pi-lens/rules/tree-sitter-queries/python/unreachable-except.yml

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# Unreachable Except Clause
# Detects except clauses that can never be reached
id: unreachable-except
name: Unreachable Except Clause
severity: warning
category: reliability
defect_class: correctness
inline_tier: blocking
language: python

message: "Unreachable except clause — earlier except catches all"

description: |
  When a bare 'except' or 'except Exception' comes before specific
  exception handlers, those specific handlers are never reached.
  
  ✅ FIX: Order from specific to general
  
  ```python
  try:
      process()
  except ValueError:  # Specific first
      handle_value_error()
  except Exception:  # General last
      handle_general()
  ```

query: |
  (try_statement
    (except_clause
      "except") @GENERAL
    (except_clause
      "except"
      (identifier) @SPECIFIC))

metavars:
  - GENERAL
  - SPECIFIC

tags:
  - reliability
  - dead-code
  - exceptions

examples:
  bad: |
    try:
        process()
    except:  # BAD - catches everything
        handle_all()
    except ValueError:  # UNREACHABLE!
        handle_value()
  
  good: |
    try:
        process()
    except ValueError:  # GOOD - specific first
        handle_value()
    except Exception:  # GOOD - general last
        handle_general()

has_fix: false