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>

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')]))]),