From 671d83e81adecf37258532fd8e6d061f0d0d888c Mon Sep 17 00:00:00 2001
From: Ryan Cavanaugh <RyanCavanaugh@users.noreply.github.com>
Date: Mon, 1 Feb 2016 20:59:37 -0800
Subject: [PATCH] Treat multiple prototype property assignments as union
 property declarations

(cherry picked from commit a4c6f666862d14e187bb7e09615fdfc0c92ab875)
---
 src/compiler/checker.ts                          |  2 +-
 .../getJavaScriptSemanticDiagnostics24.ts        | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)
 create mode 100644 tests/cases/fourslash/getJavaScriptSemanticDiagnostics24.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index e0caf84fa9d..93339901c07 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -2845,7 +2845,7 @@ namespace ts {
                 }
                 // Handle module.exports = expr
                 if (declaration.kind === SyntaxKind.BinaryExpression) {
-                    return links.type = checkExpression((<BinaryExpression>declaration).right);
+                    return links.type = getUnionType(map(symbol.declarations, (decl: BinaryExpression) => checkExpressionCached(decl.right)));
                 }
                 if (declaration.kind === SyntaxKind.PropertyAccessExpression) {
                     // Declarations only exist for property access expressions for certain
diff --git a/tests/cases/fourslash/getJavaScriptSemanticDiagnostics24.ts b/tests/cases/fourslash/getJavaScriptSemanticDiagnostics24.ts
new file mode 100644
index 00000000000..cf70f883e99
--- /dev/null
+++ b/tests/cases/fourslash/getJavaScriptSemanticDiagnostics24.ts
@@ -0,0 +1,16 @@
+/// <reference path="fourslash.ts" />
+
+// @allowJs: true
+// @Filename: a.js
+//// function Person(age) {
+////     if (age >= 18) {
+////         this.canVote = true;
+////     } else {
+////         this.canVote = 23;
+////     }
+//// }
+//// let x = new Person(100);
+//// x.canVote/**/;
+
+goTo.marker();
+verify.quickInfoIs('(property) Person.canVote: boolean | number');