[FIR] Ignore fake functions in FirExposedVisibilityDeclarationChecker ^KT-51229 Fixed

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/declaration/FirExposedVisibilityDeclarationChecker.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.fir.analysis.checkers.declaration
 
+import org.jetbrains.kotlin.KtFakeSourceElementKind
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.EffectiveVisibility
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
@@ -101,8 +102,11 @@ object FirExposedVisibilityDeclarationChecker : FirBasicDeclarationChecker() {
     }
 
     private fun checkFunction(declaration: FirFunction, reporter: DiagnosticReporter, context: CheckerContext) {
-        var functionVisibility = (declaration as FirMemberDeclaration).effectiveVisibility
+        if (declaration.source?.kind is KtFakeSourceElementKind) {
+            return
+        }
 
+        var functionVisibility = (declaration as FirMemberDeclaration).effectiveVisibility
         if (declaration is FirConstructor && declaration.isFromSealedClass) {
             functionVisibility = EffectiveVisibility.PrivateInClass
         }

compiler/testData/diagnostics/tests/sealed/privateTypeInConstructor.fir.kt

@@ -1,4 +1,4 @@
-// ISSUE: KT-45043
+// ISSUE: KT-45043, KT-51229
 // DIAGNOSTICS: -UNUSED_PARAMETER
 
 private class Bar
@@ -14,3 +14,11 @@ abstract class AbstractFoo(
     <!EXPOSED_PARAMETER_TYPE!>private val y: Bar<!>,
     <!EXPOSED_PARAMETER_TYPE!>z: Bar<!>
 )
+
+internal sealed class A {
+    protected abstract val b: B?
+    protected data class B(val s: String)
+    internal data class C private constructor(override val b: B?) : A() {
+        constructor() : this(null)
+    }
+}

compiler/testData/diagnostics/tests/sealed/privateTypeInConstructor.kt

@@ -1,4 +1,4 @@
-// ISSUE: KT-45043
+// ISSUE: KT-45043, KT-51229
 // DIAGNOSTICS: -UNUSED_PARAMETER
 
 private class Bar
@@ -14,3 +14,11 @@ abstract class AbstractFoo(
     <!EXPOSED_PARAMETER_TYPE!>private val y: Bar<!>,
     <!EXPOSED_PARAMETER_TYPE!>z: Bar<!>
 )
+
+internal sealed class A {
+    protected abstract val b: B?
+    protected data class B(val s: String)
+    internal data class C private constructor(override val b: B?) : A() {
+        constructor() : this(null)
+    }
+}

compiler/testData/diagnostics/tests/sealed/privateTypeInConstructor.txt

@@ -1,5 +1,34 @@
 package
 
+internal sealed class A {
+    protected constructor A()
+    protected abstract val b: A.B?
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    protected final data class B {
+        public constructor B(/*0*/ s: kotlin.String)
+        public final val s: kotlin.String
+        public final operator /*synthesized*/ fun component1(): kotlin.String
+        public final /*synthesized*/ fun copy(/*0*/ s: kotlin.String = ...): A.B
+        public open override /*1*/ /*synthesized*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*synthesized*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ /*synthesized*/ fun toString(): kotlin.String
+    }
+
+    internal final data class C : A {
+        public constructor C()
+        private constructor C(/*0*/ b: A.B?)
+        protected open override /*1*/ val b: A.B?
+        protected final operator /*synthesized*/ fun component1(): A.B?
+        public final /*synthesized*/ fun copy(/*0*/ b: A.B? = ...): A.C
+        public open override /*1*/ /*synthesized*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*1*/ /*synthesized*/ fun hashCode(): kotlin.Int
+        public open override /*1*/ /*synthesized*/ fun toString(): kotlin.String
+    }
+}
+
 public abstract class AbstractFoo {
     public constructor AbstractFoo(/*0*/ x: Bar, /*1*/ y: Bar, /*2*/ z: Bar)
     public final val x: Bar