Re: [RFC][PATCH 03/12] digest_lists: Basic definitions

Matthew Wilcox
2021-06-27T15:24:02Z

On Sun, Jun 27, 2021 at 12:53:47PM +0200, Greg KH wrote:
> > +enum ops { DIGEST_LIST_ADD, DIGEST_LIST_DEL, DIGEST_LIST_OP__LAST };
> > +
>
> For enums you export to userspace, you need to specify the values so
> that all compilers get them right.

I've never heard that rule before. Where does it come from?
https://en.cppreference.com/w/c/language/enum
says:

If enumeration-constant is not followed by = constant-expression,
its value is the value one greater than the value of the previous
enumerator in the same enumeration. The value of the first enumerator
(if it does not use = constant-expression) is zero.