rust-lang/rust-clippy

if_same_then_else Should not warn for `else if` blocks.

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#3,770 创建于 2019年2月16日

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I-false-positiveS-needs-discussiongood first issue

描述

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
}

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研究方向
Modify the `if same then else` lint in `clippy lints/src/if same then else.rs` to skip warning on `else if` blocks where the last `if` does not have the same condition as the final `else`. The current logic should be adjusted so that only when the last `if` matches the `else` branch does it warn. Update the corresponding test file `tests/ui/if same then else.rs` to include new test cases. Comments in the issue discuss edge cases like non trivial conditions and nested else ifs.