Fix a false positive with 'too-many-format-args', when the format string contains mixed attribute access arguments and manual fields. Closes issue #322.

4 files changed, 16 insertions, 8 deletions

diff --git a/ChangeLog b/ChangeLog
index 3375a71..d9276d8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -88,6 +88,10 @@ ChangeLog for Pylint
 
     * Generate html output for missing files. Closes issue #320.
 
+    * Fix a false positive with 'too-many-format-args', when the format
+      string contains mixed attribute access arguments and manual
+      fields. Closes issue #322.
+
 
 2014-07-26  --  1.3.0
 
diff --git a/checkers/strings.py b/checkers/strings.py
index a30d29c..40995f6 100644
--- a/checkers/strings.py
+++ b/checkers/strings.py
@@ -178,6 +178,7 @@ def parse_format_method_string(format_string):
             if isinstance(keyname, numbers.Number):
                 # In Python 2 it will return long which will lead
                 # to different output between 2 and 3
+                manual_pos_arg.add(keyname)
                 keyname = int(keyname)
             keys.append((keyname, list(fielditerator)))
         else:
@@ -363,8 +364,6 @@ class StringMethodsChecker(BaseChecker):
             self.add_message('bad-format-string', node=node)
             return
 
-        manual_fields = set(field[0] for field in fields
-                            if isinstance(field[0], numbers.Number))
         named_fields = set(field[0] for field in fields
                            if isinstance(field[0], basestring))
         if num_args and manual_pos:
@@ -405,12 +404,7 @@ class StringMethodsChecker(BaseChecker):
             # num_args can be 0 if manual_pos is not.
             num_args = num_args or manual_pos
             if positional > num_args:
-                # We can have two possibilities:
-                # * "{0} {1}".format(a, b)
-                # * "{} {} {}".format(a, b, c, d)
-                # We can check the manual keys for the first one.
-                if len(manual_fields) != positional:
-                    self.add_message('too-many-format-args', node=node)
+                self.add_message('too-many-format-args', node=node)
             elif positional < num_args:
                 self.add_message('too-few-format-args', node=node)
 
diff --git a/test/functional/string_formatting.py b/test/functional/string_formatting.py
index 594c870..8d9707c 100644
--- a/test/functional/string_formatting.py
+++ b/test/functional/string_formatting.py
@@ -119,3 +119,11 @@ def issue310():
     """ Test a regression using duplicate manual position arguments. """

     '{0} {1} {0}'.format(1, 2)

     '{0} {1} {0}'.format(1) # [too-few-format-args]

+

+def issue322():

+    """ Test a regression using mixed manual position arguments

+    and attribute access arguments.

+    """

+    '{0}{1[FOO]}'.format(123, {'FOO': 456})

+    '{0}{1[FOO]}'.format(123, {'FOO': 456}, 321) # [too-many-format-args]

+    '{0}{1[FOO]}'.format(123) # [too-few-format-args]

diff --git a/test/functional/string_formatting.txt b/test/functional/string_formatting.txt
index 593c161..5a4bf66 100644
--- a/test/functional/string_formatting.txt
+++ b/test/functional/string_formatting.txt
@@ -34,3 +34,5 @@ too-many-format-args:114:nested_issue294:Too many arguments for format string
 missing-format-argument-key:115:nested_issue294:Missing keyword argument 'a' for format string
 missing-format-attribute:116:nested_issue294:Missing format attribute 'x' in format specifier 'a.x'
 too-few-format-args:121:issue310:Not enough arguments for format string
+too-many-format-args:128:issue322:Too many arguments for format string
+too-few-format-args:129:issue322:Not enough arguments for format string