[rr-]

Sphinx documents attributes with :ivar:, :var: and :cvar: fields, typed by :vartype:. ReST parsed them as plain text items, so they were missing from Docstring.attrs, and :vartype: was a text item too. Epydoc already reads @ivar as an attribute.

Short.

:ivar a: The a.
:vartype a: int

Before: DocstringMeta(kind=Kind.TEXT, key='ivar', name='a', description='The a.') and DocstringMeta(kind=Kind.TEXT, key='vartype', name='a', description='int').
After: DocstringParam(kind=Kind.ATTRIBUTE, key='ivar', arg_name='a', type_name='int', description='The a.').

:vartype x: types attributes the way :type x: types params, through _fields.assign_types, which takes a new vartypes table. Only attributes take from it, and an attribute of a name with no :vartype: still takes from :type:, so :attribute x: with :type x: keeps working. A :param x: and an :ivar x: of the same name each get their own type. A :vartype: that no attribute takes is an attribute of its own, as a lone :type: is a param.

An empty :type x: no longer gives x the type ''. Ignoring it completely would drop the name when nothing else mentions it, which the no-text-dropped invariant test catches, so a lone empty :type y: still makes a param y, now with no type.

Compose: an attribute keyed ivar, var or cvar is written back with that field name, and its type with :vartype: when it doesn't fit inline. Without this, :ivar a: would compose as :attribute a: and read back with another key. Attributes with any other key, such as the ones Google and Numpydoc give, still compose as :attribute: and :type:. Since Epydoc keys its attributes ivar, var and cvar too, converting Epydoc to ReST now writes :ivar a: instead of :attribute a:.

test_kinds.py::test_sub_kinds now expects :ivar to be an attribute.

Parity against origin/main: 926 of 29,149 docstrings differ, 18 from the case files and 908 generated, none from the stdlib.

• 4 case inputs differ in parse REST/parse AUTO and their composes: the three new rest/attribute_fields_* cases and convert/rest-params, whose :ivar z: is now an attribute. Its Google and Numpydoc output stays the same.
• The other 14 case and all 908 generated ones differ only in compose EPYDOC REST and compose AUTO REST (where auto picks Epydoc). There, @ivar, @var and @cvar now compose as :ivar:, :var: and :cvar: instead of :attribute:, and their types as :vartype: instead of :type:. With those names swapped back, every one matches main.

Bench (just bench): parse rest 93.0 ms on main vs 92.4 ms (0.99x), compose rest 1.00x, other workloads 0.99x to 1.00x.