From: "Tim Van Holder" <tim DOT van DOT holder AT pandora DOT be>
To: <djgpp-workers AT delorie DOT com>
Subject: Re: Built-in bzero
Date: Sun, 4 Nov 2001 10:54:37 +0100
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> What prototype of bzero does GCC expect?  More generally, how can one
> know what prototypes does GCC expect from functions it treats as
> built-in?

All C builtins (types and functions) are in c-common.c (function
c_common_nodes_and_builtins).  I ran into them when fiddling with a
library for dynamic-loading, as it was a bad idea to provide
  extern void* some_imported_function;
for them.

In the case of bzero, it looks like it expects
  void bzero (<anything>);
(i.e. only the return type (void) is 'hardcoded').

> Apart of using -fno-nonansi-builtins (which I don't want to do, since
> older versions of GCC will probably barf on it), can I do something
> in the GDB distribution to avoid this warning?  For example, are
> there some -Wxxx flags I can avoid using to shut this warning up?

It would seem that duplicate_decls() from c-decl.c (the function that
emits the warning) is called unconditionally, so I doubt if a -Wxxx
flag would help.
Without -fno-nonansi-builtins, the only escape is to use a compatible
declaration.  It would indeed be nice if you could use
  gcc --dump-builtins
or somesuch to get the list of what it expects.