Allowed non-this, non-super code before super call in derived classes with property initializers

src/compiler/checker.ts

@@ -23613,12 +23613,12 @@ namespace ts {
                                 superCallStatement = <ExpressionStatement>statement;
                                 break;
                             }
-                            if (!isPrologueDirective(statement)) {
+                            if (!isPrologueDirective(statement) && nodeReferencesSuperOrThis(statement)) {
                                 break;
                             }
                         }
                         if (!superCallStatement) {
-                            error(node, Diagnostics.A_super_call_must_be_the_first_statement_in_the_constructor_when_a_class_contains_initialized_properties_or_has_parameter_properties);
+                            error(node, Diagnostics.A_super_call_must_be_the_first_statement_in_the_constructor_to_refer_to_super_or_this_when_a_derived_class_contains_initialized_properties_or_has_parameter_properties);
                         }
                     }
                 }
@@ -23628,6 +23628,18 @@ namespace ts {
             }
         }
 
+        function nodeReferencesSuperOrThis(node: Statement): boolean {
+            if (node.kind === SyntaxKind.SuperKeyword || node.kind === SyntaxKind.ThisKeyword) {
+                return true;
+            }
+
+            if (isNewThisScope(node)) {
+                return false;
+            }
+
+            return !!forEachChild(node, nodeReferencesSuperOrThis);
+        }
+
         function checkAccessorDeclaration(node: AccessorDeclaration) {
             if (produceDiagnostics) {
                 // Grammar checking accessors

src/compiler/diagnosticMessages.json

@@ -1328,7 +1328,7 @@
         "category": "Error",
         "code": 2375
     },
-    "A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.": {
+    "A 'super' call must be the first statement in the constructor to refer to 'super' or 'this' when a derived class contains initialized properties or has parameter properties.": {
         "category": "Error",
         "code": 2376
     },

src/compiler/utilities.ts

@@ -6258,6 +6258,33 @@ namespace ts {
         return isSourceFile(node) || isModuleBlock(node) || isBlock(node) && isFunctionLike(node.parent);
     }
 
+    /**
+     * @returns Whether a node or its children refer to a different `this` than its parent.
+     * @internal
+     */
+    export function isNewThisScope(node: Node): boolean {
+        switch (node.kind) {
+            case SyntaxKind.FunctionDeclaration:
+            case SyntaxKind.FunctionExpression:
+            case SyntaxKind.PropertyDeclaration:
+                return true;
+            case SyntaxKind.Block:
+                switch (node.parent.kind) {
+                    // The `extends` clause of a class is its parent scope, unlike its constructor and methods
+                    case SyntaxKind.Constructor:
+                    case SyntaxKind.MethodDeclaration:
+                    // Object properties can have computed names; only method-like bodies start a new scope
+                    case SyntaxKind.GetAccessor:
+                    case SyntaxKind.SetAccessor:
+                        return true;
+                    default:
+                        return false;
+                }
+            default:
+                return false;
+        }
+    }
+
     // Classes
     export function isClassElement(node: Node): node is ClassElement {
         const kind = node.kind;

tests/baselines/reference/classUpdateTests.errors.txt

@@ -1,11 +1,9 @@
 tests/cases/compiler/classUpdateTests.ts(34,2): error TS2377: Constructors for derived classes must contain a 'super' call.
 tests/cases/compiler/classUpdateTests.ts(43,18): error TS2335: 'super' can only be referenced in a derived class.
-tests/cases/compiler/classUpdateTests.ts(57,2): error TS2376: A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.
 tests/cases/compiler/classUpdateTests.ts(63,7): error TS2415: Class 'L' incorrectly extends base class 'G'.
   Property 'p1' is private in type 'L' but not in type 'G'.
 tests/cases/compiler/classUpdateTests.ts(69,7): error TS2415: Class 'M' incorrectly extends base class 'G'.
   Property 'p1' is private in type 'M' but not in type 'G'.
-tests/cases/compiler/classUpdateTests.ts(70,2): error TS2376: A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.
 tests/cases/compiler/classUpdateTests.ts(93,3): error TS1128: Declaration or statement expected.
 tests/cases/compiler/classUpdateTests.ts(95,1): error TS1128: Declaration or statement expected.
 tests/cases/compiler/classUpdateTests.ts(99,3): error TS1128: Declaration or statement expected.
@@ -18,7 +16,7 @@ tests/cases/compiler/classUpdateTests.ts(111,15): error TS1005: ';' expected.
 tests/cases/compiler/classUpdateTests.ts(113,1): error TS1128: Declaration or statement expected.
 
 
-==== tests/cases/compiler/classUpdateTests.ts (16 errors) ====
+==== tests/cases/compiler/classUpdateTests.ts (14 errors) ====
     //
     // test codegen for instance properties
     //
@@ -80,14 +78,9 @@ tests/cases/compiler/classUpdateTests.ts(113,1): error TS1128: Declaration or st
 
     class K extends G {
     	constructor(public p1:number) { // ERROR
-    	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     		var i = 0;
-    ~~~~~~~~~~~~
     		super();
-    ~~~~~~~~~~
     	}
-    ~~
-!!! error TS2376: A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.
     }
 
     class L extends G {
@@ -104,14 +97,9 @@ tests/cases/compiler/classUpdateTests.ts(113,1): error TS1128: Declaration or st
 !!! error TS2415: Class 'M' incorrectly extends base class 'G'.
 !!! error TS2415:   Property 'p1' is private in type 'M' but not in type 'G'.
     	constructor(private p1:number) { // ERROR
-    	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     		var i = 0;
-    ~~~~~~~~~~~~
     		super();
-    ~~~~~~~~~~
     	}
-    ~~
-!!! error TS2376: A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.
     }
 
     //

tests/baselines/reference/derivedClassParameterProperties.errors.txt

@@ -1,15 +1,13 @@
-tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts(15,5): error TS2376: A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.
-tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts(30,5): error TS2376: A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.
 tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts(47,9): error TS17009: 'super' must be called before accessing 'this' in the constructor of a derived class.
-tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts(56,5): error TS2376: A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.
+tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts(56,5): error TS2376: A 'super' call must be the first statement in the constructor to refer to 'super' or 'this' when a derived class contains initialized properties or has parameter properties.
 tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts(57,9): error TS17009: 'super' must be called before accessing 'this' in the constructor of a derived class.
 tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts(58,9): error TS17009: 'super' must be called before accessing 'this' in the constructor of a derived class.
-tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts(79,5): error TS2376: A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.
+tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts(79,5): error TS2376: A 'super' call must be the first statement in the constructor to refer to 'super' or 'this' when a derived class contains initialized properties or has parameter properties.
 tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts(80,9): error TS17009: 'super' must be called before accessing 'this' in the constructor of a derived class.
 tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts(81,9): error TS17009: 'super' must be called before accessing 'this' in the constructor of a derived class.
 
 
-==== tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts (9 errors) ====
+==== tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassParameterProperties.ts (7 errors) ====
     // ordering of super calls in derived constructors matters depending on other class contents
 
     class Base {
@@ -25,14 +23,9 @@ tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassP
 
     class Derived2 extends Base {
         constructor(public y: string) {
-        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
             var a = 1;
-    ~~~~~~~~~~~~~~~~~~
             super(); // error
-    ~~~~~~~~~~~~~~~~~~~~~~~~~
         }
-    ~~~~~
-!!! error TS2376: A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.
     }
 
     class Derived3 extends Base {
@@ -45,14 +38,9 @@ tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassP
     class Derived4 extends Base {
         a = 1;
         constructor(y: string) {
-        ~~~~~~~~~~~~~~~~~~~~~~~~
             var b = 2;
-    ~~~~~~~~~~~~~~~~~~
             super(); // error
-    ~~~~~~~~~~~~~~~~~~~~~~~~~
         }
-    ~~~~~
-!!! error TS2376: A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.
     }
 
     class Derived5 extends Base {
@@ -91,7 +79,7 @@ tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassP
     ~~~~~~~~~~~~~~~~~~~~~~~~~
         }
     ~~~~~
-!!! error TS2376: A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.
+!!! error TS2376: A 'super' call must be the first statement in the constructor to refer to 'super' or 'this' when a derived class contains initialized properties or has parameter properties.
     }
 
     class Derived8 extends Base {
@@ -124,7 +112,7 @@ tests/cases/conformance/classes/constructorDeclarations/superCalls/derivedClassP
     ~~~~~~~~~~~~~~~~~~~~~~~~~
         }
     ~~~~~
-!!! error TS2376: A 'super' call must be the first statement in the constructor when a class contains initialized properties or has parameter properties.
+!!! error TS2376: A 'super' call must be the first statement in the constructor to refer to 'super' or 'this' when a derived class contains initialized properties or has parameter properties.
     }
 
     class Derived10<T> extends Base2<T> {