docparams extension considers type comments as type documentation.

Closes #6287

ChangeLog

@@ -90,6 +90,10 @@ Release date: TBA
 
   Closes #4525
 
+* docparams extension considers type comments as type documentation.
+
+  Closes #6287
+
 * Fix false positive for ``unsubscriptable-object`` in Python 3.8 and below for
   statements guarded by ``if TYPE_CHECKING``.
 

doc/whatsnew/2.14.rst

@@ -118,3 +118,7 @@ Other Changes
   attribute to itself without any prior assignment.
 
   Closes #1555
+
+* docparams extension considers type comments as type documentation.
+
+  Closes #6287

pylint/extensions/_check_docs_utils.py

@@ -4,13 +4,15 @@
 
 """Utility methods for docstring checking."""
 
+import itertools
 import re
 from typing import List, Optional, Set, Tuple
 
 import astroid
 from astroid import nodes
 
 from pylint.checkers import utils
+from pylint.constants import PY38_PLUS
 
 
 def space_indentation(s):
@@ -156,6 +158,109 @@ def possible_exc_types(node: nodes.NodeNG) -> Set[nodes.ClassDef]:
         return set()
 
 
+def _is_ellipsis(node: astroid.NodeNG) -> bool:
+    if not PY38_PLUS:
+        return isinstance(node, astroid.Ellipsis)
+
+    return isinstance(node, astroid.Const) and node.value == Ellipsis
+
+
+def _merge_annotations(annotations, comment_annotations):
+    for ann, comment_ann in itertools.zip_longest(annotations, comment_annotations):
+        if ann and not _is_ellipsis(ann):
+            yield ann
+        elif comment_ann and not _is_ellipsis(comment_ann):
+            yield comment_ann
+        else:
+            yield None
+
+
+def _annotations_list(args_node: astroid.Arguments) -> List[astroid.NodeNG]:
+    """Get a merged list of annotations.
+
+    The annotations can come from:
+
+    * Real type annotations.
+    * A type comment on the function.
+    * A type common on the individual argument.
+
+    :param args_node: The node to get the annotations for.
+    :returns: The annotations.
+    """
+    plain_annotations = args_node.annotations or ()
+    func_comment_annotations = args_node.parent.type_comment_args or ()
+    comment_annotations = args_node.type_comment_posonlyargs
+    comment_annotations += args_node.type_comment_args or []
+    comment_annotations += args_node.type_comment_kwonlyargs
+    return list(
+        _merge_annotations(
+            plain_annotations,
+            _merge_annotations(func_comment_annotations, comment_annotations),
+        )
+    )
+
+
+def args_with_annotation(args_node: astroid.Arguments) -> Set[str]:
+    result = set()
+    annotations = _annotations_list(args_node)
+    annotation_offset = 0
+
+    if args_node.posonlyargs:
+        posonlyargs_annotations = args_node.posonlyargs_annotations
+        if not any(args_node.posonlyargs_annotations):
+            num_args = len(args_node.posonlyargs)
+            posonlyargs_annotations = annotations[
+                annotation_offset : annotation_offset + num_args
+            ]
+            annotation_offset += num_args
+
+        for arg, annotation in zip(args_node.posonlyargs, posonlyargs_annotations):
+            if annotation:
+                result.add(arg.name)
+
+    if args_node.args:
+        num_args = len(args_node.args)
+        for arg, annotation in zip(
+            args_node.args,
+            annotations[annotation_offset : annotation_offset + num_args],
+        ):
+            if annotation:
+                result.add(arg.name)
+
+        annotation_offset += num_args
+
+    if args_node.vararg:
+        annotation = None
+        if args_node.varargannotation:
+            result.add(args_node.vararg)
+        elif len(annotations) > annotation_offset and annotations[annotation_offset]:
+            result.add(args_node.vararg)
+            annotation_offset += 1
+
+    if args_node.kwonlyargs:
+        kwonlyargs_annotations = args_node.kwonlyargs_annotations
+        if not any(args_node.kwonlyargs_annotations):
+            num_args = len(args_node.kwonlyargs)
+            kwonlyargs_annotations = annotations[
+                annotation_offset : annotation_offset + num_args
+            ]
+            annotation_offset += num_args
+
+        for arg, annotation in zip(args_node.kwonlyargs, kwonlyargs_annotations):
+            if annotation:
+                result.add(arg.name)
+
+    if args_node.kwarg:
+        annotation = None
+        if args_node.kwargannotation:
+            result.add(args_node.kwarg)
+        elif len(annotations) > annotation_offset and annotations[annotation_offset]:
+            result.add(args_node.kwarg)
+            annotation_offset += 1
+
+    return result
+
+
 def docstringify(
     docstring: Optional[nodes.Const], default_type: str = "default"
 ) -> "Docstring":

pylint/extensions/docparams.py

@@ -330,7 +330,7 @@ def visit_return(self, node: nodes.Return) -> None:
         if not (doc.has_returns() or (doc.has_property_returns() and is_property)):
             self.add_message("missing-return-doc", node=func_node)
 
-        if func_node.returns:
+        if func_node.returns or func_node.type_comment_returns:
             return
 
         if not (doc.has_rtype() or (doc.has_property_type() and is_property)):
@@ -358,7 +358,9 @@ def visit_yield(self, node: nodes.Yield) -> None:
         if not doc_has_yields:
             self.add_message("missing-yield-doc", node=func_node)
 
-        if not (doc_has_yields_type or func_node.returns):
+        if not (
+            doc_has_yields_type or func_node.returns or func_node.type_comment_returns
+        ):
             self.add_message("missing-yield-type-doc", node=func_node)
 
     def visit_yieldfrom(self, node: nodes.YieldFrom) -> None:
@@ -524,7 +526,9 @@ class constructor.
 
         # Collect the function arguments.
         expected_argument_names = {arg.name for arg in arguments_node.args}
-        expected_argument_names.update(arg.name for arg in arguments_node.kwonlyargs)
+        expected_argument_names.update(
+            a.name for a in arguments_node.posonlyargs + arguments_node.kwonlyargs
+        )
         not_needed_type_in_docstring = self.not_needed_param_in_docstring.copy()
 
         expected_but_ignored_argument_names = set()
@@ -547,7 +551,7 @@ class constructor.
         if not params_with_doc and not params_with_type and accept_no_param_doc:
             tolerate_missing_params = True
 
-        # This is before the update of param_with_type because this must check only
+        # This is before the update of params_with_type because this must check only
         # the type documented in a docstring, not the one using pep484
         # See #4117 and #4593
         self._compare_ignored_args(
@@ -556,12 +560,7 @@ class constructor.
             expected_but_ignored_argument_names,
             warning_node,
         )
-        for index, arg_name in enumerate(arguments_node.args):
-            if arguments_node.annotations[index]:
-                params_with_type.add(arg_name.name)
-        for index, arg_name in enumerate(arguments_node.kwonlyargs):
-            if arguments_node.kwonlyargs_annotations[index]:
-                params_with_type.add(arg_name.name)
+        params_with_type |= utils.args_with_annotation(arguments_node)
 
         if not tolerate_missing_params:
             missing_param_doc = (expected_argument_names - params_with_doc) - (

tests/functional/ext/docparams/missing_param_doc.py

@@ -140,3 +140,54 @@ def foobar15(*args):
         Relevant parameters.
     """
     print(args)
+
+
+def foobar16(one: int, two: str, three: float) -> int:
+    """Description of the function
+
+    Args:
+        one: A number.
+        two: Another number.
+        three: Yes another number.
+
+    Returns:
+        The number one.
+    """
+    print(one, two, three)
+    return 1
+
+
+def foobar17(one, two, three):
+    # type: (int, str, float) -> int
+    """Description of the function
+
+    Args:
+        one: A number.
+        two: Another number.
+        three: Yes another number.
+
+    Returns:
+        The number one.
+    """
+    print(one, two, three)
+    return 1
+
+
+def foobar18(
+    one,  # type: int
+    two,  # type: str
+    three,  # type: float
+):
+    # type: (...) -> int
+    """Description of the function
+
+    Args:
+        one: A number.
+        two: Another number.
+        three: Yes another number.
+
+    Returns:
+        The number one.
+    """
+    print(one, two, three)
+    return 1

tests/functional/ext/docparams/missing_param_doc_py38.py

@@ -0,0 +1,53 @@
+#pylint: disable= missing-module-docstring
+
+def foobar1(one: int, /, two: str, *, three: float) -> int:
+    """Description of the function
+
+    Args:
+        one: A number.
+        two: Another number.
+        three: Yes another number.
+
+    Returns:
+        The number one.
+    """
+    print(one, two, three)
+    return 1
+
+
+def foobar2(one, /, two, * three):
+    # type: (int, str, float) -> int
+    """Description of the function
+
+    Args:
+        one: A number.
+        two: Another number.
+        three: Yes another number.
+
+    Returns:
+        The number one.
+    """
+    print(one, two, three)
+    return 1
+
+
+def foobar3(
+    one,  # type: int
+    /,
+    two,  # type: str
+    *,
+    three,  # type: float
+):
+    # type: (...) -> int
+    """Description of the function
+
+    Args:
+        one: A number.
+        two: Another number.
+        three: Yes another number.
+
+    Returns:
+        The number one.
+    """
+    print(one, two, three)
+    return 1

tests/functional/ext/docparams/missing_param_doc_py38.rc

@@ -0,0 +1,11 @@
+[MASTER]
+load-plugins=pylint.extensions.docparams,
+
+[testoptions]
+min_pyver=3.8
+
+[PARAMETER_DOCUMENTATION]
+accept-no-param-doc=no
+accept-no-raise-doc=no
+accept-no-return-doc=no
+accept-no-yields-doc=no