Repository: python-attrs/attrs (python)

Issue:
Suggestion: differentiate in cmp between (== , !=) and (>,>=, <, <=).
Thanks for a fantastic library!

One thing that surprised me at first was that I could not write an effective `__gt__()`-function for my attr-class. I found the `cmp`-init-parameter later (in the code), but I still wonder if it wouldn't be a good idea if I could have the option of keeping the tuple-based `__eq__` and `__ne__`-implementations, but override size-comparisons (maybe based on a single `__lt__`-function?).

Pull request description:
Split cmp into eq and order
Fixes #170

Whoa, this is a doozy. People have been asking for this for a long time and I really wanted it too. So here it is, with a lot more changes that you'd expect.

Since this one is rather radical, I think we'll give it at least 18 months of deprecation period. I also think that I'll add a `sys.version_info`-style version number so people can easily write warnings-free code that won't break.

This is a very important stepping stone towards `detect_own` (which implies `@attr.auto`/`import attrs`) and pluggable method factories. In auto/import attrs, `order` will become False by default.

Patch:
diff --git a/README.rst b/README.rst
index e0a5769..565cae4 100644
--- a/README.rst
+++ b/README.rst
@@ -72,7 +72,7 @@ After *declaring* your attributes ``attrs`` gives you:
 
 - a concise and explicit overview of the class's attributes,
 - a nice human-readable ``__repr__``,
-- a complete set of comparison methods,
+- a complete set of comparison methods (equality and ordering),
 - an initializer,
 - and much more,
 
diff --git a/changelog.d/574.deprecation.rst b/changelog.d/574.deprecation.rst
new file mode 100644
index 0000000..130fe4d
--- /dev/null
+++ b/changelog.d/574.deprecation.rst
@@ -0,0 +1,11 @@
+The ``cmp`` argument to ``attr.s()`` and ``attr.ib()`` is now deprecated.
+
+Please use ``eq`` to add equality methods (``__eq__`` and ``__ne__``) and ``order`` to add ordering methods (``__lt__``, ``__le__``, ``__gt__``, and ``__ge__``) instead – just like with `dataclasses <https://docs.python.org/3/library/dataclasses.html>`_.
+
+Both are effectively ``True`` by default but it's enough to set ``eq=False`` to disable both at once.
+Passing ``eq=False, order=True`` explicitly will raise a ``ValueError`` though.
+
+Since this is arguably a deeper backward-compatibility break, it will have an extended deprecation period until 2021-06-01.
+After that day, the ``cmp`` argument will be removed.
+
+``attr.Attribute`` also isn't orderable anymore.
diff --git a/docs/api.rst b/docs/api.rst
index 76deae3..f68aaa0 100644
--- a/docs/api.rst
+++ b/docs/api.rst
@@ -16,7 +16,7 @@ What follows is the API explanation, if you'd like a more hands-on introduction,
 Core
 ----
 
-.. autofunction:: attr.s(these=None, repr_ns=None, repr=True, cmp=True, hash=None, init=True, slots=False, frozen=False, weakref_slot=True, str=False, auto_attribs=False, kw_only=False, cache_hash=False, auto_exc=False)
+.. autofunction:: attr.s(these=None, repr_ns=None, repr=True, cmp=None, hash=None, init=True, slots=False, frozen=False, weakref_slot=True, str=False, auto_attribs=False, kw_only=False, cache_hash=False, auto_exc=False, eq=None, order=None)
 
    .. note::
 
@@ -102,7 +102,7 @@ Core
       ... class C(object):
       ...     x = attr.ib()
       >>> attr.fields(C).x
-      Attribute(name='x', default=NOTHING, validator=None, repr=True, cmp=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False)
+      Attribute(name='x', default=NOTHING, validator=None, repr=True, eq=True, order=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False)
 
 
 .. autofunction:: attr.make_class
@@ -174,9 +174,9 @@ Helpers
       ...     x = attr.ib()
       ...     y = attr.ib()
       >>> attr.fields(C)
-      (Attribute(name='x', default=NOTHING, validator=None, repr=True, cmp=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False), Attribute(name='y', default=NOTHING, validator=None, repr=True, cmp=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False))
+      (Attribute(name='x', default=NOTHING, validator=None, repr=True, eq=True, order=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False), Attribute(name='y', default=NOTHING, validator=None, repr=True, eq=True, order=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False))
       >>> attr.fields(C)[1]
-      Attribute(name='y', default=NOTHING, validator=None, repr=True, cmp=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False)
+      Attribute(name='y', default=NOTHING, validator=None, repr=True, eq=True, order=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False)
       >>> attr.fields(C).y is attr.fields(C)[1]
       True
 
@@ -191,9 +191,9 @@ Helpers
       ...     x = attr.ib()
       ...     y = attr.ib()
       >>> attr.fields_dict(C)
-      {'x': Attribute(name='x', default=NOTHING, validator=None, repr=True, cmp=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False), 'y': Attribute(name='y', default=NOTHING, validator=None, repr=True, cmp=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False)}
+      {'x': Attribute(name='x', default=NOTHING, validator=None, repr=True, eq=True, order=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False), 'y': Attribute(name='y', default=NOTHING, validator=None, repr=True, eq=True, order=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False)}
       >>> attr.fields_dict(C)['y']
-      Attribute(name='y', default=NOTHING, validator=None, repr=True, cmp=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False)
+      Attribute(name='y', default=NOTHING, validator=None, repr=True, eq=True, order=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False)
       >>> attr.fields_dict(C)['y'] is attr.fields(C).y
       True
 
@@ -288,7 +288,7 @@ See :func:`asdict` for examples.
       >>> attr.validate(i)
       Traceback (most recent call last):
          ...
-      TypeError: ("'x' must be <type 'int'> (got '1' that is a <type 'str'>).", Attribute(name='x', default=NOTHING, validator=<instance_of validator for type <type 'int'>>, repr=True, cmp=True, hash=None, init=True, type=None, kw_only=False), <type 'int'>, '1')
+      TypeError: ("'x' must be <class 'int'> (got '1' that is a <class 'str'>).", ...)
 
 
 Validators can be globally disabled if you want to run them only in development and tests but not in production because you fear their performance impact:
diff --git a/docs/examples.rst b/docs/examples.rst
index c47099c..ae40777 100644
--- a/docs/examples.rst
+++ b/docs/examples.rst
@@ -534,8 +534,6 @@ The generated ``__init__`` method will have an attribute called ``__annotations_
    However it's useful for writing your own validators or serialization frameworks.
 
 
-.. _slots:
-
 Slots
 -----
 
diff --git a/docs/extending.rst b/docs/extending.rst
index dcaebee..4ee201e 100644
--- a/docs/extending.rst
+++ b/docs/extending.rst
@@ -16,7 +16,7 @@ So it is fairly simple to build your own decorators on top of ``attrs``:
    ... @attr.s
    ... class C(object):
    ...     a = attr.ib()
-   (Attribute(name='a', default=NOTHING, validator=None, repr=True, cmp=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False),)
+   (Attribute(name='a', default=NOTHING, validator=None, repr=True, eq=True, order=True, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False),)
 
 
 .. warning::
@@ -99,10 +99,18 @@ Here are some tips for effective use of metadata:
 
     >>> MY_TYPE_METADATA = '__my_type_metadata'
     >>>
-    >>> def typed(cls, default=attr.NOTHING, validator=None, repr=True, cmp=True, hash=None, init=True, metadata={}, type=None, converter=None):
+    >>> def typed(
+    ...     cls, default=attr.NOTHING, validator=None, repr=True,
+    ...     eq=True, order=None, hash=None, init=True, metadata={},
+    ...     type=None, converter=None
+    ... ):
     ...     metadata = dict() if not metadata else metadata
     ...     metadata[MY_TYPE_METADATA] = cls
-    ...     return attr.ib(default, validator, repr, cmp, hash, init, metadata, type, converter)
+    ...     return attr.ib(
+    ...         default=default, validator=validator, repr=repr,
+    ...         eq=eq, order=order, hash=hash, init=init,
+    ...         metadata=metadata, type=type, converter=converter
+    ...     )
     >>>
     >>> @attr.s
     ... class C(object):
diff --git a/docs/hashing.rst b/docs/hashing.rst
index 8bf3540..30888f9 100644
--- a/docs/hashing.rst
+++ b/docs/hashing.rst
@@ -10,7 +10,7 @@ Hash Method Generation
    Leave it at ``None`` which means that ``attrs`` will do the right thing for you, depending on the other parameters:
 
    - If you want to make objects hashable by value: use ``@attr.s(frozen=True)``.
-   - If you want hashing and comparison by object identity: use ``@attr.s(cmp=False)``
+   - If you want hashing and equality by object identity: use ``@attr.s(eq=False)``
 
    Setting ``hash`` yourself can have unexpected consequences so we recommend to tinker with it only if you know exactly what you're doing.
 
@@ -34,13 +34,13 @@ Because according to the definition_ from the official Python docs, the returned
    Python 2 on the other hand will happily let you shoot your foot off.
    Unfortunately ``attrs`` currently mimics Python 2's behavior for backward compatibility reasons if you set ``hash=False``.
 
-   The *correct way* to achieve hashing by id is to set ``@attr.s(cmp=False)``.
-   Setting ``@attr.s(hash=False)`` (that implies ``cmp=True``) is almost certainly a *bug*.
+   The *correct way* to achieve hashing by id is to set ``@attr.s(eq=False)``.
+   Setting ``@attr.s(hash=False)`` (which implies ``eq=True``) is almost certainly a *bug*.
 
    .. warning::
 
       Be careful when subclassing!
-      Setting ``cmp=False`` on class whose base class has a non-default ``__hash__`` method, will *not* make ``attrs`` remove that ``__hash__`` for you.
+      Setting ``eq=False`` on a class whose base class has a non-default ``__hash__`` method will *not* make ``attrs`` remove that ``__hash__`` for you.
 
       It is part of ``attrs``'s philosophy to only *add* to classes so you have the freedom to customize your classes as you wish.
       So if you want to *get rid* of methods, you'll have to do it by hand.
@@ -65,8 +65,9 @@ For a more thorough explanation of this topic, please refer to this blog post: `
 
 Hashing and Mutability
 ----------------------
+
 Changing any field involved in hash code computation after the first call to ``__hash__`` (typically this would be after its insertion into a hash-based collection) can result in silent bugs.
-Therefore, it is strongly recommended that hashable classes be ``frozen.``
+Therefore, it is strongly recommended that hashable classes be ``frozen``.
 Beware, however, that this is not a complete guarantee of safety:
 if a field points to an object and that object is mutated, the hash code may change, but ``frozen`` will not protect you.
 
diff --git a/src/attr/__init__.pyi b/src/attr/__init__.pyi
index e331ea6..03bcf89 100644
--- a/src/attr/__init__.pyi
+++ b/src/attr/__init__.pyi
@@ -53,16 +53,14 @@ class Attribute(Generic[_T]):
     validator: Optional[_ValidatorType[_T]]
     repr: _ReprArgType
     cmp: bool
+    eq: bool
+    order: bool
     hash: Optional[bool]
     init: bool
     converter: Optional[_ConverterType[_T]]
     metadata: Dict[Any, Any]
     type: Optional[Type[_T]]
     kw_only: bool
-    def __lt__(self, x: Attribute[_T]) -> bool: ...
-    def __le__(self, x: Attribute[_T]) -> bool: ...
-    def __gt__(self, x: Attribute[_T]) -> bool: ...
-    def __ge__(self, x: Attribute[_T]) -> bool: ...
 
 # NOTE: We had several choices for the annotation to use for type arg:
 # 1) Type[_T]
@@ -92,7 +90,7 @@ def attrib(
     default: None = ...,
     validator: None = ...,
     repr: _ReprArgType = ...,
-    cmp: bool = ...,
+    cmp: Optional[bool] = ...,
     hash: Optional[bool] = ...,
     init: bool = ...,
     metadata: Optional[Mapping[Any, Any]] = ...,
@@ -100,6 +98,8 @@ def attrib(
     converter: None = ...,
     factory: None = ...,
     kw_only: bool = ...,
+    eq: Optional[bool] = ...,
+    order: Optional[bool] = ...,
 ) -> Any: ...
 
 # This form catches an explicit None or no default and infers the type from the other arguments.
@@ -108,7 +108,7 @@ def attrib(
     default: None = ...,
     validator: Optional[_ValidatorArgType[_T]] = ...,
     repr: _ReprArgType = ...,
-    cmp: bool = ...,
+    cmp: Optional[bool] = ...,
     hash: Optional[bool] = ...,
     init: bool = ...,
     metadata: Optional[Mapping[Any, Any]] = ...,
@@ -116,6 +116,8 @@ def attrib(
     converter: Optional[_ConverterType[_T]] = ...,
     factory: Optional[Callable[[], _T]] = ...,
     kw_only: bool = ...,
+    eq: Optional[bool] = ...,
+    order: Optional[bool] = ...,
 ) -> _T: ...
 
 # This form catches an explicit default argument.
@@ -124,7 +126,7 @@ def attrib(
     default: _T,
     validator: Optional[_ValidatorArgType[_T]] = ...,
     repr: _ReprArgType = ...,
-    cmp: bool = ...,
+    cmp: Optional[bool] = ...,
     hash: Optional[bool] = ...,
     init: bool = ...,
     metadata: Optional[Mapping[Any, Any]] = ...,
@@ -132,6 +134,8 @@ def attrib(
     converter: Optional[_ConverterType[_T]] = ...,
     factory: Optional[Callable[[], _T]] = ...,
     kw_only: bool = ...,
+    eq: Optional[bool] = ...,
+    order: Optional[bool] = ...,
 ) -> _T: ...
 
 # This form covers type=non-Type: e.g. forward references (str), Any
@@ -140,7 +144,7 @@ def attrib(
     default: Optional[_T] = ...,
     validator: Optional[_ValidatorArgType[_T]] = ...,
     repr: _ReprArgType = ...,
-    cmp: bool = ...,
+    cmp: Optional[bool] = ...,
     hash: Optional[bool] = ...,
     init: bool = ...,
     metadata: Optional[Mapping[Any, Any]] = ...,
@@ -148,6 +152,8 @@ def attrib(
     converter: Optional[_ConverterType[_T]] = ...,
     factory: Optional[Callable[[], _T]] = ...,
     kw_only: bool = ...,
+    eq: Optional[bool] = ...,
+    order: Optional[bool] = ...,
 ) -> Any: ...
 @overload
 def attrs(
@@ -155,7 +161,7 @@ def attrs(
     these: Optional[Dict[str, Any]] = ...,
     repr_ns: Optional[str] = ...,
     repr: bool = ...,
-    cmp: bool = ...,
+    cmp: Optional[bool] = ...,
     hash: Optional[bool] = ...,
     init: bool = ...,
     slots: bool = ...,
@@ -166,6 +172,8 @@ def attrs(
     kw_only: bool = ...,
     cache_hash: bool = ...,
     auto_exc: bool = ...,
+    eq: Optional[bool] = ...,
+    order: Optional[bool] = ...,
 ) -> _C: ...
 @overload
 def attrs(
@@ -173,7 +181,7 @@ def attrs(
     these: Optional[Dict[str, Any]] = ...,
     repr_ns: Optional[str] = ...,
     repr: bool = ...,
-    cmp: bool = ...,
+    cmp: Optional[bool] = ...,
     hash: Optional[bool] = ...,
     init: bool = ...,
     slots: bool = ...,
@@ -184,6 +192,8 @@ def attrs(
     kw_only: bool = ...,
     cache_hash: bool = ...,
     auto_exc: bool = ...,
+    eq: Optional[bool] = ...,
+    order: Optional[bool] = ...,
 ) -> Callable[[_C], _C]: ...
 
 # TODO: add support for returning NamedTuple from the mypy plugin
@@ -202,7 +212,7 @@ def make_class(
     bases: Tuple[type, ...] = ...,
     repr_ns: Optional[str] = ...,
     repr: bool = ...,
-    cmp: bool = ...,
+    cmp: Optional[bool] = ...,
     hash: Optional[bool] = ...,
     init: bool = ...,
     slots: bool = ...,
@@ -213,6 +223,8 @@ def make_class(
     kw_only: bool = ...,
     cache_hash: bool = ...,
     auto_exc: bool = ...,
+    eq: Optional[bool] = ...,
+    order: Optional[bool] = ...,
 ) -> type: ...
 
 # _funcs --
diff --git a/src/attr/_make.py b/src/attr/_make.py
index 51f67f7..02f6e23 100644
--- a/src/attr/_make.py
+++ b/src/attr/_make.py
@@ -5,6 +5,7 @@ import linecache
 import sys
 import threading
 import uuid
+import warnings
 
 from operator import itemgetter
 
@@ -73,7 +74,7 @@ def attrib(
     default=NOTHING,
     validator=None,
     repr=True,
-    cmp=True,
+    cmp=None,
     hash=None,
     init=True,
     metadata=None,
@@ -81,6 +82,8 @@ def attrib(
     converter=None,
     factory=None,
     kw_only=False,
+    eq=None,
+    order=None,
 ):
     """
     Create a new attribute on a class.
@@ -135,10 +138,15 @@ def attrib(
         as-is, i.e. it will be used directly *instead* of calling ``repr()``
         (the default).
     :type repr: a ``bool`` or a ``callable`` to use a custom function.
-    :param bool cmp: Include this attribute in the generated comparison methods
-        (``__eq__`` et al).
+    :param bool eq: If ``True`` (default), include this attribute in the
+        generated ``__eq__`` and ``__ne__`` methods that check two instances
+        for equality.
+    :param bool order: If ``True`` (default), include this attributes in the
+        generated ``__lt__``, ``__le__``, ``__gt__`` and ``__ge__`` methods.
+    :param bool cmp: Setting to ``True`` is equivalent to setting ``eq=True,
+        order=True``. Deprecated in favor of *eq* and *order*.
     :param hash: Include this attribute in the generated ``__hash__``
-        method.  If ``None`` (default), mirror *cmp*'s value.  This is the
+        method.  If ``None`` (default), mirror *eq*'s value.  This is the
         correct behavior according the Python spec.  Setting this value to
         anything else than ``None`` is *discouraged*.
     :type hash: ``bool`` or ``None``
@@ -171,7 +179,7 @@ def attrib(
     .. versionadded:: 16.3.0 *metadata*
     .. versionchanged:: 17.1.0 *validator* can be a ``list`` now.
     .. versionchanged:: 17.1.0
-       *hash* is ``None`` and therefore mirrors *cmp* by default.
+       *hash* is ``None`` and therefore mirrors *eq* by default.
     .. versionadded:: 17.3.0 *type*
     .. deprecated:: 17.4.0 *convert*
     .. versionadded:: 17.4.0 *converter* as a replacement for the deprecated
@@ -181,7 +189,11 @@ def attrib(
     .. versionadded:: 18.2.0 *kw_only*
     .. versionchanged:: 19.2.0 *convert* keyword argument removed
     .. versionchanged:: 19.2.0 *repr* also accepts a custom callable.
+    .. deprecated:: 19.2.0 *cmp* Removal on or after 2021-06-01.
+    .. versionadded:: 19.2.0 *eq* and *order*
     """
+    eq, order = _determine_eq_order(cmp, eq, order)
+
     if hash is not None and hash is not True and hash is not False:
         raise TypeError(
             "Invalid value for hash.  Must be True, False, or None."
@@ -204,13 +216,15 @@ def attrib(
         default=default,
         validator=validator,
         repr=repr,
-        cmp=cmp,
+        cmp=None,
         hash=hash,
         init=init,
         converter=converter,
         metadata=metadata,
         type=type,
         kw_only=kw_only,
+        eq=eq,
+        order=order,
     )
 
 
@@ -678,14 +692,22 @@ class _ClassBuilder(object):
 
         return self
 
-    def add_cmp(self):
+    def add_eq(self):
         cd = self._cls_dict
 
-        cd["__eq__"], cd["__ne__"], cd["__lt__"], cd["__le__"], cd[
-            "__gt__"
-        ], cd["__ge__"] = (
+        cd["__eq__"], cd["__ne__"] = (
             self._add_method_dunders(meth)
-            for meth in _make_cmp(self._cls, self._attrs)
+            for meth in _make_eq(self._cls, self._attrs)
+        )
+
+        return self
+
+    def add_order(self):
+        cd = self._cls_dict
+
+        cd["__lt__"], cd["__le__"], cd["__gt__"], cd["__ge__"] = (
+            self._add_method_dunders(meth)
+            for meth in _make_order(self._cls, self._attrs)
         )
 
         return self
@@ -709,12 +731,45 @@ class _ClassBuilder(object):
         return method
 
 
+_CMP_DEPRECATION = (
+    "The usage of `cmp` is deprecated and will be removed on or after "
+    "2021-06-01.  Please use `eq` and `order` instead."
+)
+
+
+def _determine_eq_order(cmp, eq, order):
+    """
+    Validate the combination of *cmp*, *eq*, and *order*. Derive the effective
+    values of eq and order.
+    """
+    if cmp is not None and any((eq is not None, order is not None)):
+        raise ValueError("Don't mix `cmp` with `eq' and `order`.")
+
+    # cmp takes precedence due to bw-compatibility.
+    if cmp is not None:
+        warnings.warn(_CMP_DEPRECATION, DeprecationWarning, stacklevel=3)
+
+        return cmp, cmp
+
+    # If left None, equality is on and ordering mirrors equality.
+    if eq is None:
+        eq = True
+
+    if order is None:
+        order = eq
+
+    if eq is False and order is True:
+        raise ValueError("`order` can only be True if `eq` is True too.")
+
+    return eq, order
+
+
 def attrs(
     maybe_cls=None,
     these=None,
     repr_ns=None,
     repr=True,
-    cmp=True,
+    cmp=None,
     hash=None,
     init=True,
     slots=False,
@@ -725,6 +780,8 @@ def attrs(
     kw_only=False,
     cache_hash=False,
     auto_exc=False,
+    eq=None,
+    order=None,
 ):
     r"""
     A class decorator that adds `dunder
@@ -754,17 +811,28 @@ def attrs(
     :param bool str: Create a ``__str__`` method that is identical to
         ``__repr__``.  This is usually not necessary except for
         `Exception`\ s.
-    :param bool cmp: Create ``__eq__``, ``__ne__``, ``__lt__``, ``__le__``,
-        ``__gt__``, and ``__ge__`` methods that compare the class as if it were
-        a tuple of its ``attrs`` attributes.  But the attributes are *only*
-        compared, if the types of both classes are *identical*!
+    :param bool eq: If ``True`` or ``None`` (default), add ``__eq__`` and
+        ``__ne__`` methods that check two instances for equality.
+
+        They compare the instances as if they were tuples of their ``attrs``
+        attributes, but only iff the types of both classes are *identical*!
+    :type eq: `bool` or `None`
+    :param bool order: If ``True``, add ``__lt__``, ``__le__``, ``__gt__``,
+        and ``__ge__`` methods that behave like *eq* above and allow instances
+        to be ordered. If ``None`` (default) mirror value of *eq*.
+    :type order: `bool` or `None`
+    :param cmp: Setting to ``True`` is equivalent to setting ``eq=True,
+        order=True``. Deprecated in favor of *eq* and *order*, has precedence
+        over them for backward-compatibility though. Must not be mixed with
+        *eq* or *order*.
+    :type cmp: `bool` or `None`
     :param hash: If ``None`` (default), the ``__hash__`` method is generated
-        according how *cmp* and *frozen* are set.
+        according how *eq* and *frozen* are set.
 
         1. If *both* are True, ``attrs`` will generate a ``__hash__`` for you.
-        2. If *cmp* is True and *frozen* is False, ``__hash__`` will be set to
+        2. If *eq* is True and *frozen* is False, ``__hash__`` will be set to
            None, marking it unhashable (which it is).
-        3. If *cmp* is False, ``__hash__`` will be left untouched meaning the
+        3. If *eq* is False, ``__hash__`` will be left untouched meaning the
            ``__hash__`` method of the base class will be used (if base class is
            ``object``, this means it will fall back to id-based hashing.).
 
@@ -838,10 +906,10 @@ def attrs(
         following happens to behave like a well-behaved Python exceptions
         class:
 
-        - the values for *cmp* and *hash* are ignored and the instances compare
-          and hash by the instance's ids (N.B. ``attrs`` will *not* remove
-          existing implementations of ``__hash__`` or the equality methods. It
-          just won't add own ones.),
+        - the values for *eq*, *order*, and *hash* are ignored and the
+          instances compare and hash by the instance's ids (N.B. ``attrs`` will
+          *not* remove existing implementations of ``__hash__`` or the equality
+          methods. It just won't add own ones.),
         - all attributes that are either passed into ``__init__`` or have a
           default value are additionally available as a tuple in the ``args``
           attribute,
@@ -869,7 +937,10 @@ def attrs(
     .. versionadded:: 18.2.0 *kw_only*
     .. versionadded:: 18.2.0 *cache_hash*
     .. versionadded:: 19.1.0 *auto_exc*
+    .. deprecated:: 19.2.0 *cmp* Removal on or after 2021-06-01.
+    .. versionadded:: 19.2.0 *eq* and *order*
     """
+    eq, order = _determine_eq_order(cmp, eq, order)
 
     def wrap(cls):
 
@@ -894,15 +965,17 @@ def attrs(
             builder.add_repr(repr_ns)
         if str is True:
             builder.add_str()
-        if cmp is True and not is_exc:
-            builder.add_cmp()
+        if eq is True and not is_exc:
+            builder.add_eq()
+        if order is True and not is_exc:
+            builder.add_order()
 
         if hash is not True and hash is not False and hash is not None:
             # Can't use `hash in` because 1 == True for example.
             raise TypeError(
                 "Invalid value for hash.  Must be True, False, or None."
             )
-        elif hash is False or (hash is None and cmp is False) or is_exc:
+        elif hash is False or (hash is None and eq is False) or is_exc:
             # Don't do anything. Should fall back to __object__'s __hash__
             # which is by id.
             if cache_hash:
@@ -911,7 +984,7 @@ def attrs(
                     " hashing must be either explicitly or implicitly "
                     "enabled."
                 )
-        elif hash is True or (hash is None and cmp is True and frozen is True):
+        elif hash is True or (hash is None and eq is True and frozen is True):
             # Build a __hash__ if told so, or if it's safe.
             builder.add_hash()
         else:
@@ -1013,9 +1086,7 @@ def _generate_unique_filename(cls, func_name):
 
 def _make_hash(cls, attrs, frozen, cache_hash):
     attrs = tuple(
-        a
-        for a in attrs
-        if a.hash is True or (a.hash is None and a.cmp is True)
+        a for a in attrs if a.hash is True or (a.hash is None and a.eq is True)
     )
 
     tab = "        "
@@ -1093,8 +1164,8 @@ def __ne__(self, other):
     return not result
 
 
-def _make_cmp(cls, attrs):
-    attrs = [a for a in attrs if a.cmp]
+def _make_eq(cls, attrs):
+    attrs = [a for a in attrs if a.eq]
 
     unique_filename = _generate_unique_filename(cls, "eq")
     lines = [
@@ -1129,8 +1200,11 @@ def _make_cmp(cls, attrs):
         script.splitlines(True),
         unique_filename,
     )
-    eq = locs["__eq__"]
-    ne = __ne__
+    return locs["__eq__"], __ne__
+
+
+def _make_order(cls, attrs):
+    attrs = [a for a in attrs if a.order]
 
     def attrs_to_tuple(obj):
         """
@@ -1174,19 +1248,17 @@ def _make_cmp(cls, attrs):
 
         return NotImplemented
 
-    return eq, ne, __lt__, __le__, __gt__, __ge__
+    return __lt__, __le__, __gt__, __ge__
 
 
-def _add_cmp(cls, attrs=None):
+def _add_eq(cls, attrs=None):
     """
-    Add comparison methods to *cls*.
+    Add equality methods to *cls* with *attrs*.
     """
     if attrs is None:
         attrs = cls.__attrs_attrs__
 
-    cls.__eq__, cls.__ne__, cls.__lt__, cls.__le__, cls.__gt__, cls.__ge__ = _make_cmp(  # noqa
-        cls, attrs
-    )
+    cls.__eq__, cls.__ne__ = _make_eq(cls, attrs)
 
     return cls
 
@@ -1682,7 +1754,8 @@ class Attribute(object):
         "default",
         "validator",
         "repr",
-        "cmp",
+        "eq",
+        "order",
         "hash",
         "init",
         "metadata",
@@ -1697,14 +1770,18 @@ class Attribute(object):
         default,
         validator,
         repr,
-        cmp,
+        cmp,  # XXX: unused, remove along with other cmp code.
         hash,
         init,
         metadata=None,
         type=None,
         converter=None,
         kw_only=False,
+        eq=None,
+        order=None,
     ):
+        eq, order = _determine_eq_order(cmp, eq, order)
+
         # Cache this descriptor here to speed things up later.
         bound_setattr = _obj_setattr.__get__(self, Attribute)
 
@@ -1714,7 +1791,8 @@ class Attribute(object):
         bound_setattr("default", default)
         bound_setattr("validator", validator)
         bound_setattr("repr", repr)
-        bound_setattr("cmp", cmp)
+        bound_setattr("eq", eq)
+        bound_setattr("order", order)
         bound_setattr("hash", hash)
         bound_setattr("init", init)
         bound_setattr("converter", converter)
@@ -1757,9 +1835,19 @@ class Attribute(object):
             validator=ca._validator,
             default=ca._default,
             type=type,
+            cmp=None,
             **inst_dict
         )
 
+    @property
+    def cmp(self):
+        """
+        Simulate the presence of a cmp attribute and warn.
+        """
+        warnings.warn(_CMP_DEPRECATION, DeprecationWarning, stacklevel=2)
+
+        return self.eq and self.order
+
     # Don't use attr.assoc since fields(Attribute) doesn't work
     def _assoc(self, **changes):
         """
@@ -1807,7 +1895,9 @@ _a = [
         default=NOTHING,
         validator=None,
         repr=True,
-        cmp=True,
+        cmp=None,
+        eq=True,
+        order=False,
         hash=(name != "metadata"),
         init=True,
     )
@@ -1815,7 +1905,7 @@ _a = [
 ]
 
 Attribute = _add_hash(
-    _add_cmp(_add_repr(Attribute, attrs=_a), attrs=_a),
+    _add_eq(_add_repr(Attribute, attrs=_a), attrs=_a),
     attrs=[a for a in _a if a.hash],
 )
 
@@ -1833,7 +1923,8 @@ class _CountingAttr(object):
         "counter",
         "_default",
         "repr",
-        "cmp",
+        "eq",
+        "order",
         "hash",
         "init",
         "metadata",
@@ -1848,22 +1939,34 @@ class _CountingAttr(object):
             default=NOTHING,
             validator=None,
             repr=True,
-            cmp=True,
+            cmp=None,
             hash=True,
             init=True,
             kw_only=False,
+            eq=True,
+            order=False,
+        )
+        for name in (
+            "counter",
+            "_default",
+            "repr",
+            "eq",
+            "order",
+            "hash",
+            "init",
         )
-        for name in ("counter", "_default", "repr", "cmp", "hash", "init")
     ) + (
         Attribute(
             name="metadata",
             default=None,
             validator=None,
             repr=True,
-            cmp=True,
+            cmp=None,
             hash=False,
             init=True,
             kw_only=False,
+            eq=True,
+            order=False,
         ),
     )
     cls_counter = 0
@@ -1873,13 +1976,15 @@ class _CountingAttr(object):
         default,
         validator,
         repr,
-        cmp,
+        cmp,  # XXX: unused, remove along with cmp
         hash,
         init,
         converter,
         metadata,
         type,
         kw_only,
+        eq,
+        order,
     ):
         _CountingAttr.cls_counter += 1
         self.counter = _CountingAttr.cls_counter
@@ -1890,7 +1995,8 @@ class _CountingAttr(object):
         else:
             self._validator = validator
         self.repr = repr
-        self.cmp = cmp
+        self.eq = eq
+        self.order = order
         self.hash = hash
         self.init = init
         self.converter = converter
@@ -1930,7 +2036,7 @@ class _CountingAttr(object):
         return meth
 
 
-_CountingAttr = _add_cmp(_add_repr(_CountingAttr))
+_CountingAttr = _add_eq(_add_repr(_CountingAttr))
 
 
 @attrs(slots=True, init=False, hash=True)
@@ -2011,6 +2117,14 @@ def make_class(name, attrs, bases=(object,), **attributes_arguments):
     except (AttributeError, ValueError):
         pass
 
+    # We do it here for proper warnings with meaningful stacklevel.
+    cmp = attributes_arguments.pop("cmp", None)
+    attributes_arguments["eq"], attributes_arguments[
+        "order"
+    ] = _determine_eq_order(
+        cmp, attributes_arguments.get("eq"), attributes_arguments.get("order")
+    )
+
     return _attrs(these=cls_dict, **attributes_arguments)(type_)
 
 


Test patch:
diff --git a/conftest.py b/conftest.py
index 9f84c34..b83f69a 100644
--- a/conftest.py
+++ b/conftest.py
@@ -2,8 +2,6 @@ from __future__ import absolute_import, division, print_function
 
 import sys
 
-import pytest
-
 from hypothesis import HealthCheck, settings
 
 
@@ -15,21 +13,6 @@ def pytest_configure(config):
     settings.load_profile("patience")
 
 
-@pytest.fixture(scope="session")
-def C():
-    """
-    Return a simple but fully featured attrs class with an x and a y attribute.
-    """
-    import attr
-
-    @attr.s
-    class C(object):
-        x = attr.ib()
-        y = attr.ib()
-
-    return C
-
-
 collect_ignore = []
 if sys.version_info[:2] < (3, 6):
     collect_ignore.extend(
diff --git a/tests/strategies.py b/tests/strategies.py
index 1ebb9e4..833778e 100644
--- a/tests/strategies.py
+++ b/tests/strategies.py
@@ -14,6 +14,9 @@ import attr
 from .utils import make_class
 
 
+optional_bool = st.one_of(st.none(), st.booleans())
+
+
 def gen_attr_names():
     """
     Generate names for attributes, 'a'...'z', then 'aa'...'zz'.
@@ -131,7 +134,8 @@ def simple_attrs_with_metadata(draw):
         default=c_attr._default,
         validator=c_attr._validator,
         repr=c_attr.repr,
-        cmp=c_attr.cmp,
+        eq=c_attr.eq,
+        order=c_attr.order,
         hash=c_attr.hash,
         init=c_attr.init,
         metadata=metadata,
diff --git a/tests/test_dark_magic.py b/tests/test_dark_magic.py
index 778fc9f..c9b8b05 100644
--- a/tests/test_dark_magic.py
+++ b/tests/test_dark_magic.py
@@ -11,15 +11,17 @@ from copy import deepcopy
 import pytest
 import six
 
-from hypothesis import given
+from hypothesis import assume, given
 from hypothesis.strategies import booleans
 
 import attr
 
-from attr._compat import TYPE
+from attr._compat import PY2, TYPE
 from attr._make import NOTHING, Attribute
 from attr.exceptions import FrozenInstanceError
 
+from .strategies import optional_bool
+
 
 @attr.s
 class C1(object):
@@ -124,7 +126,9 @@ class TestDarkMagic(object):
                 default=foo,
                 validator=None,
                 repr=True,
-                cmp=True,
+                cmp=None,
+                eq=True,
+                order=True,
                 hash=None,
                 init=True,
             ),
@@ -133,7 +137,9 @@ class TestDarkMagic(object):
                 default=attr.Factory(list),
                 validator=None,
                 repr=True,
-                cmp=True,
+                cmp=None,
+                eq=True,
+                order=True,
                 hash=None,
                 init=True,
             ),
@@ -181,13 +187,16 @@ class TestDarkMagic(object):
         `attr.make_class` works.
         """
         PC = attr.make_class("PC", ["a", "b"], slots=slots, frozen=frozen)
+
         assert (
             Attribute(
                 name="a",
                 default=NOTHING,
                 validator=None,
                 repr=True,
-                cmp=True,
+                cmp=None,
+                eq=True,
+                order=True,
                 hash=None,
                 init=True,
             ),
@@ -196,7 +205,9 @@ class TestDarkMagic(object):
                 default=NOTHING,
                 validator=None,
                 repr=True,
-                cmp=True,
+                cmp=None,
+                eq=True,
+                order=True,
                 hash=None,
                 init=True,
             ),
@@ -380,7 +391,7 @@ class TestDarkMagic(object):
             HashByIDBackwardCompat(1)
         )
 
-        @attr.s(hash=False, cmp=False)
+        @attr.s(hash=False, eq=False)
         class HashByID(object):
             x = attr.ib()
 
@@ -412,10 +423,10 @@ class TestDarkMagic(object):
     @pytest.mark.parametrize("slots", [True, False])
     def test_hash_false_cmp_false(self, slots):
         """
-        hash=False and cmp=False make a class hashable by ID.
+        hash=False and eq=False make a class hashable by ID.
         """
 
-        @attr.s(hash=False, cmp=False, slots=slots)
+        @attr.s(hash=False, eq=False, slots=slots)
         class C(object):
             pass
 
@@ -581,3 +592,76 @@ class TestDarkMagic(object):
             x = attr.ib()
 
         FooError(1)
+
+    @pytest.mark.parametrize("slots", [True, False])
+    @pytest.mark.parametrize("frozen", [True, False])
+    def test_eq_only(self, slots, frozen):
+        """
+        Classes with order=False cannot be ordered.
+
+        Python 3 throws a TypeError, in Python2 we have to check for the
+        absence.
+        """
+
+        @attr.s(eq=True, order=False, slots=slots, frozen=frozen)
+        class C(object):
+            x = attr.ib()
+
+        if not PY2:
+            possible_errors = (
+                "unorderable types: C() < C()",
+                "'<' not supported between instances of 'C' and 'C'",
+                "unorderable types: C < C",  # old PyPy 3
+            )
+
+            with pytest.raises(TypeError) as ei:
+                C(5) < C(6)
+
+            assert ei.value.args[0] in possible_errors
+        else:
+            i = C(42)
+            for m in ("lt", "le", "gt", "ge"):
+                assert None is getattr(i, "__%s__" % (m,), None)
+
+    @given(cmp=optional_bool, eq=optional_bool, order=optional_bool)
+    def test_cmp_deprecated_attribute(self, cmp, eq, order):
+        """
+        Accessing Attribute.cmp raises a deprecation warning but returns True
+        if cmp is True, or eq and order are *both* effectively True.
+        """
+        # These cases are invalid and raise a ValueError.
+        assume(cmp is None or (eq is None and order is None))
+        assume(not (eq is False and order is True))
+
+        if cmp is not None:
+            rv = cmp
+        elif eq is True or eq is None:
+            rv = order is None or order is True
+        elif cmp is None and eq is None and order is None:
+            rv = True
+        elif cmp is None or eq is None:
+            rv = False
+        else:
+            pytest.fail(
+                "Unexpected state: cmp=%r eq=%r order=%r" % (cmp, eq, order)
+            )
+
+        with pytest.deprecated_call() as dc:
+
+            @attr.s
+            class C(object):
+                x = attr.ib(cmp=cmp, eq=eq, order=order)
+
+            assert rv == attr.fields(C).x.cmp
+
+        if cmp is not None:
+            # Remove warning from creating the attribute if cmp is not None.
+            dc.pop()
+
+        w, = dc.list
+
+        assert (
+            "The usage of `cmp` is deprecated and will be removed on or after "
+            "2021-06-01.  Please use `eq` and `order` instead."
+            == w.message.args[0]
+        )
diff --git a/tests/test_dunders.py b/tests/test_dunders.py
index 84e092b..d679ecf 100644
--- a/tests/test_dunders.py
+++ b/tests/test_dunders.py
@@ -29,8 +29,10 @@ from attr.validators import instance_of
 from .utils import simple_attr, simple_class
 
 
-CmpC = simple_class(cmp=True)
-CmpCSlots = simple_class(cmp=True, slots=True)
+EqC = simple_class(eq=True)
+EqCSlots = simple_class(eq=True, slots=True)
+OrderC = simple_class(order=True)
+OrderCSlots = simple_class(order=True, slots=True)
 ReprC = simple_class(repr=True)
 ReprCSlots = simple_class(repr=True, slots=True)
 
@@ -38,10 +40,10 @@ ReprCSlots = simple_class(repr=True, slots=True)
 # implicitly.  The "Cached" versions are the same, except with hash code
 # caching enabled
 HashC = simple_class(hash=True)
-HashCSlots = simple_class(hash=None, cmp=True, frozen=True, slots=True)
+HashCSlots = simple_class(hash=None, eq=True, frozen=True, slots=True)
 HashCCached = simple_class(hash=True, cache_hash=True)
 HashCSlotsCached = simple_class(
-    hash=None, cmp=True, frozen=True, slots=True, cache_hash=True
+    hash=None, eq=True, frozen=True, slots=True, cache_hash=True
 )
 # the cached hash code is stored slightly differently in this case
 # so it needs to be tested separately
@@ -77,23 +79,23 @@ class InitC(object):
 InitC = _add_init(InitC, False)
 
 
-class TestAddCmp(object):
+class TestEqOrder(object):
     """
-    Tests for `_add_cmp`.
+    Tests for eq and order related methods.
     """
 
     @given(booleans())
-    def test_cmp(self, slots):
+    def test_eq_ignore_attrib(self, slots):
         """
-        If `cmp` is False, ignore that attribute.
+        If `eq` is False for an attribute, ignore that attribute.
         """
         C = make_class(
-            "C", {"a": attr.ib(cmp=False), "b": attr.ib()}, slots=slots
+            "C", {"a": attr.ib(eq=False), "b": attr.ib()}, slots=slots
         )
 
         assert C(1, 2) == C(2, 2)
 
-    @pytest.mark.parametrize("cls", [CmpC, CmpCSlots])
+    @pytest.mark.parametrize("cls", [EqC, EqCSlots])
     def test_equal(self, cls):
         """
         Equal objects are detected as equal.
@@ -101,7 +103,7 @@ class TestAddCmp(object):
         assert cls(1, 2) == cls(1, 2)
         assert not (cls(1, 2) != cls(1, 2))
 
-    @pytest.mark.parametrize("cls", [CmpC, CmpCSlots])
+    @pytest.mark.parametrize("cls", [EqC, EqCSlots])
     def test_unequal_same_class(self, cls):
         """
         Unequal objects of correct type are detected as unequal.
@@ -109,21 +111,21 @@ class TestAddCmp(object):
         assert cls(1, 2) != cls(2, 1)
         assert not (cls(1, 2) == cls(2, 1))
 
-    @pytest.mark.parametrize("cls", [CmpC, CmpCSlots])
+    @pytest.mark.parametrize("cls", [EqC, EqCSlots])
     def test_unequal_different_class(self, cls):
         """
         Unequal objects of different type are detected even if their attributes
         match.
         """
 
-        class NotCmpC(object):
+        class NotEqC(object):
             a = 1
             b = 2
 
-        assert cls(1, 2) != NotCmpC()
-        assert not (cls(1, 2) == NotCmpC())
+        assert cls(1, 2) != NotEqC()
+        assert not (cls(1, 2) == NotEqC())
 
-    @pytest.mark.parametrize("cls", [CmpC, CmpCSlots])
+    @pytest.mark.parametrize("cls", [OrderC, OrderCSlots])
     def test_lt(self, cls):
         """
         __lt__ compares objects as tuples of attribute values.
@@ -135,14 +137,14 @@ class TestAddCmp(object):
         ]:
             assert cls(*a) < cls(*b)
 
-    @pytest.mark.parametrize("cls", [CmpC, CmpCSlots])
+    @pytest.mark.parametrize("cls", [OrderC, OrderCSlots])
     def test_lt_unordable(self, cls):
         """
         __lt__ returns NotImplemented if classes differ.
         """
         assert NotImplemented == (cls(1, 2).__lt__(42))
 
-    @pytest.mark.parametrize("cls", [CmpC, CmpCSlots])
+    @pytest.mark.parametrize("cls", [OrderC, OrderCSlots])
     def test_le(self, cls):
         """
         __le__ compares objects as tuples of attribute values.
@@ -156,14 +158,14 @@ class TestAddCmp(object):
         ]:
             assert cls(*a) <= cls(*b)
 
-    @pytest.mark.parametrize("cls", [CmpC, CmpCSlots])
+    @pytest.mark.parametrize("cls", [OrderC, OrderCSlots])
     def test_le_unordable(self, cls):
         """
         __le__ returns NotImplemented if classes differ.
         """
         assert NotImplemented == (cls(1, 2).__le__(42))
 
-    @pytest.mark.parametrize("cls", [CmpC, CmpCSlots])
+    @pytest.mark.parametrize("cls", [OrderC, OrderCSlots])
     def test_gt(self, cls):
         """
         __gt__ compares objects as tuples of attribute values.
@@ -175,14 +177,14 @@ class TestAddCmp(object):
         ]:
             assert cls(*a) > cls(*b)
 
-    @pytest.mark.parametrize("cls", [CmpC, CmpCSlots])
+    @pytest.mark.parametrize("cls", [OrderC, OrderCSlots])
     def test_gt_unordable(self, cls):
         """
         __gt__ returns NotImplemented if classes differ.
         """
         assert NotImplemented == (cls(1, 2).__gt__(42))
 
-    @pytest.mark.parametrize("cls", [CmpC, CmpCSlots])
+    @pytest.mark.parametrize("cls", [OrderC, OrderCSlots])
     def test_ge(self, cls):
         """
         __ge__ compares objects as tuples of attribute values.
@@ -196,7 +198,7 @@ class TestAddCmp(object):
         ]:
             assert cls(*a) >= cls(*b)
 
-    @pytest.mark.parametrize("cls", [CmpC, CmpCSlots])
+    @pytest.mark.parametrize("cls", [OrderC, OrderCSlots])
     def test_ge_unordable(self, cls):
         """
         __ge__ returns NotImplemented if classes differ.
@@ -347,7 +349,7 @@ class TestAddHash(object):
         # unhashable case
         with pytest.raises(TypeError) as e:
             make_class(
-                "C", {}, hash=None, cmp=True, frozen=False, cache_hash=True
+                "C", {}, hash=None, eq=True, frozen=False, cache_hash=True
             )
         assert exc_args == e.value.args
 
@@ -380,13 +382,13 @@ class TestAddHash(object):
         assert hash(C(1, 2)) == hash(C(2, 2))
 
     @given(booleans())
-    def test_hash_attribute_mirrors_cmp(self, cmp):
+    def test_hash_attribute_mirrors_eq(self, eq):
         """
-        If `hash` is None, the hash generation mirrors `cmp`.
+        If `hash` is None, the hash generation mirrors `eq`.
         """
-        C = make_class("C", {"a": attr.ib(cmp=cmp)}, cmp=True, frozen=True)
+        C = make_class("C", {"a": attr.ib(eq=eq)}, eq=True, frozen=True)
 
-        if cmp:
+        if eq:
             assert C(1) != C(2)
             assert hash(C(1)) != hash(C(2))
             assert hash(C(1)) == hash(C(1))
@@ -395,18 +397,18 @@ class TestAddHash(object):
             assert hash(C(1)) == hash(C(2))
 
     @given(booleans())
-    def test_hash_mirrors_cmp(self, cmp):
+    def test_hash_mirrors_eq(self, eq):
         """
-        If `hash` is None, the hash generation mirrors `cmp`.
+        If `hash` is None, the hash generation mirrors `eq`.
         """
-        C = make_class("C", {"a": attr.ib()}, cmp=cmp, frozen=True)
+        C = make_class("C", {"a": attr.ib()}, eq=eq, frozen=True)
 
         i = C(1)
 
         assert i == i
         assert hash(i) == hash(i)
 
-        if cmp:
+        if eq:
             assert C(1) == C(1)
             assert hash(C(1)) == hash(C(1))
         else:
@@ -777,7 +779,7 @@ class TestNothing(object):
         assert 1 != _Nothing()
 
 
-@attr.s(hash=True, cmp=True)
+@attr.s(hash=True, order=True)
 class C(object):
     pass
 
@@ -786,7 +788,7 @@ class C(object):
 OriginalC = C
 
 
-@attr.s(hash=True, cmp=True)
+@attr.s(hash=True, order=True)
 class C(object):
     pass
 
diff --git a/tests/test_funcs.py b/tests/test_funcs.py
index eeef8bf..4d99e06 100644
--- a/tests/test_funcs.py
+++ b/tests/test_funcs.py
@@ -25,6 +25,21 @@ MAPPING_TYPES = (dict, OrderedDict)
 SEQUENCE_TYPES = (list, tuple)
 
 
+@pytest.fixture(scope="session", name="C")
+def fixture_C():
+    """
+    Return a simple but fully featured attrs class with an x and a y attribute.
+    """
+    import attr
+
+    @attr.s
+    class C(object):
+        x = attr.ib()
+        y = attr.ib()
+
+    return C
+
+
 class TestAsDict(object):
     """
     Tests for `asdict`.
diff --git a/tests/test_make.py b/tests/test_make.py
index 54e37a9..b90f1c6 100644
--- a/tests/test_make.py
+++ b/tests/test_make.py
@@ -14,7 +14,7 @@ from operator import attrgetter
 
 import pytest
 
-from hypothesis import given
+from hypothesis import assume, given
 from hypothesis.strategies import booleans, integers, lists, sampled_from, text
 
 import attr
@@ -28,6 +28,7 @@ from attr._make import (
     _Attributes,
     _ClassBuilder,
     _CountingAttr,
+    _determine_eq_order,
     _transform_attrs,
     and_,
     fields,
@@ -44,6 +45,7 @@ from attr.exceptions import (
 from .strategies import (
     gen_attr_names,
     list_of_attrs,
+    optional_bool,
     simple_attrs,
     simple_attrs_with_metadata,
     simple_attrs_without_metadata,
@@ -216,8 +218,9 @@ class TestTransformAttrs(object):
             "No mandatory attributes allowed after an attribute with a "
             "default value or factory.  Attribute in question: Attribute"
             "(name='y', default=NOTHING, validator=None, repr=True, "
-            "cmp=True, hash=None, init=True, metadata=mappingproxy({}), "
-            "type=None, converter=None, kw_only=False)",
+            "eq=True, order=True, hash=None, init=True, "
+            "metadata=mappingproxy({}), type=None, converter=None, "
+            "kw_only=False)",
         ) == e.value.args
 
     def test_kw_only(self):
@@ -411,21 +414,30 @@ class TestAttributes(object):
         "arg_name, method_name",
         [
             ("repr", "__repr__"),
-            ("cmp", "__eq__"),
+            ("eq", "__eq__"),
+            ("order", "__le__"),
             ("hash", "__hash__"),
             ("init", "__init__"),
         ],
     )
     def test_respects_add_arguments(self, arg_name, method_name):
         """
-        If a certain `add_XXX` is `False`, `__XXX__` is not added to the class.
+        If a certain `XXX` is `False`, `__XXX__` is not added to the class.
         """
         # Set the method name to a sentinel and check whether it has been
         # overwritten afterwards.
         sentinel = object()
 
-        am_args = {"repr": True, "cmp": True, "hash": True, "init": True}
+        am_args = {
+            "repr": True,
+            "eq": True,
+            "order": True,
+            "hash": True,
+            "init": True,
+        }
         am_args[arg_name] = False
+        if arg_name == "eq":
+            am_args["order"] = False
 
         class C(object):
             x = attr.ib()
@@ -918,16 +930,17 @@ class TestFields(object):
     Tests for `fields`.
     """
 
+    @given(simple_classes())
     def test_instance(self, C):
         """
         Raises `TypeError` on non-classes.
         """
         with pytest.raises(TypeError) as e:
-            fields(C(1, 2))
+            fields(C())
 
         assert "Passed object must be a class." == e.value.args[0]
 
-    def test_handler_non_attrs_class(self, C):
+    def test_handler_non_attrs_class(self):
         """
         Raises `ValueError` if passed a non-``attrs`` instance.
         """
@@ -959,16 +972,17 @@ class TestFieldsDict(object):
     Tests for `fields_dict`.
     """
 
+    @given(simple_classes())
     def test_instance(self, C):
         """
         Raises `TypeError` on non-classes.
         """
         with pytest.raises(TypeError) as e:
-            fields_dict(C(1, 2))
+            fields_dict(C())
 
         assert "Passed object must be a class." == e.value.args[0]
 
-    def test_handler_non_attrs_class(self, C):
+    def test_handler_non_attrs_class(self):
         """
         Raises `ValueError` if passed a non-``attrs`` instance.
         """
@@ -1341,7 +1355,8 @@ class TestClassBuilder(object):
         )
 
         cls = (
-            b.add_cmp()
+            b.add_eq()
+            .add_order()
             .add_hash()
             .add_init()
             .add_repr("ns")
@@ -1427,7 +1442,7 @@ class TestClassBuilder(object):
         @attr.s(slots=True)
         class C(object):
             __weakref__ = attr.ib(
-                init=False, hash=False, repr=False, cmp=False
+                init=False, hash=False, repr=False, eq=False, order=False
             )
 
         assert C() == copy.deepcopy(C())
@@ -1452,9 +1467,9 @@ class TestClassBuilder(object):
         assert [C2] == C.__subclasses__()
 
 
-class TestMakeCmp:
+class TestMakeOrder:
     """
-    Tests for _make_cmp().
+    Tests for _make_order().
     """
 
     def test_subclasses_cannot_be_compared(self):
@@ -1500,3 +1515,57 @@ class TestMakeCmp:
 
             with pytest.raises(TypeError):
                 a > b
+
+
+class TestDetermineEqOrder(object):
+    def test_default(self):
+        """
+        If all are set to None, do the default: True, True
+        """
+        assert (True, True) == _determine_eq_order(None, None, None)
+
+    @pytest.mark.parametrize("eq", [True, False])
+    def test_order_mirrors_eq_by_default(self, eq):
+        """
+        If order is None, it mirrors eq.
+        """
+        assert (eq, eq) == _determine_eq_order(None, eq, None)
+
+    def test_order_without_eq(self):
+        """
+        eq=False, order=True raises a meaningful ValueError.
+        """
+        with pytest.raises(
+            ValueError, match="`order` can only be True if `eq` is True too."
+        ):
+            _determine_eq_order(None, False, True)
+
+    @given(cmp=booleans(), eq=optional_bool, order=optional_bool)
+    def test_mix(self, cmp, eq, order):
+        """
+        If cmp is not None, eq and order must be None and vice versa.
+        """
+        assume(eq is not None or order is not None)
+
+        with pytest.raises(
+            ValueError, match="Don't mix `cmp` with `eq' and `order`."
+        ):
+            _determine_eq_order(cmp, eq, order)
+
+    def test_cmp_deprecated(self):
+        """
+        Passing a cmp that is not None raises a DeprecationWarning.
+        """
+        with pytest.deprecated_call() as dc:
+
+            @attr.s(cmp=True)
+            class C(object):
+                pass
+
+        w, = dc.list
+
+        assert (
+            "The usage of `cmp` is deprecated and will be removed on or after "
+            "2021-06-01.  Please use `eq` and `order` instead."
+            == w.message.args[0]
+        )
diff --git a/tests/test_slots.py b/tests/test_slots.py
index 3fa6a42..1fda4c1 100644
--- a/tests/test_slots.py
+++ b/tests/test_slots.py
@@ -272,7 +272,9 @@ def test_bare_inheritance_from_slots():
     Inheriting from a bare attrs slotted class works.
     """
 
-    @attr.s(init=False, cmp=False, hash=False, repr=False, slots=True)
+    @attr.s(
+        init=False, eq=False, order=False, hash=False, repr=False, slots=True
+    )
     class C1BareSlots(object):
         x = attr.ib(validator=attr.validators.instance_of(int))
         y = attr.ib()
@@ -288,7 +290,7 @@ def test_bare_inheritance_from_slots():
         def staticmethod():
             return "staticmethod"
 
-    @attr.s(init=False, cmp=False, hash=False, repr=False)
+    @attr.s(init=False, eq=False, order=False, hash=False, repr=False)
     class C1Bare(object):
         x = attr.ib(validator=attr.validators.instance_of(int))
         y = attr.ib()
@@ -533,7 +535,9 @@ def tests_weakref_does_not_add_with_weakref_attribute():
 
     @attr.s(slots=True, weakref_slot=True)
     class C(object):
-        __weakref__ = attr.ib(init=False, hash=False, repr=False, cmp=False)
+        __weakref__ = attr.ib(
+            init=False, hash=False, repr=False, eq=False, order=False
+        )
 
     c = C()
     w = weakref.ref(c)
diff --git a/tests/typing_example.py b/tests/typing_example.py
index a6c48bb..4df109d 100644
--- a/tests/typing_example.py
+++ b/tests/typing_example.py
@@ -166,3 +166,10 @@ class WithCustomRepr:
     b = attr.ib(repr=False)
     c = attr.ib(repr=lambda value: "c is for cookie")
     d = attr.ib(repr=str)
+
+
+# Check some of our own types
+@attr.s(eq=True, order=False)
+class OrderFlags:
+    a = attr.ib(eq=False, order=False)
+    b = attr.ib(eq=True, order=True)
diff --git a/tests/utils.py b/tests/utils.py
index 5a5cf07..86fa3d2 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -9,7 +9,8 @@ from attr._make import NOTHING, make_class
 
 
 def simple_class(
-    cmp=False,
+    eq=False,
+    order=False,
     repr=False,
     hash=False,
     str=False,
@@ -23,7 +24,8 @@ def simple_class(
     return make_class(
         "C",
         ["a", "b"],
-        cmp=cmp,
+        eq=eq or order,
+        order=order,
         repr=repr,
         hash=hash,
         init=True,
@@ -39,7 +41,7 @@ def simple_attr(
     default=NOTHING,
     validator=None,
     repr=True,
-    cmp=True,
+    eq=True,
     hash=None,
     init=True,
     converter=None,
@@ -53,7 +55,8 @@ def simple_attr(
         default=default,
         validator=validator,
         repr=repr,
-        cmp=cmp,
+        cmp=None,
+        eq=eq,
         hash=hash,
         init=init,
         converter=converter,