refactor: let users specify Hasher instead of BuildHasher

Author: iajoiner

src/macros.rs

@@ -4,10 +4,10 @@
 ///
 /// ```
 /// use indexmap::indexmap_with_hasher;
-/// use std::collections::hash_map::RandomState;
+/// use std::hash::DefaultHasher;
 ///
 /// let map = indexmap_with_hasher!{
-///     RandomState;
+///     DefaultHasher;
 ///     "a" => 1,
 ///     "b" => 2,
 /// };
@@ -22,10 +22,11 @@
 macro_rules! indexmap_with_hasher {
     ($S:ty; $($key:expr => $value:expr,)+) => { $crate::indexmap_with_hasher!($S; $($key => $value),+) };
     ($S:ty; $($key:expr => $value:expr),*) => {{
+        type BuildS = core::hash::BuildHasherDefault<$S>;
         const CAP: usize = <[()]>::len(&[$({ stringify!($key); }),*]);
         #[allow(unused_mut)]
-        // Specify your custom S (must implement Default) as the hasher:
-        let mut map = $crate::IndexMap::<_, _, $S>::with_capacity_and_hasher(CAP, <$S>::default());
+        // Specify your custom S (must implement Default + Hasher) as the hasher:
+        let mut map = $crate::IndexMap::<_, _, BuildS>::with_capacity_and_hasher(CAP, <BuildS>::default());
         $(
             map.insert($key, $value);
         )*
@@ -76,10 +77,10 @@ macro_rules! indexmap {
 ///
 /// ```
 /// use indexmap::indexset_with_hasher;
-/// use std::collections::hash_map::RandomState;
+/// use std::hash::DefaultHasher;
 ///
 /// let set = indexset_with_hasher!{
-///     RandomState;
+///     DefaultHasher;
 ///     "a",
 ///     "b",
 /// };
@@ -94,10 +95,11 @@ macro_rules! indexmap {
 macro_rules! indexset_with_hasher {
     ($S:ty; $($value:expr,)+) => { $crate::indexset_with_hasher!($S; $($value),+) };
     ($S:ty; $($value:expr),*) => {{
+        type BuildS = core::hash::BuildHasherDefault<$S>;
         const CAP: usize = <[()]>::len(&[$({ stringify!($value); }),*]);
         #[allow(unused_mut)]
         // Specify your custom S (must implement Default) as the hasher:
-        let mut set = $crate::IndexSet::<_, $S>::with_capacity_and_hasher(CAP, <$S>::default());
+        let mut set = $crate::IndexSet::<_, BuildS>::with_capacity_and_hasher(CAP, <BuildS>::default());
         $(
             set.insert($value);
         )*