Re: [Qemu-devel] [PATCH 2/9] qapi: allow build_params to return "void"

[Markus Armbruster <armbru@redhat.com>]

Peter Xu <peterx@redhat.com> writes:

> When there is no parameter at all for a function prototype, return
> "void" for the parameter list.  This will happen after the next patch
> where we removed the Error* for some of the emit functions.

Error **, actually.  Let's say

  qapi: Fix build_params() for empty parameter list

  build_params() returns '' instead of 'void' when there are no
  parameters.  Can't happen now, but the next commit will change that.

>
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  scripts/qapi/common.py | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
> index 8b6708dbf1..105c82742f 100644
> --- a/scripts/qapi/common.py
> +++ b/scripts/qapi/common.py
> @@ -1963,7 +1963,7 @@ extern const QEnumLookup %(c_name)s_lookup;
>  def build_params(arg_type, boxed, extra):
>      if not arg_type:
>          assert not boxed
> -        return extra
> +        return extra if extra else "void"
>      ret = ''
>      sep = ''
>      if boxed:
> @@ -1980,7 +1980,7 @@ def build_params(arg_type, boxed, extra):
>                                c_name(memb.name))
>      if extra:
>          ret += sep + extra
> -    return ret
> +    return ret if ret else "void"
>  
>  
>  #

Please use ' instead of " for local consistency.

Duplicating "if ret else 'void'" minimizes churn, but it's slightly
ugly.  I append my attempt to avoid it.  What do you think?


diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py
index 8b6708dbf1..01384c5360 100644
--- a/scripts/qapi/common.py
+++ b/scripts/qapi/common.py
@@ -1961,15 +1961,13 @@ extern const QEnumLookup %(c_name)s_lookup;
 
 
 def build_params(arg_type, boxed, extra):
-    if not arg_type:
-        assert not boxed
-        return extra
     ret = ''
     sep = ''
     if boxed:
+        assert arg_type
         ret += '%s arg' % arg_type.c_param_type()
         sep = ', '
-    else:
+    elif arg_type:
         assert not arg_type.variants
         for memb in arg_type.members:
             ret += sep
@@ -1980,7 +1978,7 @@ def build_params(arg_type, boxed, extra):
                               c_name(memb.name))
     if extra:
         ret += sep + extra
-    return ret
+    return ret if ret else 'void'
 
 
 #