Re: [RFC PATCH] qapi: Incorrect attempt to fix building with MC146818RTC=n

[Markus Armbruster <armbru@redhat.com>]

Philippe Mathieu-Daudé <philmd@redhat.com> writes:

> When configured with --without-default-devices and setting
> MC146818RTC=n, the build fails:
>
>     LINK    x86_64-softmmu/qemu-system-x86_64
>   /usr/bin/ld: qapi/qapi-commands-misc-target.o: in function `qmp_marshal_rtc_reset_reinjection':
>   qapi/qapi-commands-misc-target.c:46: undefined reference to `qmp_rtc_reset_reinjection'
>   /usr/bin/ld: qapi/qapi-commands-misc-target.c:46: undefined reference to `qmp_rtc_reset_reinjection'
>   collect2: error: ld returned 1 exit status
>   make[1]: *** [Makefile:206: qemu-system-x86_64] Error 1
>   make: *** [Makefile:483: x86_64-softmmu/all] Error 2
>
> This patch tries to fix this, but this is incorrect because QAPI
> scripts only provide TARGET definitions, so with MC146818RTC=y we
> get:
>
>   hw/rtc/mc146818rtc.c:113:6: error: no previous prototype for ‘qmp_rtc_reset_reinjection’ [-Werror=missing-prototypes]
>     113 | void qmp_rtc_reset_reinjection(Error **errp)
>         |      ^~~~~~~~~~~~~~~~~~~~~~~~~
>   cc1: all warnings being treated as errors
>   make[1]: *** [rules.mak:69: hw/rtc/mc146818rtc.o] Error 1
>
> Any idea? :)
>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  qapi/misc-target.json | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/qapi/misc-target.json b/qapi/misc-target.json
> index a00fd821eb..8e49c113d1 100644
> --- a/qapi/misc-target.json
> +++ b/qapi/misc-target.json
> @@ -41,7 +41,7 @@
>  #
>  ##
>  { 'command': 'rtc-reset-reinjection',
> -  'if': 'defined(TARGET_I386)' }
> +  'if': 'defined(TARGET_I386) && defined(CONFIG_MC146818RTC)' }
>  
>  
>  ##

The generated qapi-commands-misc-target.h duly has

    #if defined(TARGET_I386) && defined(CONFIG_MC146818RTC)
    void qmp_rtc_reset_reinjection(Error **errp);
    void qmp_marshal_rtc_reset_reinjection(QDict *args, QObject **ret, Error **errp);
    #endif /* defined(TARGET_I386) && defined(CONFIG_MC146818RTC) */

mc146818rtc.c includes it.  But since it doesn't include
config-devices.h, CONFIG_MC146818RTC remains undefined, and the
prototype gets suppressed.

Crude fix: make mc146818rtc.c #include "config-devices.h".