WebC++17 introduces inline variables. C++17 fixes this problem for constexpr static member variables requiring an out-of-line definition if it was odr-used. See the second half of this answer for pre-C++17 details. Proposal P0386 Inline Variables introduces the ability to apply the inline specifier to variables. In particular to this case constexpr implies inline for … is odr-used. However, there is a definition for it available, so there is no non-diagnosable violation here; MSVC is wrong to accept it. (This is true even without the constructor declaration; the implicitly declared B::B() is never defined, but the default member initializer is still an odr-use like it is here.) foamywader

Definitions and ODR (One Definition Rule)

WebMay 18, 2024 · Expressions &X::n and &X::m count as ODR-use of n and m, respectively (that is, an address is requested). For a constexpr static data members, a definition was required prior to C++17. From C++17, static constexpr data members are implicitly inline, which means, no out-of-class definition is needed, as they are definitions themselves. WebAn assignment operator function in a class is odr-used by an implicitly-defined copy-assignment or move-assignment function for another class as specified in [class. copy. assign]. A constructor for a class is odr-used as specified in [dcl. init]. A destructor for a class is odr-used if it is potentially invoked. 10. WebJan 5, 2024 · one-definition rule (ODR) [ISO/IEC 14882-2014] A fundamental C++ rule that states that no translation unit shall contain more than one definition of any variable, function, class type, enumeration type or template, and that every program shall contain exactly one definition of every non-inline function or variable. Some definitions may be ... greenyard stock price