https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90005
--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #3)
> Because GCC allows passing non pods via varargs now. This is an explicit
> change due to newer c++ changes.
Right. The C++ standard says:
"Passing a potentially-evaluated argument of class type (Clause 11) having a
non-trivial copy constructor, a non-trivial move constructor, or a non-trivial
destructor, with no corresponding parameter, is conditionally-supported with
implementation-defined semantics."
GCC supports passing a non-trivial type such as std::string to "...", with
implementation-defined semantics. Some other compilers do not support it.
But printf still requires a char* for a %s argument, which is what -Wformat
will warn about. Passing invalid arguments to printf often results in complete
garbage, e.g. printf("%s", &printf). That's not specific to passing a
std::string, it's just how printf works: you need to pass the right arguments.
