add more must_use annotations

src/brightness.rs

@@ -18,6 +18,7 @@ use rand::{
 /// let result = connection.send(BrightnessCommand::from(b));
 /// ```
 #[derive(Debug, Copy, Clone, PartialEq, Eq, Ord, PartialOrd)]
+#[repr(transparent)]
 pub struct Brightness(u8);
 
 impl From<Brightness> for u8 {

src/containers/bitmap.rs

@@ -153,6 +153,7 @@ impl Bitmap {
     ///     pixel.set(index % 2 == 0)
     /// }
     /// ```
+    #[must_use]
     pub fn iter_mut(&mut self) -> IterMut<u8, Msb0> {
         self.bit_vec.iter_mut()
     }
@@ -258,6 +259,7 @@ impl From<&Bitmap> for ValueGrid<bool> {
     }
 }
 
+#[must_use]
 struct IterRows<'t> {
     bitmap: &'t Bitmap,
     row: usize,

src/containers/char_grid.rs

@@ -33,6 +33,7 @@ impl CharGrid {
     /// # use servicepoint::CharGrid;
     /// let grid = CharGrid::wrap_str(2, "abc\ndef");
     /// ```
+    #[must_use]
     pub fn wrap_str(width: usize, text: &str) -> Self {
         let lines = text
             .split('\n')

src/containers/value_grid.rs

@@ -50,6 +50,7 @@ impl<T: Value> ValueGrid<T> {
     /// - height: size in y-direction
     ///
     /// returns: [ValueGrid] initialized to default value.
+    #[must_use]
     pub fn new(width: usize, height: usize) -> Self {
         Self {
             data: vec![Default::default(); width * height],
@@ -193,6 +194,7 @@ impl<T: Value> ValueGrid<T> {
     /// ```
     /// [Brightness]: [crate::Brightness]
     /// [Command]: [crate::Command]
+    #[must_use]
     pub fn map<TConverted, F>(&self, f: F) -> ValueGrid<TConverted>
     where
         TConverted: Value,
@@ -358,11 +360,13 @@ impl<T: Value> Grid<T> for ValueGrid<T> {
 
 impl<T: Value> DataRef<T> for ValueGrid<T> {
     /// Get the underlying byte rows mutable
+    #[must_use]
     fn data_ref_mut(&mut self) -> &mut [T] {
         self.data.as_mut_slice()
     }
 
     /// Get the underlying byte rows read only
+    #[must_use]
     fn data_ref(&self) -> &[T] {
         self.data.as_slice()
     }
@@ -376,6 +380,7 @@ impl<T: Value> From<ValueGrid<T>> for Vec<T> {
 }
 
 /// An iterator iver the rows in a [ValueGrid]
+#[must_use]
 pub struct IterGridRows<'t, T: Value> {
     grid: &'t ValueGrid<T>,
     row: usize,