Add the ability to build Edition 2026 codegen with protoc.

editions/BUILD

@@ -401,11 +401,24 @@ cc_proto_library(
     deps = [":test_editions_2024_default_features_proto"],
 )
 
+proto_library(
+    name = "test_editions_2026_default_features_proto",
+    testonly = True,
+    srcs = ["input/test_editions_2026_default_features.proto"],
+)
+
+cc_proto_library(
+    name = "test_editions_2026_default_features_cc_proto",
+    testonly = True,
+    deps = [":test_editions_2026_default_features_proto"],
+)
+
 cc_test(
     name = "generated_files_test",
     srcs = ["generated_files_test.cc"],
     deps = [
         ":test_editions_2024_default_features_cc_proto",
+        ":test_editions_2026_default_features_cc_proto",
         ":test_editions_default_features_cc_proto",
         ":test_messages_proto2_editions_cc_proto",
         ":test_messages_proto3_editions_cc_proto",

editions/input/test_editions_2026_default_features.proto

@@ -0,0 +1,24 @@
+edition = "2026";
+
+package protobuf_editions_test;
+
+// This file tests the default Edition2024 features in the absence of any
+// dependencies.
+
+enum Editions2026DefaultEnum {
+  EDITIONS2026_DEFAULT_ENUM_UNKNOWN = 0;
+  EDITIONS2026_DEFAULT_ENUM_VALUE1 = 1;
+}
+
+message Editions2026DefaultMessage {
+  int32 int32_field = 1;
+  string string_field = 2;
+  Editions2026DefaultEnum enum_field = 3;
+
+  repeated int32 repeated_int32_field = 4;
+
+  message SubMessage {
+    int32 nested_int32_field = 1;
+  }
+  SubMessage sub_message_field = 6;
+}

src/google/protobuf/compiler/code_generator.h

@@ -184,7 +184,7 @@ constexpr auto ProtocMaximumEdition() { return Edition::EDITION_2024; }
 // The maximum edition known to protoc, which may or may not be officially
 // supported yet.  During development of a new edition, this will typically be
 // set to that.
-constexpr auto MaximumKnownEdition() { return Edition::EDITION_2024; }
+constexpr auto MaximumKnownEdition() { return Edition::EDITION_2026; }
 
 // CodeGenerators generate one or more files in a given directory.  This
 // abstract interface represents the directory to which the CodeGenerator is