Stirling Westrup wrote:
On Sun, Mar 6, 2011 at 5:50 AM, Philipp Reh <sefi@s-e-f-i.de> wrote:
Stirling Westrup wrote:
I'm not actually sure if this is a gcc regression, or a bug in mpl, but the following code, which compiles under gcc 4.5, doesn't do so under gcc 4.6:
#include <climits> #include <boost/mpl/int.hpp> typedef boost::mpl::int_<INT_MIN> Foo; Foo f;
It produces the errors:
/usr/local/include/boost/mpl/aux_/integral_wrapper.hpp: In instantiation of ‘mpl_::int_<-0x00000000080000000>’: test_test.cpp:8:27: instantiated from here /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: ‘2147483647’ is not a valid template argument for type ‘int’ because it is a non-constant expression /usr/local/include/boost/mpl/aux_/integral_wrapper.hpp:73:96: error: overflow in constant expression [-fpermissive]
I've already created a trak ticket for this (#5268), but was wondering if anyone had any insights as to its cause and/or any workarounds. My guess is that its related to gcc rewriting parts of its constant folding code to support constexpr.
I can confirm that. INT_MIN isn't the only problem, it fails for a lot of other values as well. Can you please raise this issue on the gcc bugtracker because the release is very close.
Okay, I have done so. Its bug #48003 on the GCC bugtracker.
Thanks. After looking further into this I realized that mpl tries to calculate INT_MIN-1 which, of course, is undefined. But I'm still not sure if this is a gcc bug or not because the typedef isn't used and I don't know if gcc should evaluate this.