GCC 6.x Lambda Visibility Warning

I am creating a shared library that contains a bunch of lambdas and some of these lambdas are created inside other lambdas. But when I use -fvisibility = hidden and -Wall, I get a warning about ads for something with more visibility, which I honestly don't understand. I have a minimal example:

#include <memory>
template<class T>
class MyClass  {
public:
    MyClass() {
#if 0
        auto fn = [this]           { /*Do something useful here*/ };
        auto outer = [this,fn]()   { /*use fn for something here*/ };
#else
        auto outer = [this]()
            {
                auto fn = [this]   { /*Do something useful here */ };
                //use fn for something here
            };
#endif
        /* use outer for something */
    }
};
int main() { MyClass<int> r; }

      

        
        
        
      

    

If I compile this, I get the following warning:

% g++    -Wall -fvisibility=hidden -Wno-unused-but-set-variable  -o visibility_test.cpp.o -c visibility_test.cpp
visibility_test.cpp: In instantiation of ‘struct MyClass<T>::MyClass()::<lambda()> [with T = int]::<lambda()>’:
visibility_test.cpp:13:22:   required from ‘MyClass<T>::MyClass()::<lambda()> [with T = int]’
visibility_test.cpp:11:23:   required from ‘struct MyClass<T>::MyClass() [with T = int]::<lambda()>’
visibility_test.cpp:11:14:   required from ‘MyClass<T>::MyClass() [with T = int]’
visibility_test.cpp:22:27:   required from here
visibility_test.cpp:13:32: warning: ‘MyClass<T>::MyClass()::<lambda()> [with T = int]::<lambda()>’ declared with greater visibility than the type of its field ‘MyClass<T>::MyClass()::<lambda()> [with T = int]::<lambda()>::<this capture>’ [-Wattributes]
                 auto fn = [this]   { /*Do something useful here */ };

      

        
        
        
      

    

If I change #if 0 to #if 1, thereby moving the fn creation outside of the "outer" lambda, it all compiles fine.

This warning came up when I installed GCC 6 in the Arch box. I get it when compiling with 6.3.1 and 7.1.1.

So my questions are:

• What is this warning trying to tell me?
• How do I get rid of the warning without breaking too much code (moving the lambda as in my example is not really an option).

Update: So, I admitted that this is a bug in GCC and now I want to get rid of the warning with minimal side effects. So I added "__attribute__ ((visibility (" default ")))" to the MyClass constructor, which looks good.