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| author | Yuki Okushi <jtitor@2k36.org> | 2022-08-25 08:50:59 +0900 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2022-08-25 08:50:59 +0900 |
| commit | df354f5cf6e0c0a68d7c4d1b1d945182eb7d7811 (patch) | |
| tree | 58ea75ae736ceff488adf5f81bdedaaddf210e96 | |
| parent | 0fd4a74139347edc1429de3f9d397ec6583698fd (diff) | |
| parent | eb2fdd917ef05184c7ef2eab707183b07d68ff5e (diff) | |
| download | rust-df354f5cf6e0c0a68d7c4d1b1d945182eb7d7811.tar.gz rust-df354f5cf6e0c0a68d7c4d1b1d945182eb7d7811.zip | |
Rollup merge of #100921 - ChayimFriedman2:and-eager-eval, r=JohnTitor
Add a warning about `Option/Result::and()` being eagerly evaluated Copied from `or()`. Inspired by [this StackOverflow question](https://stackoverflow.com/questions/73461846/why-is-in-rust-the-expression-in-option-and-evaluated-if-option-is-none). [The PR for `or()`](https://github.com/rust-lang/rust/pull/46548) mentions the Clippy lint `or_fun_call` which doesn't exist for `and()` (although there is `unnecessary_lazy_evaluations`). I still think this warning is also good for `and()`. Feel free to close if you disagree.
| -rw-r--r-- | library/core/src/option.rs | 6 | ||||
| -rw-r--r-- | library/core/src/result.rs | 5 |
2 files changed, 11 insertions, 0 deletions
diff --git a/library/core/src/option.rs b/library/core/src/option.rs index bca73cb770f..93417586363 100644 --- a/library/core/src/option.rs +++ b/library/core/src/option.rs @@ -1189,6 +1189,12 @@ impl<T> Option<T> { /// Returns [`None`] if the option is [`None`], otherwise returns `optb`. /// + /// Arguments passed to `and` are eagerly evaluated; if you are passing the + /// result of a function call, it is recommended to use [`and_then`], which is + /// lazily evaluated. + /// + /// [`and_then`]: Option::and_then + /// /// # Examples /// /// ``` diff --git a/library/core/src/result.rs b/library/core/src/result.rs index 45b052c824d..75dcb4cdba9 100644 --- a/library/core/src/result.rs +++ b/library/core/src/result.rs @@ -1285,6 +1285,11 @@ impl<T, E> Result<T, E> { /// Returns `res` if the result is [`Ok`], otherwise returns the [`Err`] value of `self`. /// + /// Arguments passed to `and` are eagerly evaluated; if you are passing the + /// result of a function call, it is recommended to use [`and_then`], which is + /// lazily evaluated. + /// + /// [`and_then`]: Result::and_then /// /// # Examples /// |