Re: [Boost-users] [Boost.Optional] Compilation error with boost::optional in Boost 1.49 and GCC 4.4.6

On Fri, Apr 27, 2012 at 12:47 PM, Jonathan Jones < Jonathan.Jones@mathworks.com> wrote:

Hello,

The following code fails to compile when using GCC 4.4.6 and boost::optional from Boost 1.49:

Hmmm...seems to build fine for me with MSVC9 (also Boost 1.49.0) #include

#include

struct grill { template<typename U> grill (U) {} };

template<typename T> struct bar { template<typename U> bar (U, typename boost::is_convertible::type* = 0) {} };

void foo() { typedef bar<grill> data_type;

boost::optional opt; boost::optional opt2(opt); // this line (void)opt2; }

Here are the error messages (I apologize for the long lines, I shortened them as much as possible by truncating the header paths):

...

&, grill>::value’: type_traits/is_convertible.hpp:329: instantiated from ‘const bool boost::detail::is_convertible_impl::value’ type_traits/is_convertible.hpp:452: instantiated from ‘boost::is_convertible, grill>’

...

]’

type_traits/is_convertible.hpp: In instantiation of ‘const bool boost::detail::is_convertible_basic_impl

This reproduction case is distilled from a real world example (not my code) where bar=boost::fusion::vector1 and grill=boost::function

The code compiles fine using the same compiler and Boost 1.44.

Any ideas on the root of the problem?

I can't figure it out from a quick glance through optional.hpp :( Can you investigate what has changed in optional.hpp between 1.44 and 1.49? - Jeff