From d137029f786e63bf29db6ff36feff5e3b7733a33 Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Mon, 11 Jun 2018 09:18:38 -0700
Subject: [PATCH] goToDefinition: Don't add duplicate definitions for
 VariableDeclaration and ArrowFunction at `f = () => {}`

---
 src/services/goToDefinition.ts                        | 11 ++++++++++-
 tests/cases/fourslash/goToDefinitionSignatureAlias.ts |  9 +++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/services/goToDefinition.ts b/src/services/goToDefinition.ts
index 1281f30d73371..2c0a1f2b75655 100644
--- a/src/services/goToDefinition.ts
+++ b/src/services/goToDefinition.ts
@@ -32,7 +32,7 @@ namespace ts.GoToDefinition {
             const sigInfo = createDefinitionFromSignatureDeclaration(typeChecker, calledDeclaration);
             // For a function, if this is the original function definition, return just sigInfo.
             // If this is the original constructor definition, parent is the class.
-            if (typeChecker.getRootSymbols(symbol).some(s => calledDeclaration.symbol === s || calledDeclaration.symbol.parent === s) ||
+            if (typeChecker.getRootSymbols(symbol).some(s => symbolMatchesSignature(s, calledDeclaration)) ||
                 // TODO: GH#23742 Following check shouldn't be necessary if 'require' is an alias
                 symbol.declarations.some(d => isVariableDeclaration(d) && !!d.initializer && isRequireCall(d.initializer, /*checkArgumentIsStringLiteralLike*/ false))) {
                 return [sigInfo];
@@ -93,6 +93,15 @@ namespace ts.GoToDefinition {
         return getDefinitionFromSymbol(typeChecker, symbol, node);
     }
 
+    /**
+     * True if we should not add definitions for both the signature symbol and the definition symbol.
+     * True for `const |f = |() => 0`, false for `function |f() {} const |g = f;`.
+     */
+    function symbolMatchesSignature(s: Symbol, calledDeclaration: SignatureDeclaration) {
+        return s === calledDeclaration.symbol || s === calledDeclaration.symbol.parent ||
+            isVariableDeclaration(calledDeclaration.parent) && s === calledDeclaration.parent.symbol;
+    }
+
     export function getReferenceAtPosition(sourceFile: SourceFile, position: number, program: Program): { fileName: string, file: SourceFile } | undefined {
         const referencePath = findReferenceInPosition(sourceFile.referencedFiles, position);
         if (referencePath) {
diff --git a/tests/cases/fourslash/goToDefinitionSignatureAlias.ts b/tests/cases/fourslash/goToDefinitionSignatureAlias.ts
index 27ff0eb69d974..3657ebfd0d6a8 100644
--- a/tests/cases/fourslash/goToDefinitionSignatureAlias.ts
+++ b/tests/cases/fourslash/goToDefinitionSignatureAlias.ts
@@ -8,8 +8,17 @@
 ////[|/*useG*/g|]();
 ////[|/*useH*/h|]();
 
+////const i = /*i*/() => 0;
+////const /*j*/j = i;
+
+////[|/*useI*/i|]();
+////[|/*useJ*/j|]();
+
 verify.goToDefinition({
     useF: "f",
     useG: ["g", "f"],
     useH: ["h", "f"],
+
+    useI: "i",
+    useJ: ["j", "i"],
 });