Merge pull request #514 from Microsoft/overloadSignatureDeclaration

Correct the declaration emit for overload implementation if there is single overload signature

Author: sheetalkamat

src/compiler/checker.ts

@@ -7096,7 +7096,20 @@ module ts {
         function isImplementationOfOverload(node: FunctionDeclaration) {
             if (node.body) {
                 var symbol = getSymbolOfNode(node);
-                return getSignaturesOfSymbol(symbol).length > 1;
+                var signaturesOfSymbol = getSignaturesOfSymbol(symbol);
+                // If this function body corresponds to function with multiple signature, it is implementation of overload
+                // eg: function foo(a: string): string;
+                //     function foo(a: number): number;
+                //     function foo(a: any) { // This is implementation of the overloads
+                //         return a;
+                //     }
+                return signaturesOfSymbol.length > 1 ||
+                    // If there is single signature for the symbol, it is overload if that signature isnt coming from the node
+                    // eg: function foo(a: string): string;
+                    //     function foo(a: any) { // This is implementation of the overloads
+                    //         return a;
+                    //     }
+                    (signaturesOfSymbol.length === 1 && signaturesOfSymbol[0].declaration !== node);
             }
             return false;
         }

tests/baselines/reference/declFileFunctions.js

@@ -21,6 +21,11 @@ export function fooWithOverloads(a: any): any {
     return a;
 }
 
+export function fooWithSingleOverload(a: string): string;
+export function fooWithSingleOverload(a: any) {
+    return a;
+}
+
 /** This comment should appear for nonExportedFoo*/
 function nonExportedFoo() {
 }
@@ -83,6 +88,10 @@ function fooWithOverloads(a) {
     return a;
 }
 exports.fooWithOverloads = fooWithOverloads;
+function fooWithSingleOverload(a) {
+    return a;
+}
+exports.fooWithSingleOverload = fooWithSingleOverload;
 /** This comment should appear for nonExportedFoo*/
 function nonExportedFoo() {
 }
@@ -134,6 +143,7 @@ export declare function fooWithParameters(/** this is comment about a*/ a: strin
 export declare function fooWithRestParameters(a: string, ...rests: string[]): string;
 export declare function fooWithOverloads(a: string): string;
 export declare function fooWithOverloads(a: number): number;
+export declare function fooWithSingleOverload(a: string): string;
 //// [declFileFunctions_1.d.ts]
 /** This comment should appear for foo*/
 declare function globalfoo(): void;

tests/baselines/reference/declFileFunctions.types

@@ -47,6 +47,18 @@ export function fooWithOverloads(a: any): any {
 >a : any
 }
 
+export function fooWithSingleOverload(a: string): string;
+>fooWithSingleOverload : (a: string) => string
+>a : string
+
+export function fooWithSingleOverload(a: any) {
+>fooWithSingleOverload : (a: string) => string
+>a : any
+
+    return a;
+>a : any
+}
+
 /** This comment should appear for nonExportedFoo*/
 function nonExportedFoo() {
 >nonExportedFoo : () => void

tests/cases/compiler/declFileFunctions.ts

@@ -23,6 +23,11 @@ export function fooWithOverloads(a: any): any {
     return a;
 }
 
+export function fooWithSingleOverload(a: string): string;
+export function fooWithSingleOverload(a: any) {
+    return a;
+}
+
 /** This comment should appear for nonExportedFoo*/
 function nonExportedFoo() {
 }