Filter out non-const nodes.

2 files changed, 3 insertions, 0 deletions

diff --git a/checkers/strings.py b/checkers/strings.py
index 9be6627..2d8dce6 100644
--- a/checkers/strings.py
+++ b/checkers/strings.py
@@ -319,6 +319,8 @@ class StringMethodsChecker(BaseChecker):
             positional, named = get_args(node)
         except astroid.InferenceError:
             return
+        if not isinstance(strnode, astroid.Const):
+            return
         try:
             fields, num_args = parse_format_method_string(strnode.value)
         except utils.IncompleteFormatString:
diff --git a/test/input/func_string_format_py27.py b/test/input/func_string_format_py27.py
index a492bb2..458f462 100644
--- a/test/input/func_string_format_py27.py
+++ b/test/input/func_string_format_py27.py
@@ -69,3 +69,4 @@ def pprint():
     print log("{}".format(2, "info"))

     print "{pid}".format(pid=os.getpid())

     print "{0.missing}".format(2)

+    print str("{}").format(2)