mpl::is_lambda_expression bug

[James Hirschorn <James.Hirschorn@…>]

The metafunction boost::mpl::is_lambda_expression does not work correctly.

My attached code example give a metafunction class for which is_lambda_expression evaluates as false.

While is_lambda_expression is not a documented feature of boost::mpl, it is available in the boost::mpl namespace. Moreover, it is used in the implementation of boost::mpl::transform, and presumably results in unintended behaviour there.

The package boost::tti (in the boost/trunk) has boost::tti::detail::is_lambda_expression. I have confirmed that this works correctly on my example (see attached file). The tti author has informed me that tti depends on mpl. Perhaps then, boost::mpl::is_lambda_expression should be replaced by tti's.