Warning: definition of implicit copy constructor is deprecated

Question

I have a warning in my C++11 code that I would like to fix correctly but I don\'t really know how. I have created my own exception class that is derived from std::runt

Answer 1

Note: the same happens for much different code but I'm writing it here in case someone gets the same warning.

There was a bug in GCC versions 6.4 - 9.0 where using declarations for base_type's operator= and base_type's ctor in types inheritted from base_type which was a class template did not actually created copy/move ctor/operators (ending in very unexpected compiler errors that an object can not be copied/moved).

Since GCC 9.0, the bug is fixed but it creates this warning instead. The warning is wrong and should not appear (the using explicitly declares constructors/operators).

• Example code with workarounds and GCC version comparison: https://godbolt.org/z/WgIH4c
• GCC bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89381
• another GCC bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92145
• Origin of this discovery: https://github.com/boostorg/spirit/issues/465