More reliable mechanism for _this/_super simplification (#56130)

Author: rbuckton

src/compiler/factory/nodeFactory.ts

@@ -1,5 +1,6 @@
 import {
     __String,
+    AccessorDeclaration,
     addRange,
     append,
     appendIfUnique,
@@ -1180,6 +1181,7 @@ export function createNodeFactory(flags: NodeFactoryFlags, baseFactory: BaseNode
         mergeLexicalEnvironment,
         replaceModifiers,
         replaceDecoratorsAndModifiers,
+        replacePropertyName,
     };
 
     forEach(nodeFactoryPatchers, fn => fn(factory));
@@ -7149,6 +7151,26 @@ export function createNodeFactory(flags: NodeFactoryFlags, baseFactory: BaseNode
             Debug.assertNever(node);
     }
 
+    function replacePropertyName<T extends AccessorDeclaration | MethodDeclaration | MethodSignature | PropertyDeclaration | PropertySignature | PropertyAssignment>(node: T, name: T["name"]): T;
+    function replacePropertyName(node: AccessorDeclaration | MethodDeclaration | MethodSignature | PropertyDeclaration | PropertySignature | PropertyAssignment, name: PropertyName) {
+        switch (node.kind) {
+            case SyntaxKind.GetAccessor:
+                return updateGetAccessorDeclaration(node, node.modifiers, name, node.parameters, node.type, node.body);
+            case SyntaxKind.SetAccessor:
+                return updateSetAccessorDeclaration(node, node.modifiers, name, node.parameters, node.body);
+            case SyntaxKind.MethodDeclaration:
+                return updateMethodDeclaration(node, node.modifiers, node.asteriskToken, name, node.questionToken, node.typeParameters, node.parameters, node.type, node.body);
+            case SyntaxKind.MethodSignature:
+                return updateMethodSignature(node, node.modifiers, name, node.questionToken, node.typeParameters, node.parameters, node.type);
+            case SyntaxKind.PropertyDeclaration:
+                return updatePropertyDeclaration(node, node.modifiers, name, node.questionToken ?? node.exclamationToken, node.type, node.initializer);
+            case SyntaxKind.PropertySignature:
+                return updatePropertySignature(node, node.modifiers, name, node.questionToken, node.type);
+            case SyntaxKind.PropertyAssignment:
+                return updatePropertyAssignment(node, name, node.initializer);
+        }
+    }
+
     function asNodeArray<T extends Node>(array: readonly T[]): NodeArray<T>;
     function asNodeArray<T extends Node>(array: readonly T[] | undefined): NodeArray<T> | undefined;
     function asNodeArray<T extends Node>(array: readonly T[] | undefined): NodeArray<T> | undefined {

src/compiler/transformers/es2015.ts

@@ -9080,6 +9080,10 @@ export interface NodeFactory {
      * Updates a node that may contain decorators or modifiers, replacing only the decorators and modifiers of the node.
      */
     replaceDecoratorsAndModifiers<T extends HasModifiers & HasDecorators>(node: T, modifiers: readonly ModifierLike[] | undefined): T;
+    /**
+     * Updates a node that contains a property name, replacing only the name of the node.
+     */
+    replacePropertyName<T extends AccessorDeclaration | MethodDeclaration | MethodSignature | PropertyDeclaration | PropertySignature | PropertyAssignment>(node: T, name: T["name"]): T;
 }
 
 /** @internal */

src/compiler/types.ts

@@ -8394,6 +8394,10 @@ declare namespace ts {
          * Updates a node that may contain decorators or modifiers, replacing only the decorators and modifiers of the node.
          */
         replaceDecoratorsAndModifiers<T extends HasModifiers & HasDecorators>(node: T, modifiers: readonly ModifierLike[] | undefined): T;
+        /**
+         * Updates a node that contains a property name, replacing only the name of the node.
+         */
+        replacePropertyName<T extends AccessorDeclaration | MethodDeclaration | MethodSignature | PropertyDeclaration | PropertySignature | PropertyAssignment>(node: T, name: T["name"]): T;
     }
     interface CoreTransformationContext {
         readonly factory: NodeFactory;

tests/baselines/reference/api/typescript.d.ts

@@ -136,8 +136,7 @@ var D = /** @class */ (function (_super) {
     __extends(D, _super);
     function D() {
         var _this = _super.call(this, 1, 2) || this;
-        _this = _super.apply(this, __spreadArray([1, 2], a, false)) || this;
-        return _this;
+        return _super.apply(this, __spreadArray([1, 2], a, false)) || this;
     }
     D.prototype.foo = function () {
         _super.prototype.foo.call(this, 1, 2);

tests/baselines/reference/callWithSpread.js

@@ -42,8 +42,7 @@ var Super = /** @class */ (function (_super) {
     function Super() {
         var _this = this;
         (function () { return _this; }); // No Error
-        _this = _super.call(this) || this;
-        return _this;
+        return _this = _super.call(this) || this;
     }
     return Super;
 }(Base));

tests/baselines/reference/checkSuperCallBeforeThisAccessing6.js

@@ -35,7 +35,7 @@ var Base = /** @class */ (function () {
 var Super = /** @class */ (function (_super) {
     __extends(Super, _super);
     function Super() {
-        var _this = _super.call(this, (function () { return _this; })) || this;
+        var _this = _super.call(this, (function () { return _this; })) || this; // No error
         return _this;
     }
     return Super;

tests/baselines/reference/checkSuperCallBeforeThisAccessing7.js

@@ -42,8 +42,7 @@ var Super = /** @class */ (function (_super) {
     function Super() {
         var _this = this;
         var that = _this;
-        _this = _super.call(this) || this;
-        return _this;
+        return _this = _super.call(this) || this;
     }
     return Super;
 }(Base));

tests/baselines/reference/checkSuperCallBeforeThisAccessing8.js

@@ -208,7 +208,7 @@ var I = /** @class */ (function (_super) {
 var J = /** @class */ (function (_super) {
     __extends(J, _super);
     function J(p1) {
-        var _this = _super.call(this) || this;
+        var _this = _super.call(this) || this; // NO ERROR
         _this.p1 = p1;
         return _this;
     }
@@ -228,7 +228,7 @@ var K = /** @class */ (function (_super) {
 var L = /** @class */ (function (_super) {
     __extends(L, _super);
     function L(p1) {
-        var _this = _super.call(this) || this;
+        var _this = _super.call(this) || this; // NO ERROR
         _this.p1 = p1;
         return _this;
     }