Fixed a crash that occurred for ``bad-str-strip-call`` when ``strip()`` received ``None``

Close #2743

3 files changed, 5 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index 18703237f..e4f6d2575 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -7,6 +7,9 @@ What's New in Pylint 2.3.0?
 
 Release date: TBA
 
+* Fixed a crash that occurred for ``bad-str-strip-call`` when ``strip()`` received ``None``
+
+  Close #2743
 
 * Don't emit ``*-not-iterating`` checks for builtins consumed by ``itertools``
 
diff --git a/pylint/checkers/strings.py b/pylint/checkers/strings.py
index 8d1a101e7..dd2904301 100644
--- a/pylint/checkers/strings.py
+++ b/pylint/checkers/strings.py
@@ -345,7 +345,7 @@ class StringFormatChecker(BaseChecker):
         ):
             if func.name in ("strip", "lstrip", "rstrip") and node.args:
                 arg = utils.safe_infer(node.args[0])
-                if not isinstance(arg, astroid.Const):
+                if not isinstance(arg, astroid.Const) or not isinstance(arg.value, str):
                     return
                 if len(arg.value) != len(set(arg.value)):
                     self.add_message(
diff --git a/pylint/test/functional/suspicious_str_strip_call.py b/pylint/test/functional/suspicious_str_strip_call.py
index e859f25f8..bc3a27c27 100644
--- a/pylint/test/functional/suspicious_str_strip_call.py
+++ b/pylint/test/functional/suspicious_str_strip_call.py
@@ -7,3 +7,4 @@ __revision__ = 1
 u''.strip('http://')  # [bad-str-strip-call]
 u''.lstrip('http://')  # [bad-str-strip-call]
 b''.rstrip('http://')  # [bad-str-strip-call]
+"some_sensible_string".strip(None) # Don't crash