Basic support for dyn Trait to allow cross-contract calls only with…

… trait (#1673)

* Added `contract_ref!` macro rule that allows to create a wrapper around the trait defined via `#[ink::trait_definition]`.
Added `From<AccountId>` for the contract builder and forwarder to simplify the usage.
Added `AsRev<AccountId>` and `AsMut<AccountId>` for builder, forwarder, and contract_ref to provide the way modify the wrapper.

* Added comments for the method in the example of the `contract_ref!`

* Make clippy happy

* Make CI happy

* Changed the default behaviour to use alias generated by the `ink::contract`.
Added more examples into documentation

* Apply suggestions from code review

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

* Apply comments from the PR

* Missed the comment

* Remove error from the example

* Apply suggestions from code review

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>

* Fixed comments from PR

* Update comments around `AccountIdGuard`

* Apply suggestions from code review

Co-authored-by: Michael Müller <mich@elmueller.net>

* Mentioned the PR in the `Unreleased` section

---------

Co-authored-by: Hernando Castano <HCastano@users.noreply.github.com>
Co-authored-by: Hernando Castano <hernando@hcastano.com>
Co-authored-by: Michael Müller <mich@elmueller.net>

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- Basic support for `dyn Trait` to allow cross-contract calls only with trait - [#1673](https://github.com/paritytech/ink/pull/1673)
 
 ## Version 4.0.1
 

crates/env/src/call/create_builder.rs

@@ -44,6 +44,8 @@ pub mod state {
 ///
 /// This is needed because of conflicting implementations of `From<T> for T`
 /// in the generated code of `ink`.
+///
+/// But it is possible to use `From<AccountId> for T` with [`crate::AccountIdGuard`] bound.
 pub trait FromAccountId<T>
 where
     T: Environment,

crates/env/src/lib.rs

@@ -108,6 +108,7 @@ pub use self::{
     },
     topics::Topics,
     types::{
+        AccountIdGuard,
         DefaultEnvironment,
         Environment,
         FromLittleEndian,

crates/env/src/types.rs

@@ -94,6 +94,17 @@ impl FromLittleEndian for u128 {
     }
 }
 
+/// A trait to enforce that a type should be an [`Environment::AccountId`].
+///
+/// If you have an [`Environment`] which uses an [`Environment::AccountId`] type other than the ink!
+/// provided [`AccountId`](https://docs.rs/ink_primitives/latest/ink_primitives/struct.AccountId.html)
+/// you will need to implement this trait for your [`Environment::AccountId`] concrete type.
+pub trait AccountIdGuard {}
+
+/// The ink! provided [`AccountId`](https://docs.rs/ink_primitives/latest/ink_primitives/struct.AccountId.html)
+/// used in the [`DefaultEnvironment`].
+impl AccountIdGuard for AccountId {}
+
 /// The environmental types usable by contracts defined with ink!.
 pub trait Environment {
     /// The maximum number of supported event topics provided by the runtime.

crates/ink/codegen/src/generator/as_dependency/call_builder.rs

@@ -132,6 +132,18 @@ impl CallBuilder<'_> {
                     <AccountId as ::core::clone::Clone>::clone(&self.account_id)
                 }
             }
+
+            impl ::core::convert::AsRef<AccountId> for #cb_ident {
+                fn as_ref(&self) -> &AccountId {
+                    &self.account_id
+                }
+            }
+
+            impl ::core::convert::AsMut<AccountId> for #cb_ident {
+                fn as_mut(&mut self) -> &mut AccountId {
+                    &mut self.account_id
+                }
+            }
         )
     }
 

crates/ink/codegen/src/generator/as_dependency/contract_ref.rs

@@ -170,6 +170,18 @@ impl ContractRef<'_> {
                         as ::ink::ToAccountId<Environment>>::to_account_id(&self.inner)
                 }
             }
+
+            impl ::core::convert::AsRef<AccountId> for #ref_ident {
+                fn as_ref(&self) -> &AccountId {
+                    <_ as ::core::convert::AsRef<AccountId>>::as_ref(&self.inner)
+                }
+            }
+
+            impl ::core::convert::AsMut<AccountId> for #ref_ident {
+                fn as_mut(&mut self) -> &mut AccountId {
+                    <_ as ::core::convert::AsMut<AccountId>>::as_mut(&mut self.inner)
+                }
+            }
         )
     }
 

crates/ink/codegen/src/generator/trait_def/call_builder.rs

@@ -195,6 +195,20 @@ impl CallBuilder<'_> {
                         .finish()
                 }
             }
+
+            #[cfg(feature = "std")]
+            /// We require this manual implementation since the derive produces incorrect trait bounds.
+            impl<E> ::scale_info::TypeInfo for #call_builder_ident<E>
+            where
+                E: ::ink::env::Environment,
+                <E as ::ink::env::Environment>::AccountId: ::scale_info::TypeInfo + 'static,
+            {
+                type Identity = <E as ::ink::env::Environment>::AccountId;
+
+                fn type_info() -> ::scale_info::Type {
+                    <<E as ::ink::env::Environment>::AccountId as ::scale_info::TypeInfo>::type_info()
+                }
+            }
         )
     }
 
@@ -219,6 +233,16 @@ impl CallBuilder<'_> {
                 }
             }
 
+            impl<E, AccountId> ::core::convert::From<AccountId> for #call_builder_ident<E>
+            where
+                E: ::ink::env::Environment<AccountId = AccountId>,
+                AccountId: ::ink::env::AccountIdGuard,
+            {
+                fn from(value: AccountId) -> Self {
+                    <Self as ::ink::env::call::FromAccountId<E>>::from_account_id(value)
+                }
+            }
+
             impl<E> ::ink::ToAccountId<E> for #call_builder_ident<E>
             where
                 E: ::ink::env::Environment,
@@ -228,6 +252,24 @@ impl CallBuilder<'_> {
                     <<E as ::ink::env::Environment>::AccountId as ::core::clone::Clone>::clone(&self.account_id)
                 }
             }
+
+            impl<E, AccountId> ::core::convert::AsRef<AccountId> for #call_builder_ident<E>
+            where
+                E: ::ink::env::Environment<AccountId = AccountId>,
+            {
+                fn as_ref(&self) -> &AccountId {
+                    &self.account_id
+                }
+            }
+
+            impl<E, AccountId> ::core::convert::AsMut<AccountId> for #call_builder_ident<E>
+            where
+                E: ::ink::env::Environment<AccountId = AccountId>,
+            {
+                fn as_mut(&mut self) -> &mut AccountId {
+                    &mut self.account_id
+                }
+            }
         )
     }
 

crates/ink/codegen/src/generator/trait_def/call_forwarder.rs

@@ -163,6 +163,7 @@ impl CallForwarder<'_> {
         let span = self.span();
         let call_forwarder_ident = self.ident();
         quote_spanned!(span=>
+            /// We require this manual implementation since the derive produces incorrect trait bounds.
             impl<E> ::core::clone::Clone for #call_forwarder_ident<E>
             where
                 E: ::ink::env::Environment,
@@ -177,6 +178,7 @@ impl CallForwarder<'_> {
                 }
             }
 
+            /// We require this manual implementation since the derive produces incorrect trait bounds.
             impl<E> ::core::fmt::Debug for #call_forwarder_ident<E>
             where
                 E: ::ink::env::Environment,
@@ -188,6 +190,24 @@ impl CallForwarder<'_> {
                         .finish()
                 }
             }
+
+            #[cfg(feature = "std")]
+            /// We require this manual implementation since the derive produces incorrect trait bounds.
+            impl<E> ::scale_info::TypeInfo for #call_forwarder_ident<E>
+            where
+                E: ::ink::env::Environment,
+                <E as ::ink::env::Environment>::AccountId: ::scale_info::TypeInfo + 'static,
+            {
+                type Identity = <
+                    <Self as ::ink::codegen::TraitCallBuilder>::Builder as ::scale_info::TypeInfo
+                >::Identity;
+
+                fn type_info() -> ::scale_info::Type {
+                    <
+                        <Self as ::ink::codegen::TraitCallBuilder>::Builder as ::scale_info::TypeInfo
+                    >::type_info()
+                }
+            }
         )
     }
 
@@ -213,6 +233,16 @@ impl CallForwarder<'_> {
                 }
             }
 
+            impl<E, AccountId> ::core::convert::From<AccountId> for #call_forwarder_ident<E>
+            where
+                E: ::ink::env::Environment<AccountId = AccountId>,
+                AccountId: ::ink::env::AccountIdGuard,
+            {
+                fn from(value: AccountId) -> Self {
+                    <Self as ::ink::env::call::FromAccountId<E>>::from_account_id(value)
+                }
+            }
+
             impl<E> ::ink::ToAccountId<E> for #call_forwarder_ident<E>
             where
                 E: ::ink::env::Environment,
@@ -223,6 +253,24 @@ impl CallForwarder<'_> {
                         as ::ink::ToAccountId<E>>::to_account_id(&self.builder)
                 }
             }
+
+            impl<E, AccountId> ::core::convert::AsRef<AccountId> for #call_forwarder_ident<E>
+            where
+                E: ::ink::env::Environment<AccountId = AccountId>,
+            {
+                fn as_ref(&self) -> &AccountId {
+                    <_ as ::core::convert::AsRef<AccountId>>::as_ref(&self.builder)
+                }
+            }
+
+            impl<E, AccountId> ::core::convert::AsMut<AccountId> for #call_forwarder_ident<E>
+            where
+                E: ::ink::env::Environment<AccountId = AccountId>,
+            {
+                fn as_mut(&mut self) -> &mut AccountId {
+                    <_ as ::core::convert::AsMut<AccountId>>::as_mut(&mut self.builder)
+                }
+            }
         )
     }