tree 36ec6676451a6753377eb904f87bec6ebd7a866c
parent 897d71687e4c4e15e8f5f76f4662955c3228aedf
author Jason Rhinelander <jason@imaginary.ca> 1499123529 -0400
committer Jason Rhinelander <jason@imaginary.ca> 1499272034 -0400

Use rvalue subcasting when casting an rvalue container

This updates the std::tuple, std::pair and `stl.h` type casters to
forward their contained value according to whether the container being
cast is an lvalue or rvalue reference.  This fixes an issue where
subcaster casts were always called with a const lvalue which meant
nested type casters didn't have the desired `cast()` overload invoked.
For example, this caused Eigen values in a tuple to end up with a
readonly flag (issue #935) and made it impossible to return a container
of move-only types (issue #853).

This fixes both issues by adding templated universal reference `cast()`
methods to the various container types that forward container elements
according to the container reference type.