[Linux-ia64] gcc warnings on truncations?

[Linux-ia64] gcc warnings on truncations?

[Ted Logan]

Is there a way to get gcc to warn (or ideally, error) on truncations to
shorter types? ie:

	int len = strlen(blah);

should warn because strlen returns a size_t, which on 64-bit platforms
is 8 bits and ints are 4. This would be a nice sanity check in our
porting effort to make sure there's no possibility of loosing data. I've
poked through the docs and nothing seemed to do it.

Ted Logan
Spatial Technology

Re: [Linux-ia64] gcc warnings on truncations?

[Jim Wilson]

	Is there a way to get gcc to warn (or ideally, error) on truncations to
	shorter types? ie:

No.

The ISO C standard says that all expressions undergo default promotions, and
default promotions require promoting char/short to int.  Thus even a simple
expression like
	   short s;
	   short t;
	   s = s + t;
results in truncation to a shorter type, because the result of s+t is an int
and this result must be truncated to fit in the short destination.  A naive
implementation of this warning would give so many false warnings that it
wouldn't be very useful.  An intelligent implementation could cut down on the
false warnings, but would take much longer to write, and hence it is unlikely
that anyone will bother.

Jim