C++ can compilers inline a function pointer?

Question

Suppose I\'ve got a function functionProxy that takes a generic parameter function and call its operator():

template&l         


        

Answer 1

Have tried the following templated pointer-to-lambda code:

volatile static int a = 0;

template  class Widget {
   public: 
      Widget(const Lambda* const lambda) : lambda_(lambda) { }
      void f() { (*lambda_)(); }
   private:
      const Lambda* const lambda_;
};

int main() {
   auto lambda = [](){ a++; };
   Widget widget(&lambda);
   widget.f();
}

GNU g++ 4.9.2, Intel icpc 16.0.1, and clang++ 3.5.0 all inlined both widget.f() and (*lambda_)() calls using -O2. That is, a was incremented directly inside main() according to disassembled binaries.

Inlining was applied even with non-const lambda and lambda_ pointers (removing both const).

Ditto with a local variable and lambda capture:

int main() {
   volatile int a = 0;
   auto lambda = [&a](){ a++; };
   ...