[FIR] Add ANONYMOUS_INITIALIZER_IN_INTERFACE diagnostic

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

@@ -1083,6 +1083,8 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
         val RETURN_NOT_ALLOWED by error<KtReturnExpression>(PositioningStrategy.RETURN_WITH_LABEL)
         val RETURN_IN_FUNCTION_WITH_EXPRESSION_BODY by error<KtReturnExpression>(PositioningStrategy.RETURN_WITH_LABEL)
         val NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY by error<KtDeclarationWithBody>(PositioningStrategy.DECLARATION_WITH_BODY)
+
+        val ANONYMOUS_INITIALIZER_IN_INTERFACE by error<KtAnonymousInitializer>(PositioningStrategy.DECLARATION_SIGNATURE)
     }
 
     val INLINE by object : DiagnosticGroup("Inline") {

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

@@ -35,6 +35,7 @@ import org.jetbrains.kotlin.lexer.KtModifierKeywordToken
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi.KtAnnotationEntry
+import org.jetbrains.kotlin.psi.KtAnonymousInitializer
 import org.jetbrains.kotlin.psi.KtArrayAccessExpression
 import org.jetbrains.kotlin.psi.KtBinaryExpression
 import org.jetbrains.kotlin.psi.KtBinaryExpressionWithTypeRHS
@@ -573,6 +574,7 @@ object FirErrors {
     val RETURN_NOT_ALLOWED by error0<KtReturnExpression>(SourceElementPositioningStrategies.RETURN_WITH_LABEL)
     val RETURN_IN_FUNCTION_WITH_EXPRESSION_BODY by error0<KtReturnExpression>(SourceElementPositioningStrategies.RETURN_WITH_LABEL)
     val NO_RETURN_IN_FUNCTION_WITH_BLOCK_BODY by error0<KtDeclarationWithBody>(SourceElementPositioningStrategies.DECLARATION_WITH_BODY)
+    val ANONYMOUS_INITIALIZER_IN_INTERFACE by error0<KtAnonymousInitializer>(SourceElementPositioningStrategies.DECLARATION_SIGNATURE)
 
     // Inline
     val USAGE_IS_NOT_INLINABLE by error1<KtElement, FirBasedSymbol<*>>(SourceElementPositioningStrategies.REFERENCE_BY_QUALIFIED)

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/checkers/CommonDeclarationCheckers.kt

@@ -140,4 +140,9 @@ object CommonDeclarationCheckers : DeclarationCheckers() {
             FirAnonymousFunctionParametersChecker,
             FirAnonymousFunctionSyntaxChecker,
         )
+
+    override val anonymousInitializerCheckers: Set<FirAnonymousInitializerChecker>
+        get() = setOf(
+            FirAnonymousInitializerInInterfaceChecker
+        )
 }

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

@@ -0,0 +1,23 @@
+/*
+ * 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.checkers.declaration
+
+import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
+import org.jetbrains.kotlin.fir.analysis.checkers.findClosestClassOrObject
+import org.jetbrains.kotlin.fir.analysis.diagnostics.DiagnosticReporter
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors
+import org.jetbrains.kotlin.fir.analysis.diagnostics.reportOn
+import org.jetbrains.kotlin.fir.declarations.FirAnonymousInitializer
+import org.jetbrains.kotlin.fir.declarations.utils.isInterface
+
+object FirAnonymousInitializerInInterfaceChecker : FirAnonymousInitializerChecker() {
+    override fun check(declaration: FirAnonymousInitializer, context: CheckerContext, reporter: DiagnosticReporter) {
+        val clazz = context.findClosestClassOrObject() ?: return
+        if (clazz.isInterface) {
+            reporter.reportOn(declaration.source, FirErrors.ANONYMOUS_INITIALIZER_IN_INTERFACE, context)
+        }
+    }
+}

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

@@ -57,6 +57,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ANNOTATION_ON_SUP
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ANNOTATION_PARAMETER_DEFAULT_VALUE_MUST_BE_CONSTANT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ANNOTATION_USED_AS_ANNOTATION_ARGUMENT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ANONYMOUS_FUNCTION_PARAMETER_WITH_DEFAULT_VALUE
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ANONYMOUS_INITIALIZER_IN_INTERFACE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ARGUMENT_PASSED_TWICE
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ARGUMENT_TYPE_MISMATCH
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.ARRAY_EQUALITY_OPERATOR_CAN_BE_REPLACED_WITH_EQUALS
@@ -1366,6 +1367,7 @@ class FirDefaultErrorMessages {
                 RETURN_IN_FUNCTION_WITH_EXPRESSION_BODY,
                 "Returns are not allowed for functions with expression body. Use block body in '{...}'"
             )
+            map.put(ANONYMOUS_INITIALIZER_IN_INTERFACE, "Anonymous initializers are not allowed in interfaces")
 
             // Inline
             map.put(

compiler/testData/diagnostics/tests/AnonymousInitializers.fir.kt

@@ -1,26 +0,0 @@
-interface NoC {
-  init {
-
-  }
-
-  val a : Int get() = 1
-
-  init {
-
-  }
-}
-
-class WithC() {
-  val x : Int = 1
-  init {
-    val b = x
-
-  }
-
-  val a : Int get() = 1
-
-  init {
-    val z = <!UNRESOLVED_REFERENCE!>b<!>
-    val zz = x
-  }
-}

compiler/testData/diagnostics/tests/AnonymousInitializers.kt

@@ -1,3 +1,4 @@
+// FIR_IDENTICAL
 interface NoC {
   <!ANONYMOUS_INITIALIZER_IN_INTERFACE!>init<!> {
 

compiler/testData/diagnostics/tests/annotations/onInitializer.fir.kt

@@ -4,8 +4,8 @@ class A {
 }
 
 interface T {
-    @ann init {}
+    @ann <!ANONYMOUS_INITIALIZER_IN_INTERFACE!>init<!> {}
-    @aaa init {}
+    @aaa <!ANONYMOUS_INITIALIZER_IN_INTERFACE!>init<!> {}
 }
 
 annotation class ann

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

@@ -20,6 +20,7 @@ import org.jetbrains.kotlin.fir.declarations.FirTypeParameter
 import org.jetbrains.kotlin.fir.declarations.FirVariable
 import org.jetbrains.kotlin.fir.psi
 import org.jetbrains.kotlin.psi.KtAnnotationEntry
+import org.jetbrains.kotlin.psi.KtAnonymousInitializer
 import org.jetbrains.kotlin.psi.KtArrayAccessExpression
 import org.jetbrains.kotlin.psi.KtBinaryExpression
 import org.jetbrains.kotlin.psi.KtBinaryExpressionWithTypeRHS
@@ -2958,6 +2959,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.ANONYMOUS_INITIALIZER_IN_INTERFACE) { firDiagnostic ->
+        AnonymousInitializerInInterfaceImpl(
+            firDiagnostic as FirPsiDiagnostic,
+            token,
+        )
+    }
     add(FirErrors.USAGE_IS_NOT_INLINABLE) { firDiagnostic ->
         UsageIsNotInlinableImpl(
             firSymbolBuilder.buildSymbol(firDiagnostic.a.fir),

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

@@ -29,6 +29,7 @@ import org.jetbrains.kotlin.lexer.KtModifierKeywordToken
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi.KtAnnotationEntry
+import org.jetbrains.kotlin.psi.KtAnonymousInitializer
 import org.jetbrains.kotlin.psi.KtArrayAccessExpression
 import org.jetbrains.kotlin.psi.KtBinaryExpression
 import org.jetbrains.kotlin.psi.KtBinaryExpressionWithTypeRHS
@@ -2064,6 +2065,10 @@ sealed class KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = NoReturnInFunctionWithBlockBody::class
     }
 
+    abstract class AnonymousInitializerInInterface : KtFirDiagnostic<KtAnonymousInitializer>() {
+        override val diagnosticClass get() = AnonymousInitializerInInterface::class
+    }
+
     abstract class UsageIsNotInlinable : KtFirDiagnostic<KtElement>() {
         override val diagnosticClass get() = UsageIsNotInlinable::class
         abstract val parameter: KtSymbol

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

@@ -31,6 +31,7 @@ import org.jetbrains.kotlin.lexer.KtModifierKeywordToken
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi.KtAnnotationEntry
+import org.jetbrains.kotlin.psi.KtAnonymousInitializer
 import org.jetbrains.kotlin.psi.KtArrayAccessExpression
 import org.jetbrains.kotlin.psi.KtBinaryExpression
 import org.jetbrains.kotlin.psi.KtBinaryExpressionWithTypeRHS
@@ -3337,6 +3338,13 @@ internal class NoReturnInFunctionWithBlockBodyImpl(
     override val firDiagnostic: FirPsiDiagnostic by weakRef(firDiagnostic)
 }
 
+internal class AnonymousInitializerInInterfaceImpl(
+    firDiagnostic: FirPsiDiagnostic,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.AnonymousInitializerInInterface(), KtAbstractFirDiagnostic<KtAnonymousInitializer> {
+    override val firDiagnostic: FirPsiDiagnostic by weakRef(firDiagnostic)
+}
+
 internal class UsageIsNotInlinableImpl(
     override val parameter: KtSymbol,
     firDiagnostic: FirPsiDiagnostic,