Remove top-level consts used across the main and generated files. var newDecls []ast.Decl for _, decl := range f.Decls { switch d := decl.(type) { case *ast.GenDecl: if d.Tok == token.CONST { continue // Skip const declarations } if d.Tok == token.IMPORT { cmap[decl] = nil // Drop pre-import comments. } } newDecls = append(newDecls, decl) } f.Decls = newDecls // Replace identifiers. ast.Inspect(f, func(n ast.Node) bool { switch x := n.(type) { case *ast.Ident: if replacement, ok := replacements[x.Name];...