Useless assignment to local variable¶
ID: rb/useless-assignment-to-local
Kind: problem
Security severity:
Severity: warning
Precision: medium
Tags:
- maintainability
- external/cwe/cwe-563
Query suites:
- ruby-security-and-quality.qls
Click to see the query in the CodeQL repository
A value is assigned to a local variable, but either that variable is never read later on, or its value is always overwritten before being read. This means that the original assignment has no effect, and could indicate a logic error or incomplete code.
Recommendation¶
Ensure that you check the control and data flow in the method carefully. If a value is really not needed, consider omitting the assignment. Be careful, though: if the right-hand side has a side-effect (like performing a method call), it is important to keep this to preserve the overall behavior.
Example¶
In the following example, the return value of the call to send on line 2 is assigned to the local variable result, but then never used.
def f(x)
result = send(x)
waitForResponse
return getResponse
end
Assuming that send returns a status code indicating whether the operation succeeded or not, the value of result should be checked, perhaps like this:
def f(x)
result = send(x)
# check for error
if (result == -1)
raise "Unable to send, check network."
end
waitForResponse
return getResponse
end
References¶
Wikipedia: Dead store.
Common Weakness Enumeration: CWE-563.