struct Foo
{
        template<int U>
        // error: attributes are not allowed on a function-definition
        static int Bar()  __attribute__((always_inline))
        {
                return U;
        }

        // no error, although this is a fn definition, too
        static int Baz(bool x) __attribute__((always_inline))
        {
                return x ? Bar<5>() : Bar<42>(); 
        }
};

g++ -c 20140323-force_inline.cpp 
20140323-force_inline.cpp:5:20: error: attributes are not allowed on a function-definition
  static int Bar()  __attribute__((always_inline))

Tried with all minor versions from 4.4 to 4.9, same results.

Supporting attributes on in-class defined template members would be really useful, or rather, convenient. Otherwise, one have to declare the function with the attribute inside the class, then define it outside the class. For short and simple functions this is rather tedious.

Regards, Peter