Re: [Qemu-devel] [PATCH v10 12/25] qapi-visit: Kill unused visit_end_union()

[Markus Armbruster]

Eric Blake  writes:

> The generated code can call visit_end_union() without having called
> visit_start_union().  Example:
>
> if (!*obj) {
> goto out_obj;
> }
> visit_type_CpuInfoBase_fields(v, (CpuInfoBase **)obj, );
> if (err) {
> goto out_obj; // if we go from here...
> }
> if (!visit_start_union(v, !!(*obj)->u.data, ) || err) {
> goto out_obj;
> }
> switch ((*obj)->arch) {
> [...]
> }
> out_obj:
> // ... then *obj is true, and ...
> error_propagate(errp, err);
> err = NULL;
> if (*obj) {
> // we end up here
> visit_end_union(v, !!(*obj)->u.data, );
> }
> error_propagate(errp, err);
>
> Harmless only because no visitor implements end_union().  Clean it up
> anyway, by deleting the function as useless.

This creates an asymmetry between this and the other start_*()s. but
it's only temporary: start_union() will go away in "qapi: Rework
deallocation of partial struct" (not in this series).  Okay.

> Messed up since we have visit_end_union (commit cee2ded).
>
> Signed-off-by: Markus Armbruster 
> Message-Id: <1453902888-20457-3-git-send-email-arm...@redhat.com>
> [expand scope of patch to delete rather than repair]
> Signed-off-by: Eric Blake 
>
> ---
> v10: new patch; take Markus' commit message as a starting point (hence
> his S-o-b), but rewrite the patch and claim ownership

Patch looks good.

[Qemu-devel] [PATCH v10 12/25] qapi-visit: Kill unused visit_end_union()

[Eric Blake]

The generated code can call visit_end_union() without having called
visit_start_union().  Example:

if (!*obj) {
goto out_obj;
}
visit_type_CpuInfoBase_fields(v, (CpuInfoBase **)obj, );
if (err) {
goto out_obj; // if we go from here...
}
if (!visit_start_union(v, !!(*obj)->u.data, ) || err) {
goto out_obj;
}
switch ((*obj)->arch) {
[...]
}
out_obj:
// ... then *obj is true, and ...
error_propagate(errp, err);
err = NULL;
if (*obj) {
// we end up here
visit_end_union(v, !!(*obj)->u.data, );
}
error_propagate(errp, err);

Harmless only because no visitor implements end_union().  Clean it up
anyway, by deleting the function as useless.

Messed up since we have visit_end_union (commit cee2ded).

Signed-off-by: Markus Armbruster 
Message-Id: <1453902888-20457-3-git-send-email-arm...@redhat.com>
[expand scope of patch to delete rather than repair]
Signed-off-by: Eric Blake 

---
v10: new patch; take Markus' commit message as a starting point (hence
his S-o-b), but rewrite the patch and claim ownership
---
 include/qapi/visitor.h  | 1 -
 include/qapi/visitor-impl.h | 1 -
 scripts/qapi-visit.py   | 5 -
 qapi/qapi-visit-core.c  | 8 +---
 4 files changed, 1 insertion(+), 14 deletions(-)

diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index a14a16d..83ac3ad 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -70,6 +70,5 @@ void visit_type_str(Visitor *v, char **obj, const char *name, 
Error **errp);
 void visit_type_number(Visitor *v, double *obj, const char *name, Error 
**errp);
 void visit_type_any(Visitor *v, QObject **obj, const char *name, Error **errp);
 bool visit_start_union(Visitor *v, bool data_present, Error **errp);
-void visit_end_union(Visitor *v, bool data_present, Error **errp);

 #endif
diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 44a21b7..f314894 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -58,7 +58,6 @@ struct Visitor
 /* visit_type_size() falls back to (*type_uint64)() if type_size is unset 
*/
 void (*type_size)(Visitor *v, uint64_t *obj, const char *name, Error 
**errp);
 bool (*start_union)(Visitor *v, bool data_present, Error **errp);
-void (*end_union)(Visitor *v, bool data_present, Error **errp);
 };

 void input_type_enum(Visitor *v, int *obj, const char * const strings[],
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index ec16e36..f98bb5f 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -320,11 +320,6 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, 
const char *name, Error
 out_obj:
 error_propagate(errp, err);
 err = NULL;
-if (*obj) {
-visit_end_union(v, !!(*obj)->u.data, );
-}
-error_propagate(errp, err);
-err = NULL;
 visit_end_struct(v, );
 out:
 error_propagate(errp, err);
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 6d63e40..f96d82f 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -1,6 +1,7 @@
 /*
  * Core Definitions for QAPI Visitor Classes
  *
+ * Copyright (C) 2012-2016 Red Hat, Inc.
  * Copyright IBM, Corp. 2011
  *
  * Authors:
@@ -66,13 +67,6 @@ bool visit_start_union(Visitor *v, bool data_present, Error 
**errp)
 return true;
 }

-void visit_end_union(Visitor *v, bool data_present, Error **errp)
-{
-if (v->end_union) {
-v->end_union(v, data_present, errp);
-}
-}
-
 bool visit_optional(Visitor *v, bool *present, const char *name)
 {
 if (v->optional) {
-- 
2.5.0