codejen: Update to latest codejen (#58866)

pkg/codegen/generators.go

@@ -34,12 +34,20 @@ func ForGen(rt *thema.Runtime, decl *kindsys.SomeDecl) (*DeclForGen, error) {
 type DeclForGen struct {
 	*kindsys.SomeDecl
 	lin thema.Lineage
+	sch thema.Lineage
 }
 
+// Lineage returns the [thema.Lineage] for the underlying [kindsys.SomeDecl].
 func (decl *DeclForGen) Lineage() thema.Lineage {
 	return decl.lin
 }
 
+// Schema returns the [thema.Schema] that a jenny should operate against, for those
+// jennies that target a single schema.
+func (decl *DeclForGen) Schema() thema.Lineage {
+	return decl.sch
+}
+
 // SlashHeaderMapper produces a FileMapper that injects a comment header onto
 // a [codejen.File] indicating the main generator that produced it (via the provided
 // maingen, which should be a path) and the jenny or jennies that constructed the

pkg/codegen/jenny_basecorereg.go

@@ -31,7 +31,7 @@ func (gen *genBaseRegistry) JennyName() string {
 	return "BaseCoreRegistryJenny"
 }
 
-func (gen *genBaseRegistry) Generate(decls []*DeclForGen) (*codejen.File, error) {
+func (gen *genBaseRegistry) Generate(decls ...*DeclForGen) (*codejen.File, error) {
 	var numRaw int
 	for _, k := range decls {
 		if k.IsRaw() {

pkg/codegen/jenny_tsveneerindex.go

@@ -39,7 +39,7 @@ func (gen *genTSVeneerIndex) JennyName() string {
 	return "TSVeneerIndexJenny"
 }
 
-func (gen *genTSVeneerIndex) Generate(decls []*DeclForGen) (*codejen.File, error) {
+func (gen *genTSVeneerIndex) Generate(decls ...*DeclForGen) (*codejen.File, error) {
 	tsf := new(ast.File)
 	for _, decl := range decls {
 		if decl.IsRaw() {