Re: RFC: Support non-standard extension (call via casted function pointer)

[Florian Weimer <fweimer at redhat dot com>]

On 01/27/2016 04:17 PM, Richard Biener wrote:

> We are trying to support
> 
> t.c
> ---
> void *foo();
> 
> int bar()
> {
>   return ((int (*)())foo) ();
> }
> 
> t2.c
> -----
> int foo () { return 0; }
> 
> thus doing a direct call to a function with a (wrong) prototype via a function
> pointer cast to the correct type and having a matching implementation of
> that function elsewhere.

I suspect Ada needs something like this already.  I expect the following
to work (although it is quite hideous).

with System;

package Import is

   function Foo return System.Address;
   pragma Import (C, Foo);

   function Bar return Integer;

end Import;

package body Import is

   function Bar return Integer is
      function Foo_2 return Integer;
      pragma Import (C, Foo_2);
      for Foo_2'Address use Foo'Address;
   begin
      return Foo_2;
   end Bar;

end Import;


Florian