Merge pull request #13277 from Microsoft/fix13276

Author: rbuckton

src/compiler/transformers/es2015.ts

@@ -882,7 +882,10 @@ namespace ts {
 
             }
 
-            const superCaptureStatus = declareOrCaptureOrReturnThisForConstructorIfNeeded(statements, constructor, !!extendsClauseElement, hasSynthesizedSuper, statementOffset);
+            // determine whether the class is known syntactically to be a derived class (e.g. a
+            // class that extends a value that is not syntactically known to be `null`).
+            const isDerivedClass = extendsClauseElement && skipOuterExpressions(extendsClauseElement.expression).kind !== SyntaxKind.NullKeyword;
+            const superCaptureStatus = declareOrCaptureOrReturnThisForConstructorIfNeeded(statements, constructor, isDerivedClass, hasSynthesizedSuper, statementOffset);
 
             // The last statement expression was replaced. Skip it.
             if (superCaptureStatus === SuperCaptureResult.ReplaceSuperCapture || superCaptureStatus === SuperCaptureResult.ReplaceWithReturn) {
@@ -899,7 +902,7 @@ namespace ts {
 
             // Return `_this` unless we're sure enough that it would be pointless to add a return statement.
             // If there's a constructor that we can tell returns in enough places, then we *do not* want to add a return.
-            if (extendsClauseElement
+            if (isDerivedClass
                 && superCaptureStatus !== SuperCaptureResult.ReplaceWithReturn
                 && !(constructor && isSufficientlyCoveredByReturnStatements(constructor.body))) {
                 statements.push(
@@ -963,11 +966,11 @@ namespace ts {
         function declareOrCaptureOrReturnThisForConstructorIfNeeded(
                     statements: Statement[],
                     ctor: ConstructorDeclaration | undefined,
-                    hasExtendsClause: boolean,
+                    isDerivedClass: boolean,
                     hasSynthesizedSuper: boolean,
                     statementOffset: number) {
             // If this isn't a derived class, just capture 'this' for arrow functions if necessary.
-            if (!hasExtendsClause) {
+            if (!isDerivedClass) {
                 if (ctor) {
                     addCaptureThisForNodeIfNeeded(statements, ctor);
                 }
@@ -1047,7 +1050,7 @@ namespace ts {
             }
 
             // Perform the capture.
-            captureThisForNode(statements, ctor, superCallExpression, firstStatement);
+            captureThisForNode(statements, ctor, superCallExpression || createActualThis(), firstStatement);
 
             // If we're actually replacing the original statement, we need to signal this to the caller.
             if (superCallExpression) {
@@ -1057,15 +1060,25 @@ namespace ts {
             return SuperCaptureResult.NoReplacement;
         }
 
+        function createActualThis() {
+            return setEmitFlags(createThis(), EmitFlags.NoSubstitution);
+        }
+
         function createDefaultSuperCallOrThis() {
-            const actualThis = createThis();
-            setEmitFlags(actualThis, EmitFlags.NoSubstitution);
-            const superCall = createFunctionApply(
-                createIdentifier("_super"),
-                actualThis,
-                createIdentifier("arguments"),
+            return createLogicalOr(
+                createLogicalAnd(
+                    createStrictInequality(
+                        createIdentifier("_super"),
+                        createNull()
+                    ),
+                    createFunctionApply(
+                        createIdentifier("_super"),
+                        createActualThis(),
+                        createIdentifier("arguments")
+                    )
+                ),
+                createActualThis()
             );
-            return createLogicalOr(superCall, actualThis);
         }
 
         /**

tests/baselines/reference/ExportClassWithAccessibleTypesInTypeParameterConstraintsClassHeritageListMemberTypeAnnotations.js

@@ -38,7 +38,7 @@ var A;
     var Point3d = (function (_super) {
         __extends(Point3d, _super);
         function Point3d() {
-            return _super.apply(this, arguments) || this;
+            return _super !== null && _super.apply(this, arguments) || this;
         }
         return Point3d;
     }(Point));

tests/baselines/reference/ExportClassWithInaccessibleTypeInTypeParameterConstraint.js

@@ -41,7 +41,7 @@ var A;
     var Point3d = (function (_super) {
         __extends(Point3d, _super);
         function Point3d() {
-            return _super.apply(this, arguments) || this;
+            return _super !== null && _super.apply(this, arguments) || this;
         }
         return Point3d;
     }(Point));

tests/baselines/reference/abstractClassInLocalScope.js

@@ -22,7 +22,7 @@ var __extends = (this && this.__extends) || function (d, b) {
     var B = (function (_super) {
         __extends(B, _super);
         function B() {
-            return _super.apply(this, arguments) || this;
+            return _super !== null && _super.apply(this, arguments) || this;
         }
         return B;
     }(A));

tests/baselines/reference/abstractClassInLocalScopeIsAbstract.js

@@ -22,7 +22,7 @@ var __extends = (this && this.__extends) || function (d, b) {
     var B = (function (_super) {
         __extends(B, _super);
         function B() {
-            return _super.apply(this, arguments) || this;
+            return _super !== null && _super.apply(this, arguments) || this;
         }
         return B;
     }(A));

tests/baselines/reference/abstractProperty.js

@@ -35,7 +35,7 @@ var B = (function () {
 var C = (function (_super) {
     __extends(C, _super);
     function C() {
-        var _this = _super.apply(this, arguments) || this;
+        var _this = _super !== null && _super.apply(this, arguments) || this;
         _this.raw = "edge";
         _this.ro = "readonly please";
         return _this;

tests/baselines/reference/abstractPropertyNegative.js

@@ -57,7 +57,7 @@ var B = (function () {
 var C = (function (_super) {
     __extends(C, _super);
     function C() {
-        var _this = _super.apply(this, arguments) || this;
+        var _this = _super !== null && _super.apply(this, arguments) || this;
         _this.ro = "readonly please";
         return _this;
     }
@@ -78,7 +78,7 @@ var WrongTypeProperty = (function () {
 var WrongTypePropertyImpl = (function (_super) {
     __extends(WrongTypePropertyImpl, _super);
     function WrongTypePropertyImpl() {
-        var _this = _super.apply(this, arguments) || this;
+        var _this = _super !== null && _super.apply(this, arguments) || this;
         _this.num = "nope, wrong";
         return _this;
     }
@@ -92,7 +92,7 @@ var WrongTypeAccessor = (function () {
 var WrongTypeAccessorImpl = (function (_super) {
     __extends(WrongTypeAccessorImpl, _super);
     function WrongTypeAccessorImpl() {
-        return _super.apply(this, arguments) || this;
+        return _super !== null && _super.apply(this, arguments) || this;
     }
     Object.defineProperty(WrongTypeAccessorImpl.prototype, "num", {
         get: function () { return "nope, wrong"; },
@@ -104,7 +104,7 @@ var WrongTypeAccessorImpl = (function (_super) {
 var WrongTypeAccessorImpl2 = (function (_super) {
     __extends(WrongTypeAccessorImpl2, _super);
     function WrongTypeAccessorImpl2() {
-        var _this = _super.apply(this, arguments) || this;
+        var _this = _super !== null && _super.apply(this, arguments) || this;
         _this.num = "nope, wrong";
         return _this;
     }

tests/baselines/reference/accessors_spec_section-4.5_inference.js

@@ -38,7 +38,7 @@ var A = (function () {
 var B = (function (_super) {
     __extends(B, _super);
     function B() {
-        return _super.apply(this, arguments) || this;
+        return _super !== null && _super.apply(this, arguments) || this;
     }
     return B;
 }(A));

tests/baselines/reference/aliasUsageInAccessorsOfClass.js

@@ -46,7 +46,7 @@ var Backbone = require("./aliasUsage1_backbone");
 var VisualizationModel = (function (_super) {
     __extends(VisualizationModel, _super);
     function VisualizationModel() {
-        return _super.apply(this, arguments) || this;
+        return _super !== null && _super.apply(this, arguments) || this;
     }
     return VisualizationModel;
 }(Backbone.Model));

tests/baselines/reference/aliasUsageInArray.js

@@ -40,7 +40,7 @@ var Backbone = require("./aliasUsageInArray_backbone");
 var VisualizationModel = (function (_super) {
     __extends(VisualizationModel, _super);
     function VisualizationModel() {
-        return _super.apply(this, arguments) || this;
+        return _super !== null && _super.apply(this, arguments) || this;
     }
     return VisualizationModel;
 }(Backbone.Model));