suggest replacing let else with ? statement where applicable #8755

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1. est31 commented on Apr 27, 2022

   

   est31

   on Apr 27, 2022

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   I guess the question_mark lint could be extended to handle this case? Also, maybe one needs to watch out to not suggest let-else first (#8437) to then suggest ?, but suggest ? right away. IDK how conflicts like this are handled.

   👍React with 👍1Reacted by Marijn Suijten
2. est31 commented on Jan 11, 2023

   

   est31

   on Jan 11, 2023

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   Another example where this lint would have been useful: rust-lang/cargo@cf716fc
3. est31 commented on Jan 11, 2023

   

   est31

   on Jan 11, 2023

   Last edited by est31

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   Given the two samples that we have, I think that most of the times the lint would fire is for functions that return Option. If we simplify for Option, that means that checking for the pattern should be pretty easy. For Result it doesn't make that much sense, as the else clause can't access the thing inside Err.
4. MarijnS95 commented on Jan 24, 2023

   

   MarijnS95

   on Jan 24, 2023

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   Yes, would love to see the question_mark lint extended to let-else, and also the mention by @est31 to not first suggest manual_let_else on a block of code, followed by question_mark on the refactored code.

   We currently have two patterns in our codebase with both Option and Result where the question mark operator could/should be suggested:

       let x = None::<u32>;
       // Suggest ? here
       let Some(x) = x else {
           return None;
       };
   
       // Suggest .ok()? here
       let Ok(x) = std::fs::read_to_string("foo") else {
           return None;
       };

   Thanks!
5. bors

   added a commit that references this issue on Jul 3, 2023

   Auto merge of #10924 - est31:manual_let_else_question_mark, r=Centri3…

   ...

   This issue will close once commit 3f17c5c is merged into the 'main' branch.

   3f17c5c
6. bors

   closed this as completedin 3f17c5con Jul 3, 2023