chore: add tracers stubs (#222)

While all other stubs were present in `temporary.go`, these two methods
were missing. This sets up the config, and makes clear all the RPC
methods that still need to be implemented.

Author: JonathanOppenheimer

sae/rpc.go

@@ -23,6 +23,7 @@ import (
 	"github.com/ava-labs/libevm/core/types"
 	"github.com/ava-labs/libevm/crypto"
 	"github.com/ava-labs/libevm/eth/filters"
+	"github.com/ava-labs/libevm/eth/tracers"
 	"github.com/ava-labs/libevm/ethdb"
 	"github.com/ava-labs/libevm/event"
 	"github.com/ava-labs/libevm/libevm/debug"
@@ -38,6 +39,7 @@ import (
 // APIBackend is the union of all interfaces required to implement the SAE APIs.
 type APIBackend interface {
 	ethapi.Backend
+	tracers.Backend
 	filters.BloomOverrider
 }
 
@@ -173,6 +175,13 @@ func (vm *VM) ethRPCServer() (*rpc.Server, error) {
 		})
 	}
 
+	if !vm.config.RPCConfig.DisableTracing {
+		apis = append(apis, api{
+			// Geth-specific APIs:
+			"debug", tracers.NewAPI(b),
+		})
+	}
+
 	s := rpc.NewServer()
 	for _, api := range apis {
 		if err := s.RegisterName(api.namespace, api.api); err != nil {

sae/temporary.go

@@ -12,7 +12,11 @@ import (
 	"math/big"
 
 	"github.com/ava-labs/libevm/common"
+	"github.com/ava-labs/libevm/core"
+	"github.com/ava-labs/libevm/core/state"
 	"github.com/ava-labs/libevm/core/types"
+	"github.com/ava-labs/libevm/core/vm"
+	"github.com/ava-labs/libevm/eth/tracers"
 	"github.com/ava-labs/libevm/rpc"
 )
 
@@ -37,3 +41,11 @@ func (b *ethAPIBackend) PendingBlockAndReceipts() (*types.Block, types.Receipts)
 func (b *ethAPIBackend) GetPoolNonce(context.Context, common.Address) (uint64, error) {
 	panic(errUnimplemented)
 }
+
+func (b *ethAPIBackend) StateAtBlock(ctx context.Context, block *types.Block, reexec uint64, base *state.StateDB, readOnly bool, preferDisk bool) (*state.StateDB, tracers.StateReleaseFunc, error) {
+	panic(errUnimplemented)
+}
+
+func (b *ethAPIBackend) StateAtTransaction(ctx context.Context, block *types.Block, txIndex int, reexec uint64) (*core.Message, vm.BlockContext, *state.StateDB, tracers.StateReleaseFunc, error) {
+	panic(errUnimplemented)
+}

sae/vm.go

@@ -91,6 +91,7 @@ type RPCConfig struct {
 	BlocksPerBloomSection uint64
 	EnableDBInspecting    bool
 	EnableProfiling       bool
+	DisableTracing        bool
 	EVMTimeout            time.Duration
 	GasCap                uint64
 }