Evaluate migration of SmallVec to min_const_generics

crates/storage/Cargo.toml

@@ -25,8 +25,7 @@ scale = { package = "parity-scale-codec", version = "2.0", default-features = fa
 derive_more = { version = "0.99", default-features = false, features = ["from", "display"] }
 scale-info = { version = "0.5", default-features = false, features = ["derive"], optional = true }
 cfg-if = "1.0"
-array-init = "1.0"
-generic-array = "0.14.1"
+array-init = { version = "1.0", default-features = false, features = ["const-generics"] }
 
 # Workaround: we actually just need criterion as a dev-dependency, but
 # there is an issue with a doubly included std lib when executing

crates/storage/src/collections/smallvec/impls.rs

@@ -16,29 +16,24 @@ use super::{
     Iter,
     SmallVec,
 };
-use crate::{
-    lazy::LazyArrayLength,
-    traits::PackedLayout,
-};
+use crate::traits::PackedLayout;
 use core::iter::{
     Extend,
     FromIterator,
 };
 
-impl<T, N> Drop for SmallVec<T, N>
+impl<T, const N: usize> Drop for SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     fn drop(&mut self) {
         self.clear_cells()
     }
 }
 
-impl<T, N> core::ops::Index<u32> for SmallVec<T, N>
+impl<T, const N: usize> core::ops::Index<u32> for SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     type Output = T;
 
@@ -56,10 +51,9 @@ where
     }
 }
 
-impl<T, N> core::ops::IndexMut<u32> for SmallVec<T, N>
+impl<T, const N: usize> core::ops::IndexMut<u32> for SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     fn index_mut(&mut self, index: u32) -> &mut Self::Output {
         let len = self.len();
@@ -75,10 +69,9 @@ where
     }
 }
 
-impl<'a, T: 'a, N> IntoIterator for &'a SmallVec<T, N>
+impl<'a, T: 'a, const N: usize> IntoIterator for &'a SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     type Item = &'a T;
     type IntoIter = Iter<'a, T, N>;
@@ -88,10 +81,9 @@ where
     }
 }
 
-impl<T, N> Extend<T> for SmallVec<T, N>
+impl<T, const N: usize> Extend<T> for SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     fn extend<I>(&mut self, iter: I)
     where
@@ -103,10 +95,9 @@ where
     }
 }
 
-impl<T, N> FromIterator<T> for SmallVec<T, N>
+impl<T, const N: usize> FromIterator<T> for SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     fn from_iter<I>(iter: I) -> Self
     where
@@ -118,10 +109,9 @@ where
     }
 }
 
-impl<T, N> core::cmp::PartialEq for SmallVec<T, N>
+impl<T, const N: usize> core::cmp::PartialEq for SmallVec<T, N>
 where
     T: PartialEq + PackedLayout,
-    N: LazyArrayLength<T>,
 {
     fn eq(&self, other: &Self) -> bool {
         if self.len() != other.len() {
@@ -131,9 +121,4 @@ where
     }
 }
 
-impl<T, N> core::cmp::Eq for SmallVec<T, N>
-where
-    T: Eq + PackedLayout,
-    N: LazyArrayLength<T>,
-{
-}
+impl<T, const N: usize> core::cmp::Eq for SmallVec<T, N> where T: Eq + PackedLayout {}

crates/storage/src/collections/smallvec/iter.rs

@@ -15,16 +15,14 @@
 use super::SmallVec;
 use crate::{
     collections::extend_lifetime,
-    lazy::LazyArrayLength,
     traits::PackedLayout,
 };
 
 /// An iterator over shared references to the elements of a small storage vector.
 #[derive(Debug, Clone, Copy)]
-pub struct Iter<'a, T, N>
+pub struct Iter<'a, T, const N: usize>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     /// The storage vector to iterate over.
     vec: &'a SmallVec<T, N>,
@@ -34,10 +32,9 @@ where
     end: u32,
 }
 
-impl<'a, T, N> Iter<'a, T, N>
+impl<'a, T, const N: usize> Iter<'a, T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     /// Creates a new iterator for the given storage vector.
     pub(crate) fn new(vec: &'a SmallVec<T, N>) -> Self {
@@ -54,10 +51,9 @@ where
     }
 }
 
-impl<'a, T, N> Iterator for Iter<'a, T, N>
+impl<'a, T, const N: usize> Iterator for Iter<'a, T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     type Item = &'a T;
 
@@ -86,17 +82,11 @@ where
     }
 }
 
-impl<'a, T, N> ExactSizeIterator for Iter<'a, T, N>
-where
-    T: PackedLayout,
-    N: LazyArrayLength<T>,
-{
-}
+impl<'a, T, const N: usize> ExactSizeIterator for Iter<'a, T, N> where T: PackedLayout {}
 
-impl<'a, T, N> DoubleEndedIterator for Iter<'a, T, N>
+impl<'a, T, const N: usize> DoubleEndedIterator for Iter<'a, T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     fn next_back(&mut self) -> Option<Self::Item> {
         <Self as DoubleEndedIterator>::nth_back(self, 0)
@@ -118,10 +108,9 @@ where
 
 /// An iterator over exclusive references to the elements of a small storage vector.
 #[derive(Debug)]
-pub struct IterMut<'a, T, N>
+pub struct IterMut<'a, T, const N: usize>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     /// The storage vector to iterate over.
     vec: &'a mut SmallVec<T, N>,
@@ -131,10 +120,9 @@ where
     end: u32,
 }
 
-impl<'a, T, N> IterMut<'a, T, N>
+impl<'a, T, const N: usize> IterMut<'a, T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     /// Creates a new iterator for the given storage vector.
     pub(crate) fn new(vec: &'a mut SmallVec<T, N>) -> Self {
@@ -152,10 +140,9 @@ where
     }
 }
 
-impl<'a, T, N> IterMut<'a, T, N>
+impl<'a, T, const N: usize> IterMut<'a, T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     fn get_mut<'b>(&'b mut self, at: u32) -> Option<&'a mut T> {
         self.vec.get_mut(at).map(|value| {
@@ -171,10 +158,9 @@ where
     }
 }
 
-impl<'a, T, N> Iterator for IterMut<'a, T, N>
+impl<'a, T, const N: usize> Iterator for IterMut<'a, T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     type Item = &'a mut T;
 
@@ -203,17 +189,11 @@ where
     }
 }
 
-impl<'a, T, N> ExactSizeIterator for IterMut<'a, T, N>
-where
-    T: PackedLayout,
-    N: LazyArrayLength<T>,
-{
-}
+impl<'a, T, const N: usize> ExactSizeIterator for IterMut<'a, T, N> where T: PackedLayout {}
 
-impl<'a, T, N> DoubleEndedIterator for IterMut<'a, T, N>
+impl<'a, T, const N: usize> DoubleEndedIterator for IterMut<'a, T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     fn next_back(&mut self) -> Option<Self::Item> {
         <Self as DoubleEndedIterator>::nth_back(self, 0)

crates/storage/src/collections/smallvec/mod.rs

@@ -34,7 +34,6 @@ use crate::{
     lazy::{
         Lazy,
         LazyArray,
-        LazyArrayLength,
     },
     traits::PackedLayout,
 };
@@ -55,31 +54,28 @@ type Index = u32;
 ///   `Vec` due to the internal differences.
 /// - Allows to store up to N elements.
 #[derive(Debug)]
-pub struct SmallVec<T, N>
+pub struct SmallVec<T, const N: usize>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     /// The current length of the small vector.
     len: Lazy<u32>,
     /// The entries of the small vector.
     elems: LazyArray<T, N>,
 }
 
-impl<T, N> Default for SmallVec<T, N>
+impl<T, const N: usize> Default for SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     fn default() -> Self {
         Self::new()
     }
 }
 
-impl<T, N> SmallVec<T, N>
+impl<T, const N: usize> SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     /// Clears the underlying storage cells of the storage vector.
     ///
@@ -102,10 +98,9 @@ where
     }
 }
 
-impl<T, N> SmallVec<T, N>
+impl<T, const N: usize> SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     /// Creates a new empty vector.
     pub fn new() -> Self {
@@ -134,10 +129,9 @@ where
     }
 }
 
-impl<T, N> SmallVec<T, N>
+impl<T, const N: usize> SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     /// Returns an iterator yielding shared references to all elements.
     ///
@@ -195,10 +189,9 @@ where
     }
 }
 
-impl<T, N> SmallVec<T, N>
+impl<T, const N: usize> SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     /// Appends an element to the back of the vector.
     pub fn push(&mut self, value: T) {
@@ -212,10 +205,9 @@ where
     }
 }
 
-impl<T, N> SmallVec<T, N>
+impl<T, const N: usize> SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
     /// Pops the last element from the vector and returns it.
     //

crates/storage/src/collections/smallvec/storage.rs

@@ -13,15 +13,11 @@
 // limitations under the License.
 
 use super::SmallVec;
-use crate::{
-    lazy::LazyArrayLength,
-    traits::{
-        KeyPtr,
-        PackedLayout,
-        SpreadLayout,
-    },
+use crate::traits::{
+    KeyPtr,
+    PackedLayout,
+    SpreadLayout,
 };
-use generic_array::typenum::Unsigned;
 
 #[cfg(feature = "std")]
 const _: () = {
@@ -36,10 +32,9 @@ const _: () = {
     };
     use scale_info::TypeInfo;
 
-    impl<T, N> StorageLayout for SmallVec<T, N>
+    impl<T, const N: usize> StorageLayout for SmallVec<T, N>
     where
         T: PackedLayout + TypeInfo + 'static,
-        N: LazyArrayLength<T>,
     {
         fn layout(key_ptr: &mut KeyPtr) -> Layout {
             Layout::Struct(StructLayout::new(vec![
@@ -53,12 +48,11 @@ const _: () = {
     }
 };
 
-impl<T, N> SpreadLayout for SmallVec<T, N>
+impl<T, const N: usize> SpreadLayout for SmallVec<T, N>
 where
     T: PackedLayout,
-    N: LazyArrayLength<T>,
 {
-    const FOOTPRINT: u64 = 1 + <N as Unsigned>::U64;
+    const FOOTPRINT: u64 = 1 + N as u64;
 
     fn pull_spread(ptr: &mut KeyPtr) -> Self {
         Self {