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>

qapi/block-core.json

@@ -1503,8 +1503,7 @@
 #
 # Since: 2.2
 ##
-{ 'union': 'Qcow2OverlapChecks',
-  'discriminator': {},
+{ 'alternate': 'Qcow2OverlapChecks',
   'data': { 'flags': 'Qcow2OverlapCheckFlags',
             'mode':  'Qcow2OverlapCheckMode' } }
 
@@ -1795,8 +1794,7 @@
 #
 # Since: 1.7
 ##
-{ 'union': 'BlockdevRef',
-  'discriminator': {},
+{ 'alternate': 'BlockdevRef',
   'data': { 'definition': 'BlockdevOptions',
             'reference': 'str' } }
 

scripts/qapi-types.py

@@ -172,7 +172,7 @@ def generate_enum(name, values):
 
 def generate_alternate_qtypes(expr):
 
-    name = expr['union']
+    name = expr['alternate']
     members = expr['data']
 
     ret = mcgen('''
@@ -182,7 +182,7 @@ def generate_alternate_qtypes(expr):
 
     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 @@ def generate_alternate_qtypes(expr):
     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 @@ def generate_union(expr):
     ret += mcgen('''
 };
 ''')
-    if discriminator == {}:
+    if meta == 'alternate':
         ret += mcgen('''
 extern const int %(name)s_qtypes[];
 ''',
@@ -407,8 +407,12 @@ def maybe_open(really, name, opt):
             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 @@ def maybe_open(really, name, opt):
         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")

scripts/qapi-visit.py

@@ -256,7 +256,7 @@ def generate_visit_alternate(name, members):
 ''',
     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 @@ def generate_visit_alternate(name, members):
         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 @@ def maybe_open(really, name, opt):
                                      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'])

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

tests/qapi-schema/alternate-array.err

@@ -1 +1 @@
-tests/qapi-schema/alternate-array.json:5: Anonymous union 'MyUnion' member 'two' must not be array type
+tests/qapi-schema/alternate-array.json:5: Alternate 'Alt' member 'two' must not be array type

tests/qapi-schema/alternate-array.json

@@ -1,8 +1,7 @@
-# we do not allow array branches in anonymous unions
+# we do not allow array branches in alternates
 # TODO: should we support this?
 { 'type': 'One',
   'data': { 'name': 'str' } }
-{ 'union': 'MyUnion',
-  'discriminator': {},
+{ 'alternate': 'Alt',
   'data': { 'one': 'One',
             'two': [ 'int' ] } }

tests/qapi-schema/alternate-base.err

@@ -1 +1 @@
-tests/qapi-schema/alternate-base.json:4: Anonymous union 'MyUnion' must not have a base
+tests/qapi-schema/alternate-base.json:4: Alternate 'Alt' must not have a base

tests/qapi-schema/alternate-base.json

@@ -1,7 +1,6 @@
-# we reject anonymous union with base type
+# we reject alternate with base type
 { 'type': 'Base',
   'data': { 'string': 'str' } }
-{ 'union': 'MyUnion',
+{ 'alternate': 'Alt',
   'base': 'Base',
-  'discriminator': {},
   'data': { 'number': 'int' } }

tests/qapi-schema/alternate-clash.err

@@ -1 +1 @@
-tests/qapi-schema/alternate-clash.json:2: Anonymous union 'Union1' member 'ONE' clashes with 'one'
+tests/qapi-schema/alternate-clash.json:2: Alternate 'Alt1' member 'ONE' clashes with 'one'

tests/qapi-schema/alternate-clash.json

@@ -1,4 +1,3 @@
-# we detect C enum collisions in an anonymous union
-{ 'union': 'Union1',
-  'discriminator': {},
+# we detect C enum collisions in an alternate
+{ 'alternate': 'Alt1',
   'data': { 'one': 'str', 'ONE': 'int' } }

tests/qapi-schema/alternate-conflict-dict.err

@@ -1 +1 @@
-tests/qapi-schema/alternate-conflict-dict.json:6: Anonymous union 'MyUnion' member 'two' can't be distinguished from member 'one'
+tests/qapi-schema/alternate-conflict-dict.json:6: Alternate 'Alt' member 'two' can't be distinguished from member 'one'

tests/qapi-schema/alternate-conflict-dict.json

@@ -1,9 +1,8 @@
-# we reject anonymous unions with multiple object branches
+# we reject alternates with multiple object branches
 { 'type': 'One',
   'data': { 'name': 'str' } }
 { 'type': 'Two',
   'data': { 'value': 'int' } }
-{ 'union': 'MyUnion',
-  'discriminator': {},
+{ 'alternate': 'Alt',
   'data': { 'one': 'One',
             'two': 'Two' } }

tests/qapi-schema/alternate-conflict-string.err

@@ -1 +1 @@
-tests/qapi-schema/alternate-conflict-string.json:4: Anonymous union 'MyUnion' member 'two' can't be distinguished from member 'one'
+tests/qapi-schema/alternate-conflict-string.json:4: Alternate 'Alt' member 'two' can't be distinguished from member 'one'

tests/qapi-schema/alternate-conflict-string.json

@@ -1,7 +1,6 @@
-# we reject anonymous unions with multiple string-like branches
+# we reject alternates with multiple string-like branches
 { 'enum': 'Enum',
   'data': [ 'hello', 'world' ] }
-{ 'union': 'MyUnion',
-  'discriminator': {},
+{ 'alternate': 'Alt',
   'data': { 'one': 'str',
             'two': 'Enum' } }

tests/qapi-schema/alternate-good.json

@@ -1,10 +1,9 @@
-# Working example of anonymous union
+# Working example of alternate
 { 'type': 'Data',
   'data': { '*number': 'int', '*name': 'str' } }
 { 'enum': 'Enum',
   'data': [ 'hello', 'world' ] }
-{ 'union': 'MyUnion',
-  'discriminator': {},
+{ 'alternate': 'Alt',
   'data': { 'value': 'int',
             'string': 'Enum',
             'struct': 'Data' } }

tests/qapi-schema/alternate-good.out

@@ -1,6 +1,6 @@
 [OrderedDict([('type', 'Data'), ('data', OrderedDict([('*number', 'int'), ('*name', 'str')]))]),
  OrderedDict([('enum', 'Enum'), ('data', ['hello', 'world'])]),
- OrderedDict([('union', 'MyUnion'), ('discriminator', OrderedDict()), ('data', OrderedDict([('value', 'int'), ('string', 'Enum'), ('struct', 'Data')]))])]
+ OrderedDict([('alternate', 'Alt'), ('data', OrderedDict([('value', 'int'), ('string', 'Enum'), ('struct', 'Data')]))])]
 [{'enum_name': 'Enum', 'enum_values': ['hello', 'world']},
- {'enum_name': 'MyUnionKind', 'enum_values': None}]
+ {'enum_name': 'AltKind', 'enum_values': None}]
 [OrderedDict([('type', 'Data'), ('data', OrderedDict([('*number', 'int'), ('*name', 'str')]))])]

tests/qapi-schema/alternate-nested.err

@@ -1 +1 @@
-tests/qapi-schema/alternate-nested.json:5: Anonymous union 'Union2' member 'nested' has invalid type 'Union1'
+tests/qapi-schema/alternate-nested.json:4: Alternate 'Alt2' member 'nested' has invalid type 'Alt1'

tests/qapi-schema/alternate-nested.json

@@ -1,7 +1,5 @@
-# we reject a nested anonymous union branch
-{ 'union': 'Union1',
-  'discriminator': {},
+# we reject a nested alternate branch
+{ 'alternate': 'Alt1',
   'data': { 'name': 'str', 'value': 'int' } }
-{ 'union': 'Union2',
-  'discriminator': {},
-  'data': { 'nested': 'Union1' } }
+{ 'alternate': 'Alt2',
+  'data': { 'nested': 'Alt1' } }

tests/qapi-schema/alternate-unknown.err

@@ -1 +1 @@
-tests/qapi-schema/alternate-unknown.json:2: Anonymous union 'Union' member 'unknown' has invalid type 'MissingType'
+tests/qapi-schema/alternate-unknown.json:2: Alternate 'Alt' member 'unknown' has invalid type 'MissingType'

tests/qapi-schema/alternate-unknown.json

@@ -1,4 +1,3 @@
-# we reject an anonymous union with unknown type in branch
-{ 'union': 'Union',
-  'discriminator': {},
+# we reject an alternate with unknown type in branch
+{ 'alternate': 'Alt',
   'data': { 'unknown': 'MissingType' } }

tests/qapi-schema/flat-union-bad-discriminator.err

@@ -1 +1 @@
-tests/qapi-schema/flat-union-bad-discriminator.json:10: Flat union 'TestUnion' discriminator must be a string
+tests/qapi-schema/flat-union-bad-discriminator.json:11: Flat union 'TestUnion' discriminator must be a string

tests/qapi-schema/flat-union-bad-discriminator.json

@@ -1,4 +1,5 @@
 # we require the discriminator to be a string naming a base-type member
+# this tests the old syntax for anonymous unions before we added alternates
 { 'enum': 'TestEnum',
   'data': [ 'value1', 'value2' ] }
 { 'type': 'TestBase',
@@ -9,6 +10,6 @@
   'data': { 'integer': 'int' } }
 { 'union': 'TestUnion',
   'base': 'TestBase',
-  'discriminator': [],
+  'discriminator': {},
   'data': { 'kind1': 'TestTypeA',
             'kind2': 'TestTypeB' } }

tests/qapi-schema/qapi-schema-test.json

@@ -53,8 +53,7 @@
   'discriminator': 'enum1',
   'data': { 'value1' : 'UserDefC', 'value2' : 'UserDefB', 'value3' : 'UserDefA' } }
 
-{ 'union': 'UserDefAlternate',
-  'discriminator': {},
+{ 'alternate': 'UserDefAlternate',
   'data': { 'uda': 'UserDefA', 's': 'str', 'i': 'int' } }
 
 # for testing native lists

tests/qapi-schema/qapi-schema-test.out

@@ -10,7 +10,7 @@
  OrderedDict([('type', 'UserDefUnionBase'), ('data', OrderedDict([('string', 'str'), ('enum1', 'EnumOne')]))]),
  OrderedDict([('union', 'UserDefFlatUnion'), ('base', 'UserDefUnionBase'), ('discriminator', 'enum1'), ('data', OrderedDict([('value1', 'UserDefA'), ('value2', 'UserDefB'), ('value3', 'UserDefB')]))]),
  OrderedDict([('union', 'UserDefFlatUnion2'), ('base', 'UserDefUnionBase'), ('discriminator', 'enum1'), ('data', OrderedDict([('value1', 'UserDefC'), ('value2', 'UserDefB'), ('value3', 'UserDefA')]))]),
- OrderedDict([('union', 'UserDefAlternate'), ('discriminator', OrderedDict()), ('data', OrderedDict([('uda', 'UserDefA'), ('s', 'str'), ('i', 'int')]))]),
+ OrderedDict([('alternate', 'UserDefAlternate'), ('data', OrderedDict([('uda', 'UserDefA'), ('s', 'str'), ('i', 'int')]))]),
  OrderedDict([('union', 'UserDefNativeListUnion'), ('data', OrderedDict([('integer', ['int']), ('s8', ['int8']), ('s16', ['int16']), ('s32', ['int32']), ('s64', ['int64']), ('u8', ['uint8']), ('u16', ['uint16']), ('u32', ['uint32']), ('u64', ['uint64']), ('number', ['number']), ('boolean', ['bool']), ('string', ['str']), ('sizes', ['size'])]))]),
  OrderedDict([('command', 'user_def_cmd'), ('data', OrderedDict())]),
  OrderedDict([('command', 'user_def_cmd1'), ('data', OrderedDict([('ud1a', 'UserDefOne')]))]),