Hi Roger
and thanks for your explanations. Just a couple of additional remarks.
I agree with Paolo that this is a change for C++, and should at least be
documented in changes.html, and probably be tweaked to avoid warning in
system headers.
Note that, AFAICS, the issue would boil down to fixing pragma
system_headers to work with templates. I don't think it's trivial and /
or someone is already working on it. In any case, if we agree that the
warning is meaningful, our (v3) policy asks for avoiding it in the code,
whenever possible: in short, I mean to change v3 in any case.
Specifically, for PR 30465 "((T)1 << 31) - 1" is potentially undefined
when T is a 32-bit signed type, but well-defined if T is unsigned or
wider than 32-bits.
FYI: this specific issue arises from std::numeric_limits<wchar_t> on
x86-linux: in particular from the __glibcxx_max macro at the beginning
of the header. Luckily, since we are dealing with template
specializations, the pragma is sufficient to suppress the warning, but
if you can figure out a better way to compute the max itself, just speak...
Thanks,
Paolo.
