[FIR] Fix incorrect resolve of callable reference in function signature (^KT-48304 Fixed)

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/FirCallResolver.kt

@@ -378,7 +378,12 @@ class FirCallResolver(
             noSuccessfulCandidates -> {
                 val errorReference = buildErrorReference(
                     info,
-                    ConeUnresolvedReferenceError(info.name),
+                    if (applicability == CandidateApplicability.UNSUPPORTED) {
+                        val unsupportedResolutionDiagnostic = reducedCandidates.firstOrNull()?.diagnostics?.firstOrNull() as? Unsupported
+                        ConeUnsupported(unsupportedResolutionDiagnostic?.message ?: "", unsupportedResolutionDiagnostic?.source)
+                    } else {
+                        ConeUnresolvedReferenceError(info.name)
+                    },
                     callableReferenceAccess.source
                 )
                 resolvedCallableReferenceAtom.resultingReference = errorReference

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/CandidateFactory.kt

@@ -17,8 +17,7 @@ import org.jetbrains.kotlin.fir.moduleData
 import org.jetbrains.kotlin.fir.returnExpressions
 import org.jetbrains.kotlin.fir.scopes.FirScope
 import org.jetbrains.kotlin.fir.symbols.FirBasedSymbol
-import org.jetbrains.kotlin.fir.symbols.impl.FirErrorFunctionSymbol
-import org.jetbrains.kotlin.fir.symbols.impl.FirErrorPropertySymbol
+import org.jetbrains.kotlin.fir.symbols.impl.*
 import org.jetbrains.kotlin.fir.types.classId
 import org.jetbrains.kotlin.resolve.calls.components.PostponedArgumentsAnalyzerContext
 import org.jetbrains.kotlin.resolve.calls.inference.model.ConstraintStorage
@@ -51,7 +50,7 @@ class CandidateFactory private constructor(
         extensionReceiverValue: ReceiverValue? = null,
         builtInExtensionFunctionReceiverValue: ReceiverValue? = null
     ): Candidate {
-        return Candidate(
+        val result = Candidate(
             symbol, dispatchReceiverValue, extensionReceiverValue,
             explicitReceiverKind, context.inferenceComponents.constraintSystemFactory, baseSystem,
             builtInExtensionFunctionReceiverValue?.receiverExpression?.let {
@@ -65,6 +64,16 @@ class CandidateFactory private constructor(
                 ExplicitReceiverKind.NO_EXPLICIT_RECEIVER, ExplicitReceiverKind.BOTH_RECEIVERS -> false
             }
         )
+
+        // The counterpart in FE 1.0 checks if the given descriptor is VariableDescriptor yet not PropertyDescriptor.
+        // Here, we explicitly check if the referred declaration/symbol is value parameter, local variable, or backing field.
+        val callSite = callInfo.callSite
+        if (callSite is FirCallableReferenceAccess) {
+            if (symbol is FirValueParameterSymbol || symbol is FirPropertySymbol && symbol.isLocal || symbol is FirBackingFieldSymbol) {
+                result.addDiagnostic(Unsupported("References to variables aren't supported yet", callSite.calleeReference.source))
+            }
+        }
+        return result
     }
 
     private fun ReceiverValue?.isCandidateFromCompanionObjectTypeScope(): Boolean {

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/calls/ResolutionDiagnostic.kt

@@ -5,6 +5,7 @@
 
 package org.jetbrains.kotlin.fir.resolve.calls
 
+import org.jetbrains.kotlin.fir.FirSourceElement
 import org.jetbrains.kotlin.fir.declarations.FirFunction
 import org.jetbrains.kotlin.fir.declarations.FirValueParameter
 import org.jetbrains.kotlin.fir.expressions.FirExpression
@@ -94,3 +95,5 @@ class ManyLambdaExpressionArguments(
 
 class InfixCallOfNonInfixFunction(val function: FirNamedFunctionSymbol) : ResolutionDiagnostic(INAPPLICABLE_MODIFIER)
 class OperatorCallOfNonOperatorFunction(val function: FirNamedFunctionSymbol) : ResolutionDiagnostic(INAPPLICABLE_MODIFIER)
+
+class Unsupported(val message: String, val source: FirSourceElement? = null) : ResolutionDiagnostic(UNSUPPORTED)

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/diagnostics/FirDiagnostics.kt

@@ -156,10 +156,12 @@ class ConeImportFromSingleton(val name: Name) : ConeDiagnostic() {
     override val reason: String get() = "Import from singleton $name is not allowed"
 }
 
-class ConeUnsupportedDynamicType() : ConeDiagnostic() {
-    override val reason: String get() = "Dynamic types are not supported in this context"
+open class ConeUnsupported(val message: String, val source: FirSourceElement? = null) : ConeDiagnostic() {
+    override val reason: String get() = message
 }
 
+class ConeUnsupportedDynamicType : ConeUnsupported("Dynamic types are not supported in this context")
+
 class ConeDeprecated(val source: FirSourceElement?, val symbol: FirBasedSymbol<*>, val deprecation: Deprecation) : ConeDiagnostic() {
     override val reason: String get() = "Deprecated: ${deprecation.message}"
 }