------- Comment #7 from gdr at cs dot tamu dot edu 2007-01-15 16:14 ------- Subject: Re: [regression] -Wconversion triggers warnings for deque<>::push_back()
"pcarlini at suse dot de" <[EMAIL PROTECTED]> writes: | (In reply to comment #5) | > Sorry I read your reply later. | > | > So, that is it, isn't it? Wsystem-headers needs to be fixed since we don't want | > to emit warnings for system headers even if those warnings are correct. | | Well, first we don't know when, how, if, the pragma system_header will be ever | fixed. Then, assuming the warning is correct, certainly we want to adjust the | library, that, in my opinion, makes certainly for good engineering (in fact, we | are generally relying on the effect of the pragma only in very few, | last-resort, situations). Alternately, never emit the warning, of course. I agree with Paolo that we use the system_header hack only as a last resort -- in general. However, there is a fundamental tension between unsigned<integer> and <integer> use in the the C++ standard library and in libstdc++ in particular. Many, among whom the designers of C++, consider most uses of unsigned as indices or sizes as mistake (alas, the LWG did not listen). I'm sure middle-end people could argue that they can generate better codes if signed is used instead -- but that is a different issue :-) For libstdc++, we need to understand what gaurantees we give for max_size() -- e.g. can we really handle elements that fill up the whole range of size_type? If yes, then the warning is good in the sense that it draws our attention to an untenable promise. If not, then the warning isn't that useful -- well, in some sense it is useful as it would force us to introduce more casts than we would like. No wonder why people introduced ssize_t :-) -- Gaby -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30464
