From dd06cbb3156aa6499756cf4da75e3492ae4b2e0a Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Mon, 27 Mar 2017 14:32:45 -0700
Subject: [PATCH] getSpecialPropertyAssignmentKind: Always check for
 BinaryExpression *outside*, always check for JS file *inside*

---
 src/compiler/binder.ts    | 48 +++++++++++++++++++--------------------
 src/compiler/checker.ts   |  6 ++---
 src/compiler/utilities.ts |  5 +---
 3 files changed, 27 insertions(+), 32 deletions(-)

diff --git a/src/compiler/binder.ts b/src/compiler/binder.ts
index 650797c6dba2a..45e8efdf5128c 100644
--- a/src/compiler/binder.ts
+++ b/src/compiler/binder.ts
@@ -259,7 +259,7 @@ namespace ts {
                 case SyntaxKind.ExportAssignment:
                     return (<ExportAssignment>node).isExportEquals ? "export=" : "default";
                 case SyntaxKind.BinaryExpression:
-                    switch (getSpecialPropertyAssignmentKind(node)) {
+                    switch (getSpecialPropertyAssignmentKind(node as BinaryExpression)) {
                         case SpecialPropertyAssignmentKind.ModuleExports:
                             // module.exports = ...
                             return "export=";
@@ -2017,30 +2017,28 @@ namespace ts {
                     }
                     break;
                 case SyntaxKind.BinaryExpression:
-                    if (isInJavaScriptFile(node)) {
-                        const specialKind = getSpecialPropertyAssignmentKind(node);
-                        switch (specialKind) {
-                            case SpecialPropertyAssignmentKind.ExportsProperty:
-                                bindExportsPropertyAssignment(<BinaryExpression>node);
-                                break;
-                            case SpecialPropertyAssignmentKind.ModuleExports:
-                                bindModuleExportsAssignment(<BinaryExpression>node);
-                                break;
-                            case SpecialPropertyAssignmentKind.PrototypeProperty:
-                                bindPrototypePropertyAssignment(<BinaryExpression>node);
-                                break;
-                            case SpecialPropertyAssignmentKind.ThisProperty:
-                                bindThisPropertyAssignment(<BinaryExpression>node);
-                                break;
-                            case SpecialPropertyAssignmentKind.Property:
-                                bindStaticPropertyAssignment(<BinaryExpression>node);
-                                break;
-                            case SpecialPropertyAssignmentKind.None:
-                                // Nothing to do
-                                break;
-                            default:
-                                Debug.fail("Unknown special property assignment kind");
-                        }
+                    const specialKind = getSpecialPropertyAssignmentKind(node as BinaryExpression);
+                    switch (specialKind) {
+                        case SpecialPropertyAssignmentKind.ExportsProperty:
+                            bindExportsPropertyAssignment(<BinaryExpression>node);
+                            break;
+                        case SpecialPropertyAssignmentKind.ModuleExports:
+                            bindModuleExportsAssignment(<BinaryExpression>node);
+                            break;
+                        case SpecialPropertyAssignmentKind.PrototypeProperty:
+                            bindPrototypePropertyAssignment(<BinaryExpression>node);
+                            break;
+                        case SpecialPropertyAssignmentKind.ThisProperty:
+                            bindThisPropertyAssignment(<BinaryExpression>node);
+                            break;
+                        case SpecialPropertyAssignmentKind.Property:
+                            bindStaticPropertyAssignment(<BinaryExpression>node);
+                            break;
+                        case SpecialPropertyAssignmentKind.None:
+                            // Nothing to do
+                            break;
+                        default:
+                            Debug.fail("Unknown special property assignment kind");
                     }
                     return checkStrictModeBinaryExpression(<BinaryExpression>node);
                 case SyntaxKind.CatchClause:
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 4e55a1c46b564..408739f480f25 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -11929,8 +11929,8 @@ namespace ts {
                 // If this is a function in a JS file, it might be a class method. Check if it's the RHS
                 // of a x.prototype.y = function [name]() { .... }
                 if (container.kind === SyntaxKind.FunctionExpression &&
-                    isInJavaScriptFile(container.parent) &&
-                    getSpecialPropertyAssignmentKind(container.parent) === SpecialPropertyAssignmentKind.PrototypeProperty) {
+                    container.parent.kind === SyntaxKind.BinaryExpression &&
+                    getSpecialPropertyAssignmentKind(container.parent as BinaryExpression) === SpecialPropertyAssignmentKind.PrototypeProperty) {
                     // Get the 'x' of 'x.prototype.y = f' (here, 'f' is 'container')
                     const className = (((container.parent as BinaryExpression)   // x.prototype.y = f
                         .left as PropertyAccessExpression)       // x.prototype.y
@@ -21641,7 +21641,7 @@ namespace ts {
         }
 
         function getSpecialPropertyAssignmentSymbolFromEntityName(entityName: EntityName | PropertyAccessExpression) {
-            const specialPropertyAssignmentKind = getSpecialPropertyAssignmentKind(entityName.parent.parent);
+            const specialPropertyAssignmentKind = getSpecialPropertyAssignmentKind(entityName.parent.parent as BinaryExpression);
             switch (specialPropertyAssignmentKind) {
                 case SpecialPropertyAssignmentKind.ExportsProperty:
                 case SpecialPropertyAssignmentKind.PrototypeProperty:
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
index 33cb0d8f4898d..f0916855986cc 100644
--- a/src/compiler/utilities.ts
+++ b/src/compiler/utilities.ts
@@ -1450,13 +1450,10 @@ namespace ts {
 
     /// Given a BinaryExpression, returns SpecialPropertyAssignmentKind for the various kinds of property
     /// assignments we treat as special in the binder
-    export function getSpecialPropertyAssignmentKind(expression: Node): SpecialPropertyAssignmentKind {
+    export function getSpecialPropertyAssignmentKind(expression: ts.BinaryExpression): SpecialPropertyAssignmentKind {
         if (!isInJavaScriptFile(expression)) {
             return SpecialPropertyAssignmentKind.None;
         }
-        if (expression.kind !== SyntaxKind.BinaryExpression) {
-            return SpecialPropertyAssignmentKind.None;
-        }
         const expr = <BinaryExpression>expression;
         if (expr.operatorToken.kind !== SyntaxKind.EqualsToken || expr.left.kind !== SyntaxKind.PropertyAccessExpression) {
             return SpecialPropertyAssignmentKind.None;