http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52119
ajf <alan.j.flavell at gmail dot com> changed:
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CC| |alan.j.flavell at gmail dot com
--- Comment #10 from ajf <alan.j.flavell at gmail dot com> ---
(In reply to Jeffrey Yasskin from comment #0)
> numeric_limits<T>::min() is defined as (__glibcxx_signed (T) ? (T)1 <<
> __glibcxx_digits (T) : (T)0). Unfortunately, shifting into the sign bit is
> undefined behavior (C++11[expr.shift]p2), and undefined behavior makes an
> expression non-constant.
MY apologies if I am missing something obvious, but what exactly makes shifting
a 1 into the sign bit undefined behavior? Seems rather defined to me, assuming
it's actually being using as a integral numerical data-type (in this case,
32-bit int, long), which would result in a signed numerical value.In other
words, the sign bit, like any other bit, can only be 0 or 1, so I honestly do
not understand how undefined behavior enters the equation, or what impact it
may have.
