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Don't emit redundant and invalid extra renamed keyword exports in JS files #62104

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Don't emit redundant and invalid extra renamed keyword exports in JS files #62104

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c2688e4
Don't emit redundant and invalid extra renamed keyword exports in JS …
Andarist Jul 22, 2025
d89419e
simplify further
Andarist Jul 22, 2025
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20 changes: 1 addition & 19 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -9552,11 +9552,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
symbol.flags & SymbolFlags.ExportDoesNotSupportDefaultModifier
|| (symbol.flags & SymbolFlags.Function && length(getPropertiesOfType(getTypeOfSymbol(symbol))))
) && !(symbol.flags & SymbolFlags.Alias); // An alias symbol should preclude needing to make an alias ourselves
let needsExportDeclaration = !needsPostExportDefault && !isPrivate && isStringANonContextualKeyword(symbolName) && !isDefault;
// `serializeVariableOrProperty` will handle adding the export declaration if it is run (since `getInternalSymbolName` will create the name mapping), so we need to ensuer we unset `needsExportDeclaration` if it is
if (needsPostExportDefault || needsExportDeclaration) {
isPrivate = true;
}
isPrivate ||= needsPostExportDefault;
const modifierFlags = (!isPrivate ? ModifierFlags.Export : 0) | (isDefault && !needsPostExportDefault ? ModifierFlags.Default : 0);
const isConstMergedWithNS = symbol.flags & SymbolFlags.Module &&
symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.FunctionScopedVariable | SymbolFlags.Property) &&
Expand All @@ -9581,7 +9577,6 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
if (propertyAsAlias) {
const createdExport = serializeMaybeAliasAssignment(symbol);
if (createdExport) {
needsExportDeclaration = false;
needsPostExportDefault = false;
}
}
Expand Down Expand Up @@ -9679,7 +9674,6 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
),
ModifierFlags.None,
);
needsExportDeclaration = false;
needsPostExportDefault = false;
}
}
Expand Down Expand Up @@ -9737,18 +9731,6 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
context.approximateLength += 16 + internalSymbolName.length; // `export default internalName;`
addResult(factory.createExportAssignment(/*modifiers*/ undefined, /*isExportEquals*/ false, factory.createIdentifier(internalSymbolName)), ModifierFlags.None);
}
else if (needsExportDeclaration) {
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this was originally added by @weswigham in #38982

I tried to think of a potential missing test case, but I couldn't find one. Perhaps this just became handled by other code paths since this was introduced

const internalSymbolName = getInternalSymbolName(symbol, symbolName);
context.approximateLength += 22 + symbolName.length + internalSymbolName.length; // `export { internalName as symbolName };`
addResult(
factory.createExportDeclaration(
/*modifiers*/ undefined,
/*isTypeOnly*/ false,
factory.createNamedExports([factory.createExportSpecifier(/*isTypeOnly*/ false, internalSymbolName, symbolName)]),
),
ModifierFlags.None,
);
}
}

function includePrivateSymbol(symbol: Symbol) {
Expand Down
26 changes: 26 additions & 0 deletions tests/baselines/reference/jsDeclarationsKeywordExport1.js
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@@ -0,0 +1,26 @@
//// [tests/cases/conformance/jsdoc/declarations/jsDeclarationsKeywordExport1.ts] ////

//// [source.js]
// https://github.com/microsoft/TypeScript/issues/62081

const _null = {}
const $void = {}

export { _null as null, $void as void }


//// [source.js]
"use strict";
// https://github.com/microsoft/TypeScript/issues/62081
Object.defineProperty(exports, "__esModule", { value: true });
exports.void = exports.null = void 0;
var _null = {};
exports.null = _null;
var $void = {};
exports.void = $void;


//// [source.d.ts]
declare const _null: {};
declare const $void: {};
export { _null as null, $void as void };
17 changes: 17 additions & 0 deletions tests/baselines/reference/jsDeclarationsKeywordExport1.symbols
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@@ -0,0 +1,17 @@
//// [tests/cases/conformance/jsdoc/declarations/jsDeclarationsKeywordExport1.ts] ////

=== source.js ===
// https://github.com/microsoft/TypeScript/issues/62081

const _null = {}
>_null : Symbol(_null, Decl(source.js, 2, 5))

const $void = {}
>$void : Symbol($void, Decl(source.js, 3, 5))

export { _null as null, $void as void }
>_null : Symbol(_null, Decl(source.js, 2, 5))
>null : Symbol(null, Decl(source.js, 5, 8))
>$void : Symbol($void, Decl(source.js, 3, 5))
>void : Symbol(void, Decl(source.js, 5, 23))

27 changes: 27 additions & 0 deletions tests/baselines/reference/jsDeclarationsKeywordExport1.types
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@@ -0,0 +1,27 @@
//// [tests/cases/conformance/jsdoc/declarations/jsDeclarationsKeywordExport1.ts] ////

=== source.js ===
// https://github.com/microsoft/TypeScript/issues/62081

const _null = {}
>_null : {}
> : ^^
>{} : {}
> : ^^

const $void = {}
>$void : {}
> : ^^
>{} : {}
> : ^^

export { _null as null, $void as void }
>_null : {}
> : ^^
>null : {}
> : ^^
>$void : {}
> : ^^
>void : {}
> : ^^

13 changes: 13 additions & 0 deletions tests/cases/conformance/jsdoc/declarations/jsDeclarationsKeywordExport1.ts
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Original file line number Diff line number Diff line change
@@ -0,0 +1,13 @@
// @allowJs: true
// @checkJs: true
// @target: es5
// @outDir: ./out
// @declaration: true
// @filename: source.js

// https://github.com/microsoft/TypeScript/issues/62081

const _null = {}
const $void = {}

export { _null as null, $void as void }
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