feat(47595): Inability to use typeof on an ES private property

src/compiler/parser.ts

@@ -875,7 +875,7 @@ namespace ts {
             initializeState("", content, languageVersion, /*syntaxCursor*/ undefined, ScriptKind.JS);
             // Prime the scanner.
             nextToken();
-            const entityName = parseEntityName(/*allowReservedWords*/ true);
+            const entityName = parseEntityName(/*allowReservedWords*/ true, /*allowPrivateIdentifiers*/ false);
             const isInvalid = token() === SyntaxKind.EndOfFileToken && !parseDiagnostics.length;
             clearState();
             return isInvalid ? entityName : undefined;
@@ -2719,7 +2719,7 @@ namespace ts {
             return createMissingList<T>();
         }
 
-        function parseEntityName(allowReservedWords: boolean, diagnosticMessage?: DiagnosticMessage): EntityName {
+        function parseEntityName(allowReservedWords: boolean, allowPrivateIdentifiers: boolean, diagnosticMessage?: DiagnosticMessage): EntityName {
             const pos = getNodePos();
             let entity: EntityName = allowReservedWords ? parseIdentifierName(diagnosticMessage) : parseIdentifier(diagnosticMessage);
             let dotPos = getNodePos();
@@ -2733,7 +2733,7 @@ namespace ts {
                 entity = finishNode(
                     factory.createQualifiedName(
                         entity,
-                        parseRightSideOfDot(allowReservedWords, /* allowPrivateIdentifiers */ false) as Identifier
+                        parseRightSideOfDot(allowReservedWords, allowPrivateIdentifiers) as Identifier
                     ),
                     pos
                 );
@@ -2918,7 +2918,7 @@ namespace ts {
         // TYPES
 
         function parseEntityNameOfTypeReference() {
-            return parseEntityName(/*allowReservedWords*/ true, Diagnostics.Type_expected);
+            return parseEntityName(/*allowReservedWords*/ true, /*allowPrivateIdentifiers*/ false, Diagnostics.Type_expected);
         }
 
         function parseTypeArgumentsOfTypeReference() {
@@ -3078,7 +3078,7 @@ namespace ts {
         function parseTypeQuery(): TypeQueryNode {
             const pos = getNodePos();
             parseExpected(SyntaxKind.TypeOfKeyword);
-            return finishNode(factory.createTypeQueryNode(parseEntityName(/*allowReservedWords*/ true)), pos);
+            return finishNode(factory.createTypeQueryNode(parseEntityName(/*allowReservedWords*/ true, /*allowPrivateIdentifiers*/ true)), pos);
         }
 
         function parseTypeParameter(): TypeParameterDeclaration {
@@ -7350,7 +7350,7 @@ namespace ts {
         function parseModuleReference() {
             return isExternalModuleReference()
                 ? parseExternalModuleReference()
-                : parseEntityName(/*allowReservedWords*/ false);
+                : parseEntityName(/*allowReservedWords*/ false, /*allowPrivateIdentifiers*/ false);
         }
 
         function parseExternalModuleReference() {
@@ -7658,7 +7658,7 @@ namespace ts {
                 const pos = getNodePos();
                 const hasBrace = parseOptional(SyntaxKind.OpenBraceToken);
                 const p2 = getNodePos();
-                let entityName: EntityName | JSDocMemberName = parseEntityName(/* allowReservedWords*/ false);
+                let entityName: EntityName | JSDocMemberName = parseEntityName(/* allowReservedWords*/ false, /*allowPrivateIdentifiers*/ false);
                 while (token() === SyntaxKind.PrivateIdentifier) {
                     reScanHashToken(); // rescan #id as # id
                     nextTokenJSDoc(); // then skip the #
@@ -8121,7 +8121,7 @@ namespace ts {
                     // parseEntityName logs an error for non-identifier, so create a MissingNode ourselves to avoid the error
                     const p2 = getNodePos();
                     let name: EntityName | JSDocMemberName | undefined = tokenIsIdentifierOrKeyword(token())
-                        ? parseEntityName(/*allowReservedWords*/ true)
+                        ? parseEntityName(/*allowReservedWords*/ true, /*allowPrivateIdentifiers*/ false)
                         : undefined;
                     if (name) {
                         while (token() === SyntaxKind.PrivateIdentifier) {

tests/baselines/reference/privateNameInTypeQuery.errors.txt

@@ -0,0 +1,21 @@
+tests/cases/conformance/classes/members/privateNames/privateNameInTypeQuery.ts(6,15): error TS2322: Type 'number' is not assignable to type 'string'.
+tests/cases/conformance/classes/members/privateNames/privateNameInTypeQuery.ts(11,19): error TS18013: Property '#a' is not accessible outside class 'C' because it has a private identifier.
+
+
+==== tests/cases/conformance/classes/members/privateNames/privateNameInTypeQuery.ts (2 errors) ====
+    class C {
+        #a = 'a';
+
+        constructor() {
+            const a: typeof this.#a = ''; // Ok
+            const b: typeof this.#a = 1;  // Error
+                  ~
+!!! error TS2322: Type 'number' is not assignable to type 'string'.
+        }
+    }
+
+    const c = new C();
+    const a: typeof c.#a = '';
+                      ~~
+!!! error TS18013: Property '#a' is not accessible outside class 'C' because it has a private identifier.
+

tests/baselines/reference/privateNameInTypeQuery.js

@@ -0,0 +1,25 @@
+//// [privateNameInTypeQuery.ts]
+class C {
+    #a = 'a';
+
+    constructor() {
+        const a: typeof this.#a = ''; // Ok
+        const b: typeof this.#a = 1;  // Error
+    }
+}
+
+const c = new C();
+const a: typeof c.#a = '';
+
+
+//// [privateNameInTypeQuery.js]
+"use strict";
+class C {
+    #a = 'a';
+    constructor() {
+        const a = ''; // Ok
+        const b = 1; // Error
+    }
+}
+const c = new C();
+const a = '';

tests/baselines/reference/privateNameInTypeQuery.symbols

@@ -0,0 +1,28 @@
+=== tests/cases/conformance/classes/members/privateNames/privateNameInTypeQuery.ts ===
+class C {
+>C : Symbol(C, Decl(privateNameInTypeQuery.ts, 0, 0))
+
+    #a = 'a';
+>#a : Symbol(C.#a, Decl(privateNameInTypeQuery.ts, 0, 9))
+
+    constructor() {
+        const a: typeof this.#a = ''; // Ok
+>a : Symbol(a, Decl(privateNameInTypeQuery.ts, 4, 13))
+>this.#a : Symbol(C.#a, Decl(privateNameInTypeQuery.ts, 0, 9))
+>this : Symbol(C, Decl(privateNameInTypeQuery.ts, 0, 0))
+
+        const b: typeof this.#a = 1;  // Error
+>b : Symbol(b, Decl(privateNameInTypeQuery.ts, 5, 13))
+>this.#a : Symbol(C.#a, Decl(privateNameInTypeQuery.ts, 0, 9))
+>this : Symbol(C, Decl(privateNameInTypeQuery.ts, 0, 0))
+    }
+}
+
+const c = new C();
+>c : Symbol(c, Decl(privateNameInTypeQuery.ts, 9, 5))
+>C : Symbol(C, Decl(privateNameInTypeQuery.ts, 0, 0))
+
+const a: typeof c.#a = '';
+>a : Symbol(a, Decl(privateNameInTypeQuery.ts, 10, 5))
+>c : Symbol(c, Decl(privateNameInTypeQuery.ts, 9, 5))
+

tests/baselines/reference/privateNameInTypeQuery.types

@@ -0,0 +1,34 @@
+=== tests/cases/conformance/classes/members/privateNames/privateNameInTypeQuery.ts ===
+class C {
+>C : C
+
+    #a = 'a';
+>#a : string
+>'a' : "a"
+
+    constructor() {
+        const a: typeof this.#a = ''; // Ok
+>a : string
+>this.#a : string
+>this : this
+>'' : ""
+
+        const b: typeof this.#a = 1;  // Error
+>b : string
+>this.#a : string
+>this : this
+>1 : 1
+    }
+}
+
+const c = new C();
+>c : C
+>new C() : C
+>C : typeof C
+
+const a: typeof c.#a = '';
+>a : any
+>c.#a : any
+>c : C
+>'' : ""
+

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

@@ -0,0 +1,14 @@
+// @strict: true
+// @target: esnext
+
+class C {
+    #a = 'a';
+
+    constructor() {
+        const a: typeof this.#a = ''; // Ok
+        const b: typeof this.#a = 1;  // Error
+    }
+}
+
+const c = new C();
+const a: typeof c.#a = '';