hashes: Remove code deprecated in 0.15.0

diff --git a/hashes/src/hmac/mod.rs b/hashes/src/hmac/mod.rs
index aebe2e60..8651aa4d 100644
--- a/hashes/src/hmac/mod.rs
+++ b/hashes/src/hmac/mod.rs
@@ -123,11 +123,6 @@ impl<T: Hash> Hash for Hmac<T> {
 
     fn from_byte_array(bytes: T::Bytes) -> Self { Hmac(T::from_byte_array(bytes)) }
 
-    #[allow(deprecated_in_future)] // Because of `FromSliceError`.
-    fn from_slice(sl: &[u8]) -> Result<Hmac<T>, crate::FromSliceError> {
-        T::from_slice(sl).map(Hmac)
-    }
-
     fn to_byte_array(self) -> Self::Bytes { self.0.to_byte_array() }
 
     fn as_byte_array(&self) -> &Self::Bytes { self.0.as_byte_array() }
diff --git a/hashes/src/internal_macros.rs b/hashes/src/internal_macros.rs
index 21f37dca..a837225a 100644
--- a/hashes/src/internal_macros.rs
+++ b/hashes/src/internal_macros.rs
@@ -34,12 +34,6 @@ macro_rules! hash_trait_impls {
 
             fn from_byte_array(bytes: Self::Bytes) -> Self { Self::from_byte_array(bytes) }
 
-            #[allow(deprecated_in_future)] // Because of `FromSliceError`.
-            #[allow(deprecated)]           // Because of `from_slice`.
-            fn from_slice(sl: &[u8]) -> $crate::_export::_core::result::Result<Hash<$($gen),*>, $crate::FromSliceError> {
-                Self::from_slice(sl)
-            }
-
             fn to_byte_array(self) -> Self::Bytes { self.to_byte_array() }
 
             fn as_byte_array(&self) -> &Self::Bytes { self.as_byte_array() }
@@ -133,24 +127,6 @@ macro_rules! hash_type_no_default {
             /// Constructs a new hash from the underlying byte array.
             pub const fn from_byte_array(bytes: [u8; $bits / 8]) -> Self { Hash(bytes) }
 
-            /// Copies a byte slice into a hash object.
-            #[deprecated(since = "0.15.0", note = "use `from_byte_array` instead")]
-            #[allow(deprecated_in_future)] // Because of `FromSliceError`.
-            pub fn from_slice(
-                sl: &[u8],
-            ) -> $crate::_export::_core::result::Result<Hash, $crate::FromSliceError> {
-                if sl.len() != $bits / 8 {
-                    Err($crate::error::FromSliceError($crate::error::FromSliceErrorInner {
-                        expected: $bits / 8,
-                        got: sl.len(),
-                    }))
-                } else {
-                    let mut ret = [0; $bits / 8];
-                    ret.copy_from_slice(sl);
-                    Ok(Self::from_byte_array(ret))
-                }
-            }
-
             /// Returns the underlying byte array.
             pub const fn to_byte_array(self) -> [u8; $bits / 8] { self.0 }
 
diff --git a/hashes/src/lib.rs b/hashes/src/lib.rs
index 9258b1ad..5242ef53 100644
--- a/hashes/src/lib.rs
+++ b/hashes/src/lib.rs
@@ -117,17 +117,6 @@ pub mod sha512;
 pub mod sha512_256;
 pub mod siphash24;
 
-#[deprecated(since = "0.15.0", note = "use crate::macros instead")]
-pub mod serde_macros {
-    //! Macros for serde trait implementations, and supporting code.
-
-    #[cfg(feature = "serde")]
-    pub mod serde_details {
-        //! Functions used by serde impls of all hashes.
-        pub use crate::macros::serde_details::*;
-    }
-}
-
 use core::fmt::{self, Write as _};
 use core::{convert, hash};
 
@@ -227,11 +216,6 @@ pub trait Hash:
     /// Constructs a new hash from the underlying byte array.
     fn from_byte_array(bytes: Self::Bytes) -> Self;
 
-    /// Copies a byte slice into a hash object.
-    #[allow(deprecated_in_future)] // Because of `FromSliceError`.
-    #[deprecated(since = "TBD", note = "use `from_byte_array` instead")]
-    fn from_slice(sl: &[u8]) -> Result<Self, FromSliceError>;
-
     /// Returns the underlying byte array.
     fn to_byte_array(self) -> Self::Bytes;
 
diff --git a/hashes/src/macros.rs b/hashes/src/macros.rs
index d45ebbc5..2b1f8071 100644
--- a/hashes/src/macros.rs
+++ b/hashes/src/macros.rs
@@ -139,14 +139,6 @@ macro_rules! hash_newtype {
                 $newtype(<$hash>::from_byte_array(bytes))
             }
 
-            /// Copies a byte slice into a hash object.
-            #[deprecated(since = "0.15.0", note = "use `from_byte_array` instead")]
-            #[allow(deprecated_in_future)] // Because of `FromSliceError`.
-            #[allow(deprecated)]           // Because of `from_slice`.
-            pub fn from_slice(sl: &[u8]) -> $crate::_export::_core::result::Result<$newtype, $crate::FromSliceError> {
-                Ok($newtype(<$hash as $crate::Hash>::from_slice(sl)?))
-            }
-
             /// Returns the underlying byte array.
             pub const fn to_byte_array(self) -> <$hash as $crate::Hash>::Bytes {
                 self.0.to_byte_array()
@@ -165,13 +157,6 @@ macro_rules! hash_newtype {
 
             fn from_byte_array(bytes: Self::Bytes) -> Self { Self::from_byte_array(bytes) }
 
-            #[inline]
-            #[allow(deprecated_in_future)] // Because of `FromSliceError`.
-            #[allow(deprecated)]           // Because of `from_slice`.
-            fn from_slice(sl: &[u8]) -> $crate::_export::_core::result::Result<$newtype, $crate::FromSliceError> {
-                Self::from_slice(sl)
-            }
-
             fn to_byte_array(self) -> Self::Bytes { self.to_byte_array() }
 
             fn as_byte_array(&self) -> &Self::Bytes { self.as_byte_array() }
@@ -506,7 +491,7 @@ macro_rules! serde_impl(
 
         impl<'de $(, $gen: $gent)*> $crate::serde::Deserialize<'de> for $t<$($gen),*> {
             fn deserialize<D: $crate::serde::Deserializer<'de>>(d: D) -> core::result::Result<$t<$($gen),*>, D::Error> {
-                use $crate::serde_macros::serde_details::{BytesVisitor, HexVisitor};
+                use $crate::macros::serde_details::{BytesVisitor, HexVisitor};
 
                 if d.is_human_readable() {
                     d.deserialize_str(HexVisitor::<Self>::default())
diff --git a/hashes/src/sha256/mod.rs b/hashes/src/sha256/mod.rs
index 39c3257b..cea61a63 100644
--- a/hashes/src/sha256/mod.rs
+++ b/hashes/src/sha256/mod.rs
@@ -147,12 +147,6 @@ impl Hash {
     #[must_use]
     pub fn hash_again(&self) -> sha256d::Hash { sha256d::Hash::from_byte_array(hash(&self.0).0) }
 
-    /// Computes hash from `bytes` in `const` context.
-    ///
-    /// Warning: this function is inefficient. It should be only used in `const` context.
-    #[deprecated(since = "0.15.0", note = "use `Self::hash_unoptimized` instead")]
-    pub const fn const_hash(bytes: &[u8]) -> Self { Hash::hash_unoptimized(bytes) }
-
     /// Computes hash from `bytes` in `const` context.
     ///
     /// Warning: this function is inefficient. It should be only used in `const` context.
diff --git a/hashes/src/sha256t/mod.rs b/hashes/src/sha256t/mod.rs
index 5b6d91db..b1a3c5dc 100644
--- a/hashes/src/sha256t/mod.rs
+++ b/hashes/src/sha256t/mod.rs
@@ -65,21 +65,6 @@ where
     /// Constructs a new hash from the underlying byte array.
     pub const fn from_byte_array(bytes: [u8; 32]) -> Self { Self(PhantomData, bytes) }
 
-    /// Copies a byte slice into a hash object.
-    #[deprecated(since = "0.15.0", note = "use `from_byte_array` instead")]
-    #[allow(deprecated_in_future)] // Because of `FromSliceError`.
-    pub fn from_slice(sl: &[u8]) -> Result<Hash<T>, crate::FromSliceError> {
-        use crate::error::FromSliceErrorInner;
-
-        if sl.len() != 32 {
-            Err(crate::error::FromSliceError(FromSliceErrorInner { expected: 32, got: sl.len() }))
-        } else {
-            let mut ret = [0; 32];
-            ret.copy_from_slice(sl);
-            Ok(Self::from_byte_array(ret))
-        }
-    }
-
     /// Produces a hash from the current state of a given engine.
     pub fn from_engine(e: HashEngine<T>) -> Self {
         Hash::from_byte_array(sha256::Hash::from_engine(e.0).to_byte_array())
diff --git a/hashes/src/siphash24/mod.rs b/hashes/src/siphash24/mod.rs
index c5353629..664ee670 100644
--- a/hashes/src/siphash24/mod.rs
+++ b/hashes/src/siphash24/mod.rs
@@ -207,10 +207,6 @@ impl Hash {
         state.v0 ^ state.v1 ^ state.v2 ^ state.v3
     }
 
-    /// Returns the (little endian) 64-bit integer representation of the hash value.
-    #[deprecated(since = "0.15.0", note = "use `to_u64` instead")]
-    pub fn as_u64(&self) -> u64 { self.to_u64() }
-
     /// Returns the (little endian) 64-bit integer representation of the hash value.
     pub fn to_u64(self) -> u64 { u64::from_le_bytes(self.0) }