Avoid outer/inner class name clashes

In some cases, protoc-gen-javastream could emit outer classes
and inner classes with the same name, which is invalid java.

This commit extends protoc-gen-javastream to append an "OuterClass"
suffix, if the outer class name clashes with any message.
This behavior is consistent with the standard protoc.

Bug: 276433199
Test: presubmit
Change-Id: I4e92d70c10c4d92d103b00f15b159acc08dffff2

1 files changed, 34 insertions, 13 deletions

diff --git a/tools/streaming_proto/java/java_proto_stream_code_generator.cpp b/tools/streaming_proto/java/java_proto_stream_code_generator.cpp
index 0e5d35bada47..be5c197b7c5b 100644
--- a/tools/streaming_proto/java/java_proto_stream_code_generator.cpp
+++ b/tools/streaming_proto/java/java_proto_stream_code_generator.cpp
@@ -18,6 +18,7 @@
 
 #include <stdio.h>
 
+#include <algorithm>
 #include <iomanip>
 #include <iostream>
 #include <map>
@@ -31,21 +32,39 @@ using namespace android::stream_proto;
 using namespace google::protobuf::io;
 using namespace std;
 
+static bool outer_class_name_clashes_with_any_message(const string& outer_class_name,
+                                                      const vector<DescriptorProto>& messages) {
+    return any_of(messages.cbegin(), messages.cend(), [&](const DescriptorProto& message) {
+        return message.name() == outer_class_name;
+    });
+}
+
 /**
  * If the descriptor gives us a class name, use that. Otherwise make one up from
  * the filename of the .proto file.
  */
-static string make_outer_class_name(const FileDescriptorProto& file_descriptor) {
+static string make_outer_class_name(const FileDescriptorProto& file_descriptor,
+                                    const vector<DescriptorProto>& messages) {
     string name = file_descriptor.options().java_outer_classname();
-    if (name.size() == 0) {
-        name = to_camel_case(file_base_name(file_descriptor.name()));
-        if (name.size() == 0) {
-            ERRORS.Add(UNKNOWN_FILE, UNKNOWN_LINE,
-                       "Unable to make an outer class name for file: %s",
-                       file_descriptor.name().c_str());
-            name = "Unknown";
-        }
+    if (!name.empty()) {
+        return name;
+    }
+
+    // Outer class and messages with the same name would result in invalid java (outer class and
+    // inner class cannot have same names).
+    // If the outer class name clashes with any message, let's append an "OuterClass" suffix.
+    // This behavior is consistent with the standard protoc.
+    name = to_camel_case(file_base_name(file_descriptor.name()));
+    while (outer_class_name_clashes_with_any_message(name, messages)) {
+        name += "OuterClass";
+    }
+
+    if (name.empty()) {
+        ERRORS.Add(UNKNOWN_FILE, UNKNOWN_LINE, "Unable to make an outer class name for file: %s",
+                   file_descriptor.name().c_str());
+        name = "Unknown";
     }
+
     return name;
 }
 
@@ -172,7 +191,7 @@ static void write_file(CodeGeneratorResponse* response, const FileDescriptorProt
     stringstream text;
 
     string const package_name = make_java_package(file_descriptor);
-    string const outer_class_name = make_outer_class_name(file_descriptor);
+    string const outer_class_name = make_outer_class_name(file_descriptor, messages);
 
     text << "// Generated by protoc-gen-javastream. DO NOT MODIFY." << endl;
     text << "// source: " << file_descriptor.name() << endl << endl;
@@ -239,7 +258,8 @@ static void write_multiple_files(CodeGeneratorResponse* response,
 
         if (messages_allowlist.empty() || !enums.empty()) {
             write_file(response, file_descriptor,
-                       make_file_name(file_descriptor, make_outer_class_name(file_descriptor)),
+                       make_file_name(file_descriptor,
+                                      make_outer_class_name(file_descriptor, messages)),
                        true, enums, messages);
         }
     }
@@ -297,8 +317,9 @@ static void write_single_file(CodeGeneratorResponse* response,
 
     if (messages_allowlist.empty() || !enums.empty() || !messages.empty()) {
         write_file(response, file_descriptor,
-                   make_file_name(file_descriptor, make_outer_class_name(file_descriptor)), true,
-                   enums, messages);
+                   make_file_name(file_descriptor,
+                                  make_outer_class_name(file_descriptor, messages)),
+                   true, enums, messages);
     }
 }