link issue with proto in different project

[yang yu]

I'm working on windows, some of my projects are dlls.

i need to add __declspec dllexport/dllimport symbol with the function or variables to use the project as dll.

but when i use protoc generate the source for the proto file,  of course they don't have the dllexport/dllimport symbol.

the problem is after build dll A(have a proto), when i build B link the project A, i got some link error like this:

error LNK2019:  unresolved external symbol "void PB:protobuf_AddDesc_Point2df_2eproto(void)""..................

because the function "void PB:protobuf_AddDesc_Point2df_2eproto(void)" in dll A didn't export,

so the project B link faild.

anything help would be wonderful.

-----------------------------------------------the situation like this-------------------------------------------

in DLL-A, have a proto like this:

---------point.proto---------

package PB;

message Point2df

{

required float x = 1;

required float y = 2;

}

in DLL-B, have a proto like this;

---------path.proto---------

package PB;

import "point.proto";

message Path

{

repeated Point2df points = 1;

}

[Kenton Varda]

There is a command-line option to add an export macro to all definitions.  Use something like:

  protoc --cpp_out=dllexport_decl=MY_EXPORT_MACRO:outdir

However, be very careful when passing protobuf objects across a DLL boundary.  The code on both sides must be dynamically linked against the same version of the C runtime, otherwise you run into all kinds of binary compatibility and heap issues.  See vsprojects/readme.txt for more information.

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