FIR: report VAL_REASSIGNMENT on synthetic immutable properties

#KT-50972 Fixed

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/cfa/FirPropertyInitializationAnalyzer.kt

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.fir.expressions.FirVariableAssignment
 import org.jetbrains.kotlin.fir.resolve.dfa.cfg.*
 import org.jetbrains.kotlin.fir.symbols.SymbolInternals
 import org.jetbrains.kotlin.fir.symbols.impl.FirPropertySymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirSyntheticPropertySymbol
 import org.jetbrains.kotlin.fir.symbols.impl.FirVariableSymbol
 
 @OptIn(SymbolInternals::class)
@@ -84,7 +85,7 @@ object FirPropertyInitializationAnalyzer : AbstractFirPropertyInitializationChec
                 return true
             }
             val kind = info[symbol] ?: EventOccurrencesRange.ZERO
-            if (symbol.fir.isVal && kind.canBeRevisited()) {
+            if (symbol.fir.isVal && (symbol is FirSyntheticPropertySymbol || kind.canBeRevisited())) {
                 reporter.reportOn(node.fir.lValue.source, FirErrors.VAL_REASSIGNMENT, symbol, context)
                 return true
             }
@@ -110,7 +111,7 @@ object FirPropertyInitializationAnalyzer : AbstractFirPropertyInitializationChec
             node: QualifiedAccessNode
         ): Boolean {
             val kind = info[symbol] ?: EventOccurrencesRange.ZERO
-            if (!kind.isDefinitelyVisited()) {
+            if (symbol !is FirSyntheticPropertySymbol && !kind.isDefinitelyVisited()) {
                 reporter.reportOn(node.fir.source, FirErrors.UNINITIALIZED_VARIABLE, symbol, context)
                 return true
             }

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/cfa/util/LocalPropertyAndCapturedWriteCollector.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.fir.declarations.utils.referredPropertySymbol
 import org.jetbrains.kotlin.fir.expressions.FirVariableAssignment
 import org.jetbrains.kotlin.fir.resolve.dfa.cfg.*
 import org.jetbrains.kotlin.fir.symbols.impl.FirPropertySymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirSyntheticPropertySymbol
 
 class LocalPropertyAndCapturedWriteCollector private constructor() : ControlFlowGraphVisitorVoid() {
     companion object {
@@ -53,11 +54,16 @@ class LocalPropertyAndCapturedWriteCollector private constructor() : ControlFlow
     }
 
     override fun visitVariableAssignmentNode(node: VariableAssignmentNode) {
+        val symbol = node.fir.referredPropertySymbol ?: return
+        if (symbol is FirSyntheticPropertySymbol) {
+            symbols[symbol] = true
+            return
+        }
+
         // Check if this variable assignment is inside a lambda or a local function.
         if (lambdaOrLocalFunctionStack.isEmpty()) return
 
         // Check if the assigned variable doesn't belong to any lambda or local function.
-        val symbol = node.fir.referredPropertySymbol ?: return
         if (symbol !in symbols || symbols[symbol] == false) return
 
         // If all nested declarations are lambdas that are invoked in-place (according to the contract),