From dcbaadaa606585c8aedef8565fb284afb2621c0c Mon Sep 17 00:00:00 2001
From: Andy Hanson <anhans@microsoft.com>
Date: Fri, 20 May 2016 08:54:05 -0700
Subject: [PATCH] Allow assignment to readonly parameter property within the
 constructor

---
 src/compiler/checker.ts                          | 14 ++++++++++++--
 .../reference/readonlyConstructorAssignment.js   | 16 ++++++++++++++++
 .../readonlyConstructorAssignment.symbols        | 14 ++++++++++++++
 .../readonlyConstructorAssignment.types          | 16 ++++++++++++++++
 .../readonlyConstructorAssignment.ts             |  5 +++++
 5 files changed, 63 insertions(+), 2 deletions(-)
 create mode 100644 tests/baselines/reference/readonlyConstructorAssignment.js
 create mode 100644 tests/baselines/reference/readonlyConstructorAssignment.symbols
 create mode 100644 tests/baselines/reference/readonlyConstructorAssignment.types
 create mode 100644 tests/cases/conformance/classes/constructorDeclarations/constructorParameters/readonlyConstructorAssignment.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 476695e3ec..8b15d7291b 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -11882,8 +11882,18 @@ namespace ts {
                 if (symbol.flags & SymbolFlags.Property &&
                     (expr.kind === SyntaxKind.PropertyAccessExpression || expr.kind === SyntaxKind.ElementAccessExpression) &&
                     (expr as PropertyAccessExpression | ElementAccessExpression).expression.kind === SyntaxKind.ThisKeyword) {
-                    const func = getContainingFunction(expr);
-                    return !(func && func.kind === SyntaxKind.Constructor && func.parent === symbol.valueDeclaration.parent);
+                    return !isInConstructor(getContainingFunction(expr));
+                    function isInConstructor(func: FunctionLikeDeclaration) {
+                        if (!func)
+                            return false;
+                        if (func.kind !== SyntaxKind.Constructor)
+                            return false;
+                        if (func.parent === symbol.valueDeclaration.parent) // If the symbol was declared in the class:
+                            return true;
+                        if (func === symbol.valueDeclaration.parent) // If symbolDecl is a parameter property of the constructor:
+                            return true;
+                        return false;
+                    }
                 }
                 return true;
             }
diff --git a/tests/baselines/reference/readonlyConstructorAssignment.js b/tests/baselines/reference/readonlyConstructorAssignment.js
new file mode 100644
index 0000000000..3d00f829a7
--- /dev/null
+++ b/tests/baselines/reference/readonlyConstructorAssignment.js
@@ -0,0 +1,16 @@
+//// [readonlyConstructorAssignment.ts]
+class A {
+    constructor(readonly x: number) {
+        this.x = 7;
+    }
+}
+
+
+//// [readonlyConstructorAssignment.js]
+var A = (function () {
+    function A(x) {
+        this.x = x;
+        this.x = 7;
+    }
+    return A;
+}());
diff --git a/tests/baselines/reference/readonlyConstructorAssignment.symbols b/tests/baselines/reference/readonlyConstructorAssignment.symbols
new file mode 100644
index 0000000000..594f9e02b6
--- /dev/null
+++ b/tests/baselines/reference/readonlyConstructorAssignment.symbols
@@ -0,0 +1,14 @@
+=== tests/cases/conformance/classes/constructorDeclarations/constructorParameters/readonlyConstructorAssignment.ts ===
+class A {
+>A : Symbol(A, Decl(readonlyConstructorAssignment.ts, 0, 0))
+
+    constructor(readonly x: number) {
+>x : Symbol(A.x, Decl(readonlyConstructorAssignment.ts, 1, 16))
+
+        this.x = 7;
+>this.x : Symbol(A.x, Decl(readonlyConstructorAssignment.ts, 1, 16))
+>this : Symbol(A, Decl(readonlyConstructorAssignment.ts, 0, 0))
+>x : Symbol(A.x, Decl(readonlyConstructorAssignment.ts, 1, 16))
+    }
+}
+
diff --git a/tests/baselines/reference/readonlyConstructorAssignment.types b/tests/baselines/reference/readonlyConstructorAssignment.types
new file mode 100644
index 0000000000..10f1cd2047
--- /dev/null
+++ b/tests/baselines/reference/readonlyConstructorAssignment.types
@@ -0,0 +1,16 @@
+=== tests/cases/conformance/classes/constructorDeclarations/constructorParameters/readonlyConstructorAssignment.ts ===
+class A {
+>A : A
+
+    constructor(readonly x: number) {
+>x : number
+
+        this.x = 7;
+>this.x = 7 : number
+>this.x : number
+>this : this
+>x : number
+>7 : number
+    }
+}
+
diff --git a/tests/cases/conformance/classes/constructorDeclarations/constructorParameters/readonlyConstructorAssignment.ts b/tests/cases/conformance/classes/constructorDeclarations/constructorParameters/readonlyConstructorAssignment.ts
new file mode 100644
index 0000000000..a81bf69249
--- /dev/null
+++ b/tests/cases/conformance/classes/constructorDeclarations/constructorParameters/readonlyConstructorAssignment.ts
@@ -0,0 +1,5 @@
+class A {
+    constructor(readonly x: number) {
+        this.x = 7;
+    }
+}