Re: [Qemu-devel] [PATCH RFC v2 08/47] qapi-visit: Fix generated code when schema has forward refs

[Eric Blake]

On 07/01/2015 02:21 PM, Markus Armbruster wrote:
> The visit_type_implicit_FOO() are generated on demand, right before
> their first use.  Used by visit_type_STRUCT_fields() when STRUCT has
> base FOO, and by visit_type_UNION() when flat UNION has member a FOO.
> 
> If the schema defines FOO after its first use as struct base or flat
> union member, visit_type_implicit_FOO() calls
> visit_type_implicit_FOO() before its definition, which doesn't
> compile.

None of our public qapi .json files currently do this, so no difference
to the generated code used in qemu proper.

> 
> Rearrange qapi-schema-test.json to demonstrate the bug.

Indeed, without testsuite exposure, nothing was relying on this fix.

> 
> Fix by generating the necessary forward declaration.
> 
> Signed-off-by: Markus Armbruster <address@hidden>
> ---
>  scripts/qapi-visit.py                   | 15 ++++++++++++++-
>  tests/qapi-schema/qapi-schema-test.json | 30 +++++++++++++++++-------------
>  tests/qapi-schema/qapi-schema-test.out  | 10 +++++-----
>  3 files changed, 36 insertions(+), 19 deletions(-)
> 

> +++ b/scripts/qapi-visit.py
> @@ -17,13 +17,23 @@ from qapi import *
>  import re
>  
>  implicit_structs = []
> +struct_fields_seen = set()
>  
>  def generate_visit_implicit_struct(type):
>      global implicit_structs
>      if type in implicit_structs:
>          return ''
>      implicit_structs.append(type)
> -    return mcgen('''
...
> +    ret += mcgen('''

Oddly enough, the ''' is at the same indentation,...

>  
>  static void visit_type_implicit_%(c_type)s(Visitor *m, %(c_type)s **obj, 
> Error **errp)
>  {
> @@ -38,8 +48,11 @@ static void visit_type_implicit_%(c_type)s(Visitor *m, 
> %(c_type)s **obj, Error *
>  }
>  ''',
>                   c_type=type_name(type))
> +    return ret

so nothing needed to be reindented here :)

Reviewed-by: Eric Blake <address@hidden>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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