qapi: Drop support for boxed alternate arguments

Commands and events can define their argument type inline (default) or
by referring to another type ('boxed': true, since commit c818408e44
"qapi: Implement boxed types for commands/events", v2.7.0).  The
unboxed inline definition is an (anonymous) struct type.  The boxed
type may be a struct, union, or alternate type.

The latter is problematic: docs/interop/qemu-spec.txt requires the
value of the 'data' key to be a json-object, but any non-degenerate
alternate type has at least one branch that isn't.

Fortunately, we haven't made use of alternates in this context outside
tests/.  Drop support for them.

QAPISchemaAlternateType.is_empty() is now unused.  Drop it, too.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20190913201349.24332-4-armbru@redhat.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/docs/devel/qapi-code-gen.txt b/docs/devel/qapi-code-gen.txt
index e8ec8ac1de..3d3931fb7a 100644
--- a/docs/devel/qapi-code-gen.txt
+++ b/docs/devel/qapi-code-gen.txt
@@ -612,9 +612,9 @@ the command.  Normally, 'data' is a dictionary for an anonymous type,
 or names a struct type (possibly empty, but not a union), and its
 members are passed as separate arguments to this function.  If the
 command definition includes a key 'boxed' with the boolean value true,
-then 'data' is instead the name of any non-empty complex type
-(struct, union, or alternate), and a pointer to that QAPI type is
-passed as a single argument.
+then 'data' is instead the name of any non-empty complex type (struct
+or union), and a pointer to that QAPI type is passed as a single
+argument.
 
 The generator also emits a marshalling function that extracts
 arguments for the user's function out of an input QDict, calls the
@@ -714,9 +714,9 @@ The generator emits a function to send the event.  Normally, 'data' is
 a dictionary for an anonymous type, or names a struct type (possibly
 empty, but not a union), and its members are passed as separate
 arguments to this function.  If the event definition includes a key
-'boxed' with the boolean value true, then 'data' is instead the name of
-any non-empty complex type (struct, union, or alternate), and a
-pointer to that QAPI type is passed as a single argument.
+'boxed' with the boolean value true, then 'data' is instead the name
+of any non-empty complex type (struct or union), and a pointer to that
+QAPI type is passed as a single argument.
 
 
 === Features ===