[FIR] Allow accessing protected members via local inheritors

^KT-65058 Fixed

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

@@ -19,7 +19,9 @@ object FirInlineBodyResolvedQualifierChecker : FirResolvedQualifierChecker(MppCh
         val accessedClass = expression.symbol ?: return
         val source = expression.source ?: return
         if (accessedClass.isCompanion) {
-            inlineFunctionBodyContext.checkAccessedDeclaration(source, accessedClass, accessedClass.visibility, context, reporter)
+            inlineFunctionBodyContext.checkAccessedDeclaration(
+                source, expression, accessedClass, accessedClass.visibility, context, reporter,
+            )
         }
     }
 }

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

@@ -32,6 +32,7 @@ import org.jetbrains.kotlin.fir.symbols.FirBasedSymbol
 import org.jetbrains.kotlin.fir.symbols.impl.*
 import org.jetbrains.kotlin.fir.types.*
 import org.jetbrains.kotlin.fir.visitors.FirDefaultVisitor
+import org.jetbrains.kotlin.types.model.typeConstructor
 import org.jetbrains.kotlin.util.OperatorNameConventions
 import org.jetbrains.kotlin.utils.addToStdlib.shouldNotBeCalled
 
@@ -65,6 +66,7 @@ object FirInlineDeclarationChecker : FirFunctionChecker(MppCheckerKind.Common) {
 
         internal fun checkAccessedDeclaration(
             source: KtSourceElement,
+            accessExpression: FirStatement,
             accessedSymbol: FirBasedSymbol<*>,
             declarationVisibility: Visibility,
             context: CheckerContext,
@@ -76,12 +78,10 @@ object FirInlineDeclarationChecker : FirFunctionChecker(MppCheckerKind.Common) {
                 else -> shouldNotBeCalled()
             }
 
-            val accessedDeclarationEffectiveVisibility = recordedEffectiveVisibility.let {
-                if (it == EffectiveVisibility.Local) {
-                    EffectiveVisibility.Public
-                } else {
-                    it
-                }
+            val accessedDeclarationEffectiveVisibility = when {
+                recordedEffectiveVisibility.isReachableDueToLocalDispatchReceiver(accessExpression, context) -> EffectiveVisibility.Public
+                recordedEffectiveVisibility == EffectiveVisibility.Local -> EffectiveVisibility.Public
+                else -> recordedEffectiveVisibility
             }
             val isCalledFunPublicOrPublishedApi = accessedDeclarationEffectiveVisibility.publicApi
             val isInlineFunPublicOrPublishedApi = inlineFunEffectiveVisibility.publicApi
@@ -106,6 +106,18 @@ object FirInlineDeclarationChecker : FirFunctionChecker(MppCheckerKind.Common) {
             )
         }
 
+        private fun EffectiveVisibility.isReachableDueToLocalDispatchReceiver(access: FirStatement, context: CheckerContext): Boolean {
+            val receiverType = access.localDispatchReceiver(context) ?: return false
+            val receiverProtected = EffectiveVisibility.Protected(receiverType.typeConstructor(context.session.typeContext))
+            val relation = receiverProtected.relation(this, context.session.typeContext)
+            return relation == EffectiveVisibility.Permissiveness.SAME || relation == EffectiveVisibility.Permissiveness.LESS
+        }
+
+        private fun FirStatement.localDispatchReceiver(context: CheckerContext): ConeKotlinType? =
+            (this as? FirQualifiedAccessExpression)?.dispatchReceiver?.resolvedType?.takeIf {
+                (it.toSymbol(context.session) as? FirClassLikeSymbol<*>)?.effectiveVisibility == EffectiveVisibility.Local
+            }
+
         internal data class AccessedDeclarationVisibilityData(
             val isInlineFunPublicOrPublishedApi: Boolean,
             val isCalledFunPublicOrPublishedApi: Boolean,
@@ -239,6 +251,7 @@ object FirInlineDeclarationChecker : FirFunctionChecker(MppCheckerKind.Common) {
             }
             val (isInlineFunPublicOrPublishedApi, isCalledFunPublicOrPublishedApi, calledFunEffectiveVisibility) = checkAccessedDeclaration(
                 source,
+                accessExpression,
                 calledDeclaration,
                 calledDeclaration.visibility,
                 context,

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

@@ -1,12 +0,0 @@
-// ISSUE: KT-65058
-
-open class A {
-    protected fun foo() {
-    }
-}
-
-<!NOTHING_TO_INLINE!>inline<!> fun bar() = object : A() {
-    fun baz() {
-        <!PROTECTED_CALL_FROM_PUBLIC_INLINE_ERROR!>foo<!>()
-    }
-}

compiler/testData/diagnostics/tests/callingProtectedFromInline.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // ISSUE: KT-65058
 
 open class A {