Add type annotations to pyreverse

Closes #1548

Author: mbyrnepr2

ChangeLog

@@ -9,6 +9,10 @@ Release date: TBA
 ..
   Put new features and bugfixes here and also in 'doc/whatsnew/2.9.rst'
 
+* Add type annotations to pyreverse
+
+  Closes #1548
+
 * Added ``deprecated-decorator``: Emitted when deprecated decorator is used.
 
   Closes #4429

pylint/pyreverse/diagrams.py

@@ -122,7 +122,7 @@ def class_names(self, nodes):
             if isinstance(node, astroid.Instance):
                 node = node._proxied
             if (
-                isinstance(node, astroid.ClassDef)
+                isinstance(node, (astroid.ClassDef, astroid.Name))
                 and hasattr(node, "name")
                 and not self.has_node(node)
             ):

pylint/pyreverse/inspector.py

@@ -219,7 +219,10 @@ def visit_assignname(self, node):
 
             current = frame.locals_type[node.name]
             values = set(node.infer())
-            frame.locals_type[node.name] = list(set(current) | values)
+            ann = getattr(node.parent, "annotation", None)
+            ann = {ann} if ann else set()
+            frame.locals_type[node.name] = list(ann) or list(set(current) | values)
+
         except astroid.InferenceError:
             pass
 
@@ -229,10 +232,18 @@ def handle_assignattr_type(node, parent):
 
         handle instance_attrs_type
         """
+        try:
+            idx = list(node.parent.parent.locals).index(node.attrname)
+            ann = node.parent.parent.args.annotations[idx]
+        except ValueError:
+            ann = getattr(node.parent, "annotation", None)
         try:
             values = set(node.infer())
             current = set(parent.instance_attrs_type[node.attrname])
-            parent.instance_attrs_type[node.attrname] = list(current | values)
+            ann = {ann} if ann else set()
+            parent.instance_attrs_type[node.attrname] = list(
+                (current | ann) or (current | values)
+            )
         except astroid.InferenceError:
             pass
 

pylint/pyreverse/writer.py

@@ -134,11 +134,20 @@ def get_values(self, obj):
         if not self.config.only_classnames:
             label = r"{}|{}\l|".format(label, r"\l".join(obj.attrs))
             for func in obj.methods:
+                return_type = f": {func.returns.name}" if func.returns else ""
+
                 if func.args.args:
                     args = [arg.name for arg in func.args.args if arg.name != "self"]
                 else:
                     args = []
-                label = r"{}{}({})\l".format(label, func.name, ", ".join(args))
+
+                annotations = [a.name if a else None for a in func.args.annotations[1:]]
+                args = ", ".join(
+                    f"{arg}: {ann}" if ann else f"{arg}"
+                    for arg, ann in zip(args, annotations)
+                )
+
+                label = fr"{label}{func.name}({args}){return_type}\l"
             label = "{%s}" % label
         if is_exception(obj.node):
             return dict(fontcolor="red", label=label, shape="record")