Make sure to find both stubs and non-stubs with usages

jedi/inference/references.py

@@ -1,5 +1,6 @@
 from jedi.inference import imports
 from jedi.inference.filters import ParserTreeFilter
+from jedi.inference.gradual.conversion import convert_names
 
 
 def _resolve_names(definition_names, avoid_names=()):
@@ -29,6 +30,14 @@ def _dictionarize(names):
 def _find_defining_names(module_context, tree_name):
     found_names = _find_names(module_context, tree_name)
 
+    for name in list(found_names):
+        # Convert from/to stubs, because those might also be usages.
+        found_names |= set(convert_names(
+            [name],
+            only_stubs=not name.get_root_context().is_stub(),
+            prefer_stub_to_compiled=False
+        ))
+
     found_names |= set(_find_global_variables(found_names, tree_name.value))
     for name in list(found_names):
         if name.api_type == 'param' or name.tree_name is None \

test/completion/usages.py

@@ -349,3 +349,11 @@ class DefinitelyNotGlobal:
     def my_global(self):
         def my_global(self):
             pass
+
+# -----------------
+# stubs
+# -----------------
+
+from stub_folder import with_stub
+#< ('stub:stub_folder.with_stub', 5, 4), ('stub_folder.with_stub', 5, 4), (0, 10)
+with_stub.stub_function

test/run.py

@@ -265,7 +265,10 @@ class IntegrationTestCase(BaseTestCase):
         result = self.script(environment).find_references(self.line_nr, self.column)
         self.correct = self.correct.strip()
         compare = sorted(
-            (re.sub(r'^test\.completion\.', '', r.module_name), r.line, r.column)
+            (('stub:' if r.is_stub() else '')
+             + re.sub(r'^test\.completion\.', '', r.module_name),
+             r.line,
+             r.column)
             for r in result
         )
         wanted = []