Re: [PATCH 4/4] [broken] meson: try link tracepoints to module

[Paolo Bonzini]

On 20/11/20 12:25, Gerd Hoffmann wrote:
>    Hi,
>
> > Guess I'll go dig into the meson documentation, this looks more like a
> > build system than a tracing problem to me.
>
> Looking at https://mesonbuild.com/Syntax.html ...
>
> "all objects are immutable".
>
> So "var2 = var1" creates a copy not a reference I guess?
>
> Which implies that ...
>
>         foo_ss.add(something)
>
> ... is different from ...
>
>         bar_ss = foo_ss
>         bar_ss.add(something)
>
> ... which in turn explains why the patch doesn't work at all.
>
> Now I'm wondering how I can make trace/meson.build add the trace
> objects to the module source sets if I can't pass around references
> to the module source sets?
>
> Paolo?  Any hints how to tackle this the meson way?

You could build a separate dictionary in trace/meson.build.  Instead of 
using the 'hw_display_qxl' group, you use the module name i.e. 
'hw-display-qxl'.  trace/meson.build does:

  module_trace = {}

and in trace/meson.build

  module_trace_src = []
  foreach c : ...
    ...
    group = '--group=' + c['name'].underscorify()
    module_trace_src += [trace_h, trace_c]
    ...
    module_trace += { c['name']: module_trace_src }
  endforeach

Then when building the shared_module you add the trace files to the 
sources, like

   module_trace_src = module_trace.get(d + '-' + m, [])
   sl = static_library(d + '-' + m,
                       [genh, module_ss.sources(), module_trace_src],
                       dependencies: ...)

Paolo