[Bug tree-optimization/82192] gcc produces incorrect code with -O2 and bit-field

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82192

--- Comment #3 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
On Tue, 12 Sep 2017, vsevolod.livinskij at frtk dot ru wrote:

> struct struct_t {
>     unsigned int memb : 13;
> };
> 
> extern struct_t b;

>     printf("%llu\n", b.memb);

unsigned int : 13 (promoted to int - I think C++ promotes 
narrower-than-int bit-fields to int, though for C++ the bit-field width is 
not considered part of the type) is not valid for printf %llu.  You need 
to explicitly cast to unsigned long long.