tools: ynl-gen: handle do ops with no input attrs

The code supports dumps with no input attributes currently
thru a combination of special-casing and luck.
Clean up the handling of ops with no inputs. Create empty
Structs, and skip printing of empty types.
This makes dos with no inputs work.
Tested-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Link: https://lore.kernel.org/r/20231006135032.3328523-1-kuba@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

tools/net/ynl/ynl-gen-c.py

@@ -1041,9 +1041,11 @@ class RenderInfo:
         if op_mode == 'notify':
             op_mode = 'do'
         for op_dir in ['request', 'reply']:
-            if op and op_dir in op[op_mode]:
-                self.struct[op_dir] = Struct(family, self.attr_set,
-                                             type_list=op[op_mode][op_dir]['attributes'])
+            if op:
+                type_list = []
+                if op_dir in op[op_mode]:
+                    type_list = op[op_mode][op_dir]['attributes']
+                self.struct[op_dir] = Struct(family, self.attr_set, type_list=type_list)
         if op_mode == 'event':
             self.struct['reply'] = Struct(family, self.attr_set, type_list=op['event']['attributes'])
 
@@ -1752,6 +1754,8 @@ def print_type_helpers(ri, direction, deref=False):
 
 
 def print_req_type_helpers(ri):
+    if len(ri.struct["request"].attr_list) == 0:
+        return
     print_alloc_wrapper(ri, "request")
     print_type_helpers(ri, "request")
 
@@ -1773,6 +1777,8 @@ def print_parse_prototype(ri, direction, terminate=True):
 
 
 def print_req_type(ri):
+    if len(ri.struct["request"].attr_list) == 0:
+        return
     print_type(ri, "request")
 
 
@@ -2515,9 +2521,8 @@ def main():
                 if 'dump' in op:
                     cw.p(f"/* {op.enum_name} - dump */")
                     ri = RenderInfo(cw, parsed, args.mode, op, 'dump')
-                    if 'request' in op['dump']:
-                        print_req_type(ri)
-                        print_req_type_helpers(ri)
+                    print_req_type(ri)
+                    print_req_type_helpers(ri)
                     if not ri.type_consistent:
                         print_rsp_type(ri)
                     print_wrapped_type(ri)