chore: make more functions be const (#1574)

* feat: make more functions be const

* fix

* fix

* fix examples

* fmt

crates/e2e/src/builders.rs

@@ -50,7 +50,7 @@ pub fn constructor_exec_input<E: Environment, Args: Encode, R>(
     // set all the other properties to default values, we only require the `exec_input`.
     builder
         .endowment(0u32.into())
-        .code_hash(ink_primitives::Clear::clear())
+        .code_hash(ink_primitives::Clear::CLEAR_HASH)
         .salt_bytes(Vec::new())
         .params()
         .exec_input()

crates/env/src/call/call_builder.rs

@@ -228,7 +228,7 @@ where
 /// # type AccountId = <DefaultEnvironment as Environment>::AccountId;
 /// let my_return_value: i32 = build_call::<DefaultEnvironment>()
 ///     .call_type(DelegateCall::new()
-///                 .code_hash(<DefaultEnvironment as Environment>::Hash::clear()))
+///                 .code_hash(<DefaultEnvironment as Environment>::Hash::CLEAR_HASH))
 ///     .exec_input(
 ///         ExecutionInput::new(Selector::new([0xDE, 0xAD, 0xBE, 0xEF]))
 ///             .push_arg(42u8)
@@ -322,16 +322,16 @@ pub struct DelegateCall<E: Environment> {
 
 impl<E: Environment> DelegateCall<E> {
     /// Returns a clean builder for [`DelegateCall`]
-    pub fn new() -> Self {
-        Default::default()
+    pub const fn new() -> Self {
+        DelegateCall {
+            code_hash: E::Hash::CLEAR_HASH,
+        }
     }
 }
 
 impl<E: Environment> Default for DelegateCall<E> {
     fn default() -> Self {
-        DelegateCall {
-            code_hash: E::Hash::clear(),
-        }
+        Self::new()
     }
 }
 

crates/env/src/engine/off_chain/impls.rs

@@ -138,7 +138,7 @@ where
     {
         let encoded = topic_value.encode();
         let len_encoded = encoded.len();
-        let mut result = <E as Environment>::Hash::clear();
+        let mut result = <E as Environment>::Hash::CLEAR_HASH;
         let len_result = result.as_ref().len();
         if len_encoded <= len_result {
             result.as_mut()[..len_encoded].copy_from_slice(&encoded[..]);

crates/env/src/engine/on_chain/impls.rs

@@ -150,7 +150,7 @@ where
     {
         fn inner<E: Environment>(encoded: &mut [u8]) -> <E as Environment>::Hash {
             let len_encoded = encoded.len();
-            let mut result = <E as Environment>::Hash::clear();
+            let mut result = <E as Environment>::Hash::CLEAR_HASH;
             let len_result = result.as_ref().len();
             if len_encoded <= len_result {
                 result.as_mut()[..len_encoded].copy_from_slice(encoded);

crates/ink/src/env_access.rs

@@ -584,7 +584,7 @@ where
     ///     let call_params = build_call::<DefaultEnvironment>()
     ///             .call_type(
     ///                 DelegateCall::new()
-    ///                  .code_hash(<DefaultEnvironment as ink::env::Environment>::Hash::clear()))
+    ///                  .code_hash(<DefaultEnvironment as ink::env::Environment>::Hash::CLEAR_HASH))
     ///             .exec_input(
     ///                 ExecutionInput::new(Selector::new([0xCA, 0xFE, 0xBA, 0xBE]))
     ///                  .push_arg(42u8)

crates/primitives/src/types.rs

@@ -129,29 +129,25 @@ impl AsMut<[u8]> for Hash {
 ///
 /// A hash that consists only of 0 bits is clear.
 pub trait Clear {
+    /// The clear hash.
+    const CLEAR_HASH: Self;
+
     /// Returns `true` if the hash is clear.
     fn is_clear(&self) -> bool;
-
-    /// Returns a clear hash.
-    fn clear() -> Self;
 }
 
 impl Clear for [u8; 32] {
-    fn is_clear(&self) -> bool {
-        self.as_ref().iter().all(|&byte| byte == 0x00)
-    }
+    const CLEAR_HASH: Self = [0x00; 32];
 
-    fn clear() -> Self {
-        [0x00; 32]
+    fn is_clear(&self) -> bool {
+        self == &Self::CLEAR_HASH
     }
 }
 
 impl Clear for Hash {
+    const CLEAR_HASH: Self = Self(<[u8; 32] as Clear>::CLEAR_HASH);
+
     fn is_clear(&self) -> bool {
         <[u8; 32] as Clear>::is_clear(&self.0)
     }
-
-    fn clear() -> Self {
-        Self(<[u8; 32] as Clear>::clear())
-    }
 }

crates/storage/src/lazy/mapping.rs

@@ -93,9 +93,7 @@ where
     KeyType: StorageKey,
 {
     fn default() -> Self {
-        Self {
-            _marker: Default::default(),
-        }
+        Self::new()
     }
 }
 
@@ -105,9 +103,9 @@ where
     KeyType: StorageKey,
 {
     /// Creates a new empty `Mapping`.
-    pub fn new() -> Self {
+    pub const fn new() -> Self {
         Self {
-            _marker: Default::default(),
+            _marker: PhantomData,
         }
     }
 }

crates/storage/src/lazy/mod.rs

@@ -100,9 +100,7 @@ where
     KeyType: StorageKey,
 {
     fn default() -> Self {
-        Self {
-            _marker: Default::default(),
-        }
+        Self::new()
     }
 }
 
@@ -111,9 +109,9 @@ where
     KeyType: StorageKey,
 {
     /// Creates a new empty `Lazy`.
-    pub fn new() -> Self {
+    pub const fn new() -> Self {
         Self {
-            _marker: Default::default(),
+            _marker: PhantomData,
         }
     }
 }

examples/erc20/lib.rs

@@ -217,7 +217,10 @@ mod erc20 {
     mod tests {
         use super::*;
 
-        use ink::primitives::Clear;
+        use ink::primitives::{
+            Clear,
+            Hash,
+        };
 
         type Event = <Erc20 as ::ink::reflect::ContractEventBase>::Type;
 
@@ -259,7 +262,7 @@ mod erc20 {
             for (n, (actual_topic, expected_topic)) in
                 topics.iter().zip(expected_topics).enumerate()
             {
-                let mut topic_hash = Hash::clear();
+                let mut topic_hash = Hash::CLEAR_HASH;
                 let len = actual_topic.len();
                 topic_hash.as_mut()[0..len].copy_from_slice(&actual_topic[0..len]);
 
@@ -513,7 +516,7 @@ mod erc20 {
                 primitives::Clear,
             };
 
-            let mut result = Hash::clear();
+            let mut result = Hash::CLEAR_HASH;
             let len_result = result.as_ref().len();
             let encoded = entity.encode();
             let len_encoded = encoded.len();

examples/trait-erc20/lib.rs

@@ -290,7 +290,7 @@ mod erc20 {
             where
                 T: scale::Encode,
             {
-                let mut result = Hash::clear();
+                let mut result = Hash::CLEAR_HASH;
                 let len_result = result.as_ref().len();
                 let encoded = entity.encode();
                 let len_encoded = encoded.len();