rust-lang/rust-clippy

if_same_then_else Should not warn for `else if` blocks.

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#3,770 opened on Feb 16, 2019

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 (30 comments) (5 reactions) (0 assignees)Rust (1,391 forks)batch import
I-false-positiveS-needs-discussiongood first issue

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Description

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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
}

Contributor guide

Research direction
Review the Clippy lint implementation for `if same then else` and adjust the condition to only emit the warning when the last `if` block has the same condition as the following `else` block, ignoring intermediate `else if` blocks.
Tech stack
rust
Domain
tooling
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
RustGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65