qapi: Use 'alternate' to replace anonymous union

Previous patches have led up to the point where I create the
new meta-type "'alternate':'Foo'".  See the previous patches
for documentation; I intentionally split as much work into
earlier patches to minimize the size of this patch, but a lot
of it is churn due to testsuite fallout after updating to the
new type.

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

3 files changed, 43 insertions, 32 deletions

diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index c9e0201d10..9c8d68cfb4 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -172,7 +172,7 @@ typedef enum %(name)s
 
 def generate_alternate_qtypes(expr):
 
-    name = expr['union']
+    name = expr['alternate']
     members = expr['data']
 
     ret = mcgen('''
@@ -182,7 +182,7 @@ const int %(name)s_qtypes[QTYPE_MAX] = {
 
     for key in members:
         qtype = find_alternate_member_qtype(members[key])
-        assert qtype, "Invalid anonymous union member"
+        assert qtype, "Invalid alternate member"
 
         ret += mcgen('''
     [ %(qtype)s ] = %(abbrev)s_KIND_%(enum)s,
@@ -197,9 +197,9 @@ const int %(name)s_qtypes[QTYPE_MAX] = {
     return ret
 
 
-def generate_union(expr):
+def generate_union(expr, meta):
 
-    name = expr['union']
+    name = expr[meta]
     typeinfo = expr['data']
 
     base = expr.get('base')
@@ -243,7 +243,7 @@ struct %(name)s
     ret += mcgen('''
 };
 ''')
-    if discriminator == {}:
+    if meta == 'alternate':
         ret += mcgen('''
 extern const int %(name)s_qtypes[];
 ''',
@@ -407,8 +407,12 @@ for expr in exprs:
             ret += generate_enum('%sKind' % expr['union'], expr['data'].keys())
             fdef.write(generate_enum_lookup('%sKind' % expr['union'],
                                             expr['data'].keys()))
-        if expr.get('discriminator') == {}:
-            fdef.write(generate_alternate_qtypes(expr))
+    elif expr.has_key('alternate'):
+        ret += generate_fwd_struct(expr['alternate'], expr['data']) + "\n"
+        ret += generate_enum('%sKind' % expr['alternate'], expr['data'].keys())
+        fdef.write(generate_enum_lookup('%sKind' % expr['alternate'],
+                                        expr['data'].keys()))
+        fdef.write(generate_alternate_qtypes(expr))
     else:
         continue
     fdecl.write(ret)
@@ -438,11 +442,17 @@ for expr in exprs:
         ret += generate_type_cleanup_decl(expr['type'])
         fdef.write(generate_type_cleanup(expr['type']) + "\n")
     elif expr.has_key('union'):
-        ret += generate_union(expr)
+        ret += generate_union(expr, 'union')
         ret += generate_type_cleanup_decl(expr['union'] + "List")
         fdef.write(generate_type_cleanup(expr['union'] + "List") + "\n")
         ret += generate_type_cleanup_decl(expr['union'])
         fdef.write(generate_type_cleanup(expr['union']) + "\n")
+    elif expr.has_key('alternate'):
+        ret += generate_union(expr, 'alternate')
+        ret += generate_type_cleanup_decl(expr['alternate'] + "List")
+        fdef.write(generate_type_cleanup(expr['alternate'] + "List") + "\n")
+        ret += generate_type_cleanup_decl(expr['alternate'])
+        fdef.write(generate_type_cleanup(expr['alternate']) + "\n")
     elif expr.has_key('enum'):
         ret += generate_type_cleanup_decl(expr['enum'] + "List")
         fdef.write(generate_type_cleanup(expr['enum'] + "List") + "\n")
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 6bd2b6bfab..9222671ff8 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -256,7 +256,7 @@ void visit_type_%(name)s(Visitor *m, %(name)s **obj, const char *name, Error **e
 ''',
     name=name)
 
-    # For anon union, always use the default enum type automatically generated
+    # For alternate, always use the default enum type automatically generated
     # as "'%sKind' % (name)"
     disc_type = '%sKind' % (name)
 
@@ -264,7 +264,7 @@ void visit_type_%(name)s(Visitor *m, %(name)s **obj, const char *name, Error **e
         assert (members[key] in builtin_types.keys()
             or find_struct(members[key])
             or find_union(members[key])
-            or find_enum(members[key])), "Invalid anonymous union member"
+            or find_enum(members[key])), "Invalid alternate member"
 
         enum_full_value = generate_enum_full_value(disc_type, key)
         ret += mcgen('''
@@ -300,10 +300,6 @@ def generate_visit_union(expr):
     base = expr.get('base')
     discriminator = expr.get('discriminator')
 
-    if discriminator == {}:
-        assert not base
-        return generate_visit_alternate(name, members)
-
     enum_define = discriminator_find_enum_define(expr)
     if enum_define:
         # Use the enum type as discriminator
@@ -568,6 +564,15 @@ for expr in exprs:
                                      expr['data'].keys())
         ret += generate_declaration(expr['union'], expr['data'])
         fdecl.write(ret)
+    elif expr.has_key('alternate'):
+        ret = generate_visit_alternate(expr['alternate'], expr['data'])
+        ret += generate_visit_list(expr['alternate'], expr['data'])
+        fdef.write(ret)
+
+        ret = generate_decl_enum('%sKind' % expr['alternate'],
+                                 expr['data'].keys())
+        ret += generate_declaration(expr['alternate'], expr['data'])
+        fdecl.write(ret)
     elif expr.has_key('enum'):
         ret = generate_visit_list(expr['enum'], expr['data'])
         ret += generate_visit_enum(expr['enum'], expr['data'])
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 0b88325abd..05c38c5b00 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -281,7 +281,6 @@ def check_union(expr, expr_info):
                                 "along with base" %name)
 
     # Two types of unions, determined by discriminator.
-    assert discriminator != {}
 
     # With no discriminator it is a simple union.
     if discriminator is None:
@@ -344,17 +343,14 @@ def check_union(expr, expr_info):
             values[c_key] = key
 
 def check_alternate(expr, expr_info):
-    name = expr['union']
-    base = expr.get('base')
-    discriminator = expr.get('discriminator')
+    name = expr['alternate']
     members = expr['data']
     values = { 'MAX': '(automatic)' }
     types_seen = {}
 
-    assert discriminator == {}
-    if base is not None:
+    if expr.get('base') is not None:
         raise QAPIExprError(expr_info,
-                            "Anonymous union '%s' must not have a base"
+                            "Alternate '%s' must not have a base"
                             % name)
 
     # Check every branch
@@ -363,23 +359,23 @@ def check_alternate(expr, expr_info):
         c_key = _generate_enum_string(key)
         if c_key in values:
             raise QAPIExprError(expr_info,
-                                "Anonymous union '%s' member '%s' clashes "
-                                "with '%s'" % (name, key, values[c_key]))
+                                "Alternate '%s' member '%s' clashes with '%s'"
+                                % (name, key, values[c_key]))
         values[c_key] = key
 
         # Ensure alternates have no type conflicts.
         if isinstance(value, list):
             raise QAPIExprError(expr_info,
-                                "Anonymous union '%s' member '%s' must "
+                                "Alternate '%s' member '%s' must "
                                 "not be array type" % (name, key))
         qtype = find_alternate_member_qtype(value)
         if not qtype:
             raise QAPIExprError(expr_info,
-                                "Anonymous union '%s' member '%s' has "
+                                "Alternate '%s' member '%s' has "
                                 "invalid type '%s'" % (name, key, value))
         if qtype in types_seen:
             raise QAPIExprError(expr_info,
-                                "Anonymous union '%s' member '%s' can't "
+                                "Alternate '%s' member '%s' can't "
                                 "be distinguished from member '%s'"
                                 % (name, key, types_seen[qtype]))
         types_seen[qtype] = key
@@ -412,10 +408,9 @@ def check_exprs(schema):
         if expr.has_key('enum'):
             check_enum(expr, info)
         elif expr.has_key('union'):
-            if expr.get('discriminator') == {}:
-                check_alternate(expr, info)
-            else:
-                check_union(expr, info)
+            check_union(expr, info)
+        elif expr.has_key('alternate'):
+            check_alternate(expr, info)
         elif expr.has_key('event'):
             check_event(expr, info)
 
@@ -447,6 +442,8 @@ def parse_schema(input_file):
             if expr.has_key('union'):
                 if not discriminator_find_enum_define(expr):
                     add_enum('%sKind' % expr['union'])
+            elif expr.has_key('alternate'):
+                add_enum('%sKind' % expr['alternate'])
 
         # Final pass - validate that exprs make sense
         check_exprs(schema)
@@ -557,8 +554,7 @@ def find_struct(name):
 
 def add_union(definition):
     global union_types
-    if definition.get('discriminator') != {}:
-        union_types.append(definition)
+    union_types.append(definition)
 
 def find_union(name):
     global union_types