[FIR] Report all Visibilities.Unknown in FirOverrideChecker

Check all members for `Visibility.Unknown`,
otherwise we miss them when they come
from supertypes. This is the reason why
the FP intellij build failed with a
cryptic stacktrace instead of a
human-readable diagnostic.

Also, do report the diagnostic at all
cases of `Visibilities.Unknown`. Turns
out, there are no "simple to reason
about" situations here :(

Also, an interesting detail:
`retrieveDirectOverriddenOf` returns an
empty list for intersection overrides.
But this doesn't seem to break anything...

Replacing `CANNOT_INFER_VISIBILITY`'s
type `KtDeclaration` with
`PsiNameIdentifierOwner` and the related
changes in `PositioningStrategies`
were needed to prevent an exception saying that
`PsiClassImpl` is not a subtype of
`KtDeclaration`.

compiler/testData/diagnostics/tests/annotations/rendering/notImplementedMembers.fir.kt

@@ -45,4 +45,4 @@ interface GI : G {
 }
 
 <!MANY_IMPL_MEMBER_NOT_IMPLEMENTED("Class 'AG1'; a")!>class AG1<!>(val a: A, val g: G) : A by a, G by g
-<!MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED("Class 'AG2'; a")!>class AG2<!>() : AI, GI
+<!CANNOT_INFER_VISIBILITY("a"), MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED("Class 'AG2'; a")!>class AG2<!>() : AI, GI

compiler/testData/diagnostics/tests/delegation/Delegation_MultipleDelegates.fir.kt

@@ -0,0 +1,19 @@
+// !DIAGNOSTICS: -CONFLICTING_JVM_DECLARATIONS
+interface One {
+  public <!REDUNDANT_OPEN_IN_INTERFACE!>open<!> fun foo() : Int
+  private fun boo() = 10
+}
+interface Two {
+  public <!REDUNDANT_OPEN_IN_INTERFACE!>open<!> fun foo() : Int
+}
+
+interface OneImpl : One {
+  public override fun foo() = 1
+}
+interface TwoImpl : Two {
+  public override fun foo() = 2
+}
+
+<!CANNOT_INFER_VISIBILITY, MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED!>class Test1<!>() : TwoImpl, OneImpl {}
+class Test2(a : One) : One by a, Two {}
+<!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class Test3<!>(a : One, b : Two) : Two by b, One by a {}

compiler/testData/diagnostics/tests/delegation/Delegation_MultipleDelegates.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // !DIAGNOSTICS: -CONFLICTING_JVM_DECLARATIONS
 interface One {
   public <!REDUNDANT_OPEN_IN_INTERFACE!>open<!> fun foo() : Int

compiler/testData/diagnostics/tests/deprecated/deprecatedInheritance_after.fir.kt

@@ -78,7 +78,7 @@ open class NWEH: NotDeprecated, WarningDeprecated, ErrorDeprecated, HiddenDeprec
 
 class WE2: WE()
 
-<!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class NWE2<!>: WE(), NotDeprecated
+<!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class NWE2<!>: WE(), NotDeprecated
 
 class NWE3: WE(), NotDeprecated {
     override fun f() {

compiler/testData/diagnostics/tests/deprecated/deprecatedInheritance_before.fir.kt

@@ -78,7 +78,7 @@ open class NWEH: NotDeprecated, WarningDeprecated, ErrorDeprecated, HiddenDeprec
 
 class WE2: WE()
 
-<!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class NWE2<!>: WE(), NotDeprecated
+<!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class NWE2<!>: WE(), NotDeprecated
 
 class NWE3: WE(), NotDeprecated {
     override fun f() {

compiler/testData/diagnostics/tests/intersectionWithMultipleDefaultsInJava.fir.kt

@@ -0,0 +1,34 @@
+// TARGET_BACKEND: JVM
+
+// FILE: IntCollection.java
+interface IntCollection<E> {
+    public boolean add(int key);
+}
+
+// FILE: IntSet.java
+interface IntSet extends IntCollection {
+    public default boolean add(Integer it) { return true; }
+
+    // from the supertype
+    // public boolean add(int key);
+}
+
+// FILE: AbstractCollection.java
+abstract class AbstractCollection<E> {
+    public boolean add(E it) { return true; }
+}
+
+// FILE: AbstractIntCollection.java
+abstract class AbstractIntCollection extends AbstractCollection<Integer> {
+    public boolean add(int it) { return true; }
+
+    // from the supertype
+    // public default boolen add(Integer it) { return true; }
+}
+
+// FILE: AbstractIntSet.java
+public abstract class AbstractIntSet extends AbstractIntCollection implements IntSet {}
+
+// FILE: Main.kt
+
+<!CANNOT_INFER_VISIBILITY!>class KotlinClass<!> : AbstractIntSet()

compiler/testData/diagnostics/tests/intersectionWithMultipleDefaultsInJava.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // TARGET_BACKEND: JVM
 
 // FILE: IntCollection.java

compiler/testData/diagnostics/tests/j+k/primitiveOverrides/triangleWithFlexibleTypeAndSubstitution4.fir.kt

@@ -21,7 +21,7 @@ open class C : A<Int>()
 
 interface D : B<Int>
 
-<!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class E<!> : C(), D
+<!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class E<!> : C(), D
 
 fun main() {
     E().foo(42)

compiler/testData/diagnostics/tests/multiplatform/scopes/manyImplMemberNotImplemented.fir.kt

@@ -10,8 +10,8 @@
 expect open class C1()
 expect interface I1
 
-open <!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class Common1_1<!> : C1(), I1
-open <!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class Common1_2<!> : I1, C1()
+open <!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class Common1_1<!> : C1(), I1
+open <!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class Common1_2<!> : I1, C1()
 
 expect open class Expect1_1 : C1, I1
 expect open class Expect1_2 : I1, C1
@@ -37,8 +37,8 @@ actual interface I1 {
     fun f() {}
 }
 
-actual open <!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class Expect1_1<!> : C1(), I1
-actual open <!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class Expect1_2<!> : I1, C1()
+actual open <!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class Expect1_1<!> : C1(), I1
+actual open <!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class Expect1_2<!> : I1, C1()
 
 
 actual abstract class C2 actual constructor() {

compiler/testData/diagnostics/tests/multiplatform/scopes/manyInterfacesMemberNotImplemented.fir.kt

@@ -11,9 +11,9 @@
 expect interface S1
 expect interface S2
 
-open <!MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED!>class A<!> : S1, S2
+open <!CANNOT_INFER_VISIBILITY, MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED!>class A<!> : S1, S2
 
-class B : A()
+<!CANNOT_INFER_VISIBILITY!>class B<!> : A()
 
 // MODULE: jvm()()(common)
 // TARGET_PLATFORM: JVM

compiler/testData/diagnostics/tests/override/FakeOverrideDifferentDeclarationSignatures.fir.kt

@@ -0,0 +1,11 @@
+interface A {
+    fun f(): String = "string"
+}
+
+open class B {
+    open fun f(): CharSequence = "charSequence"
+}
+
+<!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C<!> : B(), A
+
+val obj: A = <!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>object<!> : B(), A {}

compiler/testData/diagnostics/tests/override/FakeOverrideDifferentDeclarationSignatures.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 interface A {
     fun f(): String = "string"
 }

compiler/testData/diagnostics/tests/override/ParentInheritsManyImplementations.fir.kt

@@ -0,0 +1,17 @@
+package d
+
+interface A {
+    fun foo() = 1
+}
+
+interface B {
+    fun foo() = 2
+}
+
+open <!CANNOT_INFER_VISIBILITY, MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED!>class C<!> : A, B {}
+
+interface E {
+    fun foo(): Int
+}
+
+<!CANNOT_INFER_VISIBILITY!>class D<!> : C() {}

compiler/testData/diagnostics/tests/override/ParentInheritsManyImplementations.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 package d
 
 interface A {

compiler/testData/diagnostics/tests/override/varImplementedByInheritedVal.fir.kt

@@ -20,9 +20,9 @@ open class CVar {
 
 <!MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED!>class C1<!> : IVar, IVarDefault
 <!VAR_IMPLEMENTED_BY_INHERITED_VAL_WARNING!>class C2<!> : CVal(), IVar
-<!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C3<!> : CVal(), IVarDefault
-<!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C4<!> : CVal(), IVar, IVarDefault
+<!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C3<!> : CVal(), IVarDefault
+<!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C4<!> : CVal(), IVar, IVarDefault
 class C5 : CVar(), IVar
-<!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C6<!> : CVar(), IVarDefault
-<!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C7<!> : CVar(), IVar, IVarDefault
+<!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C6<!> : CVar(), IVarDefault
+<!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C7<!> : CVar(), IVar, IVarDefault
 <!VAR_OVERRIDDEN_BY_VAL_BY_DELEGATION!>class C8<!>(ival: IVal) : IVar, IVal by ival

compiler/testData/diagnostics/tests/override/varImplementedByInheritedValError.fir.kt

@@ -20,9 +20,9 @@ open class CVar {
 
 <!MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED!>class C1<!> : IVar, IVarDefault
 <!VAR_IMPLEMENTED_BY_INHERITED_VAL_ERROR!>class C2<!> : CVal(), IVar
-<!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C3<!> : CVal(), IVarDefault
-<!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C4<!> : CVal(), IVar, IVarDefault
+<!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C3<!> : CVal(), IVarDefault
+<!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C4<!> : CVal(), IVar, IVarDefault
 class C5 : CVar(), IVar
-<!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C6<!> : CVar(), IVarDefault
-<!MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C7<!> : CVar(), IVar, IVarDefault
+<!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C6<!> : CVar(), IVarDefault
+<!CANNOT_INFER_VISIBILITY, MANY_IMPL_MEMBER_NOT_IMPLEMENTED!>class C7<!> : CVar(), IVar, IVarDefault
 <!VAR_OVERRIDDEN_BY_VAL_BY_DELEGATION!>class C8<!>(ival: IVal) : IVar, IVal by ival

compiler/testData/diagnostics/tests/regressions/kt302.fir.kt

@@ -0,0 +1,13 @@
+// KT-302 Report an error when inheriting many implementations of the same member
+
+package kt302
+
+interface A {
+    open fun foo() {}
+}
+
+interface B {
+    open fun foo() {}
+}
+
+<!CANNOT_INFER_VISIBILITY, MANY_INTERFACES_MEMBER_NOT_IMPLEMENTED!>class C<!> : A, B {} //should be error here

compiler/testData/diagnostics/tests/regressions/kt302.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // KT-302 Report an error when inheriting many implementations of the same member
 
 package kt302