Merge pull request #12893 from Microsoft/capturedThisFix

Avoid replacing last statement of derived constructors if 'this' is referenced.

Author: DanielRosenwasser

src/compiler/transformers/es2015.ts

@@ -1024,8 +1024,11 @@ namespace ts {
                 }
             }
 
-            // Return the result if we have an immediate super() call on the last statement.
-            if (superCallExpression && statementOffset === ctorStatements.length - 1) {
+            // Return the result if we have an immediate super() call on the last statement,
+            // but only if the constructor itself doesn't use 'this' elsewhere.
+            if (superCallExpression
+                && statementOffset === ctorStatements.length - 1
+                && !(ctor.transformFlags & (TransformFlags.ContainsLexicalThis | TransformFlags.ContainsCapturedLexicalThis))) {
                 const returnStatement = createReturn(superCallExpression);
 
                 if (superCallExpression.kind !== SyntaxKind.BinaryExpression

tests/baselines/reference/arrowFunctionContexts.js

@@ -116,7 +116,8 @@ var Base = (function () {
 var Derived = (function (_super) {
     __extends(Derived, _super);
     function Derived() {
-        return _super.call(this, function () { return _this; }) || this;
+        var _this = _super.call(this, function () { return _this; }) || this;
+        return _this;
     }
     return Derived;
 }(Base));
@@ -157,7 +158,8 @@ var M2;
     var Derived = (function (_super) {
         __extends(Derived, _super);
         function Derived() {
-            return _super.call(this, function () { return _this; }) || this;
+            var _this = _super.call(this, function () { return _this; }) || this;
+            return _this;
         }
         return Derived;
     }(Base));

tests/baselines/reference/captureSuperPropertyAccessInSuperCall01.errors.txt

@@ -0,0 +1,17 @@
+tests/cases/compiler/captureSuperPropertyAccessInSuperCall01.ts(9,24): error TS17011: 'super' must be called before accessing a property of 'super' in the constructor of a derived class.
+
+
+==== tests/cases/compiler/captureSuperPropertyAccessInSuperCall01.ts (1 errors) ====
+    class A {
+    	constructor(f: () => string) {
+    	}
+    	public blah(): string { return ""; }
+    }
+    
+    class B extends A {
+    	constructor() {
+    		super(() => { return super.blah(); })
+    		                     ~~~~~
+!!! error TS17011: 'super' must be called before accessing a property of 'super' in the constructor of a derived class.
+    	}
+    }

tests/baselines/reference/captureSuperPropertyAccessInSuperCall01.js

@@ -0,0 +1,33 @@
+//// [captureSuperPropertyAccessInSuperCall01.ts]
+class A {
+	constructor(f: () => string) {
+	}
+	public blah(): string { return ""; }
+}
+
+class B extends A {
+	constructor() {
+		super(() => { return super.blah(); })
+	}
+}
+
+//// [captureSuperPropertyAccessInSuperCall01.js]
+var __extends = (this && this.__extends) || function (d, b) {
+    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
+    function __() { this.constructor = d; }
+    d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
+};
+var A = (function () {
+    function A(f) {
+    }
+    A.prototype.blah = function () { return ""; };
+    return A;
+}());
+var B = (function (_super) {
+    __extends(B, _super);
+    function B() {
+        var _this = _super.call(this, function () { return _super.blah.call(_this); }) || this;
+        return _this;
+    }
+    return B;
+}(A));

tests/baselines/reference/captureThisInSuperCall.js

@@ -22,7 +22,8 @@ var A = (function () {
 var B = (function (_super) {
     __extends(B, _super);
     function B() {
-        return _super.call(this, { test: function () { return _this.someMethod(); } }) || this;
+        var _this = _super.call(this, { test: function () { return _this.someMethod(); } }) || this;
+        return _this;
     }
     B.prototype.someMethod = function () { };
     return B;

tests/baselines/reference/checkSuperCallBeforeThisAccessing5.js

@@ -25,7 +25,8 @@ var Based = (function () {
 var Derived = (function (_super) {
     __extends(Derived, _super);
     function Derived() {
-        return _super.call(this, this.x) || this;
+        var _this = _super.call(this, _this.x) || this;
+        return _this;
     }
     return Derived;
 }(Based));

tests/baselines/reference/checkSuperCallBeforeThisAccessing7.js

@@ -23,7 +23,8 @@ var Base = (function () {
 var Super = (function (_super) {
     __extends(Super, _super);
     function Super() {
-        return _super.call(this, (function () { return _this; })) || this;
+        var _this = _super.call(this, (function () { return _this; })) || this;
+        return _this;
     }
     return Super;
 }(Base));

tests/baselines/reference/derivedClassSuperCallsWithThisArg.js

@@ -42,7 +42,8 @@ var Base = (function () {
 var Derived = (function (_super) {
     __extends(Derived, _super);
     function Derived() {
-        return _super.call(this, _this) || this;
+        var _this = _super.call(this, _this) || this;
+        return _this;
     }
     return Derived;
 }(Base));

tests/baselines/reference/superCallBeforeThisAccessing2.js

@@ -24,7 +24,8 @@ var Base = (function () {
 var D = (function (_super) {
     __extends(D, _super);
     function D() {
-        return _super.call(this, function () { _this._t; }) || this;
+        var _this = _super.call(this, function () { _this._t; }) || this;
+        return _this;
     }
     return D;
 }(Base));

tests/baselines/reference/superCallBeforeThisAccessing6.js

@@ -24,7 +24,8 @@ var Base = (function () {
 var D = (function (_super) {
     __extends(D, _super);
     function D() {
-        return _super.call(this, this) || this;
+        var _this = _super.call(this, _this) || this;
+        return _this;
     }
     return D;
 }(Base));