[K/N][FIR] Do not emit CAST_NEVER_SUCCEEDS when casting to forward declarations

^KT-61841 Fixed

compiler/fir/checkers/checkers.native/src/org/jetbrains/kotlin/fir/analysis/native/checkers/FirNativeCastChecker.kt

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2010-2024 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir.analysis.native.checkers
+
+import org.jetbrains.kotlin.fir.FirPlatformSpecificCastChecker
+import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.types.ConeKotlinType
+import org.jetbrains.kotlin.fir.types.toRegularClassSymbol
+
+object FirNativeCastChecker : FirPlatformSpecificCastChecker() {
+    override fun shouldSuppressImpossibleCast(session: FirSession, fromType: ConeKotlinType, toType: ConeKotlinType): Boolean {
+        return isCastToAForwardDeclaration(session, toType)
+    }
+
+    /**
+     * Here, we only check that we are casting to a forward declaration to suppress a CAST_NEVER_SUCCEEDS warning.
+     * The cast would be further checked with FirNativeForwardDeclarationTypeOperatorChecker and FirNativeForwardDeclarationGetClassCallChecker.
+     */
+    private fun isCastToAForwardDeclaration(session: FirSession, forwardDeclarationType: ConeKotlinType): Boolean {
+        return forwardDeclarationType.toRegularClassSymbol(session)?.forwardDeclarationKindOrNull() != null
+    }
+}