The big rustc format made some code I care about much less readable. Here's an example:

- ref mut local @ LocalValue::Live(Operand::Immediate(_)) | - ref mut local @ LocalValue::Uninitialized => { - Ok(Ok(local)) - } + ref mut local @ LocalValue::Live(Operand::Immediate(_)) + | ref mut local @ LocalValue::Uninitialized => Ok(Ok(local)),

The actual code running here for this branch got moved onto the same line as the last line of a pattern. That makes it quite hard to visually identify this code -- compared to the old version of the code, the visual separation of pattern and code got lost.