From 59ba91bd59c7a96b8cf9b0b9312748f5aa20c813 Mon Sep 17 00:00:00 2001
From: Erik Hedvall <erikwhedvall@gmail.com>
Date: Wed, 31 Jul 2024 12:59:34 +0200
Subject: [PATCH] Make a few `palette::cast::*` functions `const fn`

---
 palette/src/cast/array.rs | 54 +++++++++++++--------------------------
 palette/src/cast/uint.rs  | 24 ++++++++---------
 2 files changed, 30 insertions(+), 48 deletions(-)

diff --git a/palette/src/cast/array.rs b/palette/src/cast/array.rs
index 25c9e9f2d..7e64ef49b 100644
--- a/palette/src/cast/array.rs
+++ b/palette/src/cast/array.rs
@@ -238,15 +238,12 @@ where
 /// let array3 = <&[_; 3]>::from(&color);
 /// ```
 #[inline]
-pub fn into_array_ref<T>(value: &T) -> &T::Array
+pub const fn into_array_ref<T>(value: &T) -> &T::Array
 where
     T: ArrayCast,
 {
-    assert_eq!(core::mem::size_of::<T::Array>(), core::mem::size_of::<T>());
-    assert_eq!(
-        core::mem::align_of::<T::Array>(),
-        core::mem::align_of::<T>()
-    );
+    assert!(core::mem::size_of::<T::Array>() == core::mem::size_of::<T>());
+    assert!(core::mem::align_of::<T::Array>() == core::mem::align_of::<T>());
 
     let value: *const T = value;
 
@@ -282,15 +279,12 @@ where
 /// let color3 = <&Srgb<u8>>::from(&array);
 /// ```
 #[inline]
-pub fn from_array_ref<T>(value: &T::Array) -> &T
+pub const fn from_array_ref<T>(value: &T::Array) -> &T
 where
     T: ArrayCast,
 {
-    assert_eq!(core::mem::size_of::<T::Array>(), core::mem::size_of::<T>());
-    assert_eq!(
-        core::mem::align_of::<T::Array>(),
-        core::mem::align_of::<T>()
-    );
+    assert!(core::mem::size_of::<T::Array>() == core::mem::size_of::<T>());
+    assert!(core::mem::align_of::<T::Array>() == core::mem::align_of::<T>());
 
     let value: *const T::Array = value;
 
@@ -598,15 +592,12 @@ where
 /// assert_eq!(cast::into_array_slice(colors), &[[64, 139, 10], [93, 18, 214]])
 /// ```
 #[inline]
-pub fn into_array_slice<T>(values: &[T]) -> &[T::Array]
+pub const fn into_array_slice<T>(values: &[T]) -> &[T::Array]
 where
     T: ArrayCast,
 {
-    assert_eq!(core::mem::size_of::<T::Array>(), core::mem::size_of::<T>());
-    assert_eq!(
-        core::mem::align_of::<T::Array>(),
-        core::mem::align_of::<T>()
-    );
+    assert!(core::mem::size_of::<T::Array>() == core::mem::size_of::<T>());
+    assert!(core::mem::align_of::<T::Array>() == core::mem::align_of::<T>());
 
     // Safety: The requirements of implementing `ArrayCast`, as well as the size
     // and alignment asserts, ensures that reading `T` as `T::Array` is safe.
@@ -623,15 +614,12 @@ where
 /// assert_eq!(cast::into_component_slice(colors), &[64, 139, 10, 93, 18, 214])
 /// ```
 #[inline]
-pub fn into_component_slice<T>(values: &[T]) -> &[<T::Array as ArrayExt>::Item]
+pub const fn into_component_slice<T>(values: &[T]) -> &[<T::Array as ArrayExt>::Item]
 where
     T: ArrayCast,
 {
-    assert_eq!(core::mem::size_of::<T::Array>(), core::mem::size_of::<T>());
-    assert_eq!(
-        core::mem::align_of::<T::Array>(),
-        core::mem::align_of::<T>()
-    );
+    assert!(core::mem::size_of::<T::Array>() == core::mem::size_of::<T>());
+    assert!(core::mem::align_of::<T::Array>() == core::mem::align_of::<T>());
 
     let length = values.len() * T::Array::LENGTH;
 
@@ -658,15 +646,12 @@ where
 /// )
 /// ```
 #[inline]
-pub fn from_array_slice<T>(values: &[T::Array]) -> &[T]
+pub const fn from_array_slice<T>(values: &[T::Array]) -> &[T]
 where
     T: ArrayCast,
 {
-    assert_eq!(core::mem::size_of::<T::Array>(), core::mem::size_of::<T>());
-    assert_eq!(
-        core::mem::align_of::<T::Array>(),
-        core::mem::align_of::<T>()
-    );
+    assert!(core::mem::size_of::<T::Array>() == core::mem::size_of::<T>());
+    assert!(core::mem::align_of::<T::Array>() == core::mem::align_of::<T>());
 
     // Safety: The requirements of implementing `ArrayCast`, as well as the size
     // and alignment asserts, ensures that reading `T::Array` as `T` is safe.
@@ -737,17 +722,14 @@ where
 /// assert!(cast::try_from_component_slice::<Srgb<u8>>(components).is_err());
 /// ```
 #[inline]
-pub fn try_from_component_slice<T>(
+pub const fn try_from_component_slice<T>(
     values: &[<T::Array as ArrayExt>::Item],
 ) -> Result<&[T], SliceCastError>
 where
     T: ArrayCast,
 {
-    assert_eq!(core::mem::size_of::<T::Array>(), core::mem::size_of::<T>());
-    assert_eq!(
-        core::mem::align_of::<T::Array>(),
-        core::mem::align_of::<T>()
-    );
+    assert!(core::mem::size_of::<T::Array>() == core::mem::size_of::<T>());
+    assert!(core::mem::align_of::<T::Array>() == core::mem::align_of::<T>());
 
     if values.len() % T::Array::LENGTH != 0 {
         return Err(SliceCastError);
diff --git a/palette/src/cast/uint.rs b/palette/src/cast/uint.rs
index fc2ff022f..4868997f7 100644
--- a/palette/src/cast/uint.rs
+++ b/palette/src/cast/uint.rs
@@ -110,12 +110,12 @@ where
 /// assert_eq!(cast::into_uint_ref(&color), &0xFF17C64C);
 /// ```
 #[inline]
-pub fn into_uint_ref<T>(value: &T) -> &T::Uint
+pub const fn into_uint_ref<T>(value: &T) -> &T::Uint
 where
     T: UintCast,
 {
-    assert_eq!(core::mem::size_of::<T::Uint>(), core::mem::size_of::<T>());
-    assert_eq!(core::mem::align_of::<T::Uint>(), core::mem::align_of::<T>());
+    assert!(core::mem::size_of::<T::Uint>() == core::mem::size_of::<T>());
+    assert!(core::mem::align_of::<T::Uint>() == core::mem::align_of::<T>());
 
     let value: *const T = value;
 
@@ -133,12 +133,12 @@ where
 /// assert_eq!(cast::from_uint_ref::<PackedArgb>(&0xFF17C64C), &color);
 /// ```
 #[inline]
-pub fn from_uint_ref<T>(value: &T::Uint) -> &T
+pub const fn from_uint_ref<T>(value: &T::Uint) -> &T
 where
     T: UintCast,
 {
-    assert_eq!(core::mem::size_of::<T::Uint>(), core::mem::size_of::<T>());
-    assert_eq!(core::mem::align_of::<T::Uint>(), core::mem::align_of::<T>());
+    assert!(core::mem::size_of::<T::Uint>() == core::mem::size_of::<T>());
+    assert!(core::mem::align_of::<T::Uint>() == core::mem::align_of::<T>());
 
     let value: *const T::Uint = value;
 
@@ -255,12 +255,12 @@ where
 /// assert_eq!(cast::into_uint_slice(colors), &[0xFF17C64C, 0xFF5D12D6])
 /// ```
 #[inline]
-pub fn into_uint_slice<T>(values: &[T]) -> &[T::Uint]
+pub const fn into_uint_slice<T>(values: &[T]) -> &[T::Uint]
 where
     T: UintCast,
 {
-    assert_eq!(core::mem::size_of::<T::Uint>(), core::mem::size_of::<T>());
-    assert_eq!(core::mem::align_of::<T::Uint>(), core::mem::align_of::<T>());
+    assert!(core::mem::size_of::<T::Uint>() == core::mem::size_of::<T>());
+    assert!(core::mem::align_of::<T::Uint>() == core::mem::align_of::<T>());
 
     // Safety: The requirements of implementing `UintCast`, as well as the size
     // and alignment asserts, ensures that reading `T` as `T::Uint` is safe.
@@ -280,12 +280,12 @@ where
 /// assert_eq!(cast::from_uint_slice::<PackedArgb>(&[0xFF17C64C, 0xFF5D12D6]), colors)
 /// ```
 #[inline]
-pub fn from_uint_slice<T>(values: &[T::Uint]) -> &[T]
+pub const fn from_uint_slice<T>(values: &[T::Uint]) -> &[T]
 where
     T: UintCast,
 {
-    assert_eq!(core::mem::size_of::<T::Uint>(), core::mem::size_of::<T>());
-    assert_eq!(core::mem::align_of::<T::Uint>(), core::mem::align_of::<T>());
+    assert!(core::mem::size_of::<T::Uint>() == core::mem::size_of::<T>());
+    assert!(core::mem::align_of::<T::Uint>() == core::mem::align_of::<T>());
 
     // Safety: The requirements of implementing `UintCast`, as well as the size
     // and alignment asserts, ensures that reading `T::Uint` as `T` is safe.