Add option for a flat directory layout

[jpakkane]

Currently if you have protobuf files in a hierarchical tree and then compile them with something like:

protoc -I proto_subdir --cpp_out outdir proto_subdir/dummy_service.proto
protoc -I proto_subdir --cpp_out outdir proto_subdir/messages/dummy_messages.proto 

this results in files

outdir/dummy_service.pb.*
outdir/messages/dummy_messages.pb.*

And inside dummy_service.pb.cc there is this:

#include "messages/dummy_messages2.pb.h"

Besides looking like Java, this forces a directory layout on generated sources which makes integration difficult.

It would be nice to add a flag to the protoc compiler, say --flat-layout which would do the following:

• output all files to cpp_out subdir without any extra directory segments
• change #include statements to not have extra directory segments

[anandolee]

If you want dummy_messages.pb.* under outdir/ directly, try -I proto_subdir/messages/