handle private name with index signature

"Property _ does not exist on type _"
error should still happen with private
names even if the class has an index signature (new test case)

Signed-off-by: Max Heiber <mheiber@bloomberg.net>

Author: Max Heiber

src/compiler/checker.ts

@@ -17780,7 +17780,7 @@ namespace ts {
             }
             if (!prop) {
                 const indexInfo = getIndexInfoOfType(apparentType, IndexKind.String);
-                if (!(indexInfo && indexInfo.type)) {
+                if (!(indexInfo && indexInfo.type) || isPrivateName(right)) {
                     if (right.escapedText && !checkAndReportErrorForExtendingInterface(node)) {
                         reportNonexistentProperty(right, leftType.flags & TypeFlags.TypeParameter && (leftType as TypeParameter).isThisType ? apparentType : leftType);
                     }

tests/baselines/reference/privateNameAndIndexSignature.errors.txt

@@ -0,0 +1,13 @@
+tests/cases/conformance/classes/members/privateNames/privateNameAndIndexSignature.ts(4,14): error TS2339: Property '#f' does not exist on type 'A'.
+
+
+==== tests/cases/conformance/classes/members/privateNames/privateNameAndIndexSignature.ts (1 errors) ====
+    class A {
+        [k: string]: any;
+        constructor(message: string) {
+            this.#f = 3                 // Error Property '#f' does not exist on type 'A'.
+                 ~~
+!!! error TS2339: Property '#f' does not exist on type 'A'.
+        }
+    }
+    

tests/baselines/reference/privateNameAndIndexSignature.js

@@ -0,0 +1,16 @@
+//// [privateNameAndIndexSignature.ts]
+class A {
+    [k: string]: any;
+    constructor(message: string) {
+        this.#f = 3                 // Error Property '#f' does not exist on type 'A'.
+    }
+}
+
+
+//// [privateNameAndIndexSignature.js]
+var A = /** @class */ (function () {
+    function A(message) {
+        this.#f = 3; // Error Property '#f' does not exist on type 'A'.
+    }
+    return A;
+}());

tests/baselines/reference/privateNameAndIndexSignature.symbols

@@ -0,0 +1,15 @@
+=== tests/cases/conformance/classes/members/privateNames/privateNameAndIndexSignature.ts ===
+class A {
+>A : Symbol(A, Decl(privateNameAndIndexSignature.ts, 0, 0))
+
+    [k: string]: any;
+>k : Symbol(k, Decl(privateNameAndIndexSignature.ts, 1, 5))
+
+    constructor(message: string) {
+>message : Symbol(message, Decl(privateNameAndIndexSignature.ts, 2, 16))
+
+        this.#f = 3                 // Error Property '#f' does not exist on type 'A'.
+>this : Symbol(A, Decl(privateNameAndIndexSignature.ts, 0, 0))
+    }
+}
+

tests/baselines/reference/privateNameAndIndexSignature.types

@@ -0,0 +1,18 @@
+=== tests/cases/conformance/classes/members/privateNames/privateNameAndIndexSignature.ts ===
+class A {
+>A : A
+
+    [k: string]: any;
+>k : string
+
+    constructor(message: string) {
+>message : string
+
+        this.#f = 3                 // Error Property '#f' does not exist on type 'A'.
+>this.#f = 3 : 3
+>this.#f : any
+>this : this
+>3 : 3
+    }
+}
+

tests/cases/conformance/classes/members/privateNames/privateNameAndIndexSignature.ts

@@ -0,0 +1,6 @@
+class A {
+    [k: string]: any;
+    constructor(message: string) {
+        this.#f = 3                 // Error Property '#f' does not exist on type 'A'.
+    }
+}