CodeQL documentation

Use of ‘return’ or ‘yield’ outside a function

ID: py/return-or-yield-outside-function
Kind: problem
Severity: error
Precision: medium
   - reliability
   - correctness
Query suites:
   - python-security-and-quality.qls

Click to see the query in the CodeQL repository

In Python, return and yield statements and the yield from expression can only be used within a function. Using them outside a function or a class method results in a SyntaxError at runtime.


Using these elements outside a function or a class method usually indicates an error in the logic. Consequently, it is not possible to suggest a general fix.


In this example, a return statement is used outside a class method in a class and a yield statement is used outside a function in a scope of a module which would result in a SyntaxError when running this code. In this example, the invalid class could be corrected by placing the return statement in a class method, or by refactoring the class into a function. The invalid yield statement could become part of a new generator function containing the for loop.

# invalid class with return outside a function
class InvalidClass1(object):
    if [1, 2, 3]:
        return "Exists"

# invalid statement with yield outside a function
for i in [1, 2, 3]:
    yield i