Add a new error, 'invalid-unary-type-operand'.

This new error is emitted when an unary operand is used on
something which doesn't support that operation (for instance,
using the unary bitwise inversion operator on an instance which
doesn't implement __invert__).

2 files changed, 19 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 29cbc87..e6204fc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -155,6 +155,12 @@ ChangeLog for Pylint
       if pylintrc is not found. Dotted pylintrc files will not be searched
       in the parents of the current folder, as it is done for pylintrc.
 
+    * Add a new error, 'invalid-unary-type-operand', emitted when
+      an unary operand is used on something which doesn't support that
+      operation (for instance, using the unary bitwise inversion operator
+      on an instance which doesn't implement __invert__).
+      
+
 
 2015-03-14 -- 1.4.3
 
diff --git a/pylint/checkers/typecheck.py b/pylint/checkers/typecheck.py
index c7c2200..5dd3ff9 100644
--- a/pylint/checkers/typecheck.py
+++ b/pylint/checkers/typecheck.py
@@ -88,6 +88,10 @@ MSGS = {
               'not-context-manager',
               'Used when an instance in a with statement doesn\'t implement '
               'the context manager protocol(__enter__/__exit__).'),
+    'E1130': ('%s',
+              'invalid-unary-operand-type',
+              'Emitted when an unary operand is used on an object which does not '
+              'support this type of operation'),
     }
 
 # builtin sequence types in Python 2 and 3.
@@ -702,6 +706,15 @@ accessed. Python regular expressions are accepted.'}
                     self.add_message('not-context-manager',
                                      node=node, args=(infered.name, ))
 
+    @check_messages('invalid-unary-operand-type')
+    def visit_unaryop(self, node):
+        """Detect TypeErrors for unary operands."""
+
+        for error in node.type_errors():
+            # Let the error customize its output.
+            self.add_message('invalid-unary-operand-type',
+                             args=str(error), node=node)
+
 
 def register(linter):
     """required method to auto register this checker """