On Wed, 19 Sep 2018 at 06:21, Vegard Nossum <vegard.nossum@xxxxxxxxxx> wrote:
>
> With the following code:
>
> enum foo {
> BAR = 1ULL << 63,
> };
>
> I was seeing the following warning:
>
> enum.c:2:20: warning: cast truncates bits from constant value (8000000000000000 becomes 0)
>
> parse_enum_declaration() keeps track of the minimum and maximum values of
> the enum's values and tries to find a data type that contain it. In this
> case it ought to match 'unsigned long long', but it doesn't. The reason is
> that ullong_ctype->bit_size == 64 and type_is_ok() will do a left shift of
> 64 on the maximum/minimum values, which is undefined in C.
>
> My compiler (gcc 5.5.0) gives a non-zero value for (1ULL << 63) >> 64, and
> the enum's underlying type becomes bad_ctype which has ->bit_size == -1,
> thus failing the cast truncation test in cast_value().
Ahh, never mind, I saw you already have a patch for this when checking
if my email made it to the list :-/
Vegard
