[FE 1.0] Refactoring: replace defensive NonPrivateCallableAdded with Unknown

Motivation: I'm going to drop NonPrivateCallableAdded (KT-62655) in the
next commits. But I don't want to change the existing logic when I drop
it. That's why I have to introduce the "Unknown" case

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/Errors.java

@@ -842,6 +842,8 @@ public interface Errors {
             DiagnosticFactory3.create(WARNING, DECLARATION_NAME);
     DiagnosticFactory1<KtCallableDeclaration, K1ExpectActualMemberDiff<CallableMemberDescriptor, ClassDescriptor>>
             NON_ACTUAL_MEMBER_DECLARED_IN_EXPECT_NON_FINAL_CLASSIFIER_ACTUALIZATION_WARNING = DiagnosticFactory1.create(WARNING, DECLARATION_NAME);
+    DiagnosticFactory1<KtCallableDeclaration, K1ExpectActualMemberDiff<CallableMemberDescriptor, ClassDescriptor>>
+            UNKNOWN_PROBLEM_DURING_NON_FINAL_CLASSIFIER_ACTUALIZATION_WARNING = DiagnosticFactory1.create(WARNING, DECLARATION_NAME);
     DiagnosticFactory1<KtCallableDeclaration, K1ExpectActualMemberDiff<CallableMemberDescriptor, ClassDescriptor>>
             RETURN_TYPE_CHANGED_IN_NON_FINAL_EXPECT_CLASSIFIER_ACTUALIZATION_WARNING = DiagnosticFactory1.create(WARNING, DECLARATION_RETURN_TYPE);
     DiagnosticFactory1<KtCallableDeclaration, K1ExpectActualMemberDiff<CallableMemberDescriptor, ClassDescriptor>>

compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

@@ -406,6 +406,9 @@ public class DefaultErrorMessages {
         MAP.put(NON_ACTUAL_MEMBER_DECLARED_IN_EXPECT_NON_FINAL_CLASSIFIER_ACTUALIZATION_WARNING,
                 "{0}. This warning will become an error in future releases. Also see https://youtrack.jetbrains.com/issue/KT-22841 for more details",
                 ExpectActualScopeDiffRenderer.INSTANCE);
+        MAP.put(UNKNOWN_PROBLEM_DURING_NON_FINAL_CLASSIFIER_ACTUALIZATION_WARNING,
+                "{0}. This warning will become an error in future releases. Also see https://youtrack.jetbrains.com/issue/KT-22841 for more details",
+                ExpectActualScopeDiffRenderer.INSTANCE);
         MAP.put(RETURN_TYPE_CHANGED_IN_NON_FINAL_EXPECT_CLASSIFIER_ACTUALIZATION_WARNING,
                 "{0}. This warning will become an error in future releases. Also see https://youtrack.jetbrains.com/issue/KT-22841 for more details",
                 ExpectActualScopeDiffRenderer.INSTANCE);

compiler/frontend/src/org/jetbrains/kotlin/resolve/checkers/ActualClassifierMustHasTheSameMembersAsNonFinalExpectClassifierChecker.kt

@@ -175,9 +175,9 @@ private fun calculateExpectActualScopeDiff(
                         // If toMemberDiffKind returns null then some Kotlin invariants described in toMemberDiffKind no longer hold.
                         // We can't throw exception here because it would crash the compilation.
                         // Those broken invariants just needs to be reported by other checkers.
-                        // But it's better to report some error (ExpectActualMemberDiff.Kind.NonPrivateCallableAdded in our case) to
-                        // make sure that we don't have missed compilation errors if the invariants change
-                            ?: K1ExpectActualMemberDiff.Kind.NonPrivateCallableAdded
+                        // But it's better to report K1ExpectActualMemberDiff.Kind.Unknown to make sure that we don't have missed
+                        // compilation errors if the invariants change
+                            ?: K1ExpectActualMemberDiff.Kind.Unknown
                     }
                 }
         }
@@ -227,6 +227,8 @@ private fun BindingTrace.reportIfPossible(diff: K1ExpectActualMemberDiff<Callabl
             Errors.VARARG_CHANGED_IN_NON_FINAL_EXPECT_CLASSIFIER_ACTUALIZATION_WARNING.on(psi, diff)
         K1ExpectActualMemberDiff.Kind.TypeParameterNamesChangedInOverride ->
             Errors.TYPE_PARAMETER_NAMES_CHANGED_IN_NON_FINAL_EXPECT_CLASSIFIER_ACTUALIZATION_WARNING.on(psi, diff)
+        K1ExpectActualMemberDiff.Kind.Unknown ->
+            Errors.UNKNOWN_PROBLEM_DURING_NON_FINAL_CLASSIFIER_ACTUALIZATION_WARNING.on(psi, diff)
     }
     report(diagnostic)
 }

compiler/resolution/src/org/jetbrains/kotlin/resolve/multiplatform/K1ExpectActualMemberDiff.kt

@@ -53,6 +53,10 @@ data class K1ExpectActualMemberDiff<out M, out C>(val kind: Kind, val actualMemb
             "{0}: the type parameter names of this member must be the same in the expect class and the actual class. " +
                     "This error happens because the expect class ''{1}'' is non-final"
         ),
+        Unknown(
+            "{0}: normally, this error should never happen. Please report to https://kotl.in/issue. " +
+                    "This error happens because the expect class ''{1}'' is non-final"
+        )
     }
 }
 

core/compiler.common/src/org/jetbrains/kotlin/resolve/multiplatform/ExpectActualMemberDiff.kt

@@ -53,6 +53,10 @@ data class ExpectActualMemberDiff<out M, out C>(val kind: Kind, val actualMember
             "{0}: the type parameter names of this member must be the same in the expect class and the actual class. " +
                     "This error happens because the expect class ''{1}'' is non-final"
         ),
+        Unknown(
+            "{0}: normally, this error should never happen. Please report to https://kotl.in/issue. " +
+                    "This error happens because the expect class ''{1}'' is non-final"
+        )
     }
 }