Re: PATCH: flag_external and DECL_EXTERNAL documentation

[Fergus Henderson <fjh at cs dot mu dot oz dot au>]

On 01-Feb-2001, Jason Merrill <jason@redhat.com> wrote:
> >>>>> "Lars" == Lars Brinkhoff <lars.spam@nocrew.org> writes:
> 
> > Jason Merrill <jason@redhat.com> writes:
> >> No, this is wrong.  DECL_EXTERNAL is set on a function declaration when
> >> created, but it is cleared in start_function if the declaration is also a
> >> definition.
> 
> > Right.  How about this patch?
> 
> > -/* In a VAR_DECL or FUNCTION_DECL,
> > -   nonzero means external reference:
> > -   do not allocate storage, and refer to a definition elsewhere.  */
> > +/* In a VAR_DECL or FUNCTION_DECL, nonzero means external reference:
> > +   do not allocate storage, and refer to a definition elsewhere.
> > +   Note that DECL_EXTERNAL is always set when a non-nested function is
> > +   declared, and cleared when the function definition is encountered. */
> 
> This is describing C-specific behavior, and should not be in a backend
> file.  In C, function declarations are implicitly extern, but this may not
> be true of other languages.
> 
> I think the existing comment is fine.

I think the existing comment in tree.h is fine (now that I understand
what the C front-end does!).  But it might be helpful to add a comment
in c-decl.c, where it sets DECL_EXTERNAL, mentioning that start_function()
will clear that flag if it turns out to be a function definition
rather than just a declaration.

-- 
Fergus Henderson <fjh@cs.mu.oz.au>  |  "I have always known that the pursuit
                                    |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.