readability-const-return-type

Checks for functions with a const-qualified return type and recommends removal of the const keyword. Such use of const is usually superfluous, and can prevent valuable compiler optimizations. Does not (yet) fix trailing return types.

Examples:

const int foo();
const Clazz foo();
Clazz *const foo();

Note that this applies strictly to top-level qualification, which excludes pointers or references to const values. For example, these are fine:

const int* foo();
const int& foo();
const Clazz* foo();