跳转至

unreachable-after-raise

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

What it does

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

Why is this a problem?

A raise unconditionally unwinds the stack. Any statement following it in the same block is never executed.

This usually points to:

  • Stale cleanup — code that was supposed to run before the exception was thrown.
  • A refactor artefact — the raise replaced an earlier branch and surrounding lines were left behind.
  • A logic bug — the author assumed execution would continue past the raise.

Dead code after raise will never be exercised by tests and will never surface in production, so any bug it hides is silent.

Example

def withdraw(account, amount):
    if amount > account.balance:
        raise InsufficientFunds(account.id)
        account.balance -= amount   # ← never executes
    account.balance -= amount

Use instead

Move the statement above the raise, or delete it.

def withdraw(account, amount):
    if amount > account.balance:
        raise InsufficientFunds(account.id)
    account.balance -= amount

Options

Option Default Description
dead_code.detect_after_raise 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