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If I try to convert a json object into my concrete type through a reference, the compile fails claiming that operator= is ambiguous. Do you have any thoughts on why that might be the case and what I could do to work around it? I'd like to avoid having to do a 2 step, convert to local value then copy to where it needs to be.
edit: I've just discovered that the problem seems to be because only the copy constructor works, not the assignment operator. See "edit" in the code below. Is this by design?
typedef std::map<std::string, std::string> MyMap;
MyMap m1{ {"a", "A"}, {"b", "B"} };
json j = m1;
#if 1
MyMap m2 = j; // only this works
edit: #elif 0
edit: MyMap m2;
edit: m2 = j; // fails claiming = operator is ambiguous
#elif 0
MyMap* m2 = new MyMap();
*m2 = j; // fails claiming = operator is ambiguous
#elif 0
MyMap m;
MyMap& m2 = m;
m2 = j; // fails claiming = operator is ambiguous
#elif 0
auto m2 = std::make_shared<MyMap>();
*m2 = j; // fails claiming = operator is ambiguous
#endif
EXPECT_EQ(m1, m2);
The specific error is as follows (for the above case when using the pointer):
1>test.cpp
1>test.cpp(154): error C2593: 'operator =' is ambiguous
1>c:\program files (x86)\microsoft visual studio\2017\professional\vc\tools\msvc\14.16.27023\include\map(354): note: could be 'std::map<std::string,std::string,std::less<_Kty>,std::allocator<std::pair<const _Kty,_Ty>>> &std::map<_Kty,_Ty,std::less<_Ty>,std::allocator<std::pair<const _Kty,_Ty>>>::operator =(std::initializer_list<std::pair<const _Kty,_Ty>>)'
1> with
1> [
1> _Kty=std::string,
1> _Ty=std::string
1> ]
1>c:\program files (x86)\microsoft visual studio\2017\professional\vc\tools\msvc\14.16.27023\include\map(189): note: or 'std::map<std::string,std::string,std::less<_Kty>,std::allocator<std::pair<const _Kty,_Ty>>> &std::map<_Kty,_Ty,std::less<_Ty>,std::allocator<std::pair<const _Kty,_Ty>>>::operator =(std::map<_Kty,_Ty,std::less<_Ty>,std::allocator<std::pair<const _Kty,_Ty>>> &&) noexcept(<expr>)'
1> with
1> [
1> _Kty=std::string,
1> _Ty=std::string
1> ]
1>c:\program files (x86)\microsoft visual studio\2017\professional\vc\tools\msvc\14.16.27023\include\map(173): note: or 'std::map<std::string,std::string,std::less<_Kty>,std::allocator<std::pair<const _Kty,_Ty>>> &std::map<_Kty,_Ty,std::less<_Ty>,std::allocator<std::pair<const _Kty,_Ty>>>::operator =(const std::map<_Kty,_Ty,std::less<_Ty>,std::allocator<std::pair<const _Kty,_Ty>>> &)'
1> with
1> [
1> _Kty=std::string,
1> _Ty=std::string
1> ]
1>test.cpp(154): note: while trying to match the argument list '(MyMap, json)'
The text was updated successfully, but these errors were encountered:
If I try to convert a json object into my concrete type through a reference, the compile fails claiming that operator= is ambiguous. Do you have any thoughts on why that might be the case and what I could do to work around it? I'd like to avoid having to do a 2 step, convert to local value then copy to where it needs to be.
edit: I've just discovered that the problem seems to be because only the copy constructor works, not the assignment operator. See "edit" in the code below. Is this by design?
The specific error is as follows (for the above case when using the pointer):
The text was updated successfully, but these errors were encountered: