[Qemu-devel] [PATCH v10 07/25] qapi-visit: Split off visit_type_FOO_fields forward decl

[Eric Blake <eblake@redhat.com>]

We generate a static visit_type_FOO_fields() for every type
FOO.  However, sometimes we need a forward declaration. Split
the code to generate the forward declaration out of
gen_visit_implicit_struct() into a new gen_visit_fields_decl(),
and also prepare for a forward declaration to be emitted
during gen_visit_struct(), so that a future patch can switch
from using visit_type_FOO_implicit() to the simpler
visit_type_FOO_fields() as part of unboxing the base class
of a struct.

No change to generated code.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v10: new patch, split from 5/17
---
 scripts/qapi-visit.py | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index e878018..7204ed0 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -15,7 +15,12 @@
 from qapi import *
 import re

+# visit_type_FOO_implicit() is emitted as needed; track if it has already
+# been output. No forward declaration is needed.
 implicit_structs_seen = set()
+
+# visit_type_FOO_fields() is always emitted; track if a forward declaration
+# or implementation has already been output.
 struct_fields_seen = set()


@@ -29,19 +34,24 @@ void visit_type_%(c_name)s(Visitor *v, %(c_type)sobj, const char *name, Error **
                  c_name=c_name(name), c_type=c_type)


+def gen_visit_fields_decl(typ):
+    ret = ''
+    if typ.name not in struct_fields_seen:
+        ret += mcgen('''
+
+static void visit_type_%(c_type)s_fields(Visitor *v, %(c_type)s **obj, Error **errp);
+''',
+                     c_type=typ.c_name())
+        struct_fields_seen.add(typ.name)
+    return ret
+
+
 def gen_visit_implicit_struct(typ):
     if typ in implicit_structs_seen:
         return ''
     implicit_structs_seen.add(typ)

-    ret = ''
-    if typ.name not in struct_fields_seen:
-        # Need a forward declaration
-        ret += mcgen('''
-
-static void visit_type_%(c_type)s_fields(Visitor *v, %(c_type)s **obj, Error **errp);
-''',
-                     c_type=typ.c_name())
+    ret = gen_visit_fields_decl(typ)

     ret += mcgen('''

@@ -62,13 +72,12 @@ static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error *


 def gen_visit_struct_fields(name, base, members):
-    struct_fields_seen.add(name)
-
     ret = ''

     if base:
         ret += gen_visit_implicit_struct(base)

+    struct_fields_seen.add(name)
     ret += mcgen('''

 static void visit_type_%(c_name)s_fields(Visitor *v, %(c_name)s **obj, Error **errp)
@@ -100,7 +109,11 @@ out:


 def gen_visit_struct(name, base, members):
-    ret = gen_visit_struct_fields(name, base, members)
+    ret = ''
+    if base:
+        ret += gen_visit_fields_decl(base)
+
+    ret += gen_visit_struct_fields(name, base, members)

     # FIXME: if *obj is NULL on entry, and visit_start_struct() assigns to
     # *obj, but then visit_type_FOO_fields() fails, we should clean up *obj
-- 
2.4.3