Re: [PATCH] b43: Fix sparse warnings

[Pavel Roskin <proski@gnu.org>]

On Sat, 2009-08-15 at 12:04 +0200, Michael Buesch wrote:

> I still do not understand why it does complain about an _explicit_ truncation.
> That's simply stupid. If I program an explicit truncation I _do_ mean to truncate the value.

Actually, it's a bug in sparse.  Sparse acts inconsistently.

This causes a warning:

void mask(unsigned short mask);
static void test(void)
{
        mask((unsigned short)0xffff0000);
}

test.c:4:30: warning: cast truncates bits from constant value (ffff0000
becomes 0)

But this is OK:

void mask(unsigned short mask);
static void test(void)
{
        mask((unsigned short)0xfffff000);
}

Moreover, this is OK, even though the cast changes the value of the
constant:

void mask(unsigned short mask);
static void test(void)
{
        mask((unsigned short)0xfffff000U);
}

I suggest that we take no action until sparse is fixed.  I'm going to
report the issue to the sparse mailing list now.

-- 
Regards,
Pavel Roskin