Mark SubmoduleImportation imported with Importation with alias as used

If the name of SubmoduleImportation is same with the alias of other Importation
and it is used, the SubmoduleImportation should be marked as used, too.

Fixes https://github.com/PyCQA/pyflakes/issues/298

2 files changed, 26 insertions, 0 deletions

diff --git a/pyflakes/checker.py b/pyflakes/checker.py
index ad25b5e..756b77e 100644
--- a/pyflakes/checker.py
+++ b/pyflakes/checker.py
@@ -818,6 +818,16 @@ class Checker(object):
 
             try:
                 scope[name].used = (self.scope, node)
+
+                # if the name of SubImportation is same as
+                # alias of other Importation and the alias
+                # is used, SubImportation also should be marked as used.
+                n = scope[name]
+                if isinstance(n, Importation) and n._has_alias():
+                    try:
+                        scope[n.fullName].used = (self.scope, node)
+                    except KeyError:
+                        pass
             except KeyError:
                 pass
             else:
diff --git a/pyflakes/test/test_imports.py b/pyflakes/test/test_imports.py
index f83e77e..4272186 100644
--- a/pyflakes/test/test_imports.py
+++ b/pyflakes/test/test_imports.py
@@ -887,6 +887,22 @@ class Test(TestCase):
         fu.x
         ''')
 
+    def test_used_package_with_submodule_import_of_alias(self):
+        """
+        Usage of package by alias marks submodule imports as used.
+        """
+        self.flakes('''
+        import foo as f
+        import foo.bar
+        f.bar.do_something()
+        ''')
+
+        self.flakes('''
+        import foo as f
+        import foo.bar.blah
+        f.bar.blah.do_something()
+        ''')
+
     def test_unused_package_with_submodule_import(self):
         """
         When a package and its submodule are imported, only report once.