python.lang.correctness.common-mistakes.is-comparison-string.identical-is-comparison

Community Favorite
profile photo of semgrepsemgrep
Author
46,927
Download Count*
LGPL Commons Clause
License

Found identical comparison using is. Ensure this is what you intended.

Run Locally

Run in CI

Semgrep CI docs

Defintion

Edit RuleView Source
Open in Playground 
rules:
  - id: identical-is-comparison
    pattern: $S is $S
    message: Found identical comparison using is. Ensure this is what you intended.
    languages:
      - python
    severity: ERROR
    metadata:
      category: correctness
      technology:
        - python
      license: Commons Clause License Condition v1.0[LGPL-2.1-only]

Examples

is-comparison-string.py

x = object()

# ruleid:identical-is-comparison
if x is x:
  print('true')

# ok:identical-is-comparison
if x is None:
  pass

# ok:identical-is-comparison
if (type(X) is str):
  pass

# ok:identical-is-comparison
if x is True:
  pass

# ok:identical-is-comparison
if x is False:
  pass

# ruleid: string-is-comparison
if x is 'hello there':
  pass

# ruleid: string-is-comparison
if "hello there" is x:
  pass

# ok: string-is-comparison
if x is '':
  pass