Static variables in the autogenerated C++ headers prevent delay loading of dll

[stolstov]

What language does this apply to? C++ Auto-generated code for C++

Describe the problem you are trying to solve. We build protobuf auto generated code into a dll. We would like to use delay-loading with this dll (DELAYLOAD linker option in Visual Studio). The auto generated header files contain exported static variables that produce the following link error: fatal error LNK1194: cannot delay-load 'mydll.dll' due to import of data symbol '"__declspec(dllimport) class xxxx::XXXXXDefaultTypeInternal xxxx::XXXX_default_instance"

Describe the solution you'd like Allow delay loading of the dll that exports protobuf autogenerated structures. A solution would be to avoid declaring exported static variables in the auto generated header files.

Describe alternatives you've considered We don't use delay load option right now.

[acozzette]

@stolstov I'm not sure if it's feasible for us to get rid of those static variables but do you have any ideas on how to do it?

[stolstov]

@acozzette In the header file you have this:

namespace xxx { __declspec(dllexport) XXXXXDefaultTypeInternal XXXX_default_instance }

Is it possible to replace these export variables with export functions that return the reference? namespace xxx { _declspec(dllexport) XXXXXDefaultTypeInternal& get_XXXX_default_instance(); }

In the cpp

XXXXXDefaultTypeInternal& get_XXXX_default_instance_() { return XXXX_default_instance }

Use get_XXXX_default_instance_() functions instead of global variables XXXX_default_instance in the auto generated code?

[acozzette]

The one potential issue is that if those functions are not inlined then there may be a performance cost.

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