Re: [PATCH v5 6/7] meson: document, why we don't generate trace events for tests/ and qga/

[Markus Armbruster <armbru@redhat.com>]

Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> writes:

> Making trace generation work for tests/ and qga/ would involve some
> Meson hackery to ensure we generate the trace-events files before
> trace-tool uses them. Since we don't actually support tracing there
> anyway, we bypass that problem.
>
> Let's add corresponding comments.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
> ---
>  qga/meson.build   | 8 ++++++++
>  tests/meson.build | 8 ++++++++
>  2 files changed, 16 insertions(+)
>
> diff --git a/qga/meson.build b/qga/meson.build
> index cfb1fbc085..79fcf91751 100644
> --- a/qga/meson.build
> +++ b/qga/meson.build
> @@ -15,6 +15,14 @@ qga_qapi_outputs = [
>    'qga-qapi-visit.h',
>  ]
>  
> +# We don't generate trace-events, just because it's not simple. For do it,
> +# we also should add .trace-events file into qga_qapi_outputs, and than
> +# add corresponding element of qga_qapi_files into qapi_trace_events
> +# global list, which is processed than in trace/meson.build.
> +# This means, that we'll have to move subdir('qga') above subdir('trace')
> +# in root meson.build. But that in turn will break the dependency of
> +# qga on qemuutil (which depends on trace_ss).
> +# So, resolving these dependencies and drop --no-trace-events is a TODO.

The option is still called --gen-trace at this point.  Easy fix: squash
into the next commit.

Suggest

   # Problem: to generate trace events, we'd have to add the .trace-events
   # file to qapi_trace_events like we do in qapi/meson.build.  Since
   # qapi_trace_events is used by trace/meson.build, we'd have to move
   # subdir('qga') above subdir('trace') in the top-level meson.build.
   # Can't, because it would break the dependency of qga on qemuutil (which
   # depends on trace_ss).  Not worth solving now; simply suppress trace
   # event generation instead.

>  qga_qapi_files = custom_target('QGA QAPI files',
>                                 output: qga_qapi_outputs,
>                                 input: 'qapi-schema.json',
> diff --git a/tests/meson.build b/tests/meson.build
> index 3f3882748a..21857d8b01 100644
> --- a/tests/meson.build
> +++ b/tests/meson.build
> @@ -31,6 +31,14 @@ test_qapi_outputs = [
>    'test-qapi-visit.h',
>  ]
>  
> +# We don't generate trace-events, just because it's not simple. For do it,
> +# we also should add .trace-events file into test_qapi_outputs, and than
> +# add corresponding element of test_qapi_files into qapi_trace_events
> +# global list, which is processed than in trace/meson.build.
> +# This means, that we'll have to move subdir('tests') above subdir('trace')
> +# in root meson.build. But that in turn will break the dependency of
> +# tests on qemuutil (which depends on trace_ss).
> +# So, resolving these dependencies and drop --no-trace-events is a TODO.
>  test_qapi_files = custom_target('Test QAPI files',
>                                  output: test_qapi_outputs,
>                                  input: files('qapi-schema/qapi-schema-test.json',

Likewise.