On 08/13/12 11:16, Steven Watanabe wrote:
AMDG
On 08/13/2012 09:06 AM, Larry Evans wrote:
The attached runs OK without any compile or runtime errors. It seems to create a type_uns<1> from a type_uns<0> although there's no type_uns<1> CTOR for that.
This sounds like another instance of the bug reported here:
http://article.gmane.org/gmane.comp.lib.boost.devel/233101
Is it?
It's similar, but this is really undefined behavior,
And it's undefined behavior because it violates the Requires clause: the type stored in other must match the type expected by binding. from: http://steven_watanabe.users.sourceforge.net/type_erasure/libs/type_erasure/... The correspondence between the example code and the doc are: doc -> example code ----- --- ------------ other -> src_a binding -> dst_binding type stored in other -> src_concrete_t type expected by binding -> dst_concrete_t And obviously, src_concrete_t does not match dst_concrete_t, thus violating the Requires clause. Sorry, I should have read the Requires clause closer.
since there's no way to detect the problem at compile time. It's also not necessarily possible to add an assertion.
I guess one just has to be careful using this CTOR. Thanks. -Larry