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unreachable-after-return

Category: Unreachable Code
Severity: Critical
Triggered by: pyscn analyze, pyscn check

What it does

Flags statements that appear after a return statement in the same code block.

Why is this a problem?

Code placed after return never executes. This is usually one of:

  • A leftover from refactoring — the return was moved up and the code below was forgotten.
  • A bug — the programmer expected the code to run but a control-flow change made it unreachable.
  • A misplaced cleanup — something that should run before returning.

In every case, the code is dead: it takes up reading time, it isn't covered by tests (because it can't be), and if it hides a bug, that bug will never be reported from user behaviour.

Example

def charge(order):
    if order.total <= 0:
        return None
        log.debug("zero-value charge")   # ← never executes
    ...

Use instead

Move the statement above the return, or delete it if it's no longer needed.

def charge(order):
    if order.total <= 0:
        log.debug("zero-value charge")
        return None
    ...

Options

Option Default Description
dead_code.detect_after_return true Set to false to disable this rule.
dead_code.min_severity "warning" "critical" keeps only this kind of finding; "info" surfaces more.
dead_code.ignore_patterns [] Regex patterns matched against the source line; matches are suppressed.

References