(&parts[last], &ex.name);
return is_tail_match && self.is_dot_define_match(ex.target, &parts[..last]);
}

// Allow globalThis.X to match a define for X (e.g. globalThis.process.env.NODE_ENV)
if parts.len() == 1 && strings::eql(&parts[0], &ex.name) {
return self.is_global_this(ex.target);
}
}
js_ast::ExprData::EImportMeta(_) => {
return parts.len() == 2 && &*parts[0] == b"import" && &*parts[1] == b"meta";
Expand All @@ -7200,49 +7202,60 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
// we do, but only if it's a UTF8 string
// the intent is to handle people using this form instead of E.Dot. So we really only want to do this if the accessor can also be an identifier
js_ast::ExprData::EIndex(index) => {
if parts.len() > 1 {
if let js_ast::ExprData::EString(mut s) = index.index.data {
if s.is_utf8() {
if index.optional_chain.is_some() {
return false;
}
if let js_ast::ExprData::EString(mut s) = index.index.data {
if s.is_utf8() {
if parts.len() > 1 {
let last = parts.len() - 1;
let is_tail_match = strings::eql(&parts[last], s.slice(self.arena));
return is_tail_match
&& self.is_dot_define_match(index.target, &parts[..last]);
}

// Allow globalThis["X"] to match a define for X
if parts.len() == 1 && strings::eql(&parts[0], s.slice(self.arena)) {
return self.is_global_this(index.target);
}
}
}
}
js_ast::ExprData::EIdentifier(ex) => {
js_ast::ExprData::EIdentifier(_) => {
// The last expression must be an identifier
if parts.len() == 1 {
let name = self.load_name_from_ref(ex.ref_);
if !strings::eql(name, &parts[0]) {
return false;
}

let Ok(result) = self.find_symbol_with_record_usage::<false>(expr.loc, name)
else {
return false;
};

// We must not be in a "with" statement scope
if result.is_inside_with_scope {
return false;
}

// when there's actually no symbol by that name, we return Ref.None
// If a symbol had already existed by that name, we return .unbound
return result.r#ref.is_empty()
|| self.symbols[result.r#ref.inner_index() as usize].kind
== js_ast::symbol::Kind::Unbound;
return self.is_unbound_identifier_named(expr, &parts[0]);
}
}
_ => {}
}
false
}

/// `expr` is the identifier `name`, unshadowed and not inside a `with`.
fn is_unbound_identifier_named(&mut self, expr: Expr, name: &[u8]) -> bool {
let js_ast::ExprData::EIdentifier(ex) = expr.data else {
return false;
};
let ident_name = self.load_name_from_ref(ex.ref_);
if !strings::eql(ident_name, name) {
return false;
}

let Ok(result) = self.find_symbol_with_record_usage::<false>(expr.loc, ident_name) else {
return false;
};

if result.is_inside_with_scope {
return false;
}

// No symbol by that name yields Ref::None; a pre-existing one is Unbound.
result.r#ref.is_empty()
|| self.symbols[result.r#ref.inner_index() as usize].kind
== js_ast::symbol::Kind::Unbound
}
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fn is_global_this(&mut self, expr: Expr) -> bool {
self.is_unbound_identifier_named(expr, b"globalThis")
}
}

/// The unscoped npm package of a specifier (`react/x`) or path (`node_modules<sep>react<sep>x.js`).
Expand Down
52 changes: 30 additions & 22 deletions src/js_parser/visit/visit_expr.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1354,29 +1354,32 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
// while iterating without laundering.
let defines = p.define;
if let Some(parts) = defines.dots_for(e_.name.slice()) {
let mut best_value: Option<&crate::DefineData> = None;
let mut best_value_len: usize = 0;
let mut best_drop_len: usize = 0;
for define in parts.as_slice() {
if p.is_dot_define_match(expr, &define.parts) {
if in_.assign_target == js_ast::AssignTarget::None {
// Substitute user-specified defines
if !define.data.valueless() {
*e = p.value_for_define(
expr.loc,
in_.assign_target,
is_delete_target,
&define.data,
);
return;
}
if !p.is_dot_define_match(expr, &define.parts) {
continue;
}

if define.data.method_call_must_be_replaced_with_undefined()
&& in_
.property_access_for_method_call_maybe_should_replace_with_undefined
{
p.method_call_must_be_replaced_with_undefined = true;
}
}
if in_.assign_target == js_ast::AssignTarget::None
&& !define.data.valueless()
&& define.parts.len() >= best_value_len
{
best_value = Some(&define.data);
best_value_len = define.parts.len();
}

// Copy the side effect flags over in case this expression is unused
if in_.assign_target == js_ast::AssignTarget::None
&& define.data.method_call_must_be_replaced_with_undefined()
&& in_.property_access_for_method_call_maybe_should_replace_with_undefined
&& define.parts.len() >= best_drop_len
{
best_drop_len = define.parts.len();
}

// `a?.b` short-circuits observably, so `Symbol?.for(...)` is not pure.
if e_.optional_chain.is_none() {
if define.data.can_be_removed_if_unused() {
e_.can_be_removed_if_unused = true;
}
Expand All @@ -1387,10 +1390,15 @@ impl<'a, const TYPESCRIPT: bool, const SCAN_ONLY: bool> P<'a, TYPESCRIPT, SCAN_O
e_.call_can_be_unwrapped_if_unused =
define.data.call_can_be_unwrapped_if_unused();
}

break;
}
}

if best_drop_len > best_value_len {
p.method_call_must_be_replaced_with_undefined = true;
} else if let Some(data) = best_value {
*e = p.value_for_define(expr.loc, in_.assign_target, is_delete_target, data);
return;
}
}

// Track ".then().catch()" chains
Expand Down
95 changes: 90 additions & 5 deletions test/bundler/bundler_edgecase.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -172,10 +172,6 @@ describe("bundler", () => {
},
});
itBundled("edgecase/NodeEnvOptionalChaining", {
// Matching `process?.env?.NODE_ENV` against the `process.env.NODE_ENV`
// define would also match `Symbol?.for` etc. as side-effect-free; esbuild
// bails on optional-chain links for the same reason.
todo: true,
files: {
"/entry.js": /* js */ `
capture(process?.env?.NODE_ENV);
Expand All @@ -187,14 +183,103 @@ describe("bundler", () => {
capture(process?.env.NODE_ENV);
capture(process?.env.NODE_ENV === 'production');
capture(process?.env.NODE_ENV === 'development');
capture(globalThis.process.env.NODE_ENV);
capture(globalThis.process.env.NODE_ENV === 'production');
capture(globalThis.process.env.NODE_ENV === 'development');
capture(globalThis.process?.env?.NODE_ENV);
capture(globalThis.process?.env?.NODE_ENV === 'production');
capture(globalThis.process?.env?.NODE_ENV === 'development');
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capture(globalThis["process"].env.NODE_ENV);
capture(globalThis["process"].env.NODE_ENV === 'production');
capture(globalThis["process"].env.NODE_ENV === 'development');
`,
},
target: "browser",
capture: ['"development"', "false", "true", '"development"', "false", "true", '"development"', "false", "true"],
capture: [
'"development"',
"false",
"true",
'"development"',
"false",
"true",
'"development"',
"false",
"true",
'"development"',
"false",
"true",
'"development"',
"false",
"true",
'"development"',
"false",
"true",
],
env: {
NODE_ENV: "development",
},
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});
// Regression for the globalThis base case added to isDotDefineMatch: an explicit
// `--define:globalThis.X.Y` must not be shadowed by a built-in valueless define
// for `["X","Y"]` (e.g. `Math.PI`) when matching a `globalThis.X.Y` expression.
itBundled("edgecase/NodeEnvDefineOverridesBuiltinThroughGlobalThis", {
files: {
"/entry.js": /* js */ `
capture(globalThis.Math.PI);
`,
},
target: "browser",
define: { "globalThis.Math.PI": "3" },
capture: ["3"],
});
// When both `X.Y` and `globalThis.X.Y` are defined, a `globalThis.X.Y` expression
// must resolve to the more specific `globalThis.X.Y` value regardless of the
// hash-map iteration order of the two user defines.
itBundled("edgecase/NodeEnvMoreSpecificGlobalThisDefineWins", {
files: {
"/entry.js": /* js */ `
capture(globalThis.FOO.BAR);
capture(FOO.BAR);
`,
},
target: "browser",
define: {
"FOO.BAR": '"bare"',
"globalThis.FOO.BAR": '"via_globalThis"',
},
capture: ['"via_globalThis"', '"bare"'],
});
// A more-specific `--define:globalThis.X.Y` must win over a less-specific
// `--drop=X.Y` for a `globalThis.X.Y(...)` call: the substituted identifier
// should be emitted, not dropped to `undefined`.
itBundled("edgecase/NodeEnvDefineBeatsDropAcrossGlobalThis", {
files: {
"/entry.js": /* js */ `
capture(globalThis.console.log("x"));
`,
},
target: "browser",
drop: ["console.log"],
define: {
"globalThis.console.log": "myLogger",
},
capture: ['myLogger("x")'],
});
// The symmetric inverse: a more-specific `--drop=globalThis.X.Y` must win over
// a less-specific `--define:X.Y=v` for `globalThis.X.Y(...)`.
itBundled("edgecase/NodeEnvDropBeatsDefineAcrossGlobalThis", {
files: {
"/entry.js": /* js */ `
capture(globalThis.console.log("x"));
`,
},
target: "browser",
drop: ["globalThis.console.log"],
define: {
"console.log": "myLogger",
},
capture: ["undefined"],
});

itBundled("edgecase/StarExternal", {
files: {
Expand Down
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