CriticalFile-scopePython Plug & play

Re-raise `SystemExit` and `KeyboardInterrupt`

Ensure that SystemExit and KeyboardInterrupt are not caught without being re-raised. Preventing Python from exiting can cause unintended behavior.

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Why this matters

Catching and not re-raising SystemExit or KeyboardInterrupt prevents Python from exiting properly, leading to unexpected behavior.

Bad vs. good

Side-by-side examples engineers can pattern-match during review.

Avoid

try:
    ...
except SystemExit:  # Noncompliant: the SystemExit exception is not re-raised.
    pass

try:
    ...
except BaseException:  # Noncompliant: BaseExceptions encompass SystemExit exceptions and should be re-raised.
    pass

try:
    ...
except:  # Noncompliant: exceptions caught by this statement should be re-raised or a more specific exception should be caught.
    pass

Prefer

try:
    ...
except SystemExit as e:
    ...
    raise e

try:
    ...
except BaseException as e:
    ...
    raise e

try:
    ...
except FileNotFoundError:
    ... # Handle a more specific exception

Related rules

From the same buckets as this rule.

Critical
Avoid equality operators in loop termination conditions
Check if loops use equality operators (== or !=) in termination conditions. These can lead to infinite loops if the condition is never met exactly. Instead, use relational operators like < or > for safer loop termination.
error-handlingreadability-refactor
Critical
Avoid Returning Null in Non-Async Task Methods
Returning null from a Task or Task<T> method causes a NullReferenceException if awaited. Use Task.CompletedTask or Task.FromResult<T>(null) instead.
error-handlingreadability-refactor+1
Critical
Avoid Using Boolean Expressions in `except` Statements
Detect `except` clauses that use `or` or `and` to catch multiple exceptions. This does not work as intended. Recommend using a tuple of exceptions instead.
error-handlingstack-python

Bad vs. good

Side-by-side examples engineers can pattern-match during review.

Avoid

try:
    ...
except SystemExit:  # Noncompliant: the SystemExit exception is not re-raised.
    pass

try:
    ...
except BaseException:  # Noncompliant: BaseExceptions encompass SystemExit exceptions and should be re-raised.
    pass

try:
    ...
except:  # Noncompliant: exceptions caught by this statement should be re-raised or a more specific exception should be caught.
    pass

Prefer

try:
    ...
except SystemExit as e:
    ...
    raise e

try:
    ...
except BaseException as e:
    ...
    raise e

try:
    ...
except FileNotFoundError:
    ... # Handle a more specific exception

Related rules

From the same buckets as this rule.

Critical

Avoid equality operators in loop termination conditions

Check if loops use equality operators (== or !=) in termination conditions. These can lead to infinite loops if the condition is never met exactly. Instead, use relational operators like < or > for safer loop termination.

error-handlingreadability-refactor

Critical

Avoid Returning Null in Non-Async Task Methods

Returning null from a Task or Task<T> method causes a NullReferenceException if awaited. Use Task.CompletedTask or Task.FromResult<T>(null) instead.

error-handlingreadability-refactor+1

Critical

Avoid Using Boolean Expressions in `except` Statements

Detect `except` clauses that use `or` or `and` to catch multiple exceptions. This does not work as intended. Recommend using a tuple of exceptions instead.

error-handlingstack-python