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Re: libm error handling


On Tue, Apr 30, 2013 at 12:57:34PM -0700, Roland McGrath wrote:
> > Maybe you need symbol versioning to separate the old version of lgamma 
> > that writes to signgam for old binaries, and the new one that writes to 
> > __signgam for new binaries.
> 
> I think that is the best you can do.  But it's still not very satisfactory
> for the usual expectation of recompiling old sources: either they work as
> before, or you get some complaint.  If old sources say "int signgam;"
> instead of "extern int signgam;" they will silently change from getting
> values in signgam to it always staying its initial zero.  We can document
> that of course, but I can't think of anything we can do to ensure that such
> new compilations get an error or warning.  

Yes this is a possibility, but I've never seen such a program. If such
programs do exist, the current implementation is treating them
incorrectly; the correct interpretation of such a program as written
is that signgam is an object defined in the application, not libm.

Rich


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