Don't emit import-self and cyclic-import for relative imports of modules with the same name as the package itself.

The problem was partially the fault of astroid.modutils.get_module_part,
in combination with a given context file.
The function returned 'dummy' as the module part for the string
`dummy.dummy.Dummy`, which is in fact true, since the first dummy
is the package and the second dummy is the module from where Dummy
gets loaded. But get_module_part has no way to know this semantic
inference, that the second dummy is a relative import inside the
first one. As such, it's better to just skip the check if the
condition of being relative inside a __init__.py file is found,
since there's no way to load itself in that case.

Closes issues #708 and #706.

6 files changed, 34 insertions, 4 deletions

diff --git a/ChangeLog b/ChangeLog
index c3124e027..6136d891e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -18,6 +18,10 @@ ChangeLog for Pylint
     * Fix a crash which occurred when old visit methods are encountered
       in plugin modules. Closes issue #711.
 
+    * Don't emit import-self and cyclic-import for relative imports
+      of modules with the same name as the package itself.
+      Closes issues #708 and #706.
+
 
 2015-11-29 -- 1.5.0
 
diff --git a/pylint/checkers/imports.py b/pylint/checkers/imports.py
index a2f381cbf..0e16d1817 100644
--- a/pylint/checkers/imports.py
+++ b/pylint/checkers/imports.py
@@ -496,14 +496,26 @@ given file (report RP0402 must not be disabled)'}
 
     def _add_imported_module(self, node, importedmodname):
         """notify an imported module, used to analyze dependencies"""
+        module_file = node.root().file
+        context_name = node.root().name
+        base = os.path.splitext(os.path.basename(module_file))[0]
+
+        # Determine if we have a `from .something import` in a package's
+        # __init__. This means the module will never be able to import
+        # itself using this condition (the level will be bigger or
+        # if the same module is named as the package, it will be different
+        # anyway).
+        if isinstance(node, astroid.ImportFrom):
+            if node.level and node.level > 0 and base == '__init__':
+                return
+
         try:
             importedmodname = get_module_part(importedmodname,
-                                              node.root().file)
+                                              module_file)
         except ImportError:
             pass
-        context_name = node.root().name
+
         if context_name == importedmodname:
-            # module importing itself !
             self.add_message('import-self', node=node)
         elif not is_standard_module(importedmodname):
             # handle dependencies
diff --git a/pylint/test/regrtest_data/dummy/__init__.py b/pylint/test/regrtest_data/dummy/__init__.py
new file mode 100644
index 000000000..0b43a7096
--- /dev/null
+++ b/pylint/test/regrtest_data/dummy/__init__.py
@@ -0,0 +1,3 @@
+# pylint: disable=missing-docstring
+from .dummy import DUMMY
+from .another import ANOTHER
diff --git a/pylint/test/regrtest_data/dummy/another.py b/pylint/test/regrtest_data/dummy/another.py
new file mode 100644
index 000000000..046b44760
--- /dev/null
+++ b/pylint/test/regrtest_data/dummy/another.py
@@ -0,0 +1,4 @@
+# pylint: disable=missing-docstring
+
+ANOTHER = 42
+
diff --git a/pylint/test/regrtest_data/dummy/dummy.py b/pylint/test/regrtest_data/dummy/dummy.py
new file mode 100644
index 000000000..60345dc13
--- /dev/null
+++ b/pylint/test/regrtest_data/dummy/dummy.py
@@ -0,0 +1,2 @@
+# pylint: disable=missing-docstring
+DUMMY = 42
diff --git a/pylint/test/test_self.py b/pylint/test/test_self.py
index 69b739c09..fae640367 100644
--- a/pylint/test/test_self.py
+++ b/pylint/test/test_self.py
@@ -288,7 +288,12 @@ class RunTC(unittest.TestCase):
         actual_output = out.getvalue()
         self.assertEqual(expected_output.strip(), actual_output.strip())
 
-                      
+    def test_import_itself_not_accounted_for_relative_imports(self):
+        expected = 'No config file found, using default configuration'
+        package = join(HERE, 'regrtest_data', 'dummy')
+        self._test_output([package, '--disable=locally-disabled', '-rn'],
+                          expected_output=expected)
+                           
 
 
 if __name__ == '__main__':