numpy
diff --git a/‎numpy/core/overrides.py
Copy file name to clipboardExpand all lines: numpy/core/overrides.py
+13Lines changed: 13 additions & 0 deletions b/‎numpy/core/overrides.py
Copy file name to clipboardExpand all lines: numpy/core/overrides.py
+13Lines changed: 13 additions & 0 deletions
diff --git a/‎numpy/tests/test_public_api.py
Copy file name to clipboardExpand all lines: numpy/tests/test_public_api.py
+16Lines changed: 16 additions & 0 deletions b/‎numpy/tests/test_public_api.py
Copy file name to clipboardExpand all lines: numpy/tests/test_public_api.py
+16Lines changed: 16 additions & 0 deletions
@@ -1,6 +1,7 @@
 """Implementation of __array_function__ overrides from NEP-18."""
 import collections
 import functools
+import inspect
 import os
 import textwrap
 
@@ -34,6 +35,15 @@ def set_array_function_like_doc(public_api):
     return public_api
 
 
+def add_signature(function, docstring):
+    try:
+        function.__signature__ = inspect._signature_fromstr(
+            inspect.Signature, function,
+            docstring.strip().split('\n')[0])
+    except ValueError:
+        pass
+
+
 add_docstring(
     implement_array_function,
     """
@@ -213,6 +223,9 @@ def decorator(implementation):
         if module is not None:
             public_api.__module__ = module
 
+        if docs_from_dispatcher and dispatcher.__doc__:
+            add_signature(public_api, dispatcher.__doc__)
+
         public_api._implementation = implementation
 
         return public_api
 
@@ -2,6 +2,7 @@
 import subprocess
 import pkgutil
 import types
+import inspect
 import importlib
 import warnings
 
@@ -471,3 +472,18 @@ def check_importable(module_name):
         raise AssertionError("Modules that are not really public but looked "
                              "public and can not be imported: "
                              "{}".format(module_names))
+
+if sys.flags.optimize < 2:
+
+    def test_all_function_have_signature():
+        allowlist = {'concatenate', 'where'}
+
+        for key, value in inspect.getmembers(numpy):
+            if not inspect.isfunction(value):
+                continue
+            if key in allowlist:
+                continue
+            try:
+                inspect.signature(value)
+            except ValueError:
+                raise AssertionError("No signature found for {}".format(key))