Make variables shadow magics in autocompletion

docs/source/whatsnew/pr/variables-shadow-magics-in-autocompletion.rst

@@ -0,0 +1,1 b''
+Variables now shadow magics in autocompletion. See :ghissue:`4877` and :ghpull:`10542`.

IPython/core/completer.py

@@ -1158,10 +1158,17 b' class IPCompleter(Completer):'
         # - user gives %: do both line and cell magics
         # - no prefix: do both
         # In other words, line magics are skipped if the user gives %% explicitly
+        #
+        # We also exclude magics that match any currently visible names:
+        # https://github.com/ipython/ipython/issues/4877
         bare_text = text.lstrip(pre)
-        comp = [ pre2+m for m in cell_magics if m.startswith(bare_text)]
+        global_matches = self.global_matches(bare_text)
+        matches = lambda magic: magic.startswith(bare_text) \
+                                and magic not in global_matches
+        comp = [ pre2+m for m in cell_magics if matches(m)]
         if not text.startswith(pre2):
-            comp += [ pre+m for m in line_magics if m.startswith(bare_text)]
+            comp += [ pre+m for m in line_magics if matches(m)]
+
         return [cast_unicode_py2(c) for c in comp]
 
     def _jedi_matches(self, cursor_column:int, cursor_line:int, text:str):

IPython/core/tests/test_completer.py

@@ -519,31 +519,33 b' def test_line_cell_magics():'
 
 
 def test_magic_completion_order():
-
     ip = get_ipython()
     c = ip.Completer
 
-    # Test ordering of magics and non-magics with the same name
-    # We want the non-magic first
-
-    # Before importing matplotlib, there should only be one option:
-
-    text, matches = c.complete('mat')
-    nt.assert_equal(matches, ["%matplotlib"])
+    # Test ordering of line and cell magics.
+    text, matches = c.complete("timeit")
+    nt.assert_equal(matches, ["%timeit", "%%timeit"])
 
 
-    ip.run_cell("matplotlib = 1")  # introduce name into namespace
+def test_magic_completion_shadowing():
+    ip = get_ipython()
+    c = ip.Completer
 
-    # After the import, there should be two options, ordered like this:
-    text, matches = c.complete('mat')
-    nt.assert_equal(matches, ["matplotlib", "%matplotlib"])
+    # Before importing matplotlib, %matplotlib magic should be the only option.
+    text, matches = c.complete("mat")
+    nt.assert_equal(matches, ["%matplotlib"])
 
+    # The newly introduced name should shadow the magic.
+    ip.run_cell("matplotlib = 1")
+    text, matches = c.complete("mat")
+    nt.assert_equal(matches, ["matplotlib"])
 
-    ip.run_cell("timeit = 1")  # define a user variable called 'timeit'
+    # After removing matplotlib from namespace, the magic should again be
+    # the only option.
+    del ip.user_ns["matplotlib"]
+    text, matches = c.complete("mat")
+    nt.assert_equal(matches, ["%matplotlib"])
 
-    # Order of user variable and line and cell magics with same name:
-    text, matches = c.complete('timeit')
-    nt.assert_equal(matches, ["timeit", "%timeit", "%%timeit"])
 
 def test_match_dict_keys():
     """