From: Markus Armbruster Date: Fri, 13 Sep 2019 20:13:43 +0000 (+0200) Subject: qapi: Permit omitting all flat union branches X-Git-Tag: v4.2.0-rc0~83^2~25 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0ced9531f17c1c28fa4f29b352729c7f40c2ae30;p=thirdparty%2Fqemu.git qapi: Permit omitting all flat union branches Absent flat union branches default to the empty struct (since commit 800877bb16 "qapi: allow empty branches in flat unions"). But an attempt to omit all of them is rejected with "Union 'FOO' has no branches". Harmless oddity, but it's easy to avoid, so do that. Signed-off-by: Markus Armbruster Reviewed-by: Eric Blake Message-Id: <20190913201349.24332-11-armbru@redhat.com> [Commit message typo fixed] --- diff --git a/docs/devel/qapi-code-gen.txt b/docs/devel/qapi-code-gen.txt index 4ce67752a75..ec2d3744836 100644 --- a/docs/devel/qapi-code-gen.txt +++ b/docs/devel/qapi-code-gen.txt @@ -436,8 +436,7 @@ Union types are used to let the user choose between several different variants for an object. There are two flavors: simple (no discriminator or base), and flat (both discriminator and base). A union type is defined using a data dictionary as explained in the following -paragraphs. The data dictionary for either type of union must not -be empty. +paragraphs. Unions must have at least one branch. A simple union type defines a mapping from automatic discriminator values to data types like in this example: diff --git a/scripts/qapi/common.py b/scripts/qapi/common.py index 99db18f3d6c..3393a049cc7 100644 --- a/scripts/qapi/common.py +++ b/scripts/qapi/common.py @@ -852,7 +852,7 @@ def check_union(expr, info): # With no discriminator it is a simple union. if discriminator is None: - enum_define = None + enum_values = members.keys() allow_metas = ['built-in', 'union', 'alternate', 'struct', 'enum'] if base is not None: raise QAPISemError(info, "Simple union '%s' must not have a base" % @@ -885,16 +885,17 @@ def check_union(expr, info): 'must not be conditional' % (base, discriminator, name)) enum_define = enum_types.get(discriminator_value['type']) - allow_metas = ['struct'] # Do not allow string discriminator if not enum_define: raise QAPISemError(info, "Discriminator '%s' must be of enumeration " "type" % discriminator) + enum_values = enum_get_names(enum_define) + allow_metas = ['struct'] + + if (len(enum_values) == 0): + raise QAPISemError(info, "Union '%s' has no branches" % name) - # Check every branch; don't allow an empty union - if len(members) == 0: - raise QAPISemError(info, "Union '%s' cannot have empty 'data'" % name) for (key, value) in members.items(): check_name(info, "Member of union '%s'" % name, key) @@ -907,8 +908,8 @@ def check_union(expr, info): # If the discriminator names an enum type, then all members # of 'data' must also be members of the enum type. - if enum_define: - if key not in enum_get_names(enum_define): + if discriminator is not None: + if key not in enum_values: raise QAPISemError(info, "Discriminator value '%s' is not found in " "enum '%s'" @@ -1578,7 +1579,6 @@ class QAPISchemaObjectTypeVariants(object): assert bool(tag_member) != bool(tag_name) assert (isinstance(tag_name, str) or isinstance(tag_member, QAPISchemaObjectTypeMember)) - assert len(variants) > 0 for v in variants: assert isinstance(v, QAPISchemaObjectTypeVariant) self._tag_name = tag_name diff --git a/tests/qapi-schema/flat-union-empty.err b/tests/qapi-schema/flat-union-empty.err index 15754f54eb9..fedbc0d1cfe 100644 --- a/tests/qapi-schema/flat-union-empty.err +++ b/tests/qapi-schema/flat-union-empty.err @@ -1 +1 @@ -tests/qapi-schema/flat-union-empty.json:4: Union 'Union' cannot have empty 'data' +tests/qapi-schema/flat-union-empty.json:4: Union 'Union' has no branches diff --git a/tests/qapi-schema/flat-union-empty.json b/tests/qapi-schema/flat-union-empty.json index 77f1d9abfb8..83e1cc7b96b 100644 --- a/tests/qapi-schema/flat-union-empty.json +++ b/tests/qapi-schema/flat-union-empty.json @@ -1,4 +1,4 @@ -# flat unions cannot be empty +# flat union discriminator cannot be empty { 'enum': 'Empty', 'data': [ ] } { 'struct': 'Base', 'data': { 'type': 'Empty' } } { 'union': 'Union', 'base': 'Base', 'discriminator': 'type', 'data': { } } diff --git a/tests/qapi-schema/qapi-schema-test.json b/tests/qapi-schema/qapi-schema-test.json index 8b0d47c4ab4..75c42eb0e3e 100644 --- a/tests/qapi-schema/qapi-schema-test.json +++ b/tests/qapi-schema/qapi-schema-test.json @@ -25,6 +25,11 @@ { 'struct': 'Empty1', 'data': { } } { 'struct': 'Empty2', 'base': 'Empty1', 'data': { } } +# Likewise for an empty flat union +{ 'union': 'Union', + 'base': { 'type': 'EnumOne' }, 'discriminator': 'type', + 'data': { } } + { 'command': 'user_def_cmd0', 'data': 'Empty2', 'returns': 'Empty2' } # for testing override of default naming heuristic diff --git a/tests/qapi-schema/qapi-schema-test.out b/tests/qapi-schema/qapi-schema-test.out index bea7976bbbb..98031da96f0 100644 --- a/tests/qapi-schema/qapi-schema-test.out +++ b/tests/qapi-schema/qapi-schema-test.out @@ -23,6 +23,15 @@ enum MyEnum object Empty1 object Empty2 base Empty1 +object q_obj_Union-base + member type: EnumOne optional=False +object Union + base q_obj_Union-base + tag type + case value1: q_empty + case value2: q_empty + case value3: q_empty + case value4: q_empty command user_def_cmd0 Empty2 -> Empty2 gen=True success_response=True boxed=False oob=False preconfig=False enum QEnumTwo diff --git a/tests/qapi-schema/union-empty.err b/tests/qapi-schema/union-empty.err index 12c20221bdf..d4241a38a2c 100644 --- a/tests/qapi-schema/union-empty.err +++ b/tests/qapi-schema/union-empty.err @@ -1 +1 @@ -tests/qapi-schema/union-empty.json:2: Union 'Union' cannot have empty 'data' +tests/qapi-schema/union-empty.json:2: Union 'Union' has no branches diff --git a/tests/qapi-schema/union-empty.json b/tests/qapi-schema/union-empty.json index 1f0b13ca21a..df3e5e639a5 100644 --- a/tests/qapi-schema/union-empty.json +++ b/tests/qapi-schema/union-empty.json @@ -1,2 +1,2 @@ -# unions cannot be empty +# simple unions cannot be empty { 'union': 'Union', 'data': { } }