http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53603
--- Comment #3 from Richard Neill <gcc at richardneill dot org> 2012-06-07
14:41:10 UTC ---
Thanks for your explanation. I didn't know about -Wconversion existing
independently of -Wextra.
Might I suggest a couple of things that arise:
1. It seems a bit strange to me that there are warnings that are not enabled by
-Wall -Wextra. The man page lists so many different types of warning: perhaps
it would be useful to mention (under -Wextra) which ones it does *not* enable?
Or maybe it would be worthwhile adding something like "-Wkitchensink" to mean:
yes, really do turn on all the warnings (except maybe for pedantic).
2. Even -Wconversion misses the following:
int a=7; int b=4;
double y;
y = a/b;
I know why: a/b is a perfectly sensible integer division, and then y is being
assigned the integer value of 1, which is also a loss-freel conversion.
But, what I mean by "y=a/b" is "y is the floating point number obtained by
dividing a and b", not "do integer division of a/b and then promote to a
double"
3. As you say, -Wconversion is too noisy to include by default. But perhaps
there could be a distinction between straightforward assignment:
int a;
unsigned int b;
a=b;
and function calls with mismatched parameters:
int a;
double d;
int myfunction(int x){...} ;
a = myfunction(d);
I'd suggest that when the latter happens, it's most probably a bug, whereas the
former is (often) deliberate. This might allow for some subsets of -Wconversion
to be included within -Wextra ?
Thanks for your time.
