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Ive got a code that looks like this
template <class TDerived>
struct Event
{
inline static std::string eventId = typeid(TDerived).name();
};
struct Derived : public Event<Derived>
{
Derived() = default;
};
This compiles correctly in GNU C++, Apple Clang and even MingW in Windows).
But in windows using Visual Studio compiler (MSVC) I am getting the following error
error C2027: use of undefined type 'Derived'
message : see declaration of 'Derived'
message : see reference to class template instantiation 'Event<Derived>' being compiled
I understand that Derived is incomplete at the scope of Event, but why does other compiler can succesfuly recognize it?
Is there any workaround for it to work on VS C++?
my environment
Visual Studio Community 2019
The CXX compiler identification is MSVC 19.28.29336.0
Please help, this kind of line is rampant on what I am porting right now and changing them will be a huge effort.
Reported to Microsoft:
https://developercommunity2.visualstudio.com/t/typeid-with-template-differs-in-behaviou/1323822
A high-level, general-purpose programming language, created as an extension of the C programming language, that has object-oriented, generic, and functional features in addition to facilities for low-level memory manipulation.
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I suggest that you report this using the Visual Studio "Report a Problem" facility - be sure to include a minimal repro and point out that other compilers don't have the problem.
Post a link to your report back here so that we can follow it.
updated my post above with the link to the report
I can't see from your bug report, but it's best if you supply a simple project that illustrates the problem to make life easy for the folks on the other end to reproduce issues. Otherwise they'll more likely than not have to ask you for one anyway, and you run the chance of the issue getting dropped.
Answer accepted by question author
Try this workaround:
template <class TDerived>
struct Event
{
private:
static std::string getEventId( ) { return typeid( TDerived ).name( ); }
public:
inline static std::string eventId = getEventId();
};
this one worked, Thank you very much!
However I still reported the issue to standardize things between the compilers specially MVSC.