FIR checker: report type parameters on anonymous objects

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

@@ -500,6 +500,7 @@ object DIAGNOSTICS_LIST : DiagnosticList("FirErrors") {
             parameter<FirRegularClassSymbol>("outer")
         }
         val TYPE_PARAMETERS_IN_OBJECT by error<PsiElement>(PositioningStrategy.TYPE_PARAMETERS_LIST)
+        val TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT by error<PsiElement>(PositioningStrategy.TYPE_PARAMETERS_LIST)
         val ILLEGAL_PROJECTION_USAGE by error<PsiElement>()
         val TYPE_PARAMETERS_IN_ENUM by error<PsiElement>()
         val CONFLICTING_PROJECTION by error<KtTypeProjection>(PositioningStrategy.VARIANCE_MODIFIER) {

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

@@ -333,6 +333,7 @@ object FirErrors {
     val NO_TYPE_ARGUMENTS_ON_RHS by error2<PsiElement, Int, FirClassLikeSymbol<*>>()
     val OUTER_CLASS_ARGUMENTS_REQUIRED by error1<PsiElement, FirRegularClassSymbol>()
     val TYPE_PARAMETERS_IN_OBJECT by error0<PsiElement>(SourceElementPositioningStrategies.TYPE_PARAMETERS_LIST)
+    val TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT by error0<PsiElement>(SourceElementPositioningStrategies.TYPE_PARAMETERS_LIST)
     val ILLEGAL_PROJECTION_USAGE by error0<PsiElement>()
     val TYPE_PARAMETERS_IN_ENUM by error0<PsiElement>()
     val CONFLICTING_PROJECTION by error1<KtTypeProjection, ConeKotlinType>(SourceElementPositioningStrategies.VARIANCE_MODIFIER)

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

@@ -72,6 +72,7 @@ object CommonDeclarationCheckers : DeclarationCheckers() {
             FirMemberFunctionsChecker,
             FirMemberPropertiesChecker,
             FirImplementationMismatchChecker,
+            FirTypeParametersInObjectChecker,
         )
 
     override val regularClassCheckers: Set<FirRegularClassChecker>
@@ -89,7 +90,6 @@ object CommonDeclarationCheckers : DeclarationCheckers() {
             FirMethodOfAnyImplementedInInterfaceChecker,
             FirDataClassPrimaryConstructorChecker,
             FirPrimaryConstructorSuperTypeChecker,
-            FirTypeParametersInObjectChecker,
             FirFunInterfaceDeclarationChecker,
             FirNestedClassChecker,
             FirInlineClassDeclarationChecker,

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

@@ -5,21 +5,38 @@
 
 package org.jetbrains.kotlin.fir.analysis.checkers.declaration
 
+import org.jetbrains.kotlin.KtNodeTypes
+import org.jetbrains.kotlin.config.LanguageFeature
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.fir.analysis.checkers.context.CheckerContext
 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.analysis.getChild
+import org.jetbrains.kotlin.fir.declarations.FirAnonymousObject
+import org.jetbrains.kotlin.fir.declarations.FirClass
 import org.jetbrains.kotlin.fir.declarations.FirRegularClass
+import org.jetbrains.kotlin.fir.languageVersionSettings
 
-object FirTypeParametersInObjectChecker : FirRegularClassChecker() {
+object FirTypeParametersInObjectChecker : FirClassChecker() {
-    override fun check(declaration: FirRegularClass, context: CheckerContext, reporter: DiagnosticReporter) {
+    override fun check(declaration: FirClass, context: CheckerContext, reporter: DiagnosticReporter) {
         if (declaration.classKind != ClassKind.OBJECT) {
             return
         }
 
-        if (declaration.typeParameters.isNotEmpty()) {
+        when (declaration) {
-            reporter.reportOn(declaration.source, FirErrors.TYPE_PARAMETERS_IN_OBJECT, context)
+            is FirRegularClass -> if (declaration.typeParameters.isNotEmpty()) {
+                reporter.reportOn(declaration.source, FirErrors.TYPE_PARAMETERS_IN_OBJECT, context)
+            }
+            is FirAnonymousObject -> if (declaration.source?.getChild(KtNodeTypes.TYPE_PARAMETER_LIST, depth = 1) != null) {
+                val diagnosticFactory =
+                    if (context.session.languageVersionSettings.supportsFeature(LanguageFeature.ProhibitTypeParametersInAnonymousObjects)) {
+                        FirErrors.TYPE_PARAMETERS_IN_OBJECT
+                    } else {
+                        FirErrors.TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT
+                    }
+                reporter.reportOn(declaration.source, diagnosticFactory, context)
+            }
         }
     }
 }

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

@@ -406,6 +406,7 @@ import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.TYPE_ARGUMENTS_NO
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.TYPE_ARGUMENTS_REDUNDANT_IN_SUPER_QUALIFIER
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.TYPE_CANT_BE_USED_FOR_CONST_VAL
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.TYPE_MISMATCH
+import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.TYPE_PARAMETERS_IN_ENUM
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.TYPE_PARAMETERS_IN_OBJECT
 import org.jetbrains.kotlin.fir.analysis.diagnostics.FirErrors.TYPE_PARAMETERS_NOT_ALLOWED
@@ -825,6 +826,8 @@ class FirDefaultErrorMessages {
                 RENDER_CLASS_OR_OBJECT_NAME
             )
             map.put(TYPE_PARAMETERS_IN_OBJECT, "Type parameters are not allowed for objects")
+            map.put(TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT, "Type parameters for anonymous objects are deprecated")
+
 //            map.put(ILLEGAL_PROJECTION_USAGE, ...) // &
             map.put(TYPE_PARAMETERS_IN_ENUM, "Enum class cannot have type parameters")
             map.put(

compiler/testData/diagnostics/tests/classObjects/typeParametersInAnnonymousObject.fir.kt

@@ -3,23 +3,23 @@
 // ISSUE: KT-28999
 
 fun case_1() {
-    val x = object<T> { } // type of x is <anonymous object><T>
+    val x = object<!TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT!><T><!> { } // type of x is <anonymous object><T>
 }
 
 fun case_2() {
-    val x = object<T : Number, K: Comparable<K>> { }
+    val x = object<!TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT!><T : Number, K: Comparable<K>><!> { }
 }
 
 fun case_3() {
-    val x = object<T> <!SYNTAX!>where T : Comparable<T><!> { } // ERROR: Where clause is not allowed for objects
+    val x = object<!TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT!><T><!> <!SYNTAX!>where T : Comparable<T><!> { } // ERROR: Where clause is not allowed for objects
 }
 
-val x = object<T, K: Comparable<K>> {
+val x = object<!TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT!><T, K: Comparable<K>><!> {
     fun test() = 10 as <!UNRESOLVED_REFERENCE!>T<!> // OK
 }
 
 fun case_4() {
-    val x = object<T> {
+    val x = object<!TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT!><T><!> {
         fun test() = 10 as <!UNRESOLVED_REFERENCE!>T<!>
     }
 
@@ -27,7 +27,7 @@ fun case_4() {
 }
 
 inline fun <reified T> case_5() {
-    val x = object<T> {
+    val x = object<!TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT!><T><!> {
         fun test() = 10 as T
     }
 
@@ -38,7 +38,7 @@ inline fun <reified T> case_5() {
         <!UNRESOLVED_REFERENCE!>println<!>(z)
     }
 
-    val a = object<A> {
+    val a = object<!TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT!><A><!> {
         fun test() = 42 as <!UNRESOLVED_REFERENCE!>A<!>
     }
 

compiler/testData/diagnostics/tests/classObjects/typeParametersInAnnonymousObject_after.fir.kt

@@ -3,23 +3,23 @@
 // ISSUE: KT-28999
 
 fun case_1() {
-    val x = object<T> { } // type of x is <anonymous object><T>
+    val x = object<!TYPE_PARAMETERS_IN_OBJECT!><T><!> { } // type of x is <anonymous object><T>
 }
 
 fun case_2() {
-    val x = object<T : Number, K: Comparable<K>> { }
+    val x = object<!TYPE_PARAMETERS_IN_OBJECT!><T : Number, K: Comparable<K>><!> { }
 }
 
 fun case_3() {
-    val x = object<T> <!SYNTAX!>where T : Comparable<T><!> { } // ERROR: Where clause is not allowed for objects
+    val x = object<!TYPE_PARAMETERS_IN_OBJECT!><T><!> <!SYNTAX!>where T : Comparable<T><!> { } // ERROR: Where clause is not allowed for objects
 }
 
-val x = object<T, K: Comparable<K>> {
+val x = object<!TYPE_PARAMETERS_IN_OBJECT!><T, K: Comparable<K>><!> {
     fun test() = 10 as <!UNRESOLVED_REFERENCE!>T<!> // OK
 }
 
 fun case_4() {
-    val x = object<T> {
+    val x = object<!TYPE_PARAMETERS_IN_OBJECT!><T><!> {
         fun test() = 10 as <!UNRESOLVED_REFERENCE!>T<!>
     }
 
@@ -27,7 +27,7 @@ fun case_4() {
 }
 
 inline fun <reified T> case_5() {
-    val x = object<T> {
+    val x = object<!TYPE_PARAMETERS_IN_OBJECT!><T><!> {
         fun test() = 10 as T
     }
 
@@ -38,7 +38,7 @@ inline fun <reified T> case_5() {
         <!UNRESOLVED_REFERENCE!>println<!>(z)
     }
 
-    val a = object<A> {
+    val a = object<!TYPE_PARAMETERS_IN_OBJECT!><A><!> {
         fun test() = 42 as <!UNRESOLVED_REFERENCE!>A<!>
     }
 

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

@@ -1486,6 +1486,12 @@ internal val KT_DIAGNOSTIC_CONVERTER = KtDiagnosticConverterBuilder.buildConvert
             token,
         )
     }
+    add(FirErrors.TYPE_PARAMETERS_IN_ANONYMOUS_OBJECT) { firDiagnostic ->
+        TypeParametersInAnonymousObjectImpl(
+            firDiagnostic as FirPsiDiagnostic,
+            token,
+        )
+    }
     add(FirErrors.ILLEGAL_PROJECTION_USAGE) { firDiagnostic ->
         IllegalProjectionUsageImpl(
             firDiagnostic as FirPsiDiagnostic,

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

@@ -1057,6 +1057,10 @@ sealed class KtFirDiagnostic<PSI : PsiElement> : KtDiagnosticWithPsi<PSI> {
         override val diagnosticClass get() = TypeParametersInObject::class
     }
 
+    abstract class TypeParametersInAnonymousObject : KtFirDiagnostic<PsiElement>() {
+        override val diagnosticClass get() = TypeParametersInAnonymousObject::class
+    }
+
     abstract class IllegalProjectionUsage : KtFirDiagnostic<PsiElement>() {
         override val diagnosticClass get() = IllegalProjectionUsage::class
     }

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

@@ -1691,6 +1691,13 @@ internal class TypeParametersInObjectImpl(
     override val firDiagnostic: FirPsiDiagnostic by weakRef(firDiagnostic)
 }
 
+internal class TypeParametersInAnonymousObjectImpl(
+    firDiagnostic: FirPsiDiagnostic,
+    override val token: ValidityToken,
+) : KtFirDiagnostic.TypeParametersInAnonymousObject(), KtAbstractFirDiagnostic<PsiElement> {
+    override val firDiagnostic: FirPsiDiagnostic by weakRef(firDiagnostic)
+}
+
 internal class IllegalProjectionUsageImpl(
     firDiagnostic: FirPsiDiagnostic,
     override val token: ValidityToken,