Re: [PATCH v16 08/11] qapi/s390x/cpu topology: set-cpu-topology monitor command

[Markus Armbruster]

Nina Schoetterl-Glausch <nsg@linux.ibm.com> writes:

> On Mon, 2023-02-27 at 08:59 +0100, Thomas Huth wrote:

[...]

>> I'm not sure whether double inclusion works with the QAPI parser (since this 
>> might code to be generated twice) ... have you tried?
>
> I haven't, the documentation says:
>
>> Include directives
>> ------------------
>> 
>> Syntax::
>> 
>>     INCLUDE = { 'include': STRING }
>> 
>> The QAPI schema definitions can be modularized using the 'include' 
>> directive::
>> 
>>  { 'include': 'path/to/file.json' }
>> 
>> The directive is evaluated recursively, and include paths are relative
>> to the file using the directive.  Multiple includes of the same file
>> are idempotent.
>
> Which is why I thought it should work, but I guess this is a statement about
> including the same file twice in another file and not about including the same
> file from two files.

No, this is intended to say multiple inclusion is fine, regardless where
the include directives are.

An include directive has two effects:

1. If the included file has not been included already, pull in its
   contents.

2. Insert #include in generated C.  Example: qdev.json includes
   qom.json.  The generated qapi-*-qdev.h include qapi-types-qom.h.

   Including any required modules, as recommended by qapi-code-gen.rst,
   results in properly self-contained generated headers.

> But then, as far as I can tell, the build system only builds qapi-schema.json,
> which includes all other files, so it could apply.

Yes, qapi-schema.json is the main module, which includes all the others.

In fact, it includes all the others *directly*.  Why?

We generate documentation in source order.  Included material gets
inserted right at the first inclusion; subsequent inclusions have no
effect.

If we put all first inclusions right into qapi-schema.json, the order of
things in documentation is visible right there, and won't change just
because we change inclusions deeper down.

Questions?