From 84da090a6907fef7451eb7914ba3179f582d4380 Mon Sep 17 00:00:00 2001
From: Tomasz Chabora <kobewi4e@gmail.com>
Date: Wed, 30 Sep 2020 12:00:21 +0200
Subject: [PATCH] Warn when setting Control size inside ready()

---
 scene/gui/control.cpp | 13 ++++++++++++-
 scene/gui/control.h   |  2 ++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/scene/gui/control.cpp b/scene/gui/control.cpp
index 0e28c942f1..0c104bf318 100644
--- a/scene/gui/control.cpp
+++ b/scene/gui/control.cpp
@@ -456,6 +456,10 @@ bool Control::is_layout_rtl() const {
 	}
 }
 
+void Control::_clear_size_warning() {
+	data.size_warning = false;
+}
+
 //moved theme configuration here, so controls can set up even if still not inside active scene
 
 void Control::add_child_notify(Node *p_child) {
@@ -503,7 +507,9 @@ void Control::_notification(int p_notification) {
 		} break;
 		case NOTIFICATION_EXIT_TREE: {
 			get_viewport()->_gui_remove_control(this);
-
+		} break;
+		case NOTIFICATION_READY: {
+			connect("ready", callable_mp(this, &Control::_clear_size_warning), varray(), CONNECT_DEFERRED | CONNECT_ONESHOT);
 		} break;
 
 		case NOTIFICATION_ENTER_CANVAS: {
@@ -1702,6 +1708,11 @@ void Control::set_rect(const Rect2 &p_rect) {
 }
 
 void Control::_set_size(const Size2 &p_size) {
+#ifdef DEBUG_ENABLED
+	if (data.size_warning) {
+		WARN_PRINT("Adjusting the size of Control nodes before they are fully initialized is unreliable. Consider deferring it with set_deferred().");
+	}
+#endif
 	set_size(p_size);
 }
 
diff --git a/scene/gui/control.h b/scene/gui/control.h
index 8b24781287..8981e05872 100644
--- a/scene/gui/control.h
+++ b/scene/gui/control.h
@@ -182,6 +182,7 @@ private:
 		float rotation = 0.0;
 		Vector2 scale = Vector2(1, 1);
 		Vector2 pivot_offset;
+		bool size_warning = true;
 
 		int h_size_flags = SIZE_FILL;
 		int v_size_flags = SIZE_FILL;
@@ -235,6 +236,7 @@ private:
 
 	void _update_minimum_size();
 
+	void _clear_size_warning();
 	void _update_scroll();
 
 	void _compute_offsets(Rect2 p_rect, const float p_anchors[4], float (&r_offsets)[4]);