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boostorg / type_erasure

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Disable C++11 code path in dynamic_vtable.hpp #11

Closed jzmaddock closed 7 years ago

jzmaddock commented 8 years ago

Without this there are test failures for dynamic_any_cast. Previously this path was disabled by virtue of BOOST_NO_CXX11_CONSTEXPR, but since constexpr works just fine in VC14up3 this path now gets enabled. The failure has nothing to do with constexpr support though.

jzmaddock commented 8 years ago

This is a quick workaround, rather than a full fix:

Boost.Config has now been updated to not set BOOST_NO_CXX11_CONSTEXPR for VC14up3 which causes a new code path to be taken in this header. The change completely breaks dynamic_any_cast for reasons I don't understand but which are completely unrelated to constexpr support.

I suspect if you have a copy of VC14up3 handy then a spot of debugging will locate the cause of the failure and a better fix: for reasons I don't understand vtable lookup in dynamic_any_cast always fails. Perhaps some other config macro needs checking in the PP logic?

swatanabe commented 7 years ago

I've fixed this in develop. The pack expansion is miscompiling for mysterious reasons. I adjusted it to something that VC14 can handle.