Improve CommonJS support, round 2 by ahejlsberg · Pull Request #2946 · microsoft/typescript-go

ahejlsberg · 2026-03-02T00:17:04Z

With this PR, in a CommonJS module with an export assignment (export = in TS or module.exports = in JS) we now overlay type and uninstantiated namespace declarations in the module onto the namespace of the exported entity. An export assignment is in error if (a) the module exports value members or (b) if the module exports type or namespace members and the exported entity also exports type or namespace members.

With these changes, the following is now permitted:

// File mod.ts
export type Foo = number[];  // This declaration is overlayed onto the namespace of the `export =`
export = { greeting: "hello" };

// File main.ts
import mod = require("./mod");
const greeting = mod.greeting;
const x: mod.Foo = [1, 2, 3];

This PR furthermore aligns Corsa more closely with Strada as follows:

Permit multiple module.exports assignments in a file and union the assigned types.
Exclude module.exports assignments from stricter checking of TypeScript export = declarations.

This PR supersedes #2893.

Copilot

Pull request overview

This PR expands CommonJS export = / module.exports support by merging type/namespace-only exports into the export-assignment namespace, relaxing/aligning some restrictions, and updating tests/baselines to reflect the new behavior.

Changes:

Add new compiler tests covering export-assignment merging in .ts and @checkJs .js scenarios.
Update many conformance/compiler baselines to reflect relaxed module.exports handling (e.g., removing prior TS1203 errors and updating symbol/type displays).
Add/update baselines for multiple module.exports assignments and export-assignment namespace merging.

Reviewed changes

Copilot reviewed 300 out of 302 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
testdata/tests/cases/compiler/exportAssignmentMerging1.ts	New test covering type/namespace merging with `export =`
testdata/tests/cases/compiler/exportAssignmentMerging2.ts	New test covering merging with exported uninstantiated namespace assigned via `export =`
testdata/tests/cases/compiler/exportAssignmentMerging3.ts	New negative test for conflicting type members when merging into exported namespace
testdata/tests/cases/compiler/exportAssignmentMerging4.ts	New negative test for value exports alongside `export =`
testdata/tests/cases/compiler/exportAssignmentMerging5.ts	New `@checkJs` test for typedef merging into `module.exports`
testdata/baselines/reference/submodule/conformance/typedefCrossModule4.errors.txt.diff	Baseline update reflecting changed export-assignment error reporting
testdata/baselines/reference/submodule/conformance/typedefCrossModule4.errors.txt	Baseline removal/update reflecting changed export-assignment errors
testdata/baselines/reference/submodule/conformance/typedefCrossModule3.types.diff	Baseline update for module symbol/type display (`"export="`)
testdata/baselines/reference/submodule/conformance/typedefCrossModule3.types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/typedefCrossModule3.symbols.diff	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/typedefCrossModule3.symbols	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/typedefCrossModule3.errors.txt.diff	Baseline update removing TS1203 export-assignment errors
testdata/baselines/reference/submodule/conformance/typedefCrossModule3.errors.txt	Baseline removal/update removing TS1203 export-assignment errors
testdata/baselines/reference/submodule/conformance/typedefCrossModule.types.diff	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/typedefCrossModule.types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/typedefCrossModule.symbols.diff	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/typedefCrossModule.symbols	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/typedefCrossModule.errors.txt.diff	Baseline update removing TS1203 export-assignment errors
testdata/baselines/reference/submodule/conformance/typedefCrossModule.errors.txt	Baseline update removing TS1203 export-assignment errors
testdata/baselines/reference/submodule/conformance/typeTagModuleExports.errors.txt.diff	Baseline update for export-assignment error set
testdata/baselines/reference/submodule/conformance/typeTagModuleExports.errors.txt	Baseline update for export-assignment error set
testdata/baselines/reference/submodule/conformance/typeFromPropertyAssignment17.errors.txt.diff	Baseline update for export-assignment error set
testdata/baselines/reference/submodule/conformance/typeFromPropertyAssignment17.errors.txt	Baseline update for export-assignment error set
testdata/baselines/reference/submodule/conformance/requireTwoPropertyAccesses.errors.txt.diff	Baseline update for export-assignment error set
testdata/baselines/reference/submodule/conformance/requireTwoPropertyAccesses.errors.txt	Baseline update for export-assignment error set
testdata/baselines/reference/submodule/conformance/paramTagTypeResolution.errors.txt.diff	Baseline update for export-assignment error set
testdata/baselines/reference/submodule/conformance/paramTagTypeResolution.errors.txt	Baseline update for export-assignment error set
testdata/baselines/reference/submodule/conformance/nodeModulesAllowJsExportAssignment(module=nodenext).errors.txt	Baseline update removing TS1203 in `file.js` path
testdata/baselines/reference/submodule/conformance/nodeModulesAllowJsExportAssignment(module=node20).errors.txt	Baseline update removing TS1203 in `file.js` path
testdata/baselines/reference/submodule/conformance/nodeModulesAllowJsExportAssignment(module=node18).errors.txt	Baseline update removing TS1203 in `file.js` path
testdata/baselines/reference/submodule/conformance/nodeModulesAllowJsExportAssignment(module=node16).errors.txt	Baseline update removing TS1203 in `file.js` path
testdata/baselines/reference/submodule/conformance/moduleExportWithExportPropertyAssignment4.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportWithExportPropertyAssignment2.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportWithExportPropertyAssignment2.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportWithExportPropertyAssignment.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportWithExportPropertyAssignment.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportPropertyAssignmentDefault.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportPropertyAssignmentDefault.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAssignment7.errors.txt.diff	Baseline update removing TS1203 in `mod.js`
testdata/baselines/reference/submodule/conformance/moduleExportAssignment7.errors.txt	Baseline update removing TS1203 in `mod.js`
testdata/baselines/reference/submodule/conformance/moduleExportAssignment5.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAssignment5.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAssignment4.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAssignment4.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAssignment3.errors.txt.diff	Baseline update removing TS1203-only failure
testdata/baselines/reference/submodule/conformance/moduleExportAssignment3.errors.txt	Baseline update removing TS1203-only failure
testdata/baselines/reference/submodule/conformance/moduleExportAliasUnknown.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAliasUnknown.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAliasImported.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAliasImported.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAliasExports.errors.txt.diff	Baseline update removing TS1231 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAliasExports.errors.txt	Baseline update removing TS1231 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAlias4.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAlias4.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/moduleExportAlias3.errors.txt.diff	Baseline update removing TS1203-only failure
testdata/baselines/reference/submodule/conformance/moduleExportAlias3.errors.txt	Baseline update removing TS1203-only failure
testdata/baselines/reference/submodule/conformance/jsdocTypeReferenceToImportOfFunctionExpression.types.diff	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsdocTypeReferenceToImportOfFunctionExpression.types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsdocTypeReferenceToImportOfFunctionExpression.symbols.diff	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsdocTypeReferenceToImportOfFunctionExpression.symbols	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsdocTypeReferenceToImportOfClassExpression.types.diff	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsdocTypeReferenceToImportOfClassExpression.types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsdocTypeReferenceToImportOfClassExpression.symbols.diff	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsdocTypeReferenceToImportOfClassExpression.symbols	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsdocTypeReferenceToImportOfClassExpression.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsdocTypeReferenceToImportOfClassExpression.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsdocTypeReferenceExports.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsdocTypeReferenceExports.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsdocImportType2.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsdocImportType2.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsdocImportType.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsdocImportType.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefPropertyAndExportAssignment.types.diff	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefPropertyAndExportAssignment.types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefPropertyAndExportAssignment.symbols.diff	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefPropertyAndExportAssignment.symbols	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefPropertyAndExportAssignment.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndLatebound.types.diff	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndLatebound.types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndLatebound.symbols.diff	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndLatebound.symbols	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndLatebound.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndLatebound.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndImportTypes.types.diff	Baseline update for module type display and import typedef resolution
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndImportTypes.types	Baseline update for module type display and import typedef resolution
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndImportTypes.symbols.diff	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndImportTypes.symbols	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndImportTypes.js.diff	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndImportTypes.js	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndImportTypes.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypeReferences(target=es2015).js.diff	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypeReferences(target=es2015).js	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypeReferences(target=es2015).errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypeReferences(target=es2015).errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypeReassignmentFromDeclaration2.js.diff	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypeReassignmentFromDeclaration2.js	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypeReassignmentFromDeclaration2.errors.txt.diff	Baseline update (error output removed)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypeReassignmentFromDeclaration2.errors.txt	Baseline update (error output removed)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypeReassignmentFromDeclaration.js.diff	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypeReassignmentFromDeclaration.js	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypeReassignmentFromDeclaration.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsTypeReassignmentFromDeclaration.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsReexportedCjsAlias(target=es2015).errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsParameterTagReusesInputNodeInEmit2.js.diff	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsParameterTagReusesInputNodeInEmit2.js	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsParameterTagReusesInputNodeInEmit2.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsParameterTagReusesInputNodeInEmit2.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsParameterTagReusesInputNodeInEmit1.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsParameterTagReusesInputNodeInEmit1.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsPackageJson(target=es2015).js	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsPackageJson(target=es2015).errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsJson(target=es2015).js.diff	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsJson(target=es2015).js	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsJson(target=es2015).errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsJson(target=es2015).errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsImportAliasExposedWithinNamespace.errors.txt	Baseline update removing TS18042 error line
testdata/baselines/reference/submodule/conformance/jsDeclarationsFunctionWithDefaultAssignedMember.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsFunctionWithDefaultAssignedMember.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsFunctionPrototypeStatic(target=es2015).types.diff	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsDeclarationsFunctionPrototypeStatic(target=es2015).types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsDeclarationsFunctionPrototypeStatic(target=es2015).symbols.diff	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsDeclarationsFunctionPrototypeStatic(target=es2015).symbols	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsDeclarationsFunctionPrototypeStatic(target=es2015).errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsFunctionPrototypeStatic(target=es2015).errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsFunctionClassesCjsExportAssignment(target=es2015).types.diff	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsDeclarationsFunctionClassesCjsExportAssignment(target=es2015).types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsDeclarationsFunctionClassesCjsExportAssignment(target=es2015).symbols.diff	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsDeclarationsFunctionClassesCjsExportAssignment(target=es2015).symbols	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportedClassAliases.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportedClassAliases.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportSubAssignments(target=es2015).errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportSubAssignments(target=es2015).errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignmentWithKeywordName(target=es2015).errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignmentWithKeywordName(target=es2015).errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignmentExpressionPlusSecondary(target=es2015).errors.txt	Baseline update removing TS1203 and adjusting caret output
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedVisibility(target=es2015).js.diff	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedVisibility(target=es2015).js	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedVisibility(target=es2015).errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedVisibility(target=es2015).errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassInstance3(target=es2015).errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassInstance3(target=es2015).errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassInstance2(target=es2015).errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassInstance2(target=es2015).errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassInstance1(target=es2015).errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassInstance1(target=es2015).errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassExpressionShadowing(target=es2015).errors.txt.diff	Baseline update removing TS1203 and adjusting caret output
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassExpressionShadowing(target=es2015).errors.txt	Baseline update removing TS1203 and adjusting caret output
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassExpressionAnonymousWithSub(target=es2015).errors.txt	Baseline update removing TS1203 and adjusting caret output
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassExpressionAnonymous(target=es2015).errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassExpressionAnonymous(target=es2015).errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassExpression(target=es2015).errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsExportAssignedClassExpression(target=es2015).errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsDocCommentsOnConsts(target=es2015).errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsDocCommentsOnConsts(target=es2015).errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/jsDeclarationsClassStatic(target=es2015).types.diff	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsDeclarationsClassStatic(target=es2015).types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/jsDeclarationsClassStatic(target=es2015).symbols.diff	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsDeclarationsClassStatic(target=es2015).symbols	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/jsDeclarationsClassStatic(target=es2015).errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsDeclarationsClassStatic(target=es2015).errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/jsDeclarationsClassExtendsVisibility(target=es2015).errors.txt	Baseline update removing TS1203 in `bar.js` and adjusting counts
testdata/baselines/reference/submodule/conformance/importAliasModuleExports.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/importAliasModuleExports.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/globalMergeWithCommonJSAssignmentDeclaration.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/globalMergeWithCommonJSAssignmentDeclaration.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/enumTagOnExports2.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/enumTagOnExports2.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/contextualTypedSpecialAssignment.errors.txt.diff	Baseline update removing TS1203 and adjusting caret output
testdata/baselines/reference/submodule/conformance/contextualTypedSpecialAssignment.errors.txt	Baseline update removing TS1203 and adjusting caret output
testdata/baselines/reference/submodule/conformance/conflictingCommonJSES2015Exports.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/conflictingCommonJSES2015Exports.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/commonJSReexport.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/commonJSReexport.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/commonJSAliasedExport.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/commonJSAliasedExport.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/callbackCrossModule.types.diff	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/callbackCrossModule.types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/submodule/conformance/callbackCrossModule.symbols.diff	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/callbackCrossModule.symbols	Baseline update for symbol binding locations
testdata/baselines/reference/submodule/conformance/callbackCrossModule.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/callbackCrossModule.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/conformance/binderUninitializedModuleExportsAssignment.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/conformance/binderUninitializedModuleExportsAssignment.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/compiler/truthinessCallExpressionCoercion4.errors.txt.diff	Baseline update removing TS1231 nested export-assignment error
testdata/baselines/reference/submodule/compiler/truthinessCallExpressionCoercion4.errors.txt	Baseline update removing TS1231 nested export-assignment error
testdata/baselines/reference/submodule/compiler/requireOfJsonFileInJsFile.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/compiler/requireOfJsonFileInJsFile.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/compiler/pushTypeGetTypeOfAlias.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/compiler/pushTypeGetTypeOfAlias.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/compiler/moduleExportsTypeNoExcessPropertyCheckFromContainedLiteral.types.diff	Baseline update for symbol self-references in type printing
testdata/baselines/reference/submodule/compiler/moduleExportsTypeNoExcessPropertyCheckFromContainedLiteral.types	Baseline update for symbol self-references in type printing
testdata/baselines/reference/submodule/compiler/jsExportMemberMergedWithModuleAugmentation3.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/compiler/jsExportMemberMergedWithModuleAugmentation3.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/compiler/jsExportMemberMergedWithModuleAugmentation2.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/compiler/jsExportMemberMergedWithModuleAugmentation2.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/compiler/jsExportMemberMergedWithModuleAugmentation.errors.txt.diff	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/compiler/jsExportMemberMergedWithModuleAugmentation.errors.txt	Baseline update removing TS1203 and adjusting error counts
testdata/baselines/reference/submodule/compiler/jsDeclarationEmitExportAssignedFunctionWithExtraTypedefsMembers.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/compiler/jsDeclarationEmitExportAssignedFunctionWithExtraTypedefsMembers.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/compiler/jsDeclarationEmitExportAssignedArray.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/compiler/jsDeclarationEmitExportAssignedArray.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/compiler/javascriptImportDefaultBadExport.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/compiler/javascriptImportDefaultBadExport.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/compiler/incompatibleExports2.errors.txt.diff	Baseline update (now empty)
testdata/baselines/reference/submodule/compiler/incompatibleExports2.errors.txt	Baseline update (removed)
testdata/baselines/reference/submodule/compiler/incompatibleExports1.types.diff	Baseline update for namespace type display
testdata/baselines/reference/submodule/compiler/incompatibleExports1.types	Baseline update for namespace type display
testdata/baselines/reference/submodule/compiler/incompatibleExports1.errors.txt.diff	Baseline update removing one TS2309 instance
testdata/baselines/reference/submodule/compiler/incompatibleExports1.errors.txt	Baseline update removing one TS2309 instance
testdata/baselines/reference/submodule/compiler/importNonExportedMember12.errors.txt.diff	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/compiler/importNonExportedMember12.errors.txt	Baseline update removing TS1203-only failures
testdata/baselines/reference/submodule/compiler/importDeclWithExportModifierAndExportAssignmentInAmbientContext.errors.txt.diff	Baseline update (now empty)
testdata/baselines/reference/submodule/compiler/importDeclWithExportModifierAndExportAssignmentInAmbientContext.errors.txt	Baseline update (removed)
testdata/baselines/reference/submodule/compiler/importDeclWithExportModifierAndExportAssignment.errors.txt.diff	Baseline update removing TS2309 instance
testdata/baselines/reference/submodule/compiler/importDeclWithExportModifierAndExportAssignment.errors.txt	Baseline update removing TS2309 instance
testdata/baselines/reference/submodule/compiler/amdLikeInputDeclarationEmit.errors.txt.diff	Baseline update removing TS1231-only failure
testdata/baselines/reference/submodule/compiler/amdLikeInputDeclarationEmit.errors.txt	Baseline update removing TS1231-only failure
testdata/baselines/reference/conformance/typedefModuleExportsIndirect3.types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/conformance/typedefModuleExportsIndirect3.symbols	Baseline update for symbol binding locations
testdata/baselines/reference/conformance/typedefModuleExportsIndirect3.js	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/conformance/typedefModuleExportsIndirect3.errors.txt	Baseline update removing TS1203-only failure
testdata/baselines/reference/conformance/typedefModuleExportsIndirect2.types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/conformance/typedefModuleExportsIndirect2.symbols	Baseline update for symbol binding locations
testdata/baselines/reference/conformance/typedefModuleExportsIndirect2.js	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/conformance/typedefModuleExportsIndirect2.errors.txt	Baseline update removing TS1203-only failure
testdata/baselines/reference/conformance/typedefModuleExportsIndirect1.types	Baseline update for module type display (`"export="`)
testdata/baselines/reference/conformance/typedefModuleExportsIndirect1.symbols	Baseline update for symbol binding locations
testdata/baselines/reference/conformance/typedefModuleExportsIndirect1.js	Baseline update (now includes DtsFileErrors segment)
testdata/baselines/reference/conformance/typedefModuleExportsIndirect1.errors.txt	Baseline update removing TS1203-only failure
testdata/baselines/reference/compiler/nestedJSDocImportType.errors.txt	Baseline update removing TS1203 and adjusting caret output
testdata/baselines/reference/compiler/multipleModuleExportsAssignments.js	New baseline for multiple `module.exports` assignments
testdata/baselines/reference/compiler/exportAssignmentMerging6.js	New baseline output for JS export-assignment merging with value export error
testdata/baselines/reference/compiler/exportAssignmentMerging6.errors.txt	New baseline error output for export-assignment + value export conflict
testdata/baselines/reference/compiler/exportAssignmentMerging5.types	New baseline types output for `@checkJs` typedef merge with `module.exports`
testdata/baselines/reference/compiler/exportAssignmentMerging5.symbols	New baseline symbols output for `@checkJs` typedef merge with `module.exports`
testdata/baselines/reference/compiler/exportAssignmentMerging5.js	New baseline output for `@checkJs` typedef merge with `module.exports`
testdata/baselines/reference/compiler/exportAssignmentMerging4.js	New baseline output for negative TS export/value conflict case
testdata/baselines/reference/compiler/exportAssignmentMerging4.errors.txt	New baseline error output for negative TS export/value conflict case
testdata/baselines/reference/compiler/exportAssignmentMerging3.errors.txt	New baseline error output for negative merge conflict case
testdata/baselines/reference/compiler/exportAssignmentMerging2.types	New baseline types output for namespace assigned via `export =`
testdata/baselines/reference/compiler/exportAssignmentMerging2.js	New baseline output for namespace assigned via `export =`
testdata/baselines/reference/compiler/exportAssignmentMerging1.types	New baseline types output for type/namespace merging into export assignment
testdata/baselines/reference/compiler/exportAssignmentMerging1.js	New baseline output for type/namespace merging into export assignment
testdata/baselines/reference/compiler/erasableSyntaxOnlyJS.errors.txt	Baseline update removing TS1203 export-assignment error in JS

Copilot · 2026-03-02T00:19:36Z

testdata/tests/cases/compiler/exportAssignmentMerging1.ts

@@ -0,0 +1,14 @@
+// @module: commonjs
+// @declaration: true


New compiler tests should generally enable // @strict: true unless the behavior under test is specifically about non-strict mode. Please add // @strict: true near the top (and consider applying the same update to the other newly added exportAssignmentMerging*.ts tests in this PR).

Suggested change

// @declaration: true

// @declaration: true

// @strict: true

No need, // @strict: true is the default in Corsa.

Copilot · 2026-03-02T00:19:37Z

testdata/tests/cases/compiler/exportAssignmentMerging5.ts

@@ -0,0 +1,15 @@
+// @module: commonjs
+// @declaration: true


This new test runs in @checkJs mode but doesn't enable // @strict: true. To keep new coverage consistent and to catch regressions earlier, add // @strict: true unless this scenario is intentionally exercising non-strict behavior.

Suggested change

// @declaration: true

// @declaration: true

// @strict: true

Copilot · 2026-03-02T00:19:37Z

testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndImportTypes.js

+out/conn.d.ts(5,10): error TS2304: Cannot find name 'Conn'.
+
+
+==== out/conn.d.ts (1 errors) ====


The updated baseline now reports a declaration-emit error where the generated .d.ts contains export = Conn; but no corresponding declare class Conn/declare const Conn in that output. That strongly suggests the binder/emitter lost the value declaration for the export-assigned symbol (or is emitting export = <identifier> without emitting the identifier’s declaration). Consider ensuring the export assignment keeps a usable ValueDeclaration for the exported entity (e.g., preserve the original class/function/var declaration as the value declaration) so the declaration emitter can emit the exported symbol before export =.

Copilot · 2026-03-02T00:19:37Z

testdata/baselines/reference/submodule/conformance/jsDeclarationsTypedefAndImportTypes.js

+    export type Whatever = string | number;
+    export = Conn;
+             ~~~~
+!!! error TS2304: Cannot find name 'Conn'.


The updated baseline now reports a declaration-emit error where the generated .d.ts contains export = Conn; but no corresponding declare class Conn/declare const Conn in that output. That strongly suggests the binder/emitter lost the value declaration for the export-assigned symbol (or is emitting export = <identifier> without emitting the identifier’s declaration). Consider ensuring the export assignment keeps a usable ValueDeclaration for the exported entity (e.g., preserve the original class/function/var declaration as the value declaration) so the declaration emitter can emit the exported symbol before export =.

Copilot · 2026-03-02T00:19:38Z

testdata/baselines/reference/conformance/typedefModuleExportsIndirect1.js

+dist/typedefModuleExportsIndirect1.d.ts(5,10): error TS2304: Cannot find name 'dummy'.
+
+
+==== dist/typedefModuleExportsIndirect1.d.ts (1 errors) ====
+    export type C = {


Similar to the Conn case, this baseline introduces a .d.ts emit error where export = dummy; is emitted without any declaration for dummy in the .d.ts. If this PR’s export-assignment merging changes alter how the exported symbol’s declaration is selected (e.g., preferring the assignment node over the original variable/function declaration), the declaration emitter may no longer have a declaration to print. A concrete fix is to make sure the emitted .d.ts declares the exported binding (e.g., declare const dummy: ...;) or to emit an anonymous _default symbol for object/function/class exports when the original name isn’t directly emit-able.

Copilot · 2026-03-02T00:19:38Z

testdata/baselines/reference/conformance/typedefModuleExportsIndirect1.js

+    export = dummy;
+             ~~~~~
+!!! error TS2304: Cannot find name 'dummy'.


Similar to the Conn case, this baseline introduces a .d.ts emit error where export = dummy; is emitted without any declaration for dummy in the .d.ts. If this PR’s export-assignment merging changes alter how the exported symbol’s declaration is selected (e.g., preferring the assignment node over the original variable/function declaration), the declaration emitter may no longer have a declaration to print. A concrete fix is to make sure the emitted .d.ts declares the exported binding (e.g., declare const dummy: ...;) or to emit an anonymous _default symbol for object/function/class exports when the original name isn’t directly emit-able.

ahejlsberg · 2026-03-02T02:39:51Z

@weswigham We already have an issue around declaration file generation for CommonJS modules with module.exports assignments. For example, this:

const dummy = 0;
module.exports = dummy;

generates an invalid declaration file (an actual declaration of dummy is missing):

export = dummy;

(EDIT: The above has now been fixed.)

Furthermore, with this PR we'll permit multiple module.exports assignments and non-top-level module.exports assignments. Neither is handled correctly currently. In particular, nested module.exports assignments are simply ignored.

DanielRosenwasser · 2026-03-02T20:42:12Z

internal/binder/binder.go

-		symbol := b.declareSymbol(ast.GetExports(container.Symbol()), container.Symbol(), node, flags, ast.SymbolFlagsAll)
+		symbol := b.declareSymbol(ast.GetExports(container.Symbol()), container.Symbol(), node, flags, core.IfElse(ast.IsJSExportAssignment(node), 0, ast.SymbolFlagsAll))
 		if ast.IsJSExportAssignment(node) || node.AsExportAssignment().IsExportEquals {
 			// Will be an error later, since the module already has other exports. Just make sure this has a valueDeclaration set.


I think this is no longer true for JSExportAssignments, right?

Suggested change

// Will be an error later, since the module already has other exports. Just make sure this has a valueDeclaration set.

// This may be an error later, since the module already has other exports.

// Just make sure this has a valueDeclaration set.

Yeah, will fix.

internal/binder/binder.go

ahejlsberg · 2026-03-03T18:17:40Z

Latest commits fixes the issue in the example here. However, as can be seen in this test, the declaration emitter doesn't properly handle nested module.exports assignments. The logic that handles that in Strada is located in symbolTableToDeclarationStatements, which is stubbed out in nodebuilderimpl.go in Corsa. I'm not going to attempt to fix that in this PR.

weswigham · 2026-03-03T18:33:35Z

That's incorrect - that's a stub in corsa because it's unused, and should continue to be, since we don't do semantic js declaration emit, but syntactic emit, same as TS, now. If we want to support non-top-level export assignments in corsa, we need to add a non-top-level visitor to the declaration emitter transform - it's new logic, and should be part of the initial implementation of the checker logic, too - that's what I've been saying about how "some js checker work has included declaration emit logic and some hasn't, and we'll need to audit what's missing". We're not "waiting to port something" - the strategy is entirely different. Originally, the hope was we'd need no new declaration emitter logic since the reparser was going to handle all those transforms. If we back off that approach, that means you need declaration emitter logic to mimic the checker logic.

jakebailey · 2026-03-03T18:38:19Z

I think we have been gradually backing off on that logic, as we discover more things that the reparser can't do (e.g., the defineProperties stuff).

ahejlsberg · 2026-03-04T21:57:24Z

Just to recap, in the design meeting we agreed to merge this PR and create a separate PR to issue errors when generating declaration files for CommonJS modules with constructs that aren't supported by the emitter. Specifically, the following aren't supported when generating declaration files:

Multiple module.exports assignments in a module.
Nested module.exports assignments.
Nested exports.xxx assignments.
Nested Object.defineProperty(module.exports, ...) calls.

ahejlsberg added 9 commits February 28, 2026 08:09

Only validate TS export assignments in checkExportAssignment

2a4c868

Accept new baselines

df9b23a

Promote type and namespace exports from module to export= symbol

501a033

Accept new baselines

ea4cc92

Validate that module exports and export= are compatible

8e4eaed

Add tests

91a04d9

Permit multiple module.exports assignments and union assigned types

a6d1d03

Accept new baselines

b204481

Add test for multiple module.exports assignments

4e9b24e

ahejlsberg requested review from Copilot, jakebailey, sandersn and weswigham March 2, 2026 00:17

ahejlsberg mentioned this pull request Mar 2, 2026

Improve CommonJS support #2893

Closed

Copilot AI reviewed Mar 2, 2026

View reviewed changes

jakebailey mentioned this pull request Mar 2, 2026

tsgo does not respect esModuleInterop in certain cases #2692

Closed

DanielRosenwasser reviewed Mar 2, 2026

View reviewed changes

ahejlsberg added 3 commits March 3, 2026 09:57

Mark symbol referenced by module.exports as visible

6c8e8b5

Accept new baselines

314ca77

Fix comment

c52cfda

jakebailey mentioned this pull request Mar 3, 2026

resolving library types with import assignment import = require() fails #2781

Open

ahejlsberg requested a review from DanielRosenwasser March 3, 2026 21:27

Merge branch 'main' into cjs-exports-merging

bbd32ac

ahejlsberg enabled auto-merge March 4, 2026 22:00

jakebailey approved these changes Mar 4, 2026

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ahejlsberg added this pull request to the merge queue Mar 4, 2026

Merged via the queue into main with commit 49eb28a Mar 4, 2026
21 checks passed

ahejlsberg deleted the cjs-exports-merging branch March 4, 2026 22:43

andrewbranch mentioned this pull request Mar 19, 2026

Fix named export aliases merging with export = #3157

Merged

		out/conn.d.ts(5,10): error TS2304: Cannot find name 'Conn'.


		==== out/conn.d.ts (1 errors) ====

	// Will be an error later, since the module already has other exports. Just make sure this has a valueDeclaration set.
	// This may be an error later, since the module already has other exports.
	// Just make sure this has a valueDeclaration set.

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