Problem Compiling nested proto files that do not reside in the same physical folder/directory.

[elimn8or]

My Scenario:

I have defined four proto message types: A, B, C, D and want to
compile using the C++ option. Proto file A is located in directory .
\ProtoTop and proto files B, C, D are located in directory .\ProtoTop
\Dir. The resulting class dependencies are A->B->C->D ( where -> is
defines as depends on ). I have made this directory structure to
accomadate the eventual build of libraries ( Msgs & Types ). Proto
message class A does a import "Dir/B.proto".
I have tried packaging each proto file to remove namespace conflicts
but no joy.

The problems:

1) When I compile each class individually all is well and the source
code is autogenerated. However there is a function called from A that
is defined in B which does not
exist: ::protobuf_AddDesc_Dir_2fB_2eproto() and as such a compilation
error for A occurs in my c++ compile (VC90 version).

Note: B contains what i believe is the intended
function ::protobuf_AddDesc_B_2eproto(); Therefore it seems the
autogenerated class A adds the import path into the function name for
the above method.

Can I get around this without excplicity editing autogenerated code,
what did I do incorrectly?

2) I next tried compiling all proto files in one go, i.e one call to
protoc with the intention of mitigating the above problem. However,
this produces the following protoc errors:

B.proto:6:30: ".B.C" is already defined in file "Dir/B.proto".
1>B.proto:4:9: ".B" is already defined in file "Dir/B.proto".

Summary:
The only methodology I have succeeded with is to compile all proto
files in one directory within the same namespace. This will suffice,
however it contrains my design and usage of the libraries in that I
would be unable to seperate my 'messages' from my 'message types'.

[Jason Hsueh]

What command are you using to invoke protoc? This sort of problem usually occurs when you don't use the same root directory in protoc invocations. So you should have something like:

protoc --proto_path .\ProtoTopDir A.proto

protoc --proto_path .\ProtoTopDir Dir\B.proto Dir\C.proto

I'm not sure the issue that you have with using a single command, but perhaps you're doing something like

protoc --proto_path .\ProtoTopDir --proto_path .\ProtoTopDir\Dir A.proto B.proto C.proto ...

In this case, when you read A.proto, it will search for the import Dir\B.proto, and add those definitions. Then when it reads B.proto, it finds it in the second --proto_path, but these definitions are duplicated with what's already been read as Dir\B.proto via A's import. protoc doesn't do path canonicalization, as this gets complicated with . and ../, symlinks, etc etc.

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[elimn8or]

Thankyou for that...

Everything you suggested I thought matched what I had implemented.

However, it seems my configuration of the proto_path was incorrect, or
just my interpretation.......

Thankyou for the clarification which has proven successful.