Fix: skip CommonJS export binding when module or exports is a local variable

internal/binder/binder.go

@@ -81,6 +81,8 @@ type Binder struct {
 	singleDeclarationsPool  core.Pool[*ast.Node]
 	expandoAssignments      []ExpandoAssignmentInfo
 	nestedCJSExports        []*ast.Node
+	staleCJSIndicator       bool
+	firstValidCJSExport     *ast.Node
 }
 
 type ActiveLabel struct {
@@ -126,6 +128,7 @@ func bindSourceFile(file *ast.SourceFile) {
 		b.file = file
 		b.unreachableFlow = b.newFlowNode(ast.FlowFlagsUnreachable)
 		b.bind(file.AsNode())
+		b.fixStaleCJSIndicator()
 		b.bindDeferredExpandoAssignments()
 		file.SymbolCount = b.symbolCount
 		file.ClassifiableNames = b.classifiableNames
@@ -659,6 +662,15 @@ func (b *Binder) bind(node *ast.Node) bool {
 		node.AsBindingElement().FlowNode = b.currentFlow
 		b.bindVariableDeclarationOrBindingElement(node)
 	case ast.KindCommonJSExport:
+		if !ast.IsSourceFile(b.blockScopeContainer) && b.lookupName("exports", b.blockScopeContainer) != nil {
+			if b.file.CommonJSModuleIndicator == node {
+				b.staleCJSIndicator = true
+			}
+			break
+		}
+		if b.firstValidCJSExport == nil {
+			b.firstValidCJSExport = node
+		}
 		b.trackNestedCJSExport(node)
 		b.declareModuleMember(node, ast.SymbolFlagsFunctionScopedVariable, ast.SymbolFlagsFunctionScopedVariableExcludes)
 	case ast.KindPropertyDeclaration, ast.KindPropertySignature:
@@ -862,6 +874,15 @@ func (b *Binder) bindExportDeclaration(node *ast.Node) {
 func (b *Binder) bindExportAssignment(node *ast.Node) {
 	container := b.container
 	if ast.IsJSExportAssignment(node) {
+		if !ast.IsSourceFile(b.blockScopeContainer) && b.lookupName("module", b.blockScopeContainer) != nil {
+			if b.file.CommonJSModuleIndicator == node {
+				b.staleCJSIndicator = true
+			}
+			return
+		}
+		if b.firstValidCJSExport == nil {
+			b.firstValidCJSExport = node
+		}
 		container = b.file.AsNode()
 		b.trackNestedCJSExport(node)
 	}
@@ -951,9 +972,20 @@ func (b *Binder) setCommonJSModuleIndicator(node *ast.Node) bool {
 			b.bindSourceFileAsExternalModule()
 		}
 	}
+	if b.firstValidCJSExport == nil {
+		b.firstValidCJSExport = node
+	}
 	return true
 }
 
+// fixStaleCJSIndicator corrects CommonJSModuleIndicator if it pointed to a skipped (locally-shadowed) CJS export.
+func (b *Binder) fixStaleCJSIndicator() {
+	if !b.staleCJSIndicator {
+		return
+	}
+	b.file.CommonJSModuleIndicator = b.firstValidCJSExport
+}
+
 func (b *Binder) bindClassLikeDeclaration(node *ast.Node) {
 	name := node.Name()
 	switch node.Kind {

testdata/baselines/reference/compiler/exportsInFunctionParam.errors.txt

@@ -0,0 +1,17 @@
+/dep.js(1,20): error TS7006: Parameter 'exports' implicitly has an 'any' type.
+
+
+==== /dep.js (1 errors) ====
+    function something(exports) {
+                       ~~~~~~~
+!!! error TS7006: Parameter 'exports' implicitly has an 'any' type.
+        exports.foo = 8;
+    }
+
+    export const foo = 7;
+
+==== /main.ts (0 errors) ====
+    import { foo } from "./dep.js";
+
+    export const bar = foo + 1;
+

testdata/baselines/reference/compiler/exportsInFunctionParam.symbols

@@ -0,0 +1,22 @@
+//// [tests/cases/compiler/exportsInFunctionParam.ts] ////
+
+=== /dep.js ===
+function something(exports) {
+>something : Symbol(something, Decl(dep.js, 0, 0))
+>exports : Symbol(exports, Decl(dep.js, 0, 19))
+
+    exports.foo = 8;
+>exports : Symbol(exports, Decl(dep.js, 0, 19))
+}
+
+export const foo = 7;
+>foo : Symbol(foo, Decl(dep.js, 4, 12))
+
+=== /main.ts ===
+import { foo } from "./dep.js";
+>foo : Symbol(foo, Decl(main.ts, 0, 8))
+
+export const bar = foo + 1;
+>bar : Symbol(bar, Decl(main.ts, 2, 12))
+>foo : Symbol(foo, Decl(main.ts, 0, 8))
+

testdata/baselines/reference/compiler/exportsInFunctionParam.types

@@ -0,0 +1,29 @@
+//// [tests/cases/compiler/exportsInFunctionParam.ts] ////
+
+=== /dep.js ===
+function something(exports) {
+>something : (exports: any) => void
+>exports : any
+
+    exports.foo = 8;
+>exports.foo = 8 : 8
+>exports.foo : any
+>exports : any
+>foo : any
+>8 : 8
+}
+
+export const foo = 7;
+>foo : 7
+>7 : 7
+
+=== /main.ts ===
+import { foo } from "./dep.js";
+>foo : 7
+
+export const bar = foo + 1;
+>bar : number
+>foo + 1 : number
+>foo : 7
+>1 : 1
+

testdata/baselines/reference/compiler/moduleExportsInArrowFunctionParam.errors.txt

@@ -0,0 +1,17 @@
+/dep.js(1,20): error TS7006: Parameter 'module' implicitly has an 'any' type.
+
+
+==== /dep.js (1 errors) ====
+    const something = (module) => {
+                       ~~~~~~
+!!! error TS7006: Parameter 'module' implicitly has an 'any' type.
+        module.exports = 8;
+    };
+
+    export default 7;
+
+==== /main.ts (0 errors) ====
+    import DefaultExport from "./dep.js";
+
+    export default 3 + DefaultExport;
+

testdata/baselines/reference/compiler/moduleExportsInArrowFunctionParam.symbols

@@ -0,0 +1,21 @@
+//// [tests/cases/compiler/moduleExportsInArrowFunctionParam.ts] ////
+
+=== /dep.js ===
+const something = (module) => {
+>something : Symbol(something, Decl(dep.js, 0, 5))
+>module : Symbol(module, Decl(dep.js, 0, 19))
+
+    module.exports = 8;
+>module : Symbol(module, Decl(dep.js, 0, 19))
+
+};
+
+export default 7;
+
+=== /main.ts ===
+import DefaultExport from "./dep.js";
+>DefaultExport : Symbol(DefaultExport, Decl(main.ts, 0, 6))
+
+export default 3 + DefaultExport;
+>DefaultExport : Symbol(DefaultExport, Decl(main.ts, 0, 6))
+

testdata/baselines/reference/compiler/moduleExportsInArrowFunctionParam.types

@@ -0,0 +1,28 @@
+//// [tests/cases/compiler/moduleExportsInArrowFunctionParam.ts] ////
+
+=== /dep.js ===
+const something = (module) => {
+>something : (module: any) => void
+>(module) => {    module.exports = 8;} : (module: any) => void
+>module : any
+
+    module.exports = 8;
+>module.exports = 8 : 8
+>module.exports : any
+>module : any
+>exports : any
+>8 : 8
+
+};
+
+export default 7;
+
+=== /main.ts ===
+import DefaultExport from "./dep.js";
+>DefaultExport : 7
+
+export default 3 + DefaultExport;
+>3 + DefaultExport : number
+>3 : 3
+>DefaultExport : 7
+

testdata/baselines/reference/compiler/moduleExportsInFunctionParam.errors.txt

@@ -0,0 +1,17 @@
+/dep.js(1,20): error TS7006: Parameter 'module' implicitly has an 'any' type.
+
+
+==== /dep.js (1 errors) ====
+    function something(module) {
+                       ~~~~~~
+!!! error TS7006: Parameter 'module' implicitly has an 'any' type.
+        module.exports = 8;
+    }
+
+    export default 7;
+
+==== /main.ts (0 errors) ====
+    import DefaultExport from "./dep.js";
+
+    export default 3 + DefaultExport;
+

testdata/baselines/reference/compiler/moduleExportsInFunctionParam.symbols

@@ -0,0 +1,20 @@
+//// [tests/cases/compiler/moduleExportsInFunctionParam.ts] ////
+
+=== /dep.js ===
+function something(module) {
+>something : Symbol(something, Decl(dep.js, 0, 0))
+>module : Symbol(module, Decl(dep.js, 0, 19))
+
+    module.exports = 8;
+>module : Symbol(module, Decl(dep.js, 0, 19))
+}
+
+export default 7;
+
+=== /main.ts ===
+import DefaultExport from "./dep.js";
+>DefaultExport : Symbol(DefaultExport, Decl(main.ts, 0, 6))
+
+export default 3 + DefaultExport;
+>DefaultExport : Symbol(DefaultExport, Decl(main.ts, 0, 6))
+

testdata/baselines/reference/compiler/moduleExportsInFunctionParam.types

@@ -0,0 +1,26 @@
+//// [tests/cases/compiler/moduleExportsInFunctionParam.ts] ////
+
+=== /dep.js ===
+function something(module) {
+>something : (module: any) => void
+>module : any
+
+    module.exports = 8;
+>module.exports = 8 : 8
+>module.exports : any
+>module : any
+>exports : any
+>8 : 8
+}
+
+export default 7;
+
+=== /main.ts ===
+import DefaultExport from "./dep.js";
+>DefaultExport : 7
+
+export default 3 + DefaultExport;
+>3 + DefaultExport : number
+>3 : 3
+>DefaultExport : 7
+

testdata/baselines/reference/compiler/moduleExportsInFunctionParamNamed.errors.txt

@@ -0,0 +1,17 @@
+/dep.js(1,20): error TS7006: Parameter 'module' implicitly has an 'any' type.
+
+
+==== /dep.js (1 errors) ====
+    function something(module) {
+                       ~~~~~~
+!!! error TS7006: Parameter 'module' implicitly has an 'any' type.
+        module.exports = 8;
+    }
+
+    export const foo = 7;
+
+==== /main.ts (0 errors) ====
+    import { foo } from "./dep.js";
+
+    export const bar = foo + 1;
+

testdata/baselines/reference/compiler/moduleExportsInFunctionParamNamed.symbols

@@ -0,0 +1,22 @@
+//// [tests/cases/compiler/moduleExportsInFunctionParamNamed.ts] ////
+
+=== /dep.js ===
+function something(module) {
+>something : Symbol(something, Decl(dep.js, 0, 0))
+>module : Symbol(module, Decl(dep.js, 0, 19))
+
+    module.exports = 8;
+>module : Symbol(module, Decl(dep.js, 0, 19))
+}
+
+export const foo = 7;
+>foo : Symbol(foo, Decl(dep.js, 4, 12))
+
+=== /main.ts ===
+import { foo } from "./dep.js";
+>foo : Symbol(foo, Decl(main.ts, 0, 8))
+
+export const bar = foo + 1;
+>bar : Symbol(bar, Decl(main.ts, 2, 12))
+>foo : Symbol(foo, Decl(main.ts, 0, 8))
+

testdata/baselines/reference/compiler/moduleExportsInFunctionParamNamed.types

@@ -0,0 +1,29 @@
+//// [tests/cases/compiler/moduleExportsInFunctionParamNamed.ts] ////
+
+=== /dep.js ===
+function something(module) {
+>something : (module: any) => void
+>module : any
+
+    module.exports = 8;
+>module.exports = 8 : 8
+>module.exports : any
+>module : any
+>exports : any
+>8 : 8
+}
+
+export const foo = 7;
+>foo : 7
+>7 : 7
+
+=== /main.ts ===
+import { foo } from "./dep.js";
+>foo : 7
+
+export const bar = foo + 1;
+>bar : number
+>foo + 1 : number
+>foo : 7
+>1 : 1
+

testdata/baselines/reference/compiler/moduleExportsInFunctionParamOnlyShadowed.errors.txt

@@ -0,0 +1,17 @@
+/dep.js(1,16): error TS7006: Parameter 'module' implicitly has an 'any' type.
+
+
+==== /dep.js (1 errors) ====
+    function setup(module) {
+                   ~~~~~~
+!!! error TS7006: Parameter 'module' implicitly has an 'any' type.
+        module.exports = { configured: true };
+    }
+
+    export default 7;
+
+==== /main.ts (0 errors) ====
+    import DefaultExport from "./dep.js";
+
+    export default 3 + DefaultExport;
+

testdata/baselines/reference/compiler/moduleExportsInFunctionParamOnlyShadowed.symbols

@@ -0,0 +1,21 @@
+//// [tests/cases/compiler/moduleExportsInFunctionParamOnlyShadowed.ts] ////
+
+=== /dep.js ===
+function setup(module) {
+>setup : Symbol(setup, Decl(dep.js, 0, 0))
+>module : Symbol(module, Decl(dep.js, 0, 15))
+
+    module.exports = { configured: true };
+>module : Symbol(module, Decl(dep.js, 0, 15))
+>configured : Symbol(configured, Decl(dep.js, 1, 22))
+}
+
+export default 7;
+
+=== /main.ts ===
+import DefaultExport from "./dep.js";
+>DefaultExport : Symbol(DefaultExport, Decl(main.ts, 0, 6))
+
+export default 3 + DefaultExport;
+>DefaultExport : Symbol(DefaultExport, Decl(main.ts, 0, 6))
+