Clearifies protected error message (#42599)

Author: tarikeshaq

src/compiler/checker.ts

@@ -26538,7 +26538,7 @@ namespace ts {
                 type = (type as TypeParameter).isThisType ? getConstraintOfTypeParameter(<TypeParameter>type)! : getBaseConstraintOfType(<TypeParameter>type)!; // TODO: GH#18217 Use a different variable that's allowed to be undefined
             }
             if (!type || !hasBaseType(type, enclosingClass)) {
-                error(errorNode, Diagnostics.Property_0_is_protected_and_only_accessible_through_an_instance_of_class_1, symbolToString(prop), typeToString(enclosingClass));
+                error(errorNode, Diagnostics.Property_0_is_protected_and_only_accessible_through_an_instance_of_class_1_This_is_an_instance_of_class_2, symbolToString(prop), typeToString(enclosingClass), typeToString(type));
                 return false;
             }
             return true;

src/compiler/diagnosticMessages.json

@@ -1962,7 +1962,7 @@
         "category": "Error",
         "code": 2445
     },
-    "Property '{0}' is protected and only accessible through an instance of class '{1}'.": {
+    "Property '{0}' is protected and only accessible through an instance of class '{1}'. This is an instance of class '{2}'.": {
         "category": "Error",
         "code": 2446
     },
@@ -6258,7 +6258,6 @@
         "code": 95159
     },
 
-
     "No value exists in scope for the shorthand property '{0}'. Either declare one or provide an initializer.": {
         "category": "Error",
         "code": 18004

tests/baselines/reference/protectedClassPropertyAccessibleWithinNestedSubclass1.errors.txt

@@ -1,18 +1,18 @@
 tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(15,20): error TS2445: Property 'x' is protected and only accessible within class 'Derived3' and its subclasses.
-tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(32,19): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived1'.
-tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(34,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived1'.
+tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(32,19): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived1'. This is an instance of class 'Base'.
+tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(34,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived1'. This is an instance of class 'Derived2'.
 tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(35,20): error TS2445: Property 'x' is protected and only accessible within class 'Derived3' and its subclasses.
-tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(36,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived1'.
-tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(52,19): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived2'.
-tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(53,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived2'.
+tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(36,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived1'. This is an instance of class 'Derived4'.
+tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(52,19): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived2'. This is an instance of class 'Base'.
+tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(53,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived2'. This is an instance of class 'Derived1'.
 tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(55,20): error TS2445: Property 'x' is protected and only accessible within class 'Derived3' and its subclasses.
-tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(73,19): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'.
-tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(74,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'.
-tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(75,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'.
-tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(77,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'.
-tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(93,19): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived4'.
-tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(94,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived4'.
-tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(95,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived4'.
+tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(73,19): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'. This is an instance of class 'Base'.
+tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(74,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'. This is an instance of class 'Derived1'.
+tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(75,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'. This is an instance of class 'Derived2'.
+tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(77,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'. This is an instance of class 'Derived4'.
+tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(93,19): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived4'. This is an instance of class 'Base'.
+tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(94,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived4'. This is an instance of class 'Derived1'.
+tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(95,20): error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived4'. This is an instance of class 'Derived2'.
 tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(96,20): error TS2445: Property 'x' is protected and only accessible within class 'Derived3' and its subclasses.
 tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(110,3): error TS2445: Property 'x' is protected and only accessible within class 'Base' and its subclasses.
 tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAccessibleWithinNestedSubclass1.ts(111,4): error TS2445: Property 'x' is protected and only accessible within class 'Base' and its subclasses.
@@ -57,17 +57,17 @@ tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAcce
 
                     b.x;            // Error, isn't accessed through an instance of the enclosing class
                       ~
-!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived1'.
+!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived1'. This is an instance of class 'Base'.
                     d1.x;           // OK, accessed within a class derived from their declaring class, and through an instance of the enclosing class
                     d2.x;           // Error, isn't accessed through an instance of the enclosing class
                        ~
-!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived1'.
+!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived1'. This is an instance of class 'Derived2'.
                     d3.x;           // Error, redefined in a subclass, can only be accessed in the declaring class or one of its subclasses
                        ~
 !!! error TS2445: Property 'x' is protected and only accessible within class 'Derived3' and its subclasses.
                     d4.x;           // Error, isn't accessed through an instance of the enclosing class
                        ~
-!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived1'.
+!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived1'. This is an instance of class 'Derived4'.
                 }
             }
         }
@@ -85,10 +85,10 @@ tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAcce
 
                     b.x;            // Error, isn't accessed through an instance of the enclosing class
                       ~
-!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived2'.
+!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived2'. This is an instance of class 'Base'.
                     d1.x;           // Error, isn't accessed through an instance of the enclosing class
                        ~
-!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived2'.
+!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived2'. This is an instance of class 'Derived1'.
                     d2.x;           // OK, accessed within a class derived from their declaring class, and through an instance of the enclosing class
                     d3.x;           // Error, redefined in a subclass, can only be accessed in the declaring class or one of its subclasses
                        ~
@@ -112,17 +112,17 @@ tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAcce
 
                     b.x;            // Error, isn't accessed through an instance of the enclosing class
                       ~
-!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'.
+!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'. This is an instance of class 'Base'.
                     d1.x;           // Error, isn't accessed through an instance of the enclosing class
                        ~
-!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'.
+!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'. This is an instance of class 'Derived1'.
                     d2.x;           // Error, isn't accessed through an instance of the enclosing class
                        ~
-!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'.
+!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'. This is an instance of class 'Derived2'.
                     d3.x;           // OK, accessed within their declaring class
                     d4.x;           // Error, isn't accessed through an instance of the enclosing class
                        ~
-!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'.
+!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived3'. This is an instance of class 'Derived4'.
                 }
             }
         }
@@ -140,13 +140,13 @@ tests/cases/conformance/classes/members/accessibility/protectedClassPropertyAcce
 
                     b.x;            // Error, isn't accessed through an instance of the enclosing class
                       ~
-!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived4'.
+!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived4'. This is an instance of class 'Base'.
                     d1.x;           // Error, isn't accessed through an instance of the enclosing class
                        ~
-!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived4'.
+!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived4'. This is an instance of class 'Derived1'.
                     d2.x;           // Error, isn't accessed through an instance of the enclosing class
                        ~
-!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived4'.
+!!! error TS2446: Property 'x' is protected and only accessible through an instance of class 'Derived4'. This is an instance of class 'Derived2'.
                     d3.x;           // Error, redefined in a subclass, can only be accessed in the declaring class or one of its subclasses
                        ~
 !!! error TS2445: Property 'x' is protected and only accessible within class 'Derived3' and its subclasses.