Fixed @rpc annotation diagnostic (#258)

Author: Mr3zee

compiler-plugin/compiler-plugin-k2/src/main/core/kotlinx/rpc/codegen/FirRpcPredicates.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2023-2025 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package kotlinx.rpc.codegen
@@ -12,6 +12,10 @@ object FirRpcPredicates {
         annotated(RpcClassId.rpcAnnotation.asSingleFqName()) // @Rpc
     }
 
+    internal val rpcMeta = DeclarationPredicate.create {
+        metaAnnotated(RpcClassId.rpcAnnotation.asSingleFqName(), includeItself = true)
+    }
+
     internal val checkedAnnotationMeta = DeclarationPredicate.create {
         metaAnnotated(RpcClassId.checkedTypeAnnotation.asSingleFqName(), includeItself = false)
     }

compiler-plugin/compiler-plugin-k2/src/main/core/kotlinx/rpc/codegen/checkers/FirRpcAnnotationChecker.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2023-2025 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package kotlinx.rpc.codegen.checkers
@@ -9,7 +9,9 @@ import kotlinx.rpc.codegen.FirRpcPredicates
 import kotlinx.rpc.codegen.checkers.diagnostics.FirRpcDiagnostics
 import kotlinx.rpc.codegen.isRemoteService
 import kotlinx.rpc.codegen.remoteServiceSupertypeSource
+import kotlinx.rpc.codegen.rpcAnnotation
 import kotlinx.rpc.codegen.rpcAnnotationSource
+import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.diagnostics.DiagnosticReporter
 import org.jetbrains.kotlin.diagnostics.reportOn
 import org.jetbrains.kotlin.fir.analysis.checkers.MppCheckerKind
@@ -18,6 +20,7 @@ import org.jetbrains.kotlin.fir.analysis.checkers.declaration.FirRegularClassChe
 import org.jetbrains.kotlin.fir.declarations.FirRegularClass
 import org.jetbrains.kotlin.fir.declarations.utils.isInterface
 import org.jetbrains.kotlin.fir.extensions.predicateBasedProvider
+import org.jetbrains.kotlin.fir.types.resolvedType
 
 class FirRpcAnnotationChecker(private val ctx: FirCheckersContext) : FirRegularClassChecker(MppCheckerKind.Common) {
     override fun check(
@@ -26,12 +29,15 @@ class FirRpcAnnotationChecker(private val ctx: FirCheckersContext) : FirRegularC
         reporter: DiagnosticReporter,
     ) {
         val rpcAnnotated = context.session.predicateBasedProvider.matches(FirRpcPredicates.rpc, declaration)
+        val rpcMetaAnnotated = context.session.predicateBasedProvider.matches(FirRpcPredicates.rpcMeta, declaration)
 
-        if (!declaration.isInterface && rpcAnnotated) {
+        if (!declaration.isInterface && declaration.classKind != ClassKind.ANNOTATION_CLASS && rpcMetaAnnotated) {
             reporter.reportOn(
                 source = declaration.symbol.rpcAnnotationSource(context.session),
                 factory = FirRpcDiagnostics.WRONG_RPC_ANNOTATION_TARGET,
                 context = context,
+                a = declaration.symbol.rpcAnnotation(context.session)?.resolvedType
+                    ?: error("Unexpected unresolved annotation type for declaration: ${declaration.symbol.classId.asSingleFqName()}"),
             )
         }
 

compiler-plugin/compiler-plugin-k2/src/main/core/kotlinx/rpc/codegen/checkers/diagnostics/FirRpcDiagnostics.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2023-2025 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package kotlinx.rpc.codegen.checkers.diagnostics
@@ -19,7 +19,7 @@ import org.jetbrains.kotlin.psi.KtAnnotationEntry
 object FirRpcDiagnostics {
     val MISSING_RPC_ANNOTATION by error0<KtAnnotationEntry>()
     val MISSING_SERIALIZATION_MODULE by warning0<KtAnnotationEntry>()
-    val WRONG_RPC_ANNOTATION_TARGET by error0<KtAnnotationEntry>()
+    val WRONG_RPC_ANNOTATION_TARGET by error1<KtAnnotationEntry, ConeKotlinType>()
     val CHECKED_ANNOTATION_VIOLATION by error1<KtAnnotationEntry, ConeKotlinType>()
     val NON_SUSPENDING_REQUEST_WITHOUT_STREAMING_RETURN_TYPE by error0<PsiElement>()
     val AD_HOC_POLYMORPHISM_IN_RPC_SERVICE by error2<PsiElement, Int, Name>()

compiler-plugin/compiler-plugin-k2/src/main/core/kotlinx/rpc/codegen/checkers/diagnostics/RpcDiagnosticRendererFactory.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2023-2025 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 package kotlinx.rpc.codegen.checkers.diagnostics
@@ -29,7 +29,8 @@ object RpcDiagnosticRendererFactory : BaseDiagnosticRendererFactory() {
 
         put(
             factory = FirRpcDiagnostics.WRONG_RPC_ANNOTATION_TARGET,
-            message = "@Rpc annotation is only applicable to interfaces.",
+            message = "@{0} annotation is only applicable to interfaces and annotation classes.",
+            rendererA = FirDiagnosticRenderers.RENDER_TYPE,
         )
 
         put(

tests/compiler-plugin-tests/src/test-gen/kotlinx/rpc/codegen/test/runners/BoxTestGenerated.java

@@ -11,6 +11,7 @@
 import org.jetbrains.kotlin.test.TargetBackend;
 import org.jetbrains.kotlin.test.TestMetadata;
 import org.junit.Ignore;
+import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
 import java.io.File;
@@ -20,7 +21,7 @@
 @SuppressWarnings("all")
 @TestMetadata("src/testData/box")
 @TestDataPath("$PROJECT_ROOT")
-@Ignore
+@Disabled("KRPC-137")
 public class BoxTestGenerated extends AbstractBoxTest {
   @Test
   public void testAllFilesPresentInBox() {

tests/compiler-plugin-tests/src/test-gen/kotlinx/rpc/codegen/test/runners/DiagnosticTestGenerated.java

@@ -9,17 +9,16 @@
 import com.intellij.testFramework.TestDataPath;
 import org.jetbrains.kotlin.test.util.KtTestUtil;
 import org.jetbrains.kotlin.test.TestMetadata;
-import org.junit.Ignore;
+import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
-
 import java.io.File;
 import java.util.regex.Pattern;
 
 /** This class is generated by {@link kotlinx.rpc.codegen.test.GenerateTestsKt}. DO NOT MODIFY MANUALLY */
 @SuppressWarnings("all")
 @TestMetadata("src/testData/diagnostics")
 @TestDataPath("$PROJECT_ROOT")
-@Ignore
+@Disabled("KRPC-137")
 public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
   @Test
   public void testAllFilesPresentInDiagnostics() {

tests/compiler-plugin-tests/src/testData/diagnostics/rpcChecked.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2023-2025 JetBrains s.r.o and contributors. Use of this source code is governed by the Apache 2.0 license.
  */
 
 @file:OptIn(ExperimentalRpcApi::class)
@@ -61,3 +61,15 @@ inline suspend fun <reified T : Any> fail(client: RpcClient, server: RpcServer,
     serviceDescriptorOf<<!CHECKED_ANNOTATION_VIOLATION!>NotAService<!>>()
     serviceDescriptorOf<<!CHECKED_ANNOTATION_VIOLATION!>T<!>>()
 }
+
+@Rpc
+annotation class Grpc
+
+@Grpc
+interface MyGrpcService
+
+@Grpc
+class WrongGrpcTarget
+
+@Rpc
+class WrongRpcTarget