Re: [Qemu-devel] [PATCH v2 28/54] qapi: do not define enumeration value explicitely

[Markus Armbruster]

Marc-André Lureau <address@hidden> writes:

> The C standard has the initial value at 0 and the subsequent values
> incremented by 1. No need to set this explicitely.
>
> This will prevent from artificial "gaps" when compiling out some enum
> values and having unnecessarily large MAX values & enums arrays.

Yes, but it also risks entertaining mishaps like compiling this one

    typedef enum Color {
        COLOR_WHITE,
#if defined(NEED_CPU_H)
#if defined(TARGET_S390X)
        COLOR_BLUE,
#endif /* defined(TARGET_S390X) */
#endif /* defined(NEED_CPU_H) */
        COLOR_BLACK,
    } Color;

in s390x-code (COLOR_BLACK = 2) and in target-independent code
(COLOR_BLACK = 1), then linking the two together.

> Signed-off-by: Marc-André Lureau <address@hidden>
> ---
>  scripts/qapi.py | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/scripts/qapi.py b/scripts/qapi.py
> index 52099332f1..9d075440d3 100644
> --- a/scripts/qapi.py
> +++ b/scripts/qapi.py
> @@ -1979,14 +1979,11 @@ typedef enum %(c_name)s {
>  ''',
>                  c_name=c_name(name))
>  
> -    i = 0
>      for value in enum_values:
>          ret += mcgen('''
> -    %(c_enum)s = %(i)d,
> +    %(c_enum)s,
>  ''',
> -                     c_enum=c_enum_const(name, value, prefix),
> -                     i=i)
> -        i += 1
> +                     c_enum=c_enum_const(name, value, prefix))
>  
>      ret += mcgen('''
>  } %(c_name)s;