Self Assignment

ID

python.self_assignment

Severity

low

Remediation Complexity

trivial

Remediation Risk

low

Remediation Effort

low

Resource

Reliability

Language

Python

Tags

CWE:480, reliability, suspicious-construct

Description

Reports plain assignments whose left-hand side and right-hand side have the same source text — x = x, self.value = self.value. The statement has no semantic effect and is almost always a typo of a surrounding refactor: the developer meant x = y or self.value = value.

x = x                              # FLAW
self.value = self.value            # FLAW

x = x + 1                          # OK — augmented form
self.value = value                 # OK — distinct names

Rationale

Self-assignment slips through review because each character of the line is correct in isolation. The bug is in the relationship between the two sides, which is exactly what a static rule can check cheaply.

Remediation

Either delete the line, or fix the typo so the right-hand side is the value the author intended.

References