Do I have to repeat the inlined keyword on function implementation

I always try to keep implementation outside of headers, so for templates and inlined functions, I usually do something like this

// File.h
inline bool foo()

#include "File.hpp"

// File.hpp

inline bool foo()
{
    return 1;
}

My question is, what does the C++ specification have to say about repeating the inline keyword for the actual implementation of the function? (as shown in this example)

I don't really want to do that as it gets messy with lots and lots of functions, and while my compiler doesn't complain, I wonder if the compiler still accepts the inline hint.

Anyone know?