g ++编译器忽略const返回类型

Question

I'm one of these types of people who thinks "if it shouldn't be able to change, then it should be const ". Perhaps I take const to the extreme by doing this, but, since my function return types generally should not be able to change, I declare all my functions to return const . (Unless they return void of course - does it even make sense to return by const void ?)

You probably think either I'm kind of nutty, and I'm wearing out my keyboard typing stuff I don't need to, or that returning const makes sense because you already use it yourself. Or maybe you're thinking neither of those things in which case I guessed incorrectly.

I've compiled my program using g++4.8, and enabled the compiler switch -Wextra . When doing so, g++ warns me that it ignores every single one of my return statements. None of them are returning by const . This makes no difference after compiling obviously, but I wanted to know is there a way of forcing g++ to compile and pay some attention to my const return types.

More importantly, why does g++ ignore the const -- or is it simply because I'm nutty and g++ thinks returning const is unnecessary?

As requested: Example...

inline const bool collisionTest(...) { ... }

warning: type qualifiers ignored on function return type

Answer 1

It doesn't ignore it, it's just useless if you return primitive types by value.

Returning by value means you can't modify whatever it is you returned anyways, because it's an r-value. The const would be redundant.

See:

int foo();

How would you modify the return?

foo() = 4;

would yield a compiler error.

If you return a reference though, the const does matter:

int& foo();
const int& goo();

foo() = 42;  //okay 
goo() = 42;  //error