Raise an error if an enum has no members. Such enums cannot be populated with a valid value, and therefore they can only be used as optional members. But QAPI leaves out optional members from the serialization protocol, and therefore the existence of the enum is completely pointless.
The same limitation is not extended to an enum whose members are all compiled out; these can still be useful as optional members. However they cannot implicitly block usage of parent structures because, by virtue of having only conditional members, they are "enums with conditional first item" and must therefore be optional. Signed-off-by: Paolo Bonzini <[email protected]> --- scripts/qapi/schema.py | 4 ++++ tests/qapi-schema/enum-empty.err | 2 ++ tests/qapi-schema/enum-empty.json | 2 ++ tests/qapi-schema/enum-empty.out | 0 tests/qapi-schema/meson.build | 1 + tests/qapi-schema/qapi-schema-test.json | 3 --- tests/qapi-schema/qapi-schema-test.out | 1 - tests/qapi-schema/union-empty-if.err | 2 ++ tests/qapi-schema/union-empty-if.json | 6 ++++++ tests/qapi-schema/union-empty-if.out | 0 tests/qapi-schema/union-empty.err | 4 ++-- 11 files changed, 19 insertions(+), 6 deletions(-) create mode 100644 tests/qapi-schema/enum-empty.err create mode 100644 tests/qapi-schema/enum-empty.json create mode 100644 tests/qapi-schema/enum-empty.out create mode 100644 tests/qapi-schema/union-empty-if.err create mode 100644 tests/qapi-schema/union-empty-if.json create mode 100644 tests/qapi-schema/union-empty-if.out diff --git a/scripts/qapi/schema.py b/scripts/qapi/schema.py index 71296b15de2..a5a11298817 100644 --- a/scripts/qapi/schema.py +++ b/scripts/qapi/schema.py @@ -428,6 +428,10 @@ def __init__( def check(self, schema: QAPISchema) -> None: super().check(schema) + if not self.members: + raise QAPISemError( + self.info, + "enum '%s' must have at least one value" % self.name) seen: Dict[str, QAPISchemaMember] = {} for m in self.members: m.check_clash(self.info, seen) diff --git a/tests/qapi-schema/enum-empty.err b/tests/qapi-schema/enum-empty.err new file mode 100644 index 00000000000..6070bf62cbd --- /dev/null +++ b/tests/qapi-schema/enum-empty.err @@ -0,0 +1,2 @@ +enum-empty.json: In enum 'TestEmpty': +enum-empty.json:2: enum 'TestEmpty' must have at least one value diff --git a/tests/qapi-schema/enum-empty.json b/tests/qapi-schema/enum-empty.json new file mode 100644 index 00000000000..3b3dfb2e3d8 --- /dev/null +++ b/tests/qapi-schema/enum-empty.json @@ -0,0 +1,2 @@ +# An enum must have at least one value +{ 'enum': 'TestEmpty', 'data': [] } diff --git a/tests/qapi-schema/enum-empty.out b/tests/qapi-schema/enum-empty.out new file mode 100644 index 00000000000..e69de29bb2d diff --git a/tests/qapi-schema/meson.build b/tests/qapi-schema/meson.build index 3b0c16a8b67..1058b7ecfae 100644 --- a/tests/qapi-schema/meson.build +++ b/tests/qapi-schema/meson.build @@ -196,6 +196,7 @@ schemas = [ 'union-clash-member.json', 'union-discriminator-bad-name.json', 'union-empty.json', + 'union-empty-if.json', 'union-inline-invalid-dict.json', 'union-int-branch.json', 'union-invalid-base.json', diff --git a/tests/qapi-schema/qapi-schema-test.json b/tests/qapi-schema/qapi-schema-test.json index 8ca977c49d2..195f1c4847b 100644 --- a/tests/qapi-schema/qapi-schema-test.json +++ b/tests/qapi-schema/qapi-schema-test.json @@ -23,9 +23,6 @@ 'data': { 'enum1': 'EnumOne', # Intentional forward reference '*enum2': 'EnumOne', 'enum3': 'EnumOne', '*enum4': 'EnumOne' } } -# An empty enum, although unusual, is currently acceptable -{ 'enum': 'MyEnum', 'data': [ ] } - # Likewise for an empty struct, including an empty base { 'struct': 'Empty1', 'data': { } } { 'struct': 'Empty2', 'base': 'Empty1', 'data': { } } diff --git a/tests/qapi-schema/qapi-schema-test.out b/tests/qapi-schema/qapi-schema-test.out index 4617eb4e98a..ddd8bf80d66 100644 --- a/tests/qapi-schema/qapi-schema-test.out +++ b/tests/qapi-schema/qapi-schema-test.out @@ -18,7 +18,6 @@ object NestedEnumsOne member enum2: EnumOne optional=True member enum3: EnumOne optional=False member enum4: EnumOne optional=True -enum MyEnum object Empty1 object Empty2 base Empty1 diff --git a/tests/qapi-schema/union-empty-if.err b/tests/qapi-schema/union-empty-if.err new file mode 100644 index 00000000000..2b8691ab2f5 --- /dev/null +++ b/tests/qapi-schema/union-empty-if.err @@ -0,0 +1,2 @@ +union-empty-if.json: In struct 'Base': +union-empty-if.json:5: enum type 'Empty' of member 'type' has a conditional first value and must be optional diff --git a/tests/qapi-schema/union-empty-if.json b/tests/qapi-schema/union-empty-if.json new file mode 100644 index 00000000000..36625dc4a89 --- /dev/null +++ b/tests/qapi-schema/union-empty-if.json @@ -0,0 +1,6 @@ +# union discriminator enum cannot have only conditional items +{ 'enum': 'Empty', + 'data': [ { 'name' : 'bar', 'if': { 'all': ['FOO'] } } ] } + +{ 'struct': 'Base', 'data': { 'type': 'Empty' } } +{ 'union': 'Union', 'base': 'Base', 'discriminator': 'type', 'data': { } } diff --git a/tests/qapi-schema/union-empty-if.out b/tests/qapi-schema/union-empty-if.out new file mode 100644 index 00000000000..e69de29bb2d diff --git a/tests/qapi-schema/union-empty.err b/tests/qapi-schema/union-empty.err index d4284399621..c07dcf32a5a 100644 --- a/tests/qapi-schema/union-empty.err +++ b/tests/qapi-schema/union-empty.err @@ -1,2 +1,2 @@ -union-empty.json: In union 'Union': -union-empty.json:4: union has no branches +union-empty.json: In enum 'Empty': +union-empty.json:2: enum 'Empty' must have at least one value -- 2.55.0
