Re: Switching the default for -fabi-version

[Richard Guenther <rguenth at tat dot physik dot uni-tuebingen dot de>]

Joe Buck wrote:
>
>On Tue, Oct 21, 2003 at 04:24:38PM -0700, Mark Mitchell wrote:
>> Since nobody really objected to David Moore's suggestion that we make
>> -fabi-version=2 the default, I plan to change the default value of the
>> flag on the mainline in the next few days.
>>
>> If you object, speak up now!
>
>No objection, though I am still curious as to whether this actually makes
>a difference for any actual, widely used source code out there (that is,
>does -Wabi report anything for real programs that aren't specially
>constructed to tweak ABI bugs?  How often?)

Just throwing g++-3.4 with -Wabi at my POOMA based scientific code spits
out a lot of

warning: layout of classes derived from empty class
`XXX insert you favorite class here' may change in a future version of GCC

and

warning: the mangled name of `typename T::AddResult_t operator-(const
DomainBase<T1>&, const DomainDelta<Dim, C>&) [with T =
DomainTraits<Interval<2> >, int Dim = 2, int C = 2]' will change in a
future version of GCC

and

warning: `VectorEngine<2, double, BinaryVectorOp<Vector<2, double, Full>,
Vector<2, double, Full>, OpAdd> >::op_m' contains empty classes which may
cause base classes to be placed at different locations in a future version
of GCC

and

warning: vtable layout for class `DistributedMapper<2>' may not be
ABI-compliant and may change in a future version of GCC due to implicit
virtual destructor

which are not very clear (may vs. will) and omitting of a reason (in case
of the second warning). So to say, if I can still specify -fabi-version=0
I'm happy with changing. But you could try to make sure you dont break
libstdc++ compatibility with this change?

Thanks,

Richard.

--
Richard Guenther <richard dot guenther at uni-tuebingen dot de>
WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/