Excise well-known symbol ignoring code in index signature handling

Author: weswigham

src/compiler/checker.ts

@@ -36442,13 +36442,6 @@ namespace ts {
             if (indexInfos) {
                 forEach(getPropertiesOfObjectType(type), prop => {
                     const propType = getTypeOfSymbol(prop);
-                    // TODO: Well known symbols should _probably_ be subject to a symbol indexer, but unfortunately they have no associated literal
-                    // type right now, so they're very difficult to check/flow. They're on the chopping block for removal thanks to advancements,
-                    // and other issues though, so it's probably OK to just let their removal and simultaneous replacement with `unique symbol`s
-                    // fix this.
-                    if (isKnownSymbol(prop)) {
-                        return;
-                    }
                     checkIndexConstraintForProperty(prop, getLiteralTypeFromProperty(prop, TypeFlags.StringOrNumberLiteralOrUnique, /*retainNonpublicNames*/ true), propType, type, declaredIndexers);
                 });
 
@@ -36533,7 +36526,7 @@ namespace ts {
                 let errorNode: Node | undefined;
                 if (propDeclaration && name &&
                     (propDeclaration.kind === SyntaxKind.BinaryExpression ||
-                     name.kind === SyntaxKind.ComputedPropertyName ||
+                     (name.kind === SyntaxKind.ComputedPropertyName && name.parent.parent === containingType.symbol.valueDeclaration) ||
                      prop.parent === containingType.symbol)) {
                     errorNode = propDeclaration;
                 }

tests/baselines/reference/computedPropertyNames45_ES5.errors.txt

@@ -1,4 +1,4 @@
-tests/cases/conformance/es6/computedProperties/computedPropertyNames45_ES5.ts(5,9): error TS2411: Property '["get1"]' of type 'Foo' is not assignable to 'string' index type 'Foo2'.
+tests/cases/conformance/es6/computedProperties/computedPropertyNames45_ES5.ts(10,5): error TS2411: Property '["get1"]' of type 'Foo' is not assignable to 'string' index type 'Foo2'.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames45_ES5.ts(11,9): error TS2411: Property '["set1"]' of type 'Foo' is not assignable to 'string' index type 'Foo2'.
 
 
@@ -8,13 +8,13 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames45_ES5.ts(11
 
     class C {
         get ["get1"]() { return new Foo }
-            ~~~~~~~~
-!!! error TS2411: Property '["get1"]' of type 'Foo' is not assignable to 'string' index type 'Foo2'.
     }
 
     class D extends C {
         // No error when the indexer is in a class more derived than the computed property
         [s: string]: Foo2;
+        ~~~~~~~~~~~~~~~~~~
+!!! error TS2411: Property '["get1"]' of type 'Foo' is not assignable to 'string' index type 'Foo2'.
         set ["set1"](p: Foo) { }
             ~~~~~~~~
 !!! error TS2411: Property '["set1"]' of type 'Foo' is not assignable to 'string' index type 'Foo2'.

tests/baselines/reference/computedPropertyNames45_ES6.errors.txt

@@ -1,4 +1,4 @@
-tests/cases/conformance/es6/computedProperties/computedPropertyNames45_ES6.ts(5,9): error TS2411: Property '["get1"]' of type 'Foo' is not assignable to 'string' index type 'Foo2'.
+tests/cases/conformance/es6/computedProperties/computedPropertyNames45_ES6.ts(10,5): error TS2411: Property '["get1"]' of type 'Foo' is not assignable to 'string' index type 'Foo2'.
 tests/cases/conformance/es6/computedProperties/computedPropertyNames45_ES6.ts(11,9): error TS2411: Property '["set1"]' of type 'Foo' is not assignable to 'string' index type 'Foo2'.
 
 
@@ -8,13 +8,13 @@ tests/cases/conformance/es6/computedProperties/computedPropertyNames45_ES6.ts(11
 
     class C {
         get ["get1"]() { return new Foo }
-            ~~~~~~~~
-!!! error TS2411: Property '["get1"]' of type 'Foo' is not assignable to 'string' index type 'Foo2'.
     }
 
     class D extends C {
         // No error when the indexer is in a class more derived than the computed property
         [s: string]: Foo2;
+        ~~~~~~~~~~~~~~~~~~
+!!! error TS2411: Property '["get1"]' of type 'Foo' is not assignable to 'string' index type 'Foo2'.
         set ["set1"](p: Foo) { }
             ~~~~~~~~
 !!! error TS2411: Property '["set1"]' of type 'Foo' is not assignable to 'string' index type 'Foo2'.

tests/baselines/reference/symbolProperty17.errors.txt

@@ -0,0 +1,14 @@
+tests/cases/conformance/es6/Symbols/symbolProperty17.ts(2,5): error TS2411: Property '[Symbol.iterator]' of type 'number' is not assignable to 'symbol' index type 'string'.
+
+
+==== tests/cases/conformance/es6/Symbols/symbolProperty17.ts (1 errors) ====
+    interface I {
+        [Symbol.iterator]: number;
+        ~~~~~~~~~~~~~~~~~
+!!! error TS2411: Property '[Symbol.iterator]' of type 'number' is not assignable to 'symbol' index type 'string'.
+        [s: symbol]: string;
+        "__@iterator": string;
+    }
+    
+    var i: I;
+    var it = i[Symbol.iterator];

tests/baselines/reference/symbolProperty30.errors.txt

@@ -0,0 +1,12 @@
+tests/cases/conformance/es6/Symbols/symbolProperty30.ts(2,5): error TS2411: Property '[Symbol.toStringTag]' of type '() => { x: string; }' is not assignable to 'symbol' index type '() => { x: number; }'.
+
+
+==== tests/cases/conformance/es6/Symbols/symbolProperty30.ts (1 errors) ====
+    class C1 {
+        [Symbol.toStringTag]() {
+        ~~~~~~~~~~~~~~~~~~~~
+!!! error TS2411: Property '[Symbol.toStringTag]' of type '() => { x: string; }' is not assignable to 'symbol' index type '() => { x: number; }'.
+            return { x: "" };
+        }
+        [s: symbol]: () => { x: number };
+    }

tests/baselines/reference/symbolProperty32.errors.txt

@@ -0,0 +1,14 @@
+tests/cases/conformance/es6/Symbols/symbolProperty32.ts(7,5): error TS2411: Property '[Symbol.toStringTag]' of type '() => { x: string; }' is not assignable to 'symbol' index type '() => { x: number; }'.
+
+
+==== tests/cases/conformance/es6/Symbols/symbolProperty32.ts (1 errors) ====
+    class C1 {
+        [Symbol.toStringTag]() {
+            return { x: "" };
+        }
+    }
+    class C2 extends C1 {
+        [s: symbol]: () => { x: number };
+        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2411: Property '[Symbol.toStringTag]' of type '() => { x: string; }' is not assignable to 'symbol' index type '() => { x: number; }'.
+    }

tests/baselines/reference/symbolProperty34.errors.txt

@@ -1,12 +1,15 @@
 tests/cases/conformance/es6/Symbols/symbolProperty34.ts(1,18): error TS2449: Class 'C2' used before its declaration.
+tests/cases/conformance/es6/Symbols/symbolProperty34.ts(2,5): error TS2411: Property '[Symbol.toStringTag]' of type '() => { x: string; }' is not assignable to 'symbol' index type '() => { x: number; }'.
 
 
-==== tests/cases/conformance/es6/Symbols/symbolProperty34.ts (1 errors) ====
+==== tests/cases/conformance/es6/Symbols/symbolProperty34.ts (2 errors) ====
     class C1 extends C2 {
                      ~~
 !!! error TS2449: Class 'C2' used before its declaration.
 !!! related TS2728 tests/cases/conformance/es6/Symbols/symbolProperty34.ts:6:7: 'C2' is declared here.
         [Symbol.toStringTag]() {
+        ~~~~~~~~~~~~~~~~~~~~
+!!! error TS2411: Property '[Symbol.toStringTag]' of type '() => { x: string; }' is not assignable to 'symbol' index type '() => { x: number; }'.
             return { x: "" };
         }
     }