From 60c0dfeb2544fbbee6a1f601443a56bd07daca02 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
Date: Tue, 10 Jul 2018 08:32:56 -0700
Subject: [PATCH] Fix crash in JS when checking destructuring shorthand
 assignment (#25529)

---
 src/compiler/checker.ts                         |  2 +-
 ...ckDestructuringShorthandAssigment.errors.txt | 11 +++++++++++
 ...checkDestructuringShorthandAssigment.symbols | 10 ++++++++++
 .../checkDestructuringShorthandAssigment.types  | 17 +++++++++++++++++
 .../checkDestructuringShorthandAssigment.ts     |  8 ++++++++
 5 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/checkDestructuringShorthandAssigment.errors.txt
 create mode 100644 tests/baselines/reference/checkDestructuringShorthandAssigment.symbols
 create mode 100644 tests/baselines/reference/checkDestructuringShorthandAssigment.types
 create mode 100644 tests/cases/compiler/checkDestructuringShorthandAssigment.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index b8b215e32f9..3ddf460f80f 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -21128,7 +21128,7 @@ namespace ts {
                         getUnionType([removeDefinitelyFalsyTypes(leftType), rightType], UnionReduction.Subtype) :
                         leftType;
                 case SyntaxKind.EqualsToken:
-                    const special = getSpecialPropertyAssignmentKind(left.parent as BinaryExpression);
+                    const special = isBinaryExpression(left.parent) ? getSpecialPropertyAssignmentKind(left.parent) : SpecialPropertyAssignmentKind.None;
                     checkSpecialAssignment(special, right);
                     if (isJSSpecialPropertyAssignment(special)) {
                         return leftType;
diff --git a/tests/baselines/reference/checkDestructuringShorthandAssigment.errors.txt b/tests/baselines/reference/checkDestructuringShorthandAssigment.errors.txt
new file mode 100644
index 00000000000..aca20286905
--- /dev/null
+++ b/tests/baselines/reference/checkDestructuringShorthandAssigment.errors.txt
@@ -0,0 +1,11 @@
+tests/cases/compiler/bug25434.js(4,9): error TS2304: Cannot find name 'b'.
+
+
+==== tests/cases/compiler/bug25434.js (1 errors) ====
+    // should not crash while checking
+    function Test({ b = '' } = {}) {}
+    
+    Test(({ b = '5' } = {}));
+            ~
+!!! error TS2304: Cannot find name 'b'.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/checkDestructuringShorthandAssigment.symbols b/tests/baselines/reference/checkDestructuringShorthandAssigment.symbols
new file mode 100644
index 00000000000..efe0b4f0850
--- /dev/null
+++ b/tests/baselines/reference/checkDestructuringShorthandAssigment.symbols
@@ -0,0 +1,10 @@
+=== tests/cases/compiler/bug25434.js ===
+// should not crash while checking
+function Test({ b = '' } = {}) {}
+>Test : Symbol(Test, Decl(bug25434.js, 0, 0))
+>b : Symbol(b, Decl(bug25434.js, 1, 15))
+
+Test(({ b = '5' } = {}));
+>Test : Symbol(Test, Decl(bug25434.js, 0, 0))
+>b : Symbol(b, Decl(bug25434.js, 3, 7))
+
diff --git a/tests/baselines/reference/checkDestructuringShorthandAssigment.types b/tests/baselines/reference/checkDestructuringShorthandAssigment.types
new file mode 100644
index 00000000000..9eccb886051
--- /dev/null
+++ b/tests/baselines/reference/checkDestructuringShorthandAssigment.types
@@ -0,0 +1,17 @@
+=== tests/cases/compiler/bug25434.js ===
+// should not crash while checking
+function Test({ b = '' } = {}) {}
+>Test : ({ b }?: { [x: string]: any; }) => void
+>b : string
+>'' : ""
+>{} : { b?: string; }
+
+Test(({ b = '5' } = {}));
+>Test(({ b = '5' } = {})) : void
+>Test : ({ b }?: { [x: string]: any; }) => void
+>({ b = '5' } = {}) : { b?: any; }
+>{ b = '5' } = {} : { b?: any; }
+>{ b = '5' } : { [x: string]: any; b?: any; }
+>b : any
+>{} : { b?: any; }
+
diff --git a/tests/cases/compiler/checkDestructuringShorthandAssigment.ts b/tests/cases/compiler/checkDestructuringShorthandAssigment.ts
new file mode 100644
index 00000000000..e3422aae753
--- /dev/null
+++ b/tests/cases/compiler/checkDestructuringShorthandAssigment.ts
@@ -0,0 +1,8 @@
+// @allowjs: true
+// @checkjs: true
+// @noEmit: true
+// @Filename: bug25434.js
+// should not crash while checking
+function Test({ b = '' } = {}) {}
+
+Test(({ b = '5' } = {}));