This is an advanced diagnostics added (presumably) with GCC-13
and attempts to protect against an insidious side-effect of ''overload resolution''
Basically C++ (like its ancestor C) is oriented towards direct linkage and adds
the OO-style dynamic dispatch (through virtual functions and a VTable)
only as an extension, which must be requested explicitly.
Thus the resolution of ''overloads'' (as opposed to ''overridden'' virtual functions)
always takes precedence and happens within the directly visible scope,
which can cause the compiler to perform an implicit conversion instead of
invoking a different virtual function, which is defined in a base class.
However, this diagnostics seems to be implemented in an overly zealous way:
The compiler warns at the time of the type instantiation, and even in cases
where it is effectively impossible to encounter this dangerous shadowing situation.
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109740
This leads to several ill-guided warnings in the Lumiera code base, which unfortunately
can only be addressed by disabling this diagnostics for all usages of some header.
The reason is, we often generate chains of template instantiations driven by type lists,
and in such usage pattern, it is not even possible to bring all the other inherited overloads
into scope (with a using `BASE::func` clause), because such a specification would be ambiguous
and result in a real compile error, because even the interface is generated from a chain of mix-in templates
Ichthyostega
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