fix(46824): remove duplicate private identifier errors

Author: Andrewnt219

src/compiler/checker.ts

@@ -28235,12 +28235,18 @@ namespace ts {
             if (!getContainingClass(privId)) {
                 return grammarErrorOnNode(privId, Diagnostics.Private_identifiers_are_not_allowed_outside_class_bodies);
             }
-            if (!isExpressionNode(privId)) {
-                return grammarErrorOnNode(privId, Diagnostics.Private_identifiers_are_only_allowed_in_class_bodies_and_may_only_be_used_as_part_of_a_class_member_declaration_property_access_or_on_the_left_hand_side_of_an_in_expression);
-            }
-            if (!getSymbolForPrivateIdentifierExpression(privId)) {
-                return grammarErrorOnNode(privId, Diagnostics.Cannot_find_name_0, idText(privId));
+
+            if (!isForInStatement(privId.parent)) {
+                if (!isExpressionNode(privId)) {
+                    return grammarErrorOnNode(privId, Diagnostics.Private_identifiers_are_only_allowed_in_class_bodies_and_may_only_be_used_as_part_of_a_class_member_declaration_property_access_or_on_the_left_hand_side_of_an_in_expression);
+                }
+
+                const isInOperation = isBinaryExpression(privId.parent) && privId.parent.operatorToken.kind === SyntaxKind.InKeyword;
+                if (!getSymbolForPrivateIdentifierExpression(privId) && !isInOperation) {
+                    return grammarErrorOnNode(privId, Diagnostics.Cannot_find_name_0, idText(privId));
+                }
             }
+
             return false;
         }
 

tests/baselines/reference/privateNameInInExpression.errors.txt

@@ -1,15 +1,14 @@
 tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.ts(21,29): error TS2571: Object is of type 'unknown'.
-tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.ts(23,19): error TS2304: Cannot find name '#fiel'.
 tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.ts(23,19): error TS2339: Property '#fiel' does not exist on type 'any'.
 tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.ts(25,20): error TS1451: Private identifiers are only allowed in class bodies and may only be used as part of a class member declaration, property access, or on the left-hand-side of an 'in' expression
-tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.ts(27,14): error TS1451: Private identifiers are only allowed in class bodies and may only be used as part of a class member declaration, property access, or on the left-hand-side of an 'in' expression
+tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.ts(27,14): error TS2304: Cannot find name '#field'.
 tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.ts(27,14): error TS2406: The left-hand side of a 'for...in' statement must be a variable or a property access.
 tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.ts(29,23): error TS2407: The right-hand side of a 'for...in' statement must be of type 'any', an object type or a type parameter, but here has type 'boolean'.
 tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.ts(43,27): error TS2531: Object is possibly 'null'.
 tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.ts(114,12): error TS18016: Private identifiers are not allowed outside class bodies.
 
 
-==== tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.ts (9 errors) ====
+==== tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.ts (8 errors) ====
     class Foo {
         #field = 1;
         static #staticField = 2;
@@ -36,8 +35,6 @@ tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.t
 
             const b = #fiel in v; // Bad - typo in privateID
                       ~~~~~
-!!! error TS2304: Cannot find name '#fiel'.
-                      ~~~~~
 !!! error TS2339: Property '#fiel' does not exist on type 'any'.
 
             const c = (#field) in v; // Bad - privateID is not an expression on its own
@@ -46,7 +43,7 @@ tests/cases/conformance/classes/members/privateNames/privateNameInInExpression.t
 
             for (#field in v) { /**/ } // Bad - 'in' not allowed
                  ~~~~~~
-!!! error TS1451: Private identifiers are only allowed in class bodies and may only be used as part of a class member declaration, property access, or on the left-hand-side of an 'in' expression
+!!! error TS2304: Cannot find name '#field'.
                  ~~~~~~
 !!! error TS2406: The left-hand side of a 'for...in' statement must be a variable or a property access.