Re: [PATCH 3/3] meson: generate trace points for qmp commands

[Vladimir Sementsov-Ogievskiy]

23.12.2021 12:33, Vladimir Sementsov-Ogievskiy wrote:
> 23.12.2021 01:11, Paolo Bonzini wrote:
> > Il mar 21 dic 2021, 20:35 Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com 
> > <mailto:vsementsov@virtuozzo.com>> ha scritto:
> >
> >     --- a/trace/meson.build
> >     +++ b/trace/meson.build
> >     @@ -2,10 +2,14 @@
> >       specific_ss.add(files('control-target.c'))
> >
> >       trace_events_files = []
> >     -foreach dir : [ '.' ] + trace_events_subdirs
> >     -  trace_events_file = meson.project_source_root() / dir / 'trace-events'
> >     +foreach path : [ '.' ] + trace_events_subdirs + qapi_trace_events
> >     +  if path.contains('trace-events')
> >     +    trace_events_file = meson.project_build_root() / 'qapi' / path
> >
> >
> >
> > Just using "trace_events_file = 'qapi' / path" might work, since the build is 
> > nonrecursive.
>
> This say:
>
> ninja: error: '../trace/qapi/qapi-commands-authz.trace-events', needed by 
> 'trace/trace-events-all', missing and no known rule to make it
> make[1]: *** [Makefile:162: run-ninja] Error 1
> make[1]: Leaving directory '/work/src/qemu/up/up-trace-qmp-commands/build'
> make: *** [GNUmakefile:11: all] Error 2
>
>
> so, it consider the path relative to current "trace" directory.
>
> > If it doesn't, use the custom target object, possibly indexing it as ct[index]. You can 
> > use a dictionary to store the custom targets and find them from the "path" 
> > variable.
>
> O! Great thanks! Magic. The following hack works:
>
> diff --git a/meson.build b/meson.build
> index 20d32fd20d..c42a76a14c 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -39,6 +39,7 @@ qemu_icondir = get_option('datadir') / 'icons'
>   config_host_data = configuration_data()
>   genh = []
>   qapi_trace_events = []
> +qapi_trace_events_targets = {}
>
>   target_dirs = config_host['TARGET_DIRS'].split()
>   have_linux_user = false
> diff --git a/qapi/meson.build b/qapi/meson.build
> index 333ca60583..d4de04459d 100644
> --- a/qapi/meson.build
> +++ b/qapi/meson.build
> @@ -139,6 +139,9 @@ foreach output : qapi_util_outputs
>     if output.endswith('.h')
>       genh += qapi_files[i]
>     endif
> +  if output.endswith('.trace-events')
> +    qapi_trace_events_targets += {output: qapi_files[i]}
> +  endif
>     util_ss.add(qapi_files[i])
>     i = i + 1
>   endforeach
> @@ -147,6 +150,9 @@ foreach output : qapi_specific_outputs + 
> qapi_nonmodule_outputs
>     if output.endswith('.h')
>       genh += qapi_files[i]
>     endif
> +  if output.endswith('.trace-events')
> +    qapi_trace_events_targets += {output: qapi_files[i]}
> +  endif
>     specific_ss.add(when: 'CONFIG_SOFTMMU', if_true: qapi_files[i])
>     i = i + 1
>   endforeach
> diff --git a/trace/meson.build b/trace/meson.build
> index 77e44fa68d..daa24c3a2d 100644
> --- a/trace/meson.build
> +++ b/trace/meson.build
> @@ -4,7 +4,7 @@ specific_ss.add(files('control-target.c'))
>   trace_events_files = []
>   foreach path : [ '.' ] + trace_events_subdirs + qapi_trace_events
>     if path.contains('trace-events')
> -    trace_events_file = meson.project_build_root() / 'qapi' / path
> +    trace_events_file = qapi_trace_events_targets[path]
>     else
>       trace_events_file = meson.project_source_root() / path / 'trace-events'
>     endif

Or even simpler, I can use a list combined from needed qapi_files[] elements. 
So, the solution is to use custom target objects or their indexed subobjects 
instead of raw paths. This way Meson resolves dependencies better.

--
Best regards,
Vladimir