[Bug c++/56697] Erroneous rejection of use of private constructor in public method

[nmm1 at cam dot ac.uk]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56697

--- Comment #1 from Nick Maclaren <nmm1 at cam dot ac.uk> 2013-03-23 12:49:31 UTC ---
Sorry, I should be clearer.  I reported this because of the compiler
difference, and because I can read the relevant wording of the standard
either way.  But I should have said "Possibly erroneous".