How to extract declarations (a .hpp file) from implementation (a .cpp file)?

Question

I was wondering if there was a tool (maybe GNU C++ compiler) to obtain from a .cpp file full of functions a .hpp file with the mentioned functions declarations.

Example:

I have:
magic.cpp

int foo() { return 42; }
char bar() { return 'z'; }

And I would like to obtain this after applying the wonderful tool:
magic.hpp

int foo();
char bar();

Answer 1

On Debian-based distributions:

apt-get install cproto

Then cproto magic.cpp gives the following output:

/* magic.cpp */
int foo(void);
char bar(void);