if_same_then_else Should not warn for `else if` blocks.

View all comments

if condition1() {
  1
} else if condition2() {
  1
} else if condition3() {
  2
} else {
  3
}

There are many cases where code like this shouldn't be warned on. While you could do condition1() || condition2() often times it is more clear of the intent if they are separate. Especially if the conditions are non-trivial compared to the value being returned.

I think the right time for this warning to warn is if the last if has the same condition as the else. For example the following two cases would warn.

if condition1() {
  1
} else {
  1
}

if condition1() {
  1
} else if condition2() {
  2
} else {
  2
}

Start by locating the if_same_then_else lint entry point and its existing tests in rust-clippy. Compare the reported chained else-if example with the two cases that should warn, then update the behavior and verify that the intended warning cases still pass.