Merge pull request #7119 from Microsoft/checkRedeclarations

correctly check exported type aliases merged with overloads
microsoft · Feb 17, 2016 · 29b9fd3 · 29b9fd3
2 parents fdb8dc8 + 5e770bd
commit 29b9fd3
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Showing 5 changed files with 47 additions and 5 deletions.
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -15055,11 +15055,20 @@ namespace ts {
                         continue;
                     }
                     const { declarations, flags } = exports[id];
-                    // ECMA262: 15.2.1.1 It is a Syntax Error if the ExportedNames of ModuleItemList contains any duplicate entries. (TS Exceptions: namespaces, function overloads, enums, and interfaces)
-                    if (!(flags & (SymbolFlags.Namespace | SymbolFlags.Interface | SymbolFlags.Enum)) && (flags & SymbolFlags.TypeAlias ? declarations.length - 1 : declarations.length) > 1) {
-                        const exportedDeclarations: Declaration[] = filter(declarations, isNotOverload);
-                        if (exportedDeclarations.length > 1) {
-                            for (const declaration of exportedDeclarations) {
+                    // ECMA262: 15.2.1.1 It is a Syntax Error if the ExportedNames of ModuleItemList contains any duplicate entries. 
+                    // (TS Exceptions: namespaces, function overloads, enums, and interfaces)
+                    if (flags & (SymbolFlags.Namespace | SymbolFlags.Interface | SymbolFlags.Enum)) {
+                        continue;
+                    }
+                    const exportedDeclarationsCount = countWhere(declarations, isNotOverload);
+                    if (flags & SymbolFlags.TypeAlias && exportedDeclarationsCount <= 2) {
+                        // it is legal to merge type alias with other values
+                        // so count should be either 1 (just type alias) or 2 (type alias + merged value)
+                        continue;
+                    }
+                    if (exportedDeclarationsCount > 1) {
+                        for (const declaration of declarations) {
+                            if (isNotOverload(declaration)) {
                                 diagnostics.add(createDiagnosticForNode(declaration, Diagnostics.Cannot_redeclare_exported_variable_0, id));
                             }
                         }

diff --git a/tests/baselines/reference/exportRedeclarationTypeAliases.js b/tests/baselines/reference/exportRedeclarationTypeAliases.js
@@ -0,0 +1,9 @@
+//// [exportRedeclarationTypeAliases.ts]
+export type Foo = number;
+export function Foo(): number;
+export function Foo(): any {}
+
+//// [exportRedeclarationTypeAliases.js]
+"use strict";
+function Foo() { }
+exports.Foo = Foo;
diff --git a/tests/baselines/reference/exportRedeclarationTypeAliases.symbols b/tests/baselines/reference/exportRedeclarationTypeAliases.symbols
@@ -0,0 +1,10 @@
+=== tests/cases/compiler/exportRedeclarationTypeAliases.ts ===
+export type Foo = number;
+>Foo : Symbol(Foo, Decl(exportRedeclarationTypeAliases.ts, 0, 0), Decl(exportRedeclarationTypeAliases.ts, 0, 25), Decl(exportRedeclarationTypeAliases.ts, 1, 30))
+
+export function Foo(): number;
+>Foo : Symbol(Foo, Decl(exportRedeclarationTypeAliases.ts, 0, 0), Decl(exportRedeclarationTypeAliases.ts, 0, 25), Decl(exportRedeclarationTypeAliases.ts, 1, 30))
+
+export function Foo(): any {}
+>Foo : Symbol(Foo, Decl(exportRedeclarationTypeAliases.ts, 0, 0), Decl(exportRedeclarationTypeAliases.ts, 0, 25), Decl(exportRedeclarationTypeAliases.ts, 1, 30))
+
diff --git a/tests/baselines/reference/exportRedeclarationTypeAliases.types b/tests/baselines/reference/exportRedeclarationTypeAliases.types
@@ -0,0 +1,10 @@
+=== tests/cases/compiler/exportRedeclarationTypeAliases.ts ===
+export type Foo = number;
+>Foo : number
+
+export function Foo(): number;
+>Foo : () => number
+
+export function Foo(): any {}
+>Foo : () => number
+
diff --git a/tests/cases/compiler/exportRedeclarationTypeAliases.ts b/tests/cases/compiler/exportRedeclarationTypeAliases.ts
@@ -0,0 +1,4 @@
+// @module: commonjs
+export type Foo = number;
+export function Foo(): number;
+export function Foo(): any {}