Comment in and fix reportNonDefaultExport (#676)

Author: frodi-karlsson

internal/ast/utilities.go

@@ -2384,7 +2384,7 @@ func GetImpliedNodeFormatForEmitWorker(fileName string, options *core.CompilerOp
 		return sourceFileMetaData.ImpliedNodeFormat
 	}
 	if sourceFileMetaData != nil && sourceFileMetaData.ImpliedNodeFormat == core.ModuleKindCommonJS &&
-		(sourceFileMetaData.PackageJsonType != "module" ||
+		(sourceFileMetaData.PackageJsonType == "commonjs" ||
 			tspath.FileExtensionIsOneOf(fileName, []string{tspath.ExtensionCjs, tspath.ExtensionCts})) {
 		return core.ModuleKindCommonJS
 	}

internal/checker/checker.go

@@ -13576,7 +13576,27 @@ func (c *Checker) getTargetOfModuleDefault(moduleSymbol *ast.Symbol, node *ast.N
 }
 
 func (c *Checker) reportNonDefaultExport(moduleSymbol *ast.Symbol, node *ast.Node) {
-	// !!!
+	if moduleSymbol.Exports != nil && moduleSymbol.Exports[node.Symbol().Name] != nil {
+		c.error(node, diagnostics.Module_0_has_no_default_export_Did_you_mean_to_use_import_1_from_0_instead, c.symbolToString(moduleSymbol), c.symbolToString(node.Symbol()))
+	} else {
+		diagnostic := c.error(node.Name(), diagnostics.Module_0_has_no_default_export, c.symbolToString(moduleSymbol))
+		var exportStar *ast.Symbol
+		if moduleSymbol.Exports != nil {
+			exportStar = moduleSymbol.Exports[ast.InternalSymbolNameExportStar]
+		}
+		if exportStar != nil {
+			defaultExport := core.Find(exportStar.Declarations, func(decl *ast.Declaration) bool {
+				if !(ast.IsExportDeclaration(decl) && decl.AsExportDeclaration().ModuleSpecifier != nil) {
+					return false
+				}
+				resolvedExternalModuleName := c.resolveExternalModuleName(decl, decl.AsExportDeclaration().ModuleSpecifier, false /*ignoreErrors*/)
+				return resolvedExternalModuleName != nil && resolvedExternalModuleName.Exports[ast.InternalSymbolNameDefault] != nil
+			})
+			if defaultExport != nil {
+				diagnostic.AddRelatedInfo(createDiagnosticForNode(defaultExport, diagnostics.X_export_Asterisk_does_not_re_export_a_default))
+			}
+		}
+	}
 }
 
 func (c *Checker) resolveExportByName(moduleSymbol *ast.Symbol, name string, sourceNode *ast.Node, dontResolveAlias bool) *ast.Symbol {
@@ -13773,31 +13793,29 @@ func (c *Checker) isOnlyImportableAsDefault(usage *ast.Node, resolvedModule *ast
 }
 
 func (c *Checker) canHaveSyntheticDefault(file *ast.Node, moduleSymbol *ast.Symbol, dontResolveAlias bool, usage *ast.Node) bool {
-	// !!!
-	// var usageMode ResolutionMode
-	// if file != nil {
-	// 	usageMode = c.getEmitSyntaxForModuleSpecifierExpression(usage)
-	// }
-	// if file != nil && usageMode != core.ModuleKindNone {
-	// 	targetMode := host.getImpliedNodeFormatForEmit(file)
-	// 	if usageMode == core.ModuleKindESNext && targetMode == core.ModuleKindCommonJS && core.ModuleKindNode16 <= c.moduleKind && c.moduleKind <= core.ModuleKindNodeNext {
-	// 		// In Node.js, CommonJS modules always have a synthetic default when imported into ESM
-	// 		return true
-	// 	}
-	// 	if usageMode == core.ModuleKindESNext && targetMode == core.ModuleKindESNext {
-	// 		// No matter what the `module` setting is, if we're confident that both files
-	// 		// are ESM, there cannot be a synthetic default.
-	// 		return false
-	// 	}
-	// }
+	var usageMode core.ResolutionMode
+	if file != nil {
+		usageMode = c.getEmitSyntaxForModuleSpecifierExpression(usage)
+	}
+	if file != nil && usageMode != core.ModuleKindNone {
+		targetMode := c.program.GetImpliedNodeFormatForEmit(file.AsSourceFile())
+		if usageMode == core.ModuleKindESNext && targetMode == core.ModuleKindCommonJS && core.ModuleKindNode16 <= c.moduleKind && c.moduleKind <= core.ModuleKindNodeNext {
+			// In Node.js, CommonJS modules always have a synthetic default when imported into ESM
+			return true
+		}
+		if usageMode == core.ModuleKindESNext && targetMode == core.ModuleKindESNext {
+			// No matter what the `module` setting is, if we're confident that both files
+			// are ESM, there cannot be a synthetic default.
+			return false
+		}
+	}
 	if !c.allowSyntheticDefaultImports {
 		return false
 	}
 	// Declaration files (and ambient modules)
 	if file == nil || file.AsSourceFile().IsDeclarationFile {
 		// Definitely cannot have a synthetic default if they have a syntactic default member specified
-		defaultExportSymbol := c.resolveExportByName(moduleSymbol, ast.InternalSymbolNameDefault /*sourceNode*/, nil /*dontResolveAlias*/, true)
-		// Dont resolve alias because we want the immediately exported symbol's declaration
+		defaultExportSymbol := c.resolveExportByName(moduleSymbol, ast.InternalSymbolNameDefault /*sourceNode*/, nil /*dontResolveAlias*/, true) // Dont resolve alias because we want the immediately exported symbol's declaration
 		if defaultExportSymbol != nil && core.Some(defaultExportSymbol.Declarations, isSyntacticDefault) {
 			return false
 		}
@@ -13814,7 +13832,12 @@ func (c *Checker) canHaveSyntheticDefault(file *ast.Node, moduleSymbol *ast.Symb
 		return true
 	}
 	// TypeScript files never have a synthetic default (as they are always emitted with an __esModule marker) _unless_ they contain an export= statement
-	return hasExportAssignmentSymbol(moduleSymbol)
+	if !ast.IsInJSFile(file) {
+		return hasExportAssignmentSymbol(moduleSymbol)
+	}
+
+	// JS files have a synthetic default if they do not contain ES2015+ module syntax (export = is not valid in js) _and_ do not have an __esModule marker
+	return !ast.IsExternalModule(file.AsSourceFile()) && c.resolveExportByName(moduleSymbol, "__esModule", nil /*sourceNode*/, dontResolveAlias) == nil
 }
 
 func (c *Checker) getEmitSyntaxForModuleSpecifierExpression(usage *ast.Node) core.ResolutionMode {

testdata/baselines/reference/submodule/compiler/allowSyntheticDefaultImports3.errors.txt

@@ -0,0 +1,14 @@
+a.ts(1,8): error TS1192: Module '"b"' has no default export.
+
+
+==== a.ts (1 errors) ====
+    import Namespace from "./b";
+           ~~~~~~~~~
+!!! error TS1192: Module '"b"' has no default export.
+    export var x = new Namespace.Foo();
+    
+==== b.ts (0 errors) ====
+    export class Foo {
+    	member: string;
+    }
+    

testdata/baselines/reference/submodule/compiler/allowSyntheticDefaultImports3.errors.txt.diff

@@ -0,0 +1,27 @@
+service.ts(1,8): error TS2613: Module '"db"' has no default export. Did you mean to use 'import { db } from "db"' instead?
+
+
+==== db.ts (0 errors) ====
+    export class db {
+        public doSomething() {
+        }
+    }
+    
+==== service.ts (1 errors) ====
+    import db from './db'; // error no default export
+           ~~
+!!! error TS2613: Module '"db"' has no default export. Did you mean to use 'import { db } from "db"' instead?
+    function someDecorator(target) {
+        return target;
+    }
+    @someDecorator
+    class MyClass {
+        db: db.db;
+    
+        constructor(db: db.db) {
+            this.db = db;
+            this.db.doSomething();
+        }
+    }
+    export {MyClass};
+    

testdata/baselines/reference/submodule/compiler/decoratorMetadataWithImportDeclarationNameCollision4.errors.txt

@@ -27,19 +27,19 @@ class MyClass {
 >MyClass : MyClass
 
     db: db.db;
->db : error
+>db : db
 >db : any
 
     constructor(db: db.db) {
->db : error
+>db : db
 >db : any
 
         this.db = db;
->this.db = db : error
->this.db : error
+>this.db = db : db
+>this.db : db
 >this : this
 >db : db
->db : error
+>db : db
 
         this.db.doSomething();
 >this.db.doSomething() : any

testdata/baselines/reference/submodule/compiler/decoratorMetadataWithImportDeclarationNameCollision4.errors.txt.diff

@@ -5,24 +5,24 @@
 
      db: db.db;
 ->db : db.db
-+>db : error
++>db : db
  >db : any
 
      constructor(db: db.db) {
 ->db : db.db
-+>db : error
++>db : db
  >db : any
 
          this.db = db;
 ->this.db = db : db.db
 ->this.db : db.db
-+>this.db = db : error
-+>this.db : error
++>this.db = db : db
++>this.db : db
  >this : this
 ->db : db.db
 ->db : db.db
 +>db : db
-+>db : error
++>db : db
 
          this.db.doSomething();
  >this.db.doSomething() : any

testdata/baselines/reference/submodule/compiler/decoratorMetadataWithImportDeclarationNameCollision4.types

@@ -0,0 +1,42 @@
+client.ts(1,8): error TS1192: Module '"server"' has no default export.
+client.ts(2,8): error TS1192: Module '"server"' has no default export.
+client.ts(4,8): error TS1192: Module '"server"' has no default export.
+client.ts(6,8): error TS1192: Module '"server"' has no default export.
+client.ts(9,8): error TS1192: Module '"server"' has no default export.
+client.ts(11,8): error TS1192: Module '"server"' has no default export.
+
+
+==== server.ts (0 errors) ====
+    export class a { }
+    export class x { }
+    export class m { }
+    export class a11 { }
+    export class a12 { }
+    export class x11 { }
+    
+==== client.ts (6 errors) ====
+    import defaultBinding1, { } from "./server";
+           ~~~~~~~~~~~~~~~
+!!! error TS1192: Module '"server"' has no default export.
+    import defaultBinding2, { a } from "./server";
+           ~~~~~~~~~~~~~~~
+!!! error TS1192: Module '"server"' has no default export.
+    export var x1 = new a();
+    import defaultBinding3, { a11 as b } from "./server";
+           ~~~~~~~~~~~~~~~
+!!! error TS1192: Module '"server"' has no default export.
+    export var x2 = new b();
+    import defaultBinding4, { x, a12 as y } from "./server";
+           ~~~~~~~~~~~~~~~
+!!! error TS1192: Module '"server"' has no default export.
+    export var x4 = new x();
+    export var x5 = new y();
+    import defaultBinding5, { x11 as z,  } from "./server";
+           ~~~~~~~~~~~~~~~
+!!! error TS1192: Module '"server"' has no default export.
+    export var x3 = new z();
+    import defaultBinding6, { m,  } from "./server";
+           ~~~~~~~~~~~~~~~
+!!! error TS1192: Module '"server"' has no default export.
+    export var x6 = new m();
+    

testdata/baselines/reference/submodule/compiler/decoratorMetadataWithImportDeclarationNameCollision4.types.diff

@@ -0,0 +1,39 @@
+es6ImportDefaultBindingFollowedWithNamedImportInEs5_1.ts(1,8): error TS1192: Module '"es6ImportDefaultBindingFollowedWithNamedImportInEs5_0"' has no default export.
+es6ImportDefaultBindingFollowedWithNamedImportInEs5_1.ts(2,8): error TS1192: Module '"es6ImportDefaultBindingFollowedWithNamedImportInEs5_0"' has no default export.
+es6ImportDefaultBindingFollowedWithNamedImportInEs5_1.ts(4,8): error TS1192: Module '"es6ImportDefaultBindingFollowedWithNamedImportInEs5_0"' has no default export.
+es6ImportDefaultBindingFollowedWithNamedImportInEs5_1.ts(6,8): error TS1192: Module '"es6ImportDefaultBindingFollowedWithNamedImportInEs5_0"' has no default export.
+es6ImportDefaultBindingFollowedWithNamedImportInEs5_1.ts(9,8): error TS1192: Module '"es6ImportDefaultBindingFollowedWithNamedImportInEs5_0"' has no default export.
+es6ImportDefaultBindingFollowedWithNamedImportInEs5_1.ts(11,8): error TS1192: Module '"es6ImportDefaultBindingFollowedWithNamedImportInEs5_0"' has no default export.
+
+
+==== es6ImportDefaultBindingFollowedWithNamedImportInEs5_0.ts (0 errors) ====
+    export var a = 10;
+    export var x = a;
+    export var m = a;
+    
+==== es6ImportDefaultBindingFollowedWithNamedImportInEs5_1.ts (6 errors) ====
+    import defaultBinding1, { } from "./es6ImportDefaultBindingFollowedWithNamedImportInEs5_0";
+           ~~~~~~~~~~~~~~~
+!!! error TS1192: Module '"es6ImportDefaultBindingFollowedWithNamedImportInEs5_0"' has no default export.
+    import defaultBinding2, { a } from "./es6ImportDefaultBindingFollowedWithNamedImportInEs5_0";
+           ~~~~~~~~~~~~~~~
+!!! error TS1192: Module '"es6ImportDefaultBindingFollowedWithNamedImportInEs5_0"' has no default export.
+    var x1: number = a;
+    import defaultBinding3, { a as b } from "./es6ImportDefaultBindingFollowedWithNamedImportInEs5_0";
+           ~~~~~~~~~~~~~~~
+!!! error TS1192: Module '"es6ImportDefaultBindingFollowedWithNamedImportInEs5_0"' has no default export.
+    var x1: number = b;
+    import defaultBinding4, { x, a as y } from "./es6ImportDefaultBindingFollowedWithNamedImportInEs5_0";
+           ~~~~~~~~~~~~~~~
+!!! error TS1192: Module '"es6ImportDefaultBindingFollowedWithNamedImportInEs5_0"' has no default export.
+    var x1: number = x;
+    var x1: number = y;
+    import defaultBinding5, { x as z,  } from "./es6ImportDefaultBindingFollowedWithNamedImportInEs5_0";
+           ~~~~~~~~~~~~~~~
+!!! error TS1192: Module '"es6ImportDefaultBindingFollowedWithNamedImportInEs5_0"' has no default export.
+    var x1: number = z;
+    import defaultBinding6, { m,  } from "./es6ImportDefaultBindingFollowedWithNamedImportInEs5_0";
+           ~~~~~~~~~~~~~~~
+!!! error TS1192: Module '"es6ImportDefaultBindingFollowedWithNamedImportInEs5_0"' has no default export.
+    var x1: number = m;
+