Review use of panic in datafusion-common crate #3313
Description
Is your feature request related to a problem or challenge? Please describe what you are trying to do.
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/from_slice.rs":68 length_so_far += OffsetSize::from_usize(s.len()).unwrap();
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/pyarrow.rs":70 self.to_pyarrow(py).unwrap()
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":442 let array = $array.as_any().downcast_ref::<$ARRAYTYPE>().unwrap();
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":455 let array = $array.as_any().downcast_ref::<$ARRAYTYPE>().unwrap();
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":543 _ => panic!("Incompatible ScalarValue for list"),
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":566 _ => panic!("Incompatible ScalarValue for list"),
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":604 let array = $array.as_any().downcast_ref::<$ARRAYTYPE>().unwrap();
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":730 _ => panic!("Cannot run arithmetic negate on scalar value: {:?}", self),
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":892 sv => panic!(
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":900 sv => panic!(
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1095 panic!("Expected inner key type of {} but found: {}, value was ({:?})", key_type, inner_key_type, scalar);
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1119 _ => unreachable!("Invalid dictionary keys type: {:?}", key_type),
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1151 _ => unreachable!(),
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1165 _ => unreachable!(),
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1244 .unwrap()
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1370 .unwrap(),
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1444 _ => unreachable!("Invalid dictionary keys type: {:?}", key_type),
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1457 let array = array.as_any().downcast_ref::<Decimal128Array>().unwrap();
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1572 _ => unreachable!("Invalid dictionary keys type: {:?}", key_type),
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1605 array.as_any().downcast_ref::<FixedSizeListArray>().unwrap();
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1642 let array = array.as_any().downcast_ref::<Decimal128Array>().unwrap();
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1711 ScalarValue::List(_, _) => unimplemented!(),
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1742 ScalarValue::Struct(_, _) => unimplemented!(),
"/home/andy/git/apache/arrow-datafusion/datafusion/common/src/scalar.rs":1753 _ => unreachable!("Invalid dictionary keys type: {:?}", key_type),
Describe the solution you'd like
Review code that can panic and see where it makes sense to return a Result instead. For example, It is generally better to use ? than unwrapon results.
The goal is not to remove all panics but review and make sure we are using them appropriately. Bonus points for adding documentation for invariants.
Describe alternatives you've considered
None
Additional context
List generated by https://github.com/andygrove/no-need-to-panic