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Re: -Wconversion versus libstdc++
Paolo Carlini wrote:
Martin Sebor wrote:
FYI: HP aCC warns for some but not all of these types of lossy
initializations. For example, a double to int conversion emits
a warning but ptrdiff_t to size_t or other signed to unsigned
conversions do not, probably because they're so common. I find
this behavior useful.
Thanks Martin for the data point: I understand that this behavior is
typical of the compilers based on the EDG front-end?
aCC 3.70 is not based on the EDG front end (aCC 6 is and starting
with 6.05 it gives the same warning). The EDG 3.80 demo doesn't
give a warning for this case, so it looks like the warning might
be an HP feature.
Anyway, note that our -Wconversion is not part of -Wall, not even
-Wextra: are you maintaining that probably the bits having to do with
float <-> integer should also be part of -Wall or at least -Wextra?
We use both -Wall and -W so we don't really have a preference for
which warnings are controlled by which of the two options but since
these initializations can (unexpectedly) yield a different value
than the initializing expression I think it deserves a warning
even if it's not explicitly requested. That way users will get the
benefit of the new feature after upgrading without having to read
the new manual or tweaking their makefiles. (I think it might even
be safe to assume that most users who use -Wall actually expect to
see all warnings, or at least wouldn't be surprised if a new
warning were added).
Martin