[Qemu-devel] [PATCH v6 08/23] qapi: Drop unused error argument for list and implicit struct

[Eric Blake <eblake@redhat.com>]

No backend was setting an error when ending the visit of a list
or implicit struct.  Make the callers a bit easier to follow by
making this a part of the contract, and removing the errp
argument - callers can then unconditionally end an object as
part of cleanup without having to think about whether a second
error is dominated by a first, because there is no second error.

A later patch will then tackle the larger task of splitting
visit_end_struct(), which can indeed set an error.

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

---
v6: new patch, split from RFC on v5 7/46
---
 hw/ppc/spapr_drc.c           |  2 +-
 include/qapi/visitor-impl.h  |  4 ++--
 include/qapi/visitor.h       |  8 +++++---
 qapi/opts-visitor.c          |  2 +-
 qapi/qapi-dealloc-visitor.c  |  4 ++--
 qapi/qapi-visit-core.c       |  8 ++++----
 qapi/qmp-input-visitor.c     |  9 ++-------
 qapi/qmp-output-visitor.c    |  2 +-
 qapi/string-input-visitor.c  |  2 +-
 qapi/string-output-visitor.c |  2 +-
 scripts/qapi-visit.py        | 10 +++-------
 11 files changed, 23 insertions(+), 30 deletions(-)

diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index f34bc04..1846b4f 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -293,7 +293,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, void *opaque,
                 visit_type_uint8(v, (uint8_t *)&prop->data[i], NULL, NULL);

             }
-            visit_end_list(v, NULL);
+            visit_end_list(v);
             break;
         }
         default:
diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 2f4c89b..36984a7 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -35,14 +35,14 @@ struct Visitor
     void (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
                                   Error **errp);
     /* May be NULL */
-    void (*end_implicit_struct)(Visitor *v, Error **errp);
+    void (*end_implicit_struct)(Visitor *v);

     /* Must be set */
     void (*start_list)(Visitor *v, const char *name, Error **errp);
     /* Must be set */
     GenericList *(*next_list)(Visitor *v, GenericList **list, Error **errp);
     /* Must be set */
-    void (*end_list)(Visitor *v, Error **errp);
+    void (*end_list)(Visitor *v);

     /* Must be set, although the helpers input_type_enum() and
      * output_type_enum() can be used.  */
diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index 74159c6..b4ed469 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -77,9 +77,11 @@ void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
 /**
  * Complete an implicit struct visit started earlier.
  * Must be called after any successful use of visit_start_implicit_struct(),
- * even if intermediate processing was skipped due to errors.
+ * even if intermediate processing was skipped due to errors.  Unlike
+ * visit_end_struct(), there is no need for an error check; any errors
+ * such as extra input will be detected when ending the overall struct.
  */
-void visit_end_implicit_struct(Visitor *v, Error **errp);
+void visit_end_implicit_struct(Visitor *v);

 /**
  * Prepare to visit a list tied to an object key @name.
@@ -105,7 +107,7 @@ GenericList *visit_next_list(Visitor *v, GenericList **list, Error **errp);
  * even if intermediate processing was skipped due to errors, to allow
  * the backend to release any resources.
  */
-void visit_end_list(Visitor *v, Error **errp);
+void visit_end_list(Visitor *v);

 /**
  * Check if an optional member @name of an object needs visiting.
diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index 8104e42..37f172d 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -263,7 +263,7 @@ opts_next_list(Visitor *v, GenericList **list, Error **errp)


 static void
-opts_end_list(Visitor *v, Error **errp)
+opts_end_list(Visitor *v)
 {
     OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);

diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 5133d37..8246070 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -85,7 +85,7 @@ static void qapi_dealloc_start_implicit_struct(Visitor *v,
     qapi_dealloc_push(qov, obj);
 }

-static void qapi_dealloc_end_implicit_struct(Visitor *v, Error **errp)
+static void qapi_dealloc_end_implicit_struct(Visitor *v)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     void **obj = qapi_dealloc_pop(qov);
@@ -121,7 +121,7 @@ static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList **listp,
     return NULL;
 }

-static void qapi_dealloc_end_list(Visitor *v, Error **errp)
+static void qapi_dealloc_end_list(Visitor *v)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     void *obj = qapi_dealloc_pop(qov);
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index be1fcdd..477d73a 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -36,10 +36,10 @@ void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
     }
 }

-void visit_end_implicit_struct(Visitor *v, Error **errp)
+void visit_end_implicit_struct(Visitor *v)
 {
     if (v->end_implicit_struct) {
-        v->end_implicit_struct(v, errp);
+        v->end_implicit_struct(v);
     }
 }

@@ -53,9 +53,9 @@ GenericList *visit_next_list(Visitor *v, GenericList **list, Error **errp)
     return v->next_list(v, list, errp);
 }

-void visit_end_list(Visitor *v, Error **errp)
+void visit_end_list(Visitor *v)
 {
-    v->end_list(v, errp);
+    v->end_list(v);
 }

 bool visit_start_union(Visitor *v, bool data_present, Error **errp)
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index ba743db..9ff1e75 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -153,10 +153,6 @@ static void qmp_input_start_implicit_struct(Visitor *v, void **obj,
     }
 }

-static void qmp_input_end_implicit_struct(Visitor *v, Error **errp)
-{
-}
-
 static void qmp_input_start_list(Visitor *v, const char *name, Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
@@ -201,11 +197,11 @@ static GenericList *qmp_input_next_list(Visitor *v, GenericList **list,
     return entry;
 }

-static void qmp_input_end_list(Visitor *v, Error **errp)
+static void qmp_input_end_list(Visitor *v)
 {
     QmpInputVisitor *qiv = to_qiv(v);

-    qmp_input_pop(qiv, errp);
+    qmp_input_pop(qiv, &error_abort);
 }

 static void qmp_input_get_next_type(Visitor *v, QType *type, bool promote_int,
@@ -351,7 +347,6 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
     v->visitor.start_struct = qmp_input_start_struct;
     v->visitor.end_struct = qmp_input_end_struct;
     v->visitor.start_implicit_struct = qmp_input_start_implicit_struct;
-    v->visitor.end_implicit_struct = qmp_input_end_implicit_struct;
     v->visitor.start_list = qmp_input_start_list;
     v->visitor.next_list = qmp_input_next_list;
     v->visitor.end_list = qmp_input_end_list;
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index 4a28ce3..8035649 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -153,7 +153,7 @@ static GenericList *qmp_output_next_list(Visitor *v, GenericList **listp,
     return list ? list->next : NULL;
 }

-static void qmp_output_end_list(Visitor *v, Error **errp)
+static void qmp_output_end_list(Visitor *v)
 {
     QmpOutputVisitor *qov = to_qov(v);
     qmp_output_pop(qov);
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index 0a7ddee..5b2bc47 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -173,7 +173,7 @@ next_list(Visitor *v, GenericList **list, Error **errp)
 }

 static void
-end_list(Visitor *v, Error **errp)
+end_list(Visitor *v)
 {
     StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
     siv->head = true;
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index bcd72bb..54d4174 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -298,7 +298,7 @@ next_list(Visitor *v, GenericList **list, Error **errp)
 }

 static void
-end_list(Visitor *v, Error **errp)
+end_list(Visitor *v)
 {
     StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index ddfb769..8c964b5 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -62,7 +62,7 @@ static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error *
     visit_start_implicit_struct(v, (void **)obj, sizeof(%(c_type)s), &err);
     if (!err) {
         visit_type_%(c_type)s_fields(v, obj, errp);
-        visit_end_implicit_struct(v, &err);
+        visit_end_implicit_struct(v);
     }
     error_propagate(errp, err);
 }
@@ -161,9 +161,7 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error
         visit_type_%(c_elt_type)s(v, &native_i->value, NULL, &err);
     }

-    error_propagate(errp, err);
-    err = NULL;
-    visit_end_list(v, &err);
+    visit_end_list(v);
 out:
     error_propagate(errp, err);
 }
@@ -224,9 +222,7 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error
                    "%(name)s");
     }
 out_obj:
-    error_propagate(errp, err);
-    err = NULL;
-    visit_end_implicit_struct(v, &err);
+    visit_end_implicit_struct(v);
 out:
     error_propagate(errp, err);
 }
-- 
2.4.3