op-bindings: cleanup gen script

Does a little refactor to the gen script to dedupe some
code and clean things up.

op-bindings/foundry/artifact.go

+package foundry
+
+import (
+	"encoding/json"
+
+	"github.com/ethereum-optimism/optimism/op-bindings/solc"
+
+	"github.com/ethereum/go-ethereum/accounts/abi"
+	"github.com/ethereum/go-ethereum/common/hexutil"
+)
+
+type Artifact struct {
+	Abi              abi.ABI            `json:"abi"`
+	StorageLayout    solc.StorageLayout `json:"storageLayout"`
+	DeployedBytecode DeployedBytecode   `json:"deployedBytecode"`
+	Bytecode         Bytecode           `json:"bytecode"`
+}
+
+type DeployedBytecode struct {
+	SourceMap           string          `json:"sourceMap"`
+	Object              hexutil.Bytes   `json:"object"`
+	LinkReferences      json.RawMessage `json:"linkReferences"`
+	ImmutableReferences json.RawMessage `json:"immutableReferences"`
+}
+
+type Bytecode struct {
+	SourceMap      string          `json:"sourceMap"`
+	Object         hexutil.Bytes   `json:"object"`
+	LinkReferences json.RawMessage `json:"linkReferences"`
+}

op-bindings/gen/main.go

@@ -12,12 +12,10 @@ import (
 	"text/template"
 
 	"github.com/ethereum-optimism/optimism/op-bindings/ast"
-	"github.com/ethereum-optimism/optimism/op-bindings/solc"
-	"github.com/ethereum/go-ethereum/common/hexutil"
+	"github.com/ethereum-optimism/optimism/op-bindings/foundry"
 )
 
 type flags struct {
-	ArtifactsDir   string
 	ForgeArtifacts string
 	Contracts      string
 	SourceMaps     string
@@ -33,17 +31,8 @@ type data struct {
 	DeployedSourceMap string
 }
 
-type forgeArtifact struct {
-	StorageLayout    *solc.StorageLayout `json:"storageLayout"`
-	DeployedBytecode struct {
-		SourceMap string        `json:"sourceMap"`
-		Object    hexutil.Bytes `json:"object"`
-	} `json:"deployedBytecode"`
-}
-
 func main() {
 	var f flags
-	flag.StringVar(&f.ArtifactsDir, "artifacts", "", "Comma-separated list of directories build info")
 	flag.StringVar(&f.ForgeArtifacts, "forge-artifacts", "", "Forge artifacts directory, to load sourcemaps from, if available")
 	flag.StringVar(&f.OutDir, "out", "", "Output directory to put code in")
 	flag.StringVar(&f.Contracts, "contracts", "", "Comma-separated list of contracts to generate code for")
@@ -51,7 +40,6 @@ func main() {
 	flag.StringVar(&f.Package, "package", "artifacts", "Go package name")
 	flag.Parse()
 
-	artifacts := strings.Split(f.ArtifactsDir, ",")
 	contracts := strings.Split(f.Contracts, ",")
 	sourceMaps := strings.Split(f.SourceMaps, ",")
 	sourceMapsSet := make(map[string]struct{})
@@ -59,10 +47,6 @@ func main() {
 		sourceMapsSet[k] = struct{}{}
 	}
 
-	if len(artifacts) == 0 {
-		log.Fatalf("must define a list of artifacts")
-	}
-
 	if len(contracts) == 0 {
 		log.Fatalf("must define a list of contracts")
 	}
@@ -75,7 +59,7 @@ func main() {
 			log.Printf("cannot find forge-artifact with source-map data of %q\n", name)
 		}
 
-		var artifact forgeArtifact
+		var artifact foundry.Artifact
 		if err := json.Unmarshal(forgeArtifactData, &artifact); err != nil {
 			log.Fatalf("failed to parse forge artifact of %q: %v\n", name, err)
 		}
@@ -84,11 +68,7 @@ func main() {
 		}
 
 		storage := artifact.StorageLayout
-		if storage == nil {
-			log.Fatalf("no storage layout for %s\n", name)
-		}
-
-		canonicalStorage := ast.CanonicalizeASTIDs(storage)
+		canonicalStorage := ast.CanonicalizeASTIDs(&storage)
 		ser, err := json.Marshal(canonicalStorage)
 		if err != nil {
 			log.Fatalf("error marshaling storage: %v\n", err)
@@ -97,19 +77,8 @@ func main() {
 
 		deployedSourceMap := ""
 		if _, ok := sourceMapsSet[name]; ok {
-			// directory has .sol extension
-			forgeArtifactData, err := os.ReadFile(path.Join(f.ForgeArtifacts, name+".sol", name+".json"))
-			if errors.Is(err, os.ErrNotExist) {
-				log.Printf("cannot find forge-artifact with source-map data of %q\n", name)
-			}
-			if err == nil {
-				var artifact forgeArtifact
-				if err := json.Unmarshal(forgeArtifactData, &artifact); err != nil {
-					log.Fatalf("failed to parse forge artifact of %q: %v\n", name, err)
-				}
 			deployedSourceMap = artifact.DeployedBytecode.SourceMap
 		}
-		}
 
 		d := data{
 			Name:              name,