Don't bother trying to get the name of a default export (microsoft#25773)

Andy · web-flow · commit 751f20e8bc1b · 2018-07-18T11:43:13.000-07:00
* Don't bother trying to get the name of a default export

* Fix lint
diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
@@ -306,7 +306,7 @@ namespace ts {
         }
 
         function getDisplayName(node: Declaration): string {
-            return isNamedDeclaration(node) ? declarationNameToString(node.name) : unescapeLeadingUnderscores(getDeclarationName(node)!); // TODO: GH#18217
+            return isNamedDeclaration(node) ? declarationNameToString(node.name) : unescapeLeadingUnderscores(Debug.assertDefined(getDeclarationName(node)));
         }
 
         /**
@@ -383,9 +383,11 @@ namespace ts {
                         let message = symbol.flags & SymbolFlags.BlockScopedVariable
                             ? Diagnostics.Cannot_redeclare_block_scoped_variable_0
                             : Diagnostics.Duplicate_identifier_0;
+                        let messageNeedsName = true;
 
                         if (symbol.flags & SymbolFlags.Enum || includes & SymbolFlags.Enum) {
                             message = Diagnostics.Enum_declarations_can_only_merge_with_namespace_or_other_enum_declarations;
+                            messageNeedsName = false;
                         }
 
                         if (symbol.declarations && symbol.declarations.length) {
@@ -394,6 +396,7 @@ namespace ts {
                             // We'll know whether we have other default exports depending on if `symbol` already has a declaration list set.
                             if (isDefaultExport) {
                                 message = Diagnostics.A_module_cannot_have_multiple_default_exports;
+                                messageNeedsName = false;
                             }
                             else {
                                 // This is to properly report an error in the case "export default { }" is after export default of class declaration or function declaration.
@@ -403,14 +406,16 @@ namespace ts {
                                 if (symbol.declarations && symbol.declarations.length &&
                                     (node.kind === SyntaxKind.ExportAssignment && !(<ExportAssignment>node).isExportEquals)) {
                                     message = Diagnostics.A_module_cannot_have_multiple_default_exports;
+                                    messageNeedsName = false;
                                 }
                             }
                         }
 
-                        forEach(symbol.declarations, declaration => {
-                            file.bindDiagnostics.push(createDiagnosticForNode(getNameOfDeclaration(declaration) || declaration, message, getDisplayName(declaration)));
-                        });
-                        file.bindDiagnostics.push(createDiagnosticForNode(getNameOfDeclaration(node) || node, message, getDisplayName(node)));
+                        const addError = (decl: Declaration): void => {
+                            file.bindDiagnostics.push(createDiagnosticForNode(getNameOfDeclaration(decl) || decl, message, messageNeedsName ? getDisplayName(decl) : undefined));
+                        };
+                        forEach(symbol.declarations, addError);
+                        addError(node);
 
                         symbol = createSymbol(SymbolFlags.None, name);
                     }
diff --git a/tests/baselines/reference/duplicateDefaultExport.errors.txt b/tests/baselines/reference/duplicateDefaultExport.errors.txt
@@ -0,0 +1,12 @@
+tests/cases/compiler/duplicateDefaultExport.ts(1,1): error TS2528: A module cannot have multiple default exports.
+tests/cases/compiler/duplicateDefaultExport.ts(2,1): error TS2528: A module cannot have multiple default exports.
+
+
+==== tests/cases/compiler/duplicateDefaultExport.ts (2 errors) ====
+    export default 0;
+    ~~~~~~~~~~~~~~~~~
+!!! error TS2528: A module cannot have multiple default exports.
+    export default function() {}
+    ~~~~~~
+!!! error TS2528: A module cannot have multiple default exports.
+    
diff --git a/tests/baselines/reference/duplicateDefaultExport.js b/tests/baselines/reference/duplicateDefaultExport.js
@@ -0,0 +1,11 @@
+//// [duplicateDefaultExport.ts]
+export default 0;
+export default function() {}
+
+
+//// [duplicateDefaultExport.js]
+"use strict";
+exports.__esModule = true;
+exports["default"] = 0;
+function default_1() { }
+exports["default"] = default_1;
diff --git a/tests/baselines/reference/duplicateDefaultExport.symbols b/tests/baselines/reference/duplicateDefaultExport.symbols
@@ -0,0 +1,5 @@
+=== tests/cases/compiler/duplicateDefaultExport.ts ===
+export default 0;
+No type information for this code.export default function() {}
+No type information for this code.
+No type information for this code.
diff --git a/tests/baselines/reference/duplicateDefaultExport.types b/tests/baselines/reference/duplicateDefaultExport.types
@@ -0,0 +1,5 @@
+=== tests/cases/compiler/duplicateDefaultExport.ts ===
+export default 0;
+No type information for this code.export default function() {}
+No type information for this code.
+No type information for this code.
diff --git a/tests/cases/compiler/duplicateDefaultExport.ts b/tests/cases/compiler/duplicateDefaultExport.ts
@@ -0,0 +1,2 @@
+export default 0;
+export default function() {}

Original file line number	Diff line number	Diff line change
`@@ -306,7 +306,7 @@ namespace ts {`
`306`	`306`	`}`
`307`	`307`
`308`	`308`	`function getDisplayName(node: Declaration): string {`
`309`		`- return isNamedDeclaration(node) ? declarationNameToString(node.name) : unescapeLeadingUnderscores(getDeclarationName(node)!); // TODO: GH#18217`
	`309`	`+ return isNamedDeclaration(node) ? declarationNameToString(node.name) : unescapeLeadingUnderscores(Debug.assertDefined(getDeclarationName(node)));`
`310`	`310`	`}`
`311`	`311`
`312`	`312`	`/**`
`@@ -383,9 +383,11 @@ namespace ts {`
`383`	`383`	`let message = symbol.flags & SymbolFlags.BlockScopedVariable`
`384`	`384`	`? Diagnostics.Cannot_redeclare_block_scoped_variable_0`
`385`	`385`	`: Diagnostics.Duplicate_identifier_0;`
	`386`	`+ let messageNeedsName = true;`
`386`	`387`
`387`	`388`	`if (symbol.flags & SymbolFlags.Enum \|\| includes & SymbolFlags.Enum) {`
`388`	`389`	`message = Diagnostics.Enum_declarations_can_only_merge_with_namespace_or_other_enum_declarations;`
	`390`	`+ messageNeedsName = false;`
`389`	`391`	`}`
`390`	`392`
`391`	`393`	`if (symbol.declarations && symbol.declarations.length) {`
`@@ -394,6 +396,7 @@ namespace ts {`
`394`	`396`	// We'll know whether we have other default exports depending on if `symbol` already has a declaration list set.
`395`	`397`	`if (isDefaultExport) {`
`396`	`398`	`message = Diagnostics.A_module_cannot_have_multiple_default_exports;`
	`399`	`+ messageNeedsName = false;`
`397`	`400`	`}`
`398`	`401`	`else {`
`399`	`402`	`// This is to properly report an error in the case "export default { }" is after export default of class declaration or function declaration.`
`@@ -403,14 +406,16 @@ namespace ts {`
`403`	`406`	`if (symbol.declarations && symbol.declarations.length &&`
`404`	`407`	`(node.kind === SyntaxKind.ExportAssignment && !(<ExportAssignment>node).isExportEquals)) {`
`405`	`408`	`message = Diagnostics.A_module_cannot_have_multiple_default_exports;`
	`409`	`+ messageNeedsName = false;`
`406`	`410`	`}`
`407`	`411`	`}`
`408`	`412`	`}`
`409`	`413`
`410`		`- forEach(symbol.declarations, declaration => {`
`411`		`- file.bindDiagnostics.push(createDiagnosticForNode(getNameOfDeclaration(declaration) \|\| declaration, message, getDisplayName(declaration)));`
`412`		`- });`
`413`		`- file.bindDiagnostics.push(createDiagnosticForNode(getNameOfDeclaration(node) \|\| node, message, getDisplayName(node)));`
	`414`	`+ const addError = (decl: Declaration): void => {`
	`415`	`+ file.bindDiagnostics.push(createDiagnosticForNode(getNameOfDeclaration(decl) \|\| decl, message, messageNeedsName ? getDisplayName(decl) : undefined));`
	`416`	`+ };`
	`417`	`+ forEach(symbol.declarations, addError);`
	`418`	`+ addError(node);`
`414`	`419`
`415`	`420`	`symbol = createSymbol(SymbolFlags.None, name);`
`416`	`421`	`}`
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+export default 0;`
	`2`	`+export default function() {}`