Always use return_value_policy::move for rvalues #510
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Fixes pybind#509. The move policy was already set for rvalues in PR pybind#473, but this only applied to directly cast user-defined types. The problem is that STL containers cast values indirectly and the rvalue information is lost. Therefore the move policy was not set correctly. This commit fixes it. This also makes an additional adjustment to remove the `copy` policy exception: rvalues now always use the `move` policy. This is also safe for copy-only rvalues because the `move` policy has an internal fallback to copying.
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Thank you! |
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Thanks @dean0x7d, this seems to fix it indeed. |
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Fixes #509.
The move policy was already set for rvalues in PR #473, but this only applied to directly cast user-defined types. The problem is that STL containers cast values indirectly and the rvalue information is lost. Therefore the move policy was not set correctly. This PR fixes it.
The tests are included only for a
std::list, but the same underlying issue applies for all STL containers, includingoptional. The issue is thattype_caster_generic::casthas overloads forconst&and&&, but the STL casters such aslist_caster::castonly have aconst&overload. Thus, themovepolicy is never properly applied. Rather than add overloads to all type caster, the rvalue check is done incpp_function.This PR also makes an additional adjustment to remove the
copypolicy exception: rvalues now always use themovepolicy. This is also safe for copy-only rvalues because themovepolicy has an internal fallback to copying.