[FIR] Add pretty rendering of functional types

compiler/fir/tree/src/org/jetbrains/kotlin/fir/FirRenderer.kt

@@ -5,6 +5,8 @@
 
 package org.jetbrains.kotlin.fir
 
+import org.jetbrains.kotlin.builtins.functions.BuiltInFictitiousFunctionClassFactory
+import org.jetbrains.kotlin.builtins.functions.FunctionClassDescriptor
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.descriptors.Visibility
 import org.jetbrains.kotlin.descriptors.annotations.AnnotationUseSiteTarget
@@ -736,13 +738,27 @@ class FirRenderer(builder: StringBuilder) : FirVisitorVoid() {
     }
 
     override fun visitResolvedTypeRef(resolvedTypeRef: FirResolvedTypeRef) {
-        resolvedTypeRef.annotations.renderAnnotations()
+        val kind = resolvedTypeRef.functionTypeKind
+        val annotations = if (kind.withPrettyRender()) {
+            resolvedTypeRef.annotations.dropExtensionFunctionAnnotation()
+        } else {
+            resolvedTypeRef.annotations
+        }
+        annotations.renderAnnotations()
         print("R|")
         val coneType = resolvedTypeRef.type
-        print(coneType.render())
+        print(coneType.renderFunctionType(kind, resolvedTypeRef.isExtensionFunctionType()))
         print("|")
     }
 
+    private val FirResolvedTypeRef.functionTypeKind: FunctionClassDescriptor.Kind?
+        get() {
+            val classId = (type as? ConeClassLikeType)?.lookupTag?.classId ?: return null
+            return BuiltInFictitiousFunctionClassFactory.getFunctionalClassKind(
+                classId.shortClassName.asString(), classId.packageFqName
+            )
+        }
+
     override fun visitUserTypeRef(userTypeRef: FirUserTypeRef) {
         userTypeRef.annotations.renderAnnotations()
         for ((index, qualifier) in userTypeRef.qualifier.withIndex()) {

compiler/fir/tree/src/org/jetbrains/kotlin/fir/types/FirTypeUtils.kt

@@ -5,6 +5,8 @@
 
 package org.jetbrains.kotlin.fir.types
 
+import org.jetbrains.kotlin.fir.FirElement
+import org.jetbrains.kotlin.fir.expressions.FirAnnotationCall
 import org.jetbrains.kotlin.fir.symbols.StandardClassIds
 import org.jetbrains.kotlin.fir.types.impl.FirImplicitBuiltinTypeRef
 import org.jetbrains.kotlin.name.ClassId
@@ -32,4 +34,26 @@ val FirFunctionTypeRef.parametersCount: Int
     get() = if (receiverTypeRef != null)
         valueParameters.size + 1
     else
-        valueParameters.size
+        valueParameters.size
+
+const val EXTENSION_FUNCTION_ANNOTATION = "kotlin/ExtensionFunctionType"
+
+fun FirTypeRef.isExtensionFunctionType(): Boolean {
+    return annotations.any {
+        it.isExtensionFunctionAnnotationCall
+    }
+}
+
+val FirAnnotationCall.isExtensionFunctionAnnotationCall: Boolean
+    get() = (this as? FirAnnotationCall)?.let {
+        (it.annotationTypeRef as? FirResolvedTypeRef)?.let {
+            (it.type as? ConeClassLikeType)?.let {
+                it.lookupTag.classId.asString() == EXTENSION_FUNCTION_ANNOTATION
+            }
+        }
+    } == true
+
+
+fun List<FirAnnotationCall>.dropExtensionFunctionAnnotation(): List<FirAnnotationCall> {
+    return filterNot { it.isExtensionFunctionAnnotationCall }
+}