Re: [python-cffi] cffi.FFI.cdef and implicit function declarations

Hi Florian,

On Wed, 8 Feb 2023 at 11:10, Florian Weimer <[email protected]> wrote:
> For example, this snippet:
>
> =E2=80=9C
> import cffi
>
> ffi =3D cffi.FFI()
> ffi.cdef("int puts(const char *);")
> ffi.cdef("const char *getenv(const char *);")
> ffi.cdef("const char *gnu_get_libc_release(void);")
> lib =3D ffi.verify()
> lib.puts(lib.getenv(b"TERM"))
> lib.puts(lib.gnu_get_libc_release())

Yes, it's expected not to work.  First, the ffi.verify() should not be
used any more and has been deprecated for many, many years.  But if
you want to use it anyway, then: ffi.verify() must be called with an
argument which is the extra piece of C source code, and that *must*
make the declared functions available to the C code.  A typical usage
is to say ffi.verify('#include <something.h>').  If you are getting an
"implicit function" warning from the C compiler, then this was not
done correctly.

A bient=C3=B4t,
Armin Rigo