How to define inline lambda in GCC

With the -Winline I want to check the inlining of lambda into the code.

Where should the inline keyword be to make inline-lambda in GCC in a function call?

#include <iostream>
#include <algorithm>
#include <vector>

int main() {
  std::vector<int> numbers{3, 4, 2, 9, 15, 267};
  std::for_each(numbers.begin(), numbers.end(), /* inline */ [](int &n){ n++; });
  return 0;
}

I tried a lambda variable, but it fails:

inline auto inc = [](int &n){ n++ };

$ g++ -std=c++11 -Winline test.cpp
test.cpp:13:15: error: ‘x’ declared as an ‘inline’ variable
   inline auto x = [](int &n) { return n++; };