Consider this example code.
let startVariableWithLongName = 21
let endVariableWithLongName = 42
let offsetVariableWithLongNameToMakeLinesSuperLong = 25
let myOpenEndedRangeThatHasAReallyLongName = (startVariableWithLongName + offsetVariableWithLongNameToMakeLinesSuperLong)..<(endVariableWithLongName + offsetVariableWithLongNameToMakeLinesSuperLong)
The final line is about 200 characters, which swift format attempts to fix to 100 by default (I believe).
Running swift format using Swift 6.2.3 results in the following:
let startVariableWithLongName = 21
let endVariableWithLongName = 42
let offsetVariableWithLongNameToMakeLinesSuperLong = 25
let myOpenEndedRangeThatHasAReallyLongName =
(startVariableWithLongName + offsetVariableWithLongNameToMakeLinesSuperLong)
..<(endVariableWithLongName + offsetVariableWithLongNameToMakeLinesSuperLong)
which results in an error, since ..< is now treated as a prefix operator rather than the infix it should be.
This example is contrived, but this is quite realistic when code is deeply nested with shorter variable names.