Simplify preserve list approach #364
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DavisVaughan
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And finally provide some reasoning backed by the standard about how the preserve list is unique across the compilation units in the package!
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Closes #249 as a cool side effect
The
preservedstatic struct object has been removed in favor of some inline functionsdetail::store::insert()anddetail::store::release(). These both access the preserve list through a static local SEXP in an extern function calleddetail::store::get(). This exact setup is guaranteed by the standard to mean that the preserve list is unique across compilation units in the package (see notes and links to SO and the standard inprotect.hpp).While working on #366, I learned that the current approach with the static
preservedseems to have some issues anyways. The tests I implemented there were not consistently passing on all platforms, and seemed to change on my Mac depending on whether or not I compiled with optimization, making me think we were in undefined behavior land previously. I confirmed that everything works as expected with this new standard approved approach.