A false positive occurs when a user specifies a using declaration for…

… a stream operator:

    10: using ns::operator<<;
    file.cpp:10: Missing spaces around << [whitespace/operators] [3]

The regular expression has been updated to find this valid use case of the <<
text string.

Review URL: https://codereview.appspot.com/22190043

Patch from Matt Clarkson <[email protected]>.

cpplint/cpplint.py

@@ -2681,8 +2681,11 @@ def CheckSpacing(filename, clean_lines, linenum, nesting_state, error):
           'Missing spaces around %s' % match.group(1))
   # We allow no-spaces around << when used like this: 10<<20, but
   # not otherwise (particularly, not when used as streams)
-  match = Search(r'(\S)(?:L|UL|ULL|l|ul|ull)?<<(\S)', line)
-  if match and not (match.group(1).isdigit() and match.group(2).isdigit()):
+  # Also ignore using ns::operator<<;
+  match = Search(r'(operator|\S)(?:L|UL|ULL|l|ul|ull)?<<(\S)', line)
+  if (match and
+      not (match.group(1).isdigit() and match.group(2).isdigit()) and
+      not (match.group(1) == 'operator' and match.group(2) == ';')):
     error(filename, linenum, 'whitespace/operators', 3,
           'Missing spaces around <<')
   elif not Match(r'#.*include', line):

cpplint/cpplint_unittest.py

@@ -1562,6 +1562,8 @@ def testCheckCheck(self):
                    'Consider using CHECK_GT instead of CHECK(a > b)'
                    '  [readability/check] [2]'])
 
+    self.TestLint('using some::namespace::operator<<;', '')
+    self.TestLint('using some::namespace::operator>>;', '')
     self.TestLint('CHECK(x ^ (y < 42))', '')
     self.TestLint('CHECK((x > 42) ^ (x < 54))', '')
     self.TestLint('CHECK(a && b < 42)', '')