[PPL-devel] Re: Feature request: optionally compile with support for exceptions

Roberto Bagnara bagnara at cs.unipr.it
Tue Oct 23 15:37:53 CEST 2001


"Niels Möller" wrote:
> Are you saying that one has to use -fexceptions also when compiling
> the files that are written in C? That's news to me, but I'm mostly
> ignorant when it comes to C++ exceptions.

Yes: for exceptions to be propagated correctly, C files must be compiled
with -fexceptions.

> > Perhaps you meant
> >
> >    CFLAGS=-fexceptions && ./configure && make
> >
> > but this is also a very bad idea in GMP 3.1.1 (the current release),
> > since `-fexceptions' will _replace_ any other compilation option so
> > that a good portion of the nice work done by the configure script
> > is simply lost.  In other words, on the machine I am using this very
> > moment, I would compile GMP with `-fexceptions' instead of
> > `-g -O -fomit-frame-pointer -mcpu=pentiumpro', and these
> 
> Sorry for the typo. I meant
> 
>   CXXFLAGS=-fexceptions ./configure && make
> 
> I.e. CXXFLAGS should be set in _configure's_ environment, but not in
> _make's_. If that doesn't work, it could be considered a bug in the
> configure script.

Sorry also on my part: I copied and pasted your typo but I did try
the right thing.  To summarize, if I do (copying and pasting
what I have just redone on my machine)

 CFLAGS=-fexceptions /usr/local/distrib/gmp-3.1.1/configure

I override all the other compilation flags: I get `-fexceptions'
and not `-g -O -fomit-frame-pointer -mcpu=pentiumpro'.
If assigning to CFLAGS was meant to _add_ to the compilation flags,
then this is a bug in the configure script.  In some projects of
mine I use configure options like --with-extra-cflags for that purpose.
All the best,

    Roberto

-- 
Roberto Bagnara
Computer Science Group
Department of Mathematics, University of Parma, Italy
http://www.cs.unipr.it/~bagnara/
mailto:bagnara at cs.unipr.it



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