[Bug c/60090] For expression without ~, gcc -O1 emits "comparison of promoted ~unsigned with unsigned"

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60090

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
I believe we strive for the warnings be independent of the optimization level,
but it's not always possible, we have tons of bugs where -Wuninitialized
depends on the optimization level, sometimes -Warray-bounds warns only on -O3,
some warnings depend on VRP or SRA, on -O some uses are constant-propagated
etc.  In the middle-end we often warn only about variables in SSA form which
are made, as a part of some optimization, non-addressable.