[FIR] Properly calculate visibilities

`testIntersectionOfPrimitiveBasedFunctions`
is fine, because we deprecate this
already in ^KT-63243.

`CANNOT_INFER_VISIBILITY` is
positioned as `DECLARATION_NAME`,
just in case we decide for
some reason that we do want to
report it along with
`MANY_*_NOT_IMPLEMENTED`. In that
case, we'd get a problem that
their bounds overlap, but not
completely contain one another.

^KT-63741 Fixed
^KT-59400 Fixed

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirDiagnosticsList.kt

@@ -926,6 +926,9 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
             parameter<FirCallableSymbol<*>>("overridden")
             parameter<Name>("containingClassName")
         }
+        val CANNOT_INFER_VISIBILITY by error<KtDeclaration>(PositioningStrategy.DECLARATION_NAME) {
+            parameter<FirCallableSymbol<*>>("callable")
+        }
 
         val MULTIPLE_DEFAULTS_INHERITED_FROM_SUPERTYPES by error<KtElement>(PositioningStrategy.DECLARATION_SIGNATURE_OR_DEFAULT) {
             parameter<Name>("name")

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrors.kt

@@ -517,6 +517,7 @@ object FirErrors {
     val DATA_CLASS_OVERRIDE_DEFAULT_VALUES: KtDiagnosticFactory2<FirCallableSymbol<*>, FirClassSymbol<*>> by error2<KtElement, FirCallableSymbol<*>, FirClassSymbol<*>>(SourceElementPositioningStrategies.DATA_MODIFIER)
     val CANNOT_WEAKEN_ACCESS_PRIVILEGE: KtDiagnosticFactory3<Visibility, FirCallableSymbol<*>, Name> by error3<KtModifierListOwner, Visibility, FirCallableSymbol<*>, Name>(SourceElementPositioningStrategies.VISIBILITY_MODIFIER)
     val CANNOT_CHANGE_ACCESS_PRIVILEGE: KtDiagnosticFactory3<Visibility, FirCallableSymbol<*>, Name> by error3<KtModifierListOwner, Visibility, FirCallableSymbol<*>, Name>(SourceElementPositioningStrategies.VISIBILITY_MODIFIER)
+    val CANNOT_INFER_VISIBILITY: KtDiagnosticFactory1<FirCallableSymbol<*>> by error1<KtDeclaration, FirCallableSymbol<*>>(SourceElementPositioningStrategies.DECLARATION_NAME)
     val MULTIPLE_DEFAULTS_INHERITED_FROM_SUPERTYPES: KtDiagnosticFactory3<Name, FirValueParameterSymbol, List<FirCallableSymbol<*>>> by error3<KtElement, Name, FirValueParameterSymbol, List<FirCallableSymbol<*>>>(SourceElementPositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT)
     val MULTIPLE_DEFAULTS_INHERITED_FROM_SUPERTYPES_WHEN_NO_EXPLICIT_OVERRIDE: KtDiagnosticFactory3<Name, FirValueParameterSymbol, List<FirCallableSymbol<*>>> by error3<KtElement, Name, FirValueParameterSymbol, List<FirCallableSymbol<*>>>(SourceElementPositioningStrategies.DECLARATION_NAME)
     val MULTIPLE_DEFAULTS_INHERITED_FROM_SUPERTYPES_DEPRECATION: KtDiagnosticFactoryForDeprecation3<Name, FirValueParameterSymbol, List<FirCallableSymbol<*>>> by deprecationError3<KtElement, Name, FirValueParameterSymbol, List<FirCallableSymbol<*>>>(ProhibitAllMultipleDefaultsInheritedFromSupertypes, SourceElementPositioningStrategies.DECLARATION_SIGNATURE_OR_DEFAULT)

compiler/fir/checkers/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/FirNonSuppressibleErrorNames.kt

@@ -335,6 +335,7 @@ val FIR_NON_SUPPRESSIBLE_ERROR_NAMES: Set<String> = setOf(
     "DATA_CLASS_OVERRIDE_DEFAULT_VALUES",
     "CANNOT_WEAKEN_ACCESS_PRIVILEGE",
     "CANNOT_CHANGE_ACCESS_PRIVILEGE",
+    "CANNOT_INFER_VISIBILITY",
     "MULTIPLE_DEFAULTS_INHERITED_FROM_SUPERTYPES",
     "MULTIPLE_DEFAULTS_INHERITED_FROM_SUPERTYPES_WHEN_NO_EXPLICIT_OVERRIDE",
     "TYPEALIAS_EXPANDS_TO_ARRAY_OF_NOTHINGS",

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

@@ -25,10 +25,6 @@ import org.jetbrains.kotlin.fir.declarations.CallToPotentiallyHiddenSymbolResult
 import org.jetbrains.kotlin.fir.declarations.utils.*
 import org.jetbrains.kotlin.fir.languageVersionSettings
 import org.jetbrains.kotlin.fir.originalOrSelf
-import org.jetbrains.kotlin.fir.declarations.utils.isFinal
-import org.jetbrains.kotlin.fir.declarations.utils.isOverride
-import org.jetbrains.kotlin.fir.declarations.utils.modality
-import org.jetbrains.kotlin.fir.declarations.utils.visibility
 import org.jetbrains.kotlin.fir.resolve.substitution.substitutorByMap
 import org.jetbrains.kotlin.fir.resolve.toSymbol
 import org.jetbrains.kotlin.fir.scopes.FirTypeScope
@@ -46,7 +42,6 @@ import org.jetbrains.kotlin.fir.types.ConeKotlinType
 import org.jetbrains.kotlin.fir.types.coneType
 import org.jetbrains.kotlin.fir.types.typeContext
 import org.jetbrains.kotlin.fir.visibilityChecker
-import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.lexer.KtTokens
 import org.jetbrains.kotlin.resolve.deprecation.DeprecationLevelValue
 import org.jetbrains.kotlin.resolve.deprecation.SimpleDeprecationInfo
@@ -183,6 +178,16 @@ sealed class FirOverrideChecker(mppKind: MppCheckerKind) : FirAbstractOverrideCh
         overriddenSymbols: List<FirCallableSymbol<*>>,
         context: CheckerContext
     ) {
+        if (visibility == Visibilities.Unknown) {
+            // MANY_*_NOT_IMPLEMENTED implies CANNOT_INFER_VISIBILITY as per KT-63741
+            val isManyNotImplementedDiagnosticReported = overriddenSymbols.count { !it.isAbstract } != 1
+            val isSimpleToReasonAboutSituation = overriddenSymbols.none { it.isIntersectionOverride }
+            if (!(isManyNotImplementedDiagnosticReported && isSimpleToReasonAboutSituation)) {
+                reporter.reportOn(source, FirErrors.CANNOT_INFER_VISIBILITY, this, context)
+            }
+            return
+        }
+
         if (overriddenSymbols.isEmpty()) return
         val visibilities = overriddenSymbols.map {
             it to it.visibility

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/diagnostics/FirErrorsDefaultMessages.kt

@@ -124,6 +124,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CANNOT_BE_IMPORTE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CANNOT_CHANGE_ACCESS_PRIVILEGE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CANNOT_CHECK_FOR_ERASED
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CANNOT_INFER_PARAMETER_TYPE
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CANNOT_INFER_VISIBILITY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CANNOT_OVERRIDE_INVISIBLE_MEMBER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CANNOT_WEAKEN_ACCESS_PRIVILEGE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.CAN_BE_REPLACED_WITH_OPERATOR_ASSIGNMENT
@@ -1652,6 +1653,11 @@ object FirErrorsDefaultMessages : BaseDiagnosticRendererFactory() {
             DECLARATION_NAME,
             TO_STRING
         )
+        map.put(
+            CANNOT_INFER_VISIBILITY,
+            "Cannot infer visibility for ''{0}''. Please specify it explicitly",
+            DECLARATION_NAME,
+        )
 
         map.put(
             ABSTRACT_MEMBER_NOT_IMPLEMENTED,