diff contrib/check-code.py @ 13026:53391819f195

check-code: catch Python 'is' comparing number or string literals

The Python 'is' operator compares object identity, so it should
definitely not be applied to string or number literals, which Python
implementations are free to represent with a temporary object.

This should catch the following kinds of bogus expressions (examples):

  x is 'foo'     x is not 'foo'
  x is "bar"     x is not "bar"
  x is 42        x is not 42
  x is -36       x is not -36

As originally proposed by Martin Geisler, amended with catching
negative numbers.

--- a/contrib/check-code.py	Sun Nov 21 13:16:59 2010 +0100
+++ b/contrib/check-code.py	Sun Nov 21 11:52:27 2010 +0100
@@ -149,6 +149,7 @@
     (r'raise Exception', "don't raise generic exceptions"),
     (r'ui\.(status|progress|write|note|warn)\([\'\"]x',
      "warning: unwrapped ui message"),
+    (r' is\s+(not\s+)?["\'0-9-]', "object comparison with literal"),
 ]
 
 pyfilters = [