fix flex system ambiguity

Author: cart

crates/bevy_text/src/draw.rs

@@ -8,6 +8,7 @@ use bevy_render::{
     renderer::{BindGroup, RenderResourceBindings, RenderResourceId},
 };
 use bevy_sprite::TextureAtlasSprite;
+use bevy_utils::tracing::error;
 
 use crate::{PositionedGlyph, TextSection};
 use bevy_render::pipeline::IndexFormat;
@@ -44,7 +45,7 @@ impl<'a> Drawable for DrawableText<'a> {
         {
             draw.set_vertex_buffer(0, vertex_attribute_buffer_id, 0);
         } else {
-            println!("Could not find vertex buffer for `bevy_sprite::QUAD_HANDLE`.")
+            error!("Could not find vertex buffer for `bevy_sprite::QUAD_HANDLE`.")
         }
 
         let mut indices = 0..0;

crates/bevy_ui/src/lib.rs

@@ -20,7 +20,7 @@ pub mod prelude {
 }
 
 use bevy_app::prelude::*;
-use bevy_ecs::{IntoSystem, SystemStage};
+use bevy_ecs::{IntoSystem, ParallelSystemDescriptorCoercion, SystemStage};
 use bevy_render::render_graph::RenderGraph;
 use update::ui_z_system;
 
@@ -31,6 +31,10 @@ pub mod stage {
     pub const UI: &str = "ui";
 }
 
+pub mod system {
+    pub const FLEX: &str = "flex";
+}
+
 impl Plugin for UiPlugin {
     fn build(&self, app: &mut AppBuilder) {
         app.init_resource::<FlexSurface>()
@@ -41,10 +45,13 @@ impl Plugin for UiPlugin {
             )
             .add_system_to_stage(bevy_app::stage::PRE_UPDATE, ui_focus_system.system())
             // add these stages to front because these must run before transform update systems
-            .add_system_to_stage(stage::UI, widget::text_system.system())
-            .add_system_to_stage(stage::UI, widget::image_node_system.system())
+            .add_system_to_stage(stage::UI, widget::text_system.system().before(system::FLEX))
+            .add_system_to_stage(
+                stage::UI,
+                widget::image_node_system.system().before(system::FLEX),
+            )
+            .add_system_to_stage(stage::UI, flex_node_system.system().label(system::FLEX))
             .add_system_to_stage(stage::UI, ui_z_system.system())
-            .add_system_to_stage(stage::UI, flex_node_system.system())
             .add_system_to_stage(bevy_render::stage::DRAW, widget::draw_text_system.system());
 
         let resources = app.resources();