From 08a4179e7e3ea91cb63c07b71afae4780005cfd6 Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Wed, 13 Jan 2021 11:24:49 +0100
Subject: [PATCH] Add #[must_use] to all widget builders

---
 egui/src/widgets/button.rs     | 1 +
 egui/src/widgets/drag_value.rs | 1 +
 egui/src/widgets/slider.rs     | 1 +
 egui/src/widgets/text_edit.rs  | 1 +
 4 files changed, 4 insertions(+)

diff --git a/egui/src/widgets/button.rs b/egui/src/widgets/button.rs
index c863e51b..5b7ce421 100644
--- a/egui/src/widgets/button.rs
+++ b/egui/src/widgets/button.rs
@@ -136,6 +136,7 @@ impl Widget for Button {
 
 // TODO: allow checkbox without a text label
 /// Boolean on/off control with text label.
+#[must_use = "You should put this widget in an ui with `ui.add(widget);`"]
 #[derive(Debug)]
 pub struct Checkbox<'a> {
     checked: &'a mut bool,
diff --git a/egui/src/widgets/drag_value.rs b/egui/src/widgets/drag_value.rs
index 0a369bf2..0eb33730 100644
--- a/egui/src/widgets/drag_value.rs
+++ b/egui/src/widgets/drag_value.rs
@@ -17,6 +17,7 @@ fn set(value_function: &mut GetSetValue<'_>, value: f64) {
 }
 
 /// A numeric value that you can change by dragging the number. More compact than a [`Slider`].
+#[must_use = "You should put this widget in an ui with `ui.add(widget);`"]
 pub struct DragValue<'a> {
     value_function: GetSetValue<'a>,
     speed: f32,
diff --git a/egui/src/widgets/slider.rs b/egui/src/widgets/slider.rs
index 4d84bb7c..d3aae681 100644
--- a/egui/src/widgets/slider.rs
+++ b/egui/src/widgets/slider.rs
@@ -37,6 +37,7 @@ struct SliderSpec {
 
 /// Control a number by a horizontal slider.
 /// The range can include any numbers, and go from low-to-high or from high-to-low.
+#[must_use = "You should put this widget in an ui with `ui.add(widget);`"]
 pub struct Slider<'a> {
     get_set_value: GetSetValue<'a>,
     range: RangeInclusive<f64>,
diff --git a/egui/src/widgets/text_edit.rs b/egui/src/widgets/text_edit.rs
index 1e4f9f98..b90c2e2b 100644
--- a/egui/src/widgets/text_edit.rs
+++ b/egui/src/widgets/text_edit.rs
@@ -119,6 +119,7 @@ impl CCursorPair {
 ///     // use my_string
 /// }
 /// ```
+#[must_use = "You should put this widget in an ui with `ui.add(widget);`"]
 #[derive(Debug)]
 pub struct TextEdit<'t> {
     text: &'t mut String,