[FIR] Make rendering of properties for diagnostics more user-friendly

#KT-60137 Fixed

compiler/fir/tree/src/org/jetbrains/kotlin/fir/renderer/FirBodyRenderer.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.fir.renderer
 
 import org.jetbrains.kotlin.fir.declarations.FirFunction
+import org.jetbrains.kotlin.fir.declarations.FirVariable
 import org.jetbrains.kotlin.fir.expressions.FirBlock
 import org.jetbrains.kotlin.fir.expressions.FirDelegatedConstructorCall
 import org.jetbrains.kotlin.fir.expressions.FirLazyBlock
@@ -23,6 +24,17 @@ class FirBodyRenderer {
         renderBody(function.body)
     }
 
+    fun render(variable: FirVariable) {
+        variable.initializer?.let {
+            printer.print(" = ")
+            it.accept(visitor)
+        }
+        variable.delegate?.let {
+            printer.print("by ")
+            it.accept(visitor)
+        }
+    }
+
     fun renderBody(block: FirBlock?, additionalStatements: List<FirStatement> = emptyList()) {
         if (block == null) return
         when (block) {

compiler/fir/tree/src/org/jetbrains/kotlin/fir/renderer/FirDeclarationRenderer.kt

@@ -10,7 +10,9 @@ import org.jetbrains.kotlin.fir.declarations.impl.FirErrorConstructor
 import org.jetbrains.kotlin.fir.isCatchParameter
 import org.jetbrains.kotlin.util.capitalizeDecapitalize.toLowerCaseAsciiOnly
 
-open class FirDeclarationRenderer {
+open class FirDeclarationRenderer(
+    private val localVariablePrefix: String = "l",
+) {
 
     internal lateinit var components: FirRendererComponents
     protected val printer get() = components.printer
@@ -40,7 +42,7 @@ open class FirDeclarationRenderer {
                     if (declaration.isCatchParameter == true) {
                         ""
                     } else {
-                        val prefix = if (declaration.isLocal) "l" else ""
+                        val prefix = if (declaration.isLocal) localVariablePrefix else ""
                         prefix + if (declaration.isVal) "val" else "var"
                     }
                 }
@@ -61,4 +63,4 @@ open class FirDeclarationRenderer {
 
     protected open fun FirDeclaration.renderDeclarationAttributes() {
     }
-}
+}

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

@@ -305,14 +305,7 @@ class FirRenderer(
 
         override fun visitVariable(variable: FirVariable) {
             visitCallableDeclaration(variable)
-            variable.initializer?.let {
-                print(" = ")
-                it.accept(this)
-            }
-            variable.delegate?.let {
-                print("by ")
-                it.accept(this)
-            }
+            bodyRenderer?.render(variable)
         }
 
         override fun visitField(field: FirField) {