Fix bug with large extension field numbers.

Previously, extensions with field numbers greater than 268435455 would
result in a compile time error in generated code that looks something
like this:

Foo.java:3178: error: integer number too large: 3346754610
                3346754610);

This is because we were trying to represent the tag number (an
unsigned int) using a java int constant, but java int constants are
signed, and can't exceed Integer.MAX_VALUE.

Fixed by declaring it as a long instead, and casting it down to an
int in the implementation. This is safe, because the tag value always
fits in 32 bis.

Change-Id: If2017bacb4e20af667eaeaf9b65ddc2c30a7709f

2 files changed, 4 insertions, 1 deletions

diff --git a/src/google/protobuf/compiler/javanano/javanano_extension.cc b/src/google/protobuf/compiler/javanano/javanano_extension.cc
index 754ed55..0b9d1d8 100644
--- a/src/google/protobuf/compiler/javanano/javanano_extension.cc
+++ b/src/google/protobuf/compiler/javanano/javanano_extension.cc
@@ -140,7 +140,7 @@ void ExtensionGenerator::Generate(io::Printer* printer) const {
     "        com.google.protobuf.nano.Extension.create$repeated$$ext_type$(\n"
     "            com.google.protobuf.nano.Extension.$type$,\n"
     "            $class$.class,\n"
-    "            $tag_params$);\n");
+    "            $tag_params$L);\n");
 }
 
 }  // namespace javanano
diff --git a/src/google/protobuf/unittest_extension_nano.proto b/src/google/protobuf/unittest_extension_nano.proto
index 2a678a8..d1c5766 100644
--- a/src/google/protobuf/unittest_extension_nano.proto
+++ b/src/google/protobuf/unittest_extension_nano.proto
@@ -21,6 +21,9 @@ message AnotherMessage {
 message ContainerMessage {
   extend ExtendableMessage {
     optional bool another_thing = 100;
+    // The largest permitted field number, per
+    // https://developers.google.com/protocol-buffers/docs/proto#simple
+    optional bool large_field_number = 536870911;
   }
 }