Fix inference error on string format

2 files changed, 6 insertions, 0 deletions

diff --git a/pylint/checkers/strings.py b/pylint/checkers/strings.py
index 528aa5d..cfa1a01 100644
--- a/pylint/checkers/strings.py
+++ b/pylint/checkers/strings.py
@@ -494,6 +494,8 @@ class StringMethodsChecker(BaseChecker):
                             previous = previous.getitem(specifier)
                         except (IndexError, TypeError):
                             warn_error = True
+                        except astroid.InferenceError:
+                            break
                     else:
                         try:
                             # Lookup __getitem__ in the current node,
diff --git a/pylint/test/functional/string_formatting_failed_inference.py b/pylint/test/functional/string_formatting_failed_inference.py
new file mode 100644
index 0000000..aa8d24a
--- /dev/null
+++ b/pylint/test/functional/string_formatting_failed_inference.py
@@ -0,0 +1,4 @@
+""" Testing string format with a failed inference. This should not crash. """
+
+import collections
+"{dict[0]}".format(dict=collections.defaultdict(int))