TP0301

Warning: warning: broad except clause discards the exception

Messages

this clause catches every exception and discards it, with help catch a specific class, re-raise with 'raise', or bind it with 'as e' and use it (M16)

Example

From the golden case tests/cases/m16/tp0301_broad.tpn:

# A broad except clause that discards the exception is warning TP0301 (SPEC §3.10).
def risky(n: int) -> int:
    return [1, 2][n]

try:
    print(risky(5))
except:
    pass

try:
    print(risky(5))
except Exception:
    print("something failed")

try:
    print(risky(5))
except (KeyError, Exception):
    print("something failed")

try:
    print(risky(5))
except Exception as e:
    print("unused binding")

# Deliberate handling: logging the exception, re-raising, or catching a specific class.
try:
    print(risky(5))
except Exception as e:
    print("failed:", e)

try:
    try:
        print(risky(5))
    except:
        print("cleaning up")
        raise
except IndexError:
    print("index")

try:
    print(risky(5))
except IndexError:
    pass

def handler(f: Callable[[], None]):
    try:
        f()
    except Exception:
        def later():
            raise KeyError("not a re-raise of this clause")
        later()

The compiler reports:

tp0301_broad.tpn:7:1: warning TP0301: this clause catches every exception and discards it
  help: catch a specific class, re-raise with 'raise', or bind it with 'as e' and use it
tp0301_broad.tpn:12:1: warning TP0301: this clause catches every exception and discards it
  help: catch a specific class, re-raise with 'raise', or bind it with 'as e' and use it
tp0301_broad.tpn:17:1: warning TP0301: this clause catches every exception and discards it
  help: catch a specific class, re-raise with 'raise', or bind it with 'as e' and use it
tp0301_broad.tpn:22:1: warning TP0301: this clause catches every exception and discards it
  help: catch a specific class, re-raise with 'raise', or bind it with 'as e' and use it
tp0301_broad.tpn:48:5: warning TP0301: this clause catches every exception and discards it
  help: catch a specific class, re-raise with 'raise', or bind it with 'as e' and use it

The specification lists every code.