cast truncates bits from constant value (8000000000000000 becomes 0)

[Geert Uytterhoeven]

On Tue, 21 Nov 2006, Geoff Levand wrote:
> +enum ps3_vendor_id {
> +	PS3_VENDOR_ID_NONE = 0,
> +	PS3_VENDOR_ID_SONY = 0x8000000000000000UL,
> +};

I've just ran `make C=1' (PPC in 64-bit mode, and sparse is called with -m64),
and noticed that sparse (cloned from
git://git.kernel.org/pub/scm/devel/sparse/sparse.git a few minutes ago)
complains about the second value with:

| warning: cast truncates bits from constant value (8000000000000000 becomes 0)

Section 6.7.2.2.4 of C99 says:

| Each enumerated type shall be compatible with char, a signed integer type, or
| an unsigned integer type. The choice of type is implementation-defined, but
| shall be capable of representing the values of all the members of the
| enumeration.

The code snippet

| u64 x = PS3_VENDOR_ID_SONY;
| printk("PS3_VENDOR_ID_SONY = %lu\n", x);

does print the expected (i.e. non-zero) result.

Hence this looks like a bug in sparse.

Gr{oetje,eeting}s,

						Geert

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Geert Uytterhoeven -- Sony Network and Software Technology Center Europe (NSCE)
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