FIR: add & use hasExplicitParameterList to anonymous functions

#KT-49134 Fixed

compiler/fir/fir2ir/jvm-backend/src/org/jetbrains/kotlin/fir/backend/jvm/FirMetadataSerializer.kt

@@ -86,6 +86,7 @@ class FirMetadataSerializer(
             returnTypeRef = function.returnTypeRef.approximated(toSuper = true, typeParameterSet)
             receiverTypeRef = function.receiverTypeRef?.approximated(toSuper = false, typeParameterSet)
             isLambda = (function as? FirAnonymousFunction)?.isLambda == true
+            hasExplicitParameterList = (function as? FirAnonymousFunction)?.hasExplicitParameterList == true
             valueParameters.addAll(function.valueParameters.map {
                 buildValueParameterCopy(it) {
                     returnTypeRef = it.returnTypeRef.approximated(toSuper = false, typeParameterSet)

compiler/fir/providers/src/org/jetbrains/kotlin/fir/CopyUtils.kt

@@ -99,6 +99,7 @@ fun FirAnonymousFunction.copy(
         this.receiverTypeRef = receiverTypeRef
         symbol = this@copy.symbol
         isLambda = this@copy.isLambda
+        hasExplicitParameterList = this@copy.hasExplicitParameterList
         this.valueParameters.addAll(valueParameters)
         this.body = body
         this.annotations.addAll(annotations)

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

@@ -1548,6 +1548,7 @@ class DeclarationsConverter(
                 receiverTypeRef = receiverType
                 symbol = functionSymbol
                 isLambda = false
+                hasExplicitParameterList = true
                 label = context.getLastLabel(functionDeclaration)
                 val labelName = label?.name ?: context.calleeNamesForLambda.lastOrNull()?.identifier
                 target = FirFunctionTarget(labelName = labelName, isLambda = false)

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

@@ -125,10 +125,12 @@ class ExpressionsConverter(
     private fun convertLambdaExpression(lambdaExpression: LighterASTNode): FirExpression {
         val valueParameterList = mutableListOf<ValueParameter>()
         var block: LighterASTNode? = null
+        var hasArrow = false
         lambdaExpression.getChildNodesByType(FUNCTION_LITERAL).first().forEachChildren {
             when (it.tokenType) {
                 VALUE_PARAMETER_LIST -> valueParameterList += declarationsConverter.convertValueParameters(it, ValueParameterDeclaration.LAMBDA)
                 BLOCK -> block = it
+                ARROW -> hasArrow = true
             }
         }
 
@@ -142,6 +144,7 @@ class ExpressionsConverter(
             receiverTypeRef = implicitType
             symbol = FirAnonymousFunctionSymbol()
             isLambda = true
+            hasExplicitParameterList = hasArrow
             label = context.getLastLabel(lambdaExpression) ?: context.calleeNamesForLambda.lastOrNull()?.let {
                 buildLabel {
                     source = expressionSource.fakeElement(FirFakeSourceElementKind.GeneratedLambdaLabel)

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

@@ -1223,6 +1223,7 @@ open class RawFirBuilder(
                     receiverTypeRef = receiverType
                     symbol = FirAnonymousFunctionSymbol()
                     isLambda = false
+                    hasExplicitParameterList = true
                     label = context.getLastLabel(function)
                     labelName = label?.name ?: context.calleeNamesForLambda.lastOrNull()?.identifier
                 }
@@ -1338,6 +1339,7 @@ open class RawFirBuilder(
                 receiverTypeRef = receiverType
                 symbol = FirAnonymousFunctionSymbol()
                 isLambda = true
+                hasExplicitParameterList = expression.functionLiteral.arrow != null
 
                 val destructuringStatements = mutableListOf<FirStatement>()
                 for (valueParameter in literal.valueParameters) {

compiler/fir/raw-fir/psi2fir/testData/rawBuilder/expressions/lambda.kt

@@ -31,4 +31,6 @@ fun test(list: List<Int>) {
 
 val simple = { }
 
+val simpleWithArrow = { -> }
+
 val another = { 42 }

compiler/fir/raw-fir/psi2fir/testData/rawBuilder/expressions/lambda.lazyBodies.txt

@@ -23,5 +23,7 @@ FILE: lambda.kt
     public? final? fun test(list: List<Int>): R|kotlin/Unit| { LAZY_BLOCK }
     public? final? val simple: <implicit> = LAZY_EXPRESSION
         public? get(): <implicit>
+    public? final? val simpleWithArrow: <implicit> = LAZY_EXPRESSION
+        public? get(): <implicit>
     public? final? val another: <implicit> = LAZY_EXPRESSION
         public? get(): <implicit>

compiler/fir/raw-fir/psi2fir/testData/rawBuilder/expressions/lambda.txt

@@ -70,6 +70,11 @@ FILE: lambda.kt
         ^ Unit
     }
 
+        public? get(): <implicit>
+    public? final? val simpleWithArrow: <implicit> = fun <implicit>.<anonymous>(<no-parameters>)(): <implicit> <inline=Unknown>  {
+        ^ Unit
+    }
+
         public? get(): <implicit>
     public? final? val another: <implicit> = fun <implicit>.<anonymous>(): <implicit> <inline=Unknown>  {
         IntegerLiteral(42)

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/inference/InferenceUtils.kt

@@ -59,7 +59,7 @@ fun extractLambdaInfoFromFunctionalType(
 
     var coerceFirstParameterToExtensionReceiver = false
     val argumentValueParameters = argument.valueParameters
-    val parameters = if (argument.isLambda && argumentValueParameters.isEmpty() && expectedParameters.size < 2) {
+    val parameters = if (argument.isLambda && !argument.hasExplicitParameterList && expectedParameters.size < 2) {
         expectedParameters // Infer existence of a parameter named `it` of an appropriate type.
     } else {
         if (duringCompletion &&

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/resolve/transformers/contracts/FirContractResolveTransformer.kt

@@ -167,6 +167,7 @@ open class FirContractResolveTransformer(
                 receiverTypeRef = buildImplicitTypeRef()
                 symbol = FirAnonymousFunctionSymbol()
                 isLambda = true
+                hasExplicitParameterList = true
 
                 body = buildBlock {
                     contractDescription.rawEffects.forEach {

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/declarations/FirAnonymousFunction.kt

@@ -45,6 +45,7 @@ abstract class FirAnonymousFunction : FirFunction(), FirTypeParametersOwner {
     abstract val invocationKind: EventOccurrencesRange?
     abstract val inlineStatus: InlineStatus
     abstract val isLambda: Boolean
+    abstract val hasExplicitParameterList: Boolean
     abstract override val typeParameters: List<FirTypeParameter>
     abstract val typeRef: FirTypeRef
 

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/declarations/builder/FirAnonymousFunctionBuilder.kt

@@ -59,6 +59,7 @@ class FirAnonymousFunctionBuilder : FirFunctionBuilder, FirAnnotationContainerBu
     var invocationKind: EventOccurrencesRange? = null
     var inlineStatus: InlineStatus = InlineStatus.Unknown
     var isLambda: Boolean by kotlin.properties.Delegates.notNull<Boolean>()
+    var hasExplicitParameterList: Boolean by kotlin.properties.Delegates.notNull<Boolean>()
     val typeParameters: MutableList<FirTypeParameter> = mutableListOf()
     var typeRef: FirTypeRef = FirImplicitTypeRefImpl(null)
 
@@ -82,6 +83,7 @@ class FirAnonymousFunctionBuilder : FirFunctionBuilder, FirAnnotationContainerBu
             invocationKind,
             inlineStatus,
             isLambda,
+            hasExplicitParameterList,
             typeParameters,
             typeRef,
         )

compiler/fir/tree/gen/org/jetbrains/kotlin/fir/declarations/impl/FirAnonymousFunctionImpl.kt

@@ -52,6 +52,7 @@ internal class FirAnonymousFunctionImpl(
     override var invocationKind: EventOccurrencesRange?,
     override var inlineStatus: InlineStatus,
     override val isLambda: Boolean,
+    override val hasExplicitParameterList: Boolean,
     override val typeParameters: MutableList<FirTypeParameter>,
     override var typeRef: FirTypeRef,
 ) : FirAnonymousFunction() {

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirRenderer.kt

@@ -626,6 +626,12 @@ open class FirRenderer(builder: StringBuilder, protected val mode: RenderMode =
             print(".")
         }
         print("<anonymous>")
+        if (anonymousFunction.valueParameters.isEmpty() &&
+            anonymousFunction.hasExplicitParameterList &&
+            anonymousFunction.returnTypeRef is FirImplicitTypeRef
+        ) {
+            print("(<no-parameters>)")
+        }
         anonymousFunction.valueParameters.renderParameters()
         print(": ")
         anonymousFunction.returnTypeRef.accept(this)

compiler/fir/tree/tree-generator/src/org/jetbrains/kotlin/fir/tree/generator/NodeConfigurator.kt

@@ -282,6 +282,7 @@ object NodeConfigurator : AbstractFieldConfigurator<FirTreeBuilder>(FirTreeBuild
                 isMutable = true
             }
             +booleanField("isLambda")
+            +booleanField("hasExplicitParameterList")
             +typeParameters
             +field(typeRef, withReplace = true)
         }

compiler/testData/diagnostics/tests/functionLiterals/ExpectedParametersTypesMismatch.fir.kt

@@ -24,9 +24,9 @@ fun test1() {
     foo1 <!ARGUMENT_TYPE_MISMATCH!>{
         x, <!CANNOT_INFER_PARAMETER_TYPE!>y<!> -> ""
     }<!>
-    foo1 {
+    foo1 <!ARGUMENT_TYPE_MISMATCH!>{
         -> <!ARGUMENT_TYPE_MISMATCH!>42<!>
-    }
+    }<!>
 
 
     foo2 <!ARGUMENT_TYPE_MISMATCH!>{

compiler/testData/diagnostics/tests/overload/EmptyArgumentListInLambda.fir.kt

@@ -1,8 +0,0 @@
-// !DIAGNOSTICS: -UNUSED_PARAMETER
-
-fun foo(g: () -> Int) {}
-fun foo(f: (Int) -> Int) {}
-
-fun test() {
-    <!OVERLOAD_RESOLUTION_AMBIGUITY!>foo<!> { -> 42 }
-}

compiler/testData/diagnostics/tests/overload/EmptyArgumentListInLambda.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 
 fun foo(g: () -> Int) {}

compiler/testData/diagnostics/tests/regressions/kt30245.fir.kt

@@ -130,7 +130,7 @@ fun test4() { // to non-extension lambda 2
 }
 
 open class A(a: () -> Unit) {
-    constructor(f: (String) -> Unit) : <!OVERLOAD_RESOLUTION_AMBIGUITY!>this<!>({ -> f("") })
+    constructor(f: (String) -> Unit) : this({ -> f("") })
 }
 
 class B: A({ s -> "1" })

compiler/testData/diagnostics/tests/regressions/kt352.fir.kt

@@ -2,14 +2,14 @@
 
 package kt352
 
-val f : (Any) -> Unit = {  -> }  //type mismatch
+val f : (Any) -> Unit = <!INITIALIZER_TYPE_MISMATCH!>{  -> }<!>  //type mismatch
 
 fun foo() {
-    val f : (Any) -> Unit = { -> }  //!!! no error
+    val f : (Any) -> Unit = <!INITIALIZER_TYPE_MISMATCH!>{ -> }<!>  //!!! no error
 }
 
 class A() {
-    val f : (Any) -> Unit = { -> }  //type mismatch
+    val f : (Any) -> Unit = <!INITIALIZER_TYPE_MISMATCH!>{ -> }<!>  //type mismatch
 }
 
 //more tests
@@ -25,4 +25,4 @@ val testIt : (Any) -> Unit = {
     if (it is String) {
         doSmth(it)
     }
-}
+}