[FIR] Change default visibility for sealed class constructors from private to public

compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrDeclarationStorage.kt

@@ -444,11 +444,15 @@ class Fir2IrDeclarationStorage(
         val descriptor = WrappedClassConstructorDescriptor()
         val origin = IrDeclarationOrigin.DEFINED
         val isPrimary = constructor.isPrimary
+        val visibility = when {
+            irParent is IrClass && irParent.modality == Modality.SEALED -> Visibilities.PRIVATE
+            else -> constructor.visibility
+        }
         val created = constructor.convertWithOffsets { startOffset, endOffset ->
             irSymbolTable.declareConstructor(startOffset, endOffset, origin, descriptor) { symbol ->
                 IrConstructorImpl(
                     startOffset, endOffset, origin, symbol,
-                    constructor.name, constructor.visibility,
+                    constructor.name, visibility,
                     constructor.returnTypeRef.toIrType(session, this),
                     isInline = false, isExternal = false, isPrimary = isPrimary, isExpect = false
                 ).bindAndDeclareParameters(constructor, descriptor, irParent, isStatic = true, shouldLeaveScope = shouldLeaveScope)

compiler/fir/lightTree/src/org/jetbrains/kotlin/fir/lightTree/fir/ClassWrapper.kt

@@ -53,10 +53,11 @@ class ClassWrapper(
     }
 
     fun defaultConstructorVisibility(): Visibility {
-        return if (isObject() || isSealed() || isEnum())
-            Visibilities.PRIVATE
-        else
-            Visibilities.UNKNOWN
+        return when {
+            isObject() || isEnum() -> Visibilities.PRIVATE
+            isSealed() -> Visibilities.PUBLIC
+            else -> Visibilities.UNKNOWN
+        }
     }
 
     fun getFirUserTypeFromClassName(): FirUserTypeRef {

compiler/fir/psi2fir/src/org/jetbrains/kotlin/fir/builder/RawFirBuilder.kt

@@ -405,12 +405,12 @@ class RawFirBuilder(session: FirSession, val stubMode: Boolean) : BaseFirBuilder
                 }
             }
 
-            fun defaultVisibility() =
-                if (owner is KtObjectDeclaration || owner.hasModifier(SEALED_KEYWORD) || owner.hasModifier(ENUM_KEYWORD))
-                // TODO: sealed is FILE_PRIVATE (?) object / enum is HIDDEN (?)
-                    Visibilities.PRIVATE
-                else
-                    Visibilities.UNKNOWN
+            fun defaultVisibility() = when {
+                // TODO: object / enum is HIDDEN (?)
+                owner is KtObjectDeclaration || owner.hasModifier(ENUM_KEYWORD) -> Visibilities.PRIVATE
+                owner.hasModifier(SEALED_KEYWORD) -> Visibilities.PUBLIC
+                else -> Visibilities.UNKNOWN
+            }
 
             val status = FirDeclarationStatusImpl(this?.visibility ?: defaultVisibility(), Modality.FINAL).apply {
                 isExpect = this@toFirConstructor?.hasExpectModifier() ?: false

compiler/fir/resolve/testData/resolve/exhaustiveness_sealedClass.txt

@@ -1,6 +1,6 @@
 FILE: exhaustiveness_sealedClass.kt
     public sealed class Base : R|kotlin/Any| {
-        private constructor(): R|Base| {
+        public constructor(): R|Base| {
             super<R|kotlin/Any|>()
         }
 

compiler/fir/resolve/testData/resolve/multifile/sealedStarImport.txt

@@ -1,6 +1,6 @@
 FILE: test.kt
     public sealed class Test : R|kotlin/Any| {
-        private constructor(): R|test/Test| {
+        public constructor(): R|test/Test| {
             super<R|kotlin/Any|>()
         }
 

compiler/fir/resolve/testData/resolve/recursiveCallOnWhenWithSealedClass.txt

@@ -1,6 +1,6 @@
 FILE: recursiveCallOnWhenWithSealedClass.kt
     public sealed class Maybe<T> : R|kotlin/Any| {
-        private constructor<T>(): R|Maybe<T>| {
+        public constructor<T>(): R|Maybe<T>| {
             super<R|kotlin/Any|>()
         }