[FIR] Add visitor for validation of generated FIR

compiler/fir/resolve/src/org/jetbrains/kotlin/fir/declarations/GeneratedDeclarationValidation.kt

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2010-2020 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.declarations
+
+import org.jetbrains.kotlin.fir.FirElement
+import org.jetbrains.kotlin.fir.expressions.FirAnnotationCall
+import org.jetbrains.kotlin.fir.expressions.FirArgumentList
+import org.jetbrains.kotlin.fir.expressions.impl.FirResolvedArgumentList
+import org.jetbrains.kotlin.fir.references.FirNamedReference
+import org.jetbrains.kotlin.fir.references.FirResolvedNamedReference
+import org.jetbrains.kotlin.fir.types.FirResolvedTypeRef
+import org.jetbrains.kotlin.fir.types.FirTypeRef
+import org.jetbrains.kotlin.fir.visitors.FirDefaultVisitorVoid
+
+fun FirElement.validate() {
+    accept(FirGeneratedElementsValidator)
+}
+
+/*
+ * TODO's:
+ *  - add proper error messages to all `require`
+ *  - add validation of declaration origin and resolve phase for all declarations
+ */
+object FirGeneratedElementsValidator : FirDefaultVisitorVoid() {
+    override fun visitElement(element: FirElement) {
+        element.acceptChildren(this)
+    }
+
+    override fun visitAnnotationCall(annotationCall: FirAnnotationCall) {
+        require(annotationCall.resolved)
+        annotationCall.acceptChildren(this)
+    }
+
+    override fun visitRegularClass(regularClass: FirRegularClass) {
+        regularClass.acceptChildren(this)
+    }
+
+    override fun visitArgumentList(argumentList: FirArgumentList) {
+        require(argumentList is FirResolvedArgumentList)
+        argumentList.acceptChildren(this)
+    }
+
+    override fun visitNamedReference(namedReference: FirNamedReference) {
+        require(namedReference is FirResolvedNamedReference)
+        namedReference.acceptChildren(this)
+    }
+
+    override fun visitTypeRef(typeRef: FirTypeRef) {
+        require(typeRef is FirResolvedTypeRef)
+        typeRef.acceptChildren(this)
+    }
+
+    override fun visitDeclarationStatus(declarationStatus: FirDeclarationStatus) {
+        require(declarationStatus is FirResolvedDeclarationStatus)
+    }
+
+    override fun visitTypeParameterRef(typeParameterRef: FirTypeParameterRef) {
+        typeParameterRef.symbol.fir.accept(this)
+    }
+}