Add gas_limit host fn (#2691)

* implement `gas_limit` host fn

* add tests for `gas_limit` host fn

* remove off-chain tests for `gas_limit`

* add changes to changelog

* run formatting

* fix error in env-access ui test

* run formatting

* Apply suggestions from code review

Co-authored-by: Michael Müller <[email protected]>

* update versions in gas and misc hostfns internal tests

---------

Co-authored-by: Michael Müller <[email protected]>

Author: LucasGrasso

CHANGELOG.md

@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 [Unreleased]
 
 ### Added
+- Implements the API for the `pallet-revive` host function `gas_limit` - [#2691](https://github.com/use-ink/ink/pull/2691)
 - Implements the API for the `pallet-revive` host function `to_account_id` - [#2578](https://github.com/use-ink/ink/pull/2578)
 - Add `#[ink::contract_ref]` attribute - [#2648](https://github.com/use-ink/ink/pull/2648)
 - Add `ink_revive_types` (and remove `pallet-revive` dependency from `ink_e2e`) - [#2657](https://github.com/use-ink/ink/pull/2657)

crates/env/src/api.rs

@@ -73,6 +73,13 @@ pub fn caller() -> Address {
     <EnvInstance as OnInstance>::on_instance(TypedEnvBackend::caller)
 }
 
+/// Returns the block's `ref_time` limit.
+///
+/// See <https://use.ink/docs/v6/basics/gas/#what-is-gas-in-ink> for more information.
+pub fn gas_limit() -> u64 {
+    <EnvInstance as OnInstance>::on_instance(TypedEnvBackend::gas_limit)
+}
+
 /// Returns the transferred value for the contract execution.
 ///
 /// # Errors

crates/env/src/backend.rs

@@ -228,6 +228,13 @@ pub trait TypedEnvBackend: EnvBackend {
     /// For more details visit: [`caller`][`crate::caller`]
     fn caller(&mut self) -> Address;
 
+    /// Returns the block's `ref_time` limit.
+    ///
+    /// # Note
+    ///
+    /// For more details visit: [`gas_limit`][`crate::gas_limit`]
+    fn gas_limit(&mut self) -> u64;
+
     /// Returns the transferred value for the contract execution.
     ///
     /// # Note

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

@@ -550,6 +550,10 @@ impl TypedEnvBackend for EnvInstance {
             .unwrap_or_else(|error| panic!("could not read `caller` property: {error:?}"))
     }
 
+    fn gas_limit(&mut self) -> u64 {
+        unimplemented!("not implemented, the off-chain environment will be removed");
+    }
+
     fn transferred_value(&mut self) -> U256 {
         self.get_property(Engine::value_transferred)
             .unwrap_or_else(|error| {

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

@@ -887,6 +887,10 @@ impl TypedEnvBackend for EnvInstance {
             .expect("The executed contract must have a caller with a valid account id.")
     }
 
+    fn gas_limit(&mut self) -> u64 {
+        ext::gas_limit()
+    }
+
     fn transferred_value(&mut self) -> U256 {
         let mut scope = self.scoped_buffer();
         let u256: &mut [u8; 32] = scope.take(32).try_into().unwrap();

crates/ink/src/env_access.rs

@@ -108,6 +108,37 @@ where
         ink_env::caller()
     }
 
+    /// Returns the block ref_time limit.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// #[ink::contract]
+    /// mod my_contract {
+    ///     #[ink(storage)]
+    ///     pub struct MyContract;
+    ///
+    ///     impl MyContract {
+    ///         #[ink(constructor)]
+    ///         pub fn new() -> Self {
+    ///             Self {}
+    ///         }
+    ///
+    ///         #[ink(message)]
+    ///         pub fn get_limit(&self) -> u64 {
+    ///             self.env().gas_limit()
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// # Note
+    ///
+    /// For more details visit: [`ink_env::gas_limit`]
+    pub fn gas_limit(self) -> u64 {
+        ink_env::gas_limit()
+    }
+
     /// Returns the transferred value for the contract execution.
     ///
     /// # Example

crates/ink/tests/ui/contract/pass/env-access.rs

@@ -14,6 +14,7 @@ mod contract {
             let _ = Self::env().block_number();
             let _ = Self::env().caller();
             let _ = Self::env().minimum_balance();
+            let _ = Self::env().gas_limit();
             let _ = Self::env().transferred_value();
             let _ = Self::env().weight_to_fee(0);
             Self {}
@@ -27,6 +28,7 @@ mod contract {
             let _ = self.env().block_number();
             let _ = self.env().caller();
             let _ = self.env().minimum_balance();
+            let _ = self.env().gas_limit();
             let _ = self.env().transferred_value();
             let _ = self.env().weight_to_fee(0);
         }

integration-tests/internal/gas-hostfns/Cargo.toml

@@ -0,0 +1,27 @@
+[package]
+name = "gas_hostfns"
+description = "E2E tests for gas related host functions"
+version = "6.0.0-alpha.4"
+authors = ["Use Ink <[email protected]>"]
+edition = "2021"
+publish = false
+
+[dependencies]
+ink = { path = "../../../crates/ink", default-features = false, features = ["unstable-hostfn"] }
+
+[dev-dependencies]
+ink_e2e = { path = "../../../crates/e2e" }
+
+[lib]
+path = "lib.rs"
+
+[features]
+default = ["std"]
+std = [
+    "ink/std",
+]
+ink-as-dependency = []
+e2e-tests = []
+
+[package.metadata.ink-lang]
+abi = "ink"

integration-tests/internal/gas-hostfns/lib.rs

@@ -0,0 +1,55 @@
+#![cfg_attr(not(feature = "std"), no_std, no_main)]
+#![allow(clippy::new_without_default)]
+
+#[ink::contract]
+mod gas_hostfns {
+    #[ink(storage)]
+    pub struct GasHostfns {}
+
+    impl GasHostfns {
+        #[ink(constructor)]
+        pub fn new() -> Self {
+            Self {}
+        }
+
+        /// Checks that the host function `gas_limit` works
+        #[ink(message)]
+        pub fn gas_limit(&self) -> u64 {
+            self.env().gas_limit()
+        }
+    }
+
+    #[cfg(all(test, feature = "e2e-tests"))]
+    mod e2e_tests {
+        use super::*;
+        use ink_e2e::ContractsBackend;
+
+        type E2EResult<T> = std::result::Result<T, Box<dyn std::error::Error>>;
+
+        #[ink_e2e::test]
+        async fn e2e_gas_limit_works<Client: E2EBackend>(
+            mut client: Client,
+        ) -> E2EResult<()> {
+            // given
+            let contract = client
+                .instantiate("gas_hostfns", &ink_e2e::alice(), &mut GasHostfnsRef::new())
+                .submit()
+                .await
+                .expect("instantiate failed");
+            let call_builder = contract.call_builder::<GasHostfns>();
+
+            // then
+            let call_res = client
+                .call(&ink_e2e::alice(), &call_builder.gas_limit())
+                .submit()
+                .await
+                .unwrap_or_else(|err| {
+                    panic!("call failed: {:#?}", err);
+                });
+
+            assert!(call_res.return_value() > 0);
+
+            Ok(())
+        }
+    }
+}

integration-tests/internal/misc-hostfns/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "misc_hostfns"
 description = "E2E tests for various host functions"
-version = "6.0.0-alpha.1"
+version = "6.0.0-alpha.4"
 authors = ["Use Ink <[email protected]>"]
 edition = "2021"
 publish = false