Re: lt_dlopenadvise() inconsistencies in libtool-2.2.2

[Gary V. Vaughan]

Hi Gary,

On 22 Apr 2008, at 13:18, Gary Kumfert wrote:
> On Sun, 20 Apr 2008, Bob Friesenhahn wrote:
> > On Sun, 20 Apr 2008, Gary V. Vaughan wrote:
> >
> > > I agree that this was arguably not the best decision, and maybe  
> > > once we've branched the tree for 2.2 maintenance we should  
> > > consider putting the struct in a public header along with a  
> > > warning that it should not be accessed to give the compiler the  
> > > best chance to catch these kinds of errors in future.
> >
> > It is possible to "forward declare" a C structure without providing  
> > info about its content.  Not as nice as C++ but still good enough  
> > for the C compiler to issue useful diagnostics.
>
> IMHO I tend to agree with Bob here.  Also, judicious use of
> const-ness can force the "read only" characteristic you intend
> without complicating the API for the programmer ("do I put an
> ampersand here or not?").

I'm am leary of overuse of const, as it tends to leak out and infect  
everything, and also always results in ending up with (once again)  
pointless casting to get rid of it somewhere in the call stack  
(probably inside the API boundary, but ugly none-the-less).

The reasoning I'm trying to stick with here is, if this call might  
change the parameter I'm passing then use an ampersand, otherwise don't.

> Alternatively, for the void* and casting approach, adding and
> testing for a cookie (some secret, fixed value embedded in the
> struct) would catch most cases where the wrong pointer
> is passed in.

Most definitely a nicer solution overall, but I didn't want to  
introduce inconsistency in the way libltdl treats opaque types.  Maybe  
this is something we can evaluate for the next rould of development  
after 2.2 has branched off?

> In any case.  Your time an attention in my earlier bug
> report is most appreciated.


Not at all.  Thanks for taking the time to report bugs where we can  
try to fix them!

Cheers,
        Gary
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