Don't emit unused-argument and function-redefined for singledispatch implementations

Closes #1032 and #1034

1 files changed, 63 insertions, 0 deletions

diff --git a/pylint/test/functional/singledispatch_functions_py3.py b/pylint/test/functional/singledispatch_functions_py3.py
new file mode 100644
index 000000000..f8b816a4e
--- /dev/null
+++ b/pylint/test/functional/singledispatch_functions_py3.py
@@ -0,0 +1,63 @@
+# pylint: disable=missing-docstring,import-error,unused-import,assignment-from-no-return
+from __future__ import print_function
+from UNINFERABLE import uninferable_decorator, uninferable_func
+
+try:
+    from functools import singledispatch
+except ImportError:
+    from singledispatch import singledispatch
+
+my_single_dispatch = singledispatch  # pylint: disable=invalid-name
+
+
+@singledispatch
+def func(arg):
+    return arg
+
+
+@func.register(str)
+def _(arg):
+    return 42
+
+
+@func.register(float)
+@func.register(int)
+def _(arg):
+    return 42
+
+
+@my_single_dispatch
+def func2(arg):
+    return arg
+
+
+@func2.register(int)
+def _(arg):
+    return 42
+
+
+@singledispatch
+def with_extra_arg(arg, verbose=False):
+    if verbose:
+        print(arg)
+    return arg
+
+
+@with_extra_arg.register(str)
+def _(arg, verbose=False):
+    return arg[::-1]
+
+
+@uninferable_decorator
+def uninferable(arg):
+    return 2*arg
+
+
+@uninferable.register(str)
+def bad_single_dispatch(arg):
+    return arg
+
+
+@uninferable_func.register(str)
+def test(arg):
+    return arg