Stop requiring an out of class definition for version traits - #370
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gennaroprota wants to merge 1 commit into
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Stop requiring an out of class definition for version traits#370gennaroprota wants to merge 1 commit into
gennaroprota wants to merge 1 commit into
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`version_type` took its argument by reference, so constructing one from `version<T>::value` could bound a reference to that static data member and ODR-used it. A trait written by hand with no out-of-class definition for the data member, then left an undefined reference behind on compilers which do not fold the constant away. Spelling the value as an `int` happened to work only because the conversion to `unsigned int` created a temporary for the reference to bind to. Taking the argument by value removes the ODR-use, so both `int` and `unsigned int` work. The specializations `BOOST_CLASS_VERSION` writes have no definition either, and were relying on the same accident. `object_id_type` had the same constructor and is changed along with it. Fixes #311.
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version_typetook its argument by reference, so constructing one fromversion<T>::valuecould bound a reference to that static data member and ODR-used it. A trait written by hand with no out-of-class definition for the data member, then left an undefined reference behind on compilers which do not fold the constant away. Spelling the value as aninthappened to work only because the conversion tounsigned intcreated a temporary for the reference to bind to.Taking the argument by value removes the ODR-use, so both
intandunsigned intwork. The specializationsBOOST_CLASS_VERSIONwrites have no definition either, and were relying on the same accident.object_id_typehad the same constructor and is changed along with it.Fixes #311.