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Compilers corner

Compilers are sometimes full of surprises and such strange errors happened in the course of the development that I wanted to list the most fun for readers’ entertainment.


template <class StateType>
typename ::boost::enable_if<
       typename ::boost::mpl::and_<
                typename ::boost::mpl::not_<
                    typename has_exit_pseudo_states<StateType>::type
                typename ::boost::mpl::not_<
                    typename is_pseudo_exit<StateType>::type

I get the following error:

error C2770: invalid explicit template argument(s) for '`global namespace'::boost::enable_if<...>::...'

If I now remove the first “::” in ::boost::mpl , the compiler shuts up. So in this case, it is not possible to follow Boost’s guidelines.


g++ 4.x: Boring compiler, almost all is working almost as expected. Being not a language lawyer I am unsure about the following “Typeof problem”. VC9 and g++ disagree on the question if you can derive from the BOOST_TYPEOF generated type without first defining a typedef. I will be thankful for an answer on this. I only found two ways to break the compiler:

You can test your compiler’s decltype implementation with the following stress test and reactivate the commented-out code until the compiler crashes.