Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."

[Gabriel Dos Reis]

"Kaveh R. GHAZI" <address@hidden> writes:

[...]

| I'd like to see a -Warning flag added to GCC to spot places where GCC does
| something potentially too aggressive.  Having that would do two things, it
| would make it easier for maintainers to audit their code, and it would
| make it easier for us to get hard data on how often code will break.
| There has been too much guessing and extrapolating in this discussion so
| far IMHO.
| 
| Such a flag has been already suggested more than once.  Here are two cases
| I found without trying too hard.
| http://gcc.gnu.org/ml/gcc/2006-12/msg00507.html
| http://lists.gnu.org/archive/html/bug-gnulib/2006-12/msg00151.html
| 
| Is there some technical reason why we can't do this like we did for
| -Wstrict-aliasing?  Would we get a zillion false positives?

Indeed a warning for cases where we know GCC optimizers actively take
advantages of "undefined behaviour" will be very useful -- both for
checking and collecting data.  Do we have an approximate list of those
cases used by the optimizers? 

-- Gaby