feat: add "needs db" type state to TrevmBuilder

Author: Philogy

examples/basic_transact.rs

@@ -39,7 +39,7 @@ impl Tx for SampleTx {
 // Produce aliases for the Trevm type
 trevm_aliases!(TracerEip3155, InMemoryDB);
 
-fn main() -> Result<(), Box<dyn std::error::Error>> {
+fn main() {
     let mut db = revm::database::InMemoryDB::default();
 
     let bytecode = Bytecode::new_raw(hex::decode(CONTRACT_BYTECODE).unwrap().into());
@@ -54,7 +54,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     let trevm = TrevmBuilder::new()
         .with_db(db)
         .with_insp(insp)
-        .build_trevm()?
+        .build_trevm()
         .fill_cfg(&NoopCfg)
         .fill_block(&NoopBlock);
 
@@ -72,6 +72,4 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
             println!("Execution error: {e:?}");
         }
     };
-
-    Ok(())
 }

examples/fork_ref_transact.rs

@@ -60,7 +60,7 @@ async fn main() -> eyre::Result<()> {
     // initialise an empty (default) EVM
     let evm = TrevmBuilder::new()
         .with_db(cache_db)
-        .build_trevm()?
+        .build_trevm()
         .fill_cfg(&NoopCfg)
         .fill_block(&NoopBlock)
         .fill_tx(&GetReservesFiller)

src/evm/builder.rs

@@ -1,7 +1,7 @@
 use crate::{evm::Trevm, helpers::Ctx, EvmNeedsCfg};
 use revm::{
-    database::in_memory_db::InMemoryDB, handler::EthPrecompiles, inspector::NoOpInspector,
-    precompile::Precompiles, primitives::hardfork::SpecId, Database, Inspector, MainBuilder,
+    handler::EthPrecompiles, inspector::NoOpInspector, precompile::Precompiles,
+    primitives::hardfork::SpecId, Database, Inspector, MainBuilder,
 };
 
 /// Error that can occur when building a Trevm instance.
@@ -13,48 +13,65 @@ pub enum TrevmBuilderError {
     DatabaseNotSet,
 }
 
+#[allow(unnameable_types)]
+#[derive(Debug, Copy, Clone)]
+pub struct BuilderNeedsDb {
+    _private: (),
+}
+
+#[allow(unnameable_types)]
+#[derive(Debug, Copy, Clone)]
+pub struct BuilderReady<Db> {
+    db: Db,
+}
+
 /// A builder for [`Trevm`] that allows configuring the EVM.
 #[derive(Debug, Clone)]
-pub struct TrevmBuilder<Db, Insp> {
-    pub(crate) db: Option<Db>,
+pub struct TrevmBuilder<Insp, State = BuilderNeedsDb> {
     pub(crate) insp: Insp,
     pub(crate) spec: SpecId,
     pub(crate) precompiles: Option<&'static Precompiles>,
+    pub(crate) state: State,
 }
 
-impl TrevmBuilder<InMemoryDB, NoOpInspector> {
+impl TrevmBuilder<NoOpInspector> {
     /// Create a new builder with the default database and inspector.
     #[allow(clippy::new_without_default)] // default would make bad devex :(
     pub const fn new() -> Self {
-        Self { db: None, insp: NoOpInspector, spec: SpecId::PRAGUE, precompiles: None }
+        Self {
+            insp: NoOpInspector,
+            spec: SpecId::PRAGUE,
+            precompiles: None,
+            state: BuilderNeedsDb { _private: () },
+        }
     }
 }
 
-impl<Db, Insp> TrevmBuilder<Db, Insp> {
+impl<Insp, State> TrevmBuilder<Insp, State> {
     /// Set the database for the EVM.
-    pub fn with_db<Odb>(self, db: Odb) -> TrevmBuilder<Odb, Insp>
+    pub fn with_db<Odb>(self, db: Odb) -> TrevmBuilder<Insp, BuilderReady<Odb>>
     where
-        Db: Database,
+        Odb: Database,
     {
         TrevmBuilder {
-            db: Some(db),
             insp: self.insp,
             spec: self.spec,
             precompiles: self.precompiles,
+            state: BuilderReady { db },
         }
     }
 
     /// Set the inspector for the EVM.
     ///
     /// Equivalent to [`Self::with_inspector`].
-    pub fn with_insp<OInsp>(self, insp: OInsp) -> TrevmBuilder<Db, OInsp> {
-        TrevmBuilder { db: self.db, insp, spec: self.spec, precompiles: self.precompiles }
+    pub fn with_insp<OInsp>(self, insp: OInsp) -> TrevmBuilder<OInsp, State> {
+        TrevmBuilder { insp, spec: self.spec, precompiles: self.precompiles, state: self.state }
     }
 
     /// Set the inspector for the EVM.
     ///
     /// Equivalent to [`Self::with_insp`].
-    pub fn with_inspector<OInsp>(self, insp: OInsp) -> TrevmBuilder<Db, OInsp> {
+    pub fn with_inspector<OInsp>(self, insp: OInsp) -> TrevmBuilder<OInsp, State> {
         self.with_insp(insp)
     }
 
@@ -79,14 +96,16 @@ impl<Db, Insp> TrevmBuilder<Db, Insp> {
         self.precompiles = Some(Precompiles::new(self.spec.into()));
         self
     }
+}
 
+impl<Insp, Db> TrevmBuilder<Insp, BuilderReady<Db>> {
     /// Build the Trevm instance.
-    pub fn build_trevm(self) -> Result<EvmNeedsCfg<Db, Insp>, TrevmBuilderError>
+    pub fn build_trevm(self) -> EvmNeedsCfg<Db, Insp>
     where
         Db: Database,
         Insp: Inspector<Ctx<Db>>,
     {
-        let db = self.db.ok_or(TrevmBuilderError::DatabaseNotSet)?;
+        let db = self.state.db;
         let ctx = Ctx::new(db, self.spec);
 
         let mut evm = ctx.build_mainnet_with_inspector(self.insp);
@@ -95,7 +114,7 @@ impl<Db, Insp> TrevmBuilder<Db, Insp> {
             evm.precompiles = EthPrecompiles { precompiles, spec: self.spec };
         }
 
-        Ok(Trevm::from(evm))
+        Trevm::from(evm)
     }
 }
 

src/evm/has_tx.rs

@@ -264,8 +264,7 @@ mod tests {
         let log_address = Address::repeat_byte(0x32);
 
         // Set up trevm, and test balances.
-        let mut trevm =
-            TrevmBuilder::new().with_db(db).with_spec_id(SpecId::PRAGUE).build_trevm().unwrap();
+        let mut trevm = TrevmBuilder::new().with_db(db).with_spec_id(SpecId::PRAGUE).build_trevm();
         let _ = trevm.test_set_balance(ALICE.address(), U256::from(ETH_TO_WEI));
         let _ = trevm.set_bytecode_unchecked(log_address, Bytecode::new_raw(LOG_DEPLOYED_BYTECODE));
 

src/inspectors/mod.rs

@@ -35,7 +35,6 @@ mod test {
             .with_db(InMemoryDB::default())
             .with_insp(inspector)
             .build_trevm()
-            .unwrap()
             .fill_cfg(&NoopCfg)
             .fill_block(&NoopBlock);
 

src/lib.rs

@@ -41,15 +41,13 @@
 //! use revm::{database::in_memory_db::InMemoryDB};
 //! use trevm::{TrevmBuilder, EvmErrored, Cfg, Block, Tx};
 //!
-//! # fn t<C: Cfg, B: Block, T: Tx>(cfg: &C, block: &B, tx: &T)
-//! # -> Result<(), Box<dyn std::error::Error>> {
+//! # fn t<C: Cfg, B: Block, T: Tx>(cfg: &C, block: &B, tx: &T) {
 //! TrevmBuilder::new()
 //!     .with_db(InMemoryDB::default())
-//!     .build_trevm()?
+//!     .build_trevm()
 //!     .fill_cfg(cfg)
 //!     .fill_block(block)
 //!     .run_tx(tx);
-//! # Ok(())
 //! # }
 //! ```
 //! If you get stuck, don't worry! You _cannot_ invoke the wrong function or
@@ -118,14 +116,12 @@
 //! # use revm::{database::in_memory_db::InMemoryDB, inspector::NoOpInspector};
 //! # use trevm::{TrevmBuilder, EvmErrored, Cfg, BlockDriver};
 //! # use alloy::primitives::B256;
-//! # fn t<C: Cfg, D: BlockDriver<InMemoryDB, NoOpInspector>>(cfg: &C, mut driver: D)
-//! # -> Result<(), Box<dyn std::error::Error>> {
+//! # fn t<C: Cfg, D: BlockDriver<InMemoryDB, NoOpInspector>>(cfg: &C, mut driver: D) {
 //! let trevm = TrevmBuilder::new()
 //!     .with_db(InMemoryDB::default())
-//!     .build_trevm()?
+//!     .build_trevm()
 //!     .fill_cfg(cfg)
 //!     .drive_block(&mut driver);
-//! # Ok(())
 //! # }
 //! ```
 //!
@@ -148,19 +144,17 @@
 //! # use revm::{database::in_memory_db::InMemoryDB};
 //! # use trevm::{TrevmBuilder, EvmErrored, Cfg, Block, Tx};
 //! # use alloy::primitives::B256;
-//! # fn t<C: Cfg, B: Block, T: Tx>(cfg: &C, block: &B, tx: &T)
-//! # -> Result<(), Box<dyn std::error::Error>> {
+//! # fn t<C: Cfg, B: Block, T: Tx>(cfg: &C, block: &B, tx: &T) {
 //! let trevm = match TrevmBuilder::new()
 //!     .with_db(InMemoryDB::default())
-//!     .build_trevm()?
+//!     .build_trevm()
 //!     .fill_cfg(cfg)
 //!     .fill_block(block)
 //!     .fill_tx(tx)
 //!     .run() {
 //!         Ok(trevm) => trevm.accept_state(),
 //!         Err(e) => e.discard_error(),
 //!     };
-//! # Ok(())
 //! # }
 //! ```
 //!
@@ -245,14 +239,13 @@
 //! # State, StateBuilder}};
 //! # use trevm::{TrevmBuilder, EvmErrored, Cfg, Block, Tx, BlockOutput,
 //! # EvmNeedsCfg, EvmNeedsBlock, EvmNeedsTx, EvmReady, EvmTransacted};
-//! # fn t<C: Cfg, B: Block, T: Tx>(cfg: &C, block: &B, tx: &T)
-//! # -> Result<(), Box<dyn std::error::Error>> {
+//! # fn t<C: Cfg, B: Block, T: Tx>(cfg: &C, block: &B, tx: &T) {
 //! let state = StateBuilder::new_with_database(InMemoryDB::default()).build();
 //!
 //! // Trevm starts in `EvmNeedsCfg`.
 //! let trevm: EvmNeedsCfg<_, _> = TrevmBuilder::new()
 //!     .with_db(state)
-//!     .build_trevm()?;
+//!     .build_trevm();
 //!
 //! // Once the cfg is filled, we move to `EvmNeedsBlock`.
 //! let trevm: EvmNeedsBlock<_, _> = trevm.fill_cfg(cfg);
@@ -285,7 +278,6 @@
 //! // Finishing the EVM gets us the final changes and a list of block outputs
 //! // that includes the transaction receipts.
 //! let bundle: BundleState = trevm.finish();
-//! # Ok(())
 //! # }
 //! ```
 //!