[FIR] Fix conversion of underscored value parameters in functions

Fix false REDECLARATION

compiler/fir/raw-fir/light-tree2fir/src/org/jetbrains/kotlin/fir/lightTree/converter/DeclarationsConverter.kt

@@ -1436,7 +1436,8 @@ class DeclarationsConverter(
         val target: FirFunctionTarget
         val functionSource = functionDeclaration.toFirSourceElement()
         val functionSymbol: FirFunctionSymbol<*>
-        val functionBuilder = if (identifier == null && isLocal) {
+        val isAnonymousFunction = identifier == null && isLocal
+        val functionBuilder = if (isAnonymousFunction) {
             val labelName = functionDeclaration.getLabelName() ?: context.calleeNamesForLambda.lastOrNull()?.identifier
             target = FirFunctionTarget(labelName = labelName, isLambda = false)
             functionSymbol = FirAnonymousFunctionSymbol()
@@ -1494,7 +1495,12 @@ class DeclarationsConverter(
             }
 
             withCapturedTypeParameters(true, actualTypeParameters) {
-                valueParametersList?.let { list -> valueParameters += convertValueParameters(list).map { it.firValueParameter } }
+                valueParametersList?.let { list ->
+                    valueParameters += convertValueParameters(
+                        list,
+                        if (isAnonymousFunction) ValueParameterDeclaration.LAMBDA else ValueParameterDeclaration.OTHER
+                    ).map { it.firValueParameter }
+                }
 
                 val hasContractEffectList = outerContractDescription != null
                 val bodyWithContractDescription = convertFunctionBody(block, expression, hasContractEffectList)

compiler/fir/raw-fir/psi2fir/src/org/jetbrains/kotlin/fir/builder/RawFirBuilder.kt

@@ -1113,8 +1113,8 @@ open class RawFirBuilder(
             val receiverType = function.receiverTypeReference.convertSafe<FirTypeRef>()
 
             val labelName: String?
-            val functionIsAnonymousFunction = function.name == null && !function.parent.let { it is KtFile || it is KtClassBody }
-            val functionBuilder = if (functionIsAnonymousFunction) {
+            val isAnonymousFunction = function.name == null && !function.parent.let { it is KtFile || it is KtClassBody }
+            val functionBuilder = if (isAnonymousFunction) {
                 FirAnonymousFunctionBuilder().apply {
                     receiverTypeRef = receiverType
                     symbol = FirAnonymousFunctionSymbol()
@@ -1159,7 +1159,11 @@ open class RawFirBuilder(
                     function.extractTypeParametersTo(this, symbol)
                 }
                 for (valueParameter in function.valueParameters) {
-                    valueParameters += valueParameter.convert<FirValueParameter>()
+                    valueParameters += convertValueParameter(
+                        valueParameter,
+                        null,
+                        if (isAnonymousFunction) ValueParameterDeclaration.LAMBDA else ValueParameterDeclaration.OTHER
+                    )
                 }
                 val actualTypeParameters = if (this is FirSimpleFunctionBuilder)
                     this.typeParameters

compiler/testData/diagnostics/tests/redeclarations/RedeclaredValueParameters.fir.kt

@@ -4,4 +4,6 @@ fun test2(block: (Int, String) -> Unit) { }
 
 fun main() {
     test2 { <!REDECLARATION!>b<!>, <!REDECLARATION!>b<!> -> ; }
+
+    val func: (Int, Int) -> Int = fun(_, _): Int { return 42 }
 }

compiler/testData/diagnostics/tests/redeclarations/RedeclaredValueParameters.kt

@@ -4,4 +4,6 @@ fun test2(block: (Int, String) -> Unit) { }
 
 fun main() {
     test2 { <!REDECLARATION, REDECLARATION!>b<!>, <!REDECLARATION, REDECLARATION!>b<!> -> ; }
+
+    val func: (Int, Int) -> Int = fun(_, _): Int { return 42 }
 }