[FIR] Render full declaration header in diagnostic messages

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

@@ -64,6 +64,8 @@ open class FirRenderer(builder: StringBuilder, protected val mode: RenderMode =
         val renderDeclarationAttributes: Boolean = false,
         val renderDeclarationOrigin: Boolean = false,
         val renderPackageDirective: Boolean = false,
+        val renderNestedDeclarations: Boolean = true,
+        val renderDefaultParameterValues: Boolean = true,
     ) {
         companion object {
             val Normal = RenderMode(
@@ -109,6 +111,21 @@ open class FirRenderer(builder: StringBuilder, protected val mode: RenderMode =
                 renderPropertyAccessors = false,
             )
 
+            val DeclarationHeader = RenderMode(
+                renderLambdaBodies = false,
+                renderCallArguments = false,
+                renderCallableFqNames = false,
+                renderDeclarationResolvePhase = false,
+                renderAnnotation = true,
+                renderBodies = false,
+                renderPropertyAccessors = false,
+                renderDeclarationAttributes = false,
+                renderDeclarationOrigin = false,
+                renderPackageDirective = false,
+                renderNestedDeclarations = false,
+                renderDefaultParameterValues = false,
+            )
+
             val WithDeclarationAttributes = RenderMode(
                 renderLambdaBodies = true,
                 renderCallArguments = true,
@@ -477,7 +494,9 @@ open class FirRenderer(builder: StringBuilder, protected val mode: RenderMode =
     }
 
     protected open fun renderClassDeclarations(regularClass: FirRegularClass) {
-        regularClass.declarations.renderDeclarations()
+        if (mode.renderNestedDeclarations) {
+            regularClass.declarations.renderDeclarations()
+        }
     }
 
     override fun visitEnumEntry(enumEntry: FirEnumEntry) {
@@ -584,7 +603,7 @@ open class FirRenderer(builder: StringBuilder, protected val mode: RenderMode =
         constructor.returnTypeRef.accept(this)
         val body = constructor.body
         val delegatedConstructor = constructor.delegatedConstructor
-        if (body == null) {
+        if (body == null && mode.renderBodies) {
             if (delegatedConstructor != null) {
                 renderInBraces {
                     delegatedConstructor.accept(this)
@@ -740,7 +759,11 @@ open class FirRenderer(builder: StringBuilder, protected val mode: RenderMode =
         valueParameter.returnTypeRef.accept(this)
         valueParameter.defaultValue?.let {
             print(" = ")
-            it.accept(this)
+            if (mode.renderDefaultParameterValues) {
+                it.accept(this)
+            } else {
+                print("...")
+            }
         }
     }