[FIR] Add FUNCTION_DELEGATE_MEMBER_NAME_CLASH

compiler/fir/checkers/checkers-component-generator/src/org/jetbrains/kotlin/fir/checkers/generator/diagnostics/FirJvmDiagnosticsList.kt

@@ -35,6 +35,8 @@ object JVM_DIAGNOSTICS_LIST : DiagnosticList("FirJvmErrors") {
 
         val INAPPLICABLE_JVM_NAME by error<PsiElement>()
         val ILLEGAL_JVM_NAME by error<PsiElement>()
+
+        val FUNCTION_DELEGATE_MEMBER_NAME_CLASH by error<PsiElement>(PositioningStrategy.DECLARATION_NAME)
     }
 
     val TYPES by object : DiagnosticGroup("Types") {

compiler/fir/checkers/checkers.jvm/gen/org/jetbrains/kotlin/fir/analysis/diagnostics/jvm/FirJvmErrors.kt

@@ -39,6 +39,7 @@ object FirJvmErrors {
     val JVM_STATIC_ON_EXTERNAL_IN_INTERFACE by error0<PsiElement>(SourceElementPositioningStrategies.DECLARATION_SIGNATURE)
     val INAPPLICABLE_JVM_NAME by error0<PsiElement>()
     val ILLEGAL_JVM_NAME by error0<PsiElement>()
+    val FUNCTION_DELEGATE_MEMBER_NAME_CLASH by error0<PsiElement>(SourceElementPositioningStrategies.DECLARATION_NAME)
 
     // Types
     val JAVA_TYPE_MISMATCH by error2<KtExpression, ConeKotlinType, ConeKotlinType>()

compiler/fir/checkers/checkers.jvm/src/org/jetbrains/kotlin/fir/analysis/jvm/checkers/JvmDeclarationCheckers.kt

@@ -13,7 +13,8 @@ object JvmDeclarationCheckers : DeclarationCheckers() {
         get() = setOf(
             FirJvmExternalDeclarationChecker,
             FirJvmNameChecker,
-            FirJvmDefaultChecker
+            FirJvmDefaultChecker,
+            FirJvmFunctionDelegateMemberNameClashChecker
         )
 
     override val annotatedDeclarationCheckers: Set<FirAnnotatedDeclarationChecker>

compiler/fir/checkers/checkers.jvm/src/org/jetbrains/kotlin/fir/analysis/jvm/checkers/declaration/FirJvmFunctionDelegateMemberNameClashChecker.kt

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2010-2021 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.jvm.checkers.declaration
+
+import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
+import org.jetbrains.kotlin.fir.analysis.checkers.declaration.FirBasicDeclarationChecker
+import org.jetbrains.kotlin.fir.analysis.checkers.getContainingClassSymbol
+import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
+import org.jetbrains.kotlin.fir.analysis.diagnostics.jvm.FirJvmErrors
+import org.jetbrains.kotlin.fir.analysis.diagnostics.reportOn
+import org.jetbrains.kotlin.fir.declarations.*
+import org.jetbrains.kotlin.fir.declarations.utils.isFun
+import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
+import org.jetbrains.kotlin.fir.symbols.impl.isExtension
+import org.jetbrains.kotlin.name.Name
+
+object FirJvmFunctionDelegateMemberNameClashChecker : FirBasicDeclarationChecker() {
+    private val functionDelegateName: Name = Name.identifier("functionDelegate")
+    private val getFunctionDelegateName: Name = Name.identifier("getFunctionDelegate")
+
+    override fun check(declaration: FirDeclaration, context: CheckerContext, reporter: DiagnosticReporter) {
+        if (declaration !is FirCallableDeclaration) return
+        val containingClassSymbol = declaration.getContainingClassSymbol(context.session) as? FirRegularClassSymbol ?: return
+        if (!containingClassSymbol.isFun) return
+        if (declaration.symbol.isExtension || (declaration as? FirFunction)?.valueParameters?.isNotEmpty() == true) return
+
+        if (declaration is FirSimpleFunction && declaration.name == getFunctionDelegateName ||
+            declaration is FirProperty && declaration.name == functionDelegateName
+        ) {
+            reporter.reportOn(declaration.source, FirJvmErrors.FUNCTION_DELEGATE_MEMBER_NAME_CLASH, context)
+        }
+    }
+}

compiler/fir/checkers/checkers.jvm/src/org/jetbrains/kotlin/fir/analysis/jvm/diagnostics/FirJvmDefaultErrorMessages.kt

@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.jvm.FirJvmErrors.EXTERNAL_D
 import org.jetbrains.kotlin.fir.analysis.diagnostics.jvm.FirJvmErrors.EXTERNAL_DECLARATION_CANNOT_HAVE_BODY
 import org.jetbrains.kotlin.fir.analysis.diagnostics.jvm.FirJvmErrors.EXTERNAL_DECLARATION_IN_INTERFACE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.jvm.FirJvmErrors.FIELD_IN_JVM_RECORD
+import org.jetbrains.kotlin.fir.analysis.diagnostics.jvm.FirJvmErrors.FUNCTION_DELEGATE_MEMBER_NAME_CLASH
 import org.jetbrains.kotlin.fir.analysis.diagnostics.jvm.FirJvmErrors.ILLEGAL_JAVA_LANG_RECORD_SUPERTYPE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.jvm.FirJvmErrors.ILLEGAL_JVM_NAME
 import org.jetbrains.kotlin.fir.analysis.diagnostics.jvm.FirJvmErrors.INAPPLICABLE_JVM_FIELD
@@ -160,6 +161,8 @@ object FirJvmDefaultErrorMessages {
             map.put(INAPPLICABLE_JVM_NAME, "'@JvmName' annotation is not applicable to this declaration")
             map.put(ILLEGAL_JVM_NAME, "Illegal JVM name")
 
+            map.put(FUNCTION_DELEGATE_MEMBER_NAME_CLASH, "Spread operator is prohibited for arguments to signature-polymorphic calls")
+
             map.put(JVM_DEFAULT_NOT_IN_INTERFACE, "'@JvmDefault' is only supported on interface members")
             map.put(
                 JVM_DEFAULT_IN_JVM6_TARGET,

compiler/testData/diagnostics/tests/funInterface/functionDelegateClashOnJvm.fir.kt

@@ -1,32 +0,0 @@
-// !DIAGNOSTICS: -UNUSED_PARAMETER
-
-fun interface F1 {
-    val functionDelegate: Function<*>? get() = null
-    fun invoke()
-}
-
-fun interface F2 {
-    fun getFunctionDelegate(): Function<*>? = null
-    fun invoke()
-}
-
-fun interface F3 {
-    val getFunctionDelegate: Function<*>? get() = null
-    fun invoke()
-}
-
-fun interface F4 {
-    fun functionDelegate(): Function<*>? = null
-    fun invoke()
-}
-
-fun interface F5 {
-    val functionDelegate: Any? get() = null
-    fun invoke()
-}
-
-fun interface F6 {
-    val String.functionDelegate: Function<*>? get() = null
-    fun getFunctionDelegate(x: Any?): Function<*>? = null
-    fun invoke()
-}

compiler/testData/diagnostics/tests/funInterface/functionDelegateClashOnJvm.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 
 fun interface F1 {

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDataClassConverters.kt

@@ -3626,6 +3626,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirJvmErrors.FUNCTION_DELEGATE_MEMBER_NAME_CLASH) { firDiagnostic ->
+        FunctionDelegateMemberNameClashImpl(
+            firDiagnostic as FirPsiDiagnostic,
+            token,
+        )
+    }
     add(FirJvmErrors.JAVA_TYPE_MISMATCH) { firDiagnostic ->
         JavaTypeMismatchImpl(
             firSymbolBuilder.typeBuilder.buildKtType(firDiagnostic.a),

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnostics.kt

@@ -2525,6 +2525,10 @@ sealed class KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = IllegalJvmName::class
     }
 
+    abstract class FunctionDelegateMemberNameClash : KtFirDiagnostic<PsiElement>() {
+        override val diagnosticClass get() = FunctionDelegateMemberNameClash::class
+    }
+
     abstract class JavaTypeMismatch : KtFirDiagnostic<KtExpression>() {
         override val diagnosticClass get() = JavaTypeMismatch::class
         abstract val expectedType: KtType

idea/idea-frontend-fir/src/org/jetbrains/kotlin/idea/frontend/api/fir/diagnostics/KtFirDiagnosticsImpl.kt

@@ -4095,6 +4095,13 @@ internal class IllegalJvmNameImpl(
     override val firDiagnostic: FirPsiDiagnostic by weakRef(firDiagnostic)
 }
 
+internal class FunctionDelegateMemberNameClashImpl(
+    firDiagnostic: FirPsiDiagnostic,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.FunctionDelegateMemberNameClash(), KtAbstractFirDiagnostic<PsiElement> {
+    override val firDiagnostic: FirPsiDiagnostic by weakRef(firDiagnostic)
+}
+
 internal class JavaTypeMismatchImpl(
     override val expectedType: KtType,
     override val actualType: KtType,