Extract single_match_else UI test
There's only one test currently. I also updated the lint doc with a 'good' example and changed the lint help text a bit. cc #2038
This commit is contained in:
Philipp Hansch
parent
6253d457e1
commit
3f72d4d630
@ -45,7 +45,7 @@ declare_clippy_lint! {
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"a match statement with a single nontrivial arm (i.e. where the other arm is `_ => {}`) instead of `if let`"
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}
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/// **What it does:** Checks for matches with a two arms where an `if let` will
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/// **What it does:** Checks for matches with a two arms where an `if let else` will
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/// usually suffice.
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///
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/// **Why is this bad?** Just readability – `if let` nests less than a `match`.
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@ -53,16 +53,29 @@ declare_clippy_lint! {
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/// **Known problems:** Personal style preferences may differ.
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///
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/// **Example:**
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///
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/// Using `match`:
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///
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/// ```rust
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/// match x {
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/// Some(ref foo) => bar(foo),
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/// _ => bar(other_ref),
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/// }
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/// ```
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///
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/// Using `if let` with `else`:
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///
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/// ```rust
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/// if let Some(ref foo) = x {
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/// bar(foo);
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/// } else {
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/// bar(other_ref);
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/// }
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/// ```
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declare_clippy_lint! {
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pub SINGLE_MATCH_ELSE,
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pedantic,
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"a match statement with a two arms where the second arm's pattern is a wildcard instead of `if let`"
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"a match statement with a two arms where the second arm's pattern is a placeholder instead of a specific match pattern"
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}
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/// **What it does:** Checks for matches where all arms match a reference,
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@ -14,26 +14,12 @@
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#![warn(clippy::all)]
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#![allow(unused, clippy::redundant_pattern_matching)]
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#![warn(clippy::single_match_else, clippy::match_same_arms)]
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#![warn(clippy::match_same_arms)]
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enum ExprNode {
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ExprAddrOf,
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Butterflies,
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Unicorns,
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}
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static NODE: ExprNode = ExprNode::Unicorns;
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fn dummy() {
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}
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fn unwrap_addr() -> Option<&'static ExprNode> {
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match ExprNode::Butterflies {
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ExprNode::ExprAddrOf => Some(&NODE),
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_ => { let x = 5; None },
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}
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}
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fn ref_pats() {
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{
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let v = &Some(0);
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@ -1,155 +1,171 @@
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error: you seem to be trying to use match for destructuring a single pattern. Consider using `if let`
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--> $DIR/matches.rs:31:5
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31 | / match ExprNode::Butterflies {
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32 | | ExprNode::ExprAddrOf => Some(&NODE),
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33 | | _ => { let x = 5; None },
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34 | | }
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| |_____^ help: try this: `if let ExprNode::ExprAddrOf = ExprNode::Butterflies { Some(&NODE) } else { let x = 5; None }`
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= note: `-D clippy::single-match-else` implied by `-D warnings`
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error: you don't need to add `&` to all patterns
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--> $DIR/matches.rs:40:9
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--> $DIR/matches.rs:26:9
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40 | / match v {
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41 | | &Some(v) => println!("{:?}", v),
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42 | | &None => println!("none"),
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43 | | }
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26 | / match v {
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27 | | &Some(v) => println!("{:?}", v),
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28 | | &None => println!("none"),
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29 | | }
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| |_________^
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= note: `-D clippy::match-ref-pats` implied by `-D warnings`
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help: instead of prefixing all patterns with `&`, you can dereference the expression
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40 | match *v {
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41 | Some(v) => println!("{:?}", v),
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42 | None => println!("none"),
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26 | match *v {
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27 | Some(v) => println!("{:?}", v),
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28 | None => println!("none"),
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error: you seem to be trying to use match for destructuring a single pattern. Consider using `if let`
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--> $DIR/matches.rs:50:5
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50 | / match tup {
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51 | | &(v, 1) => println!("{}", v),
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52 | | _ => println!("none"),
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53 | | }
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| |_____^ help: try this: `if let &(v, 1) = tup { println!("{}", v) } else { println!("none") }`
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error: you don't need to add `&` to all patterns
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--> $DIR/matches.rs:50:5
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--> $DIR/matches.rs:36:5
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50 | / match tup {
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51 | | &(v, 1) => println!("{}", v),
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52 | | _ => println!("none"),
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53 | | }
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36 | / match tup {
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37 | | &(v, 1) => println!("{}", v),
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38 | | _ => println!("none"),
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39 | | }
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| |_____^
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help: instead of prefixing all patterns with `&`, you can dereference the expression
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50 | match *tup {
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51 | (v, 1) => println!("{}", v),
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36 | match *tup {
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37 | (v, 1) => println!("{}", v),
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error: you don't need to add `&` to both the expression and the patterns
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--> $DIR/matches.rs:56:5
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--> $DIR/matches.rs:42:5
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56 | / match &w {
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57 | | &Some(v) => println!("{:?}", v),
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58 | | &None => println!("none"),
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59 | | }
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42 | / match &w {
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43 | | &Some(v) => println!("{:?}", v),
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44 | | &None => println!("none"),
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45 | | }
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| |_____^
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help: try
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56 | match w {
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57 | Some(v) => println!("{:?}", v),
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58 | None => println!("none"),
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42 | match w {
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43 | Some(v) => println!("{:?}", v),
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44 | None => println!("none"),
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error: you don't need to add `&` to all patterns
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--> $DIR/matches.rs:67:5
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--> $DIR/matches.rs:53:5
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67 | / if let &None = a {
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68 | | println!("none");
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69 | | }
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53 | / if let &None = a {
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54 | | println!("none");
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55 | | }
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| |_____^
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help: instead of prefixing all patterns with `&`, you can dereference the expression
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67 | if let None = *a {
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53 | if let None = *a {
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| ^^^^ ^^
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error: you don't need to add `&` to both the expression and the patterns
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--> $DIR/matches.rs:72:5
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--> $DIR/matches.rs:58:5
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72 | / if let &None = &b {
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73 | | println!("none");
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74 | | }
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58 | / if let &None = &b {
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59 | | println!("none");
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60 | | }
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| |_____^
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help: try
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72 | if let None = b {
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58 | if let None = b {
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| ^^^^ ^
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error: Err(_) will match all errors, maybe not a good idea
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--> $DIR/matches.rs:83:9
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--> $DIR/matches.rs:69:9
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83 | Err(_) => panic!("err")
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69 | Err(_) => panic!("err")
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| ^^^^^^
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= note: `-D clippy::match-wild-err-arm` implied by `-D warnings`
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= note: to remove this warning, match each error separately or use unreachable macro
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error: this `match` has identical arm bodies
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--> $DIR/matches.rs:82:18
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--> $DIR/matches.rs:68:18
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82 | Ok(_) => println!("ok"),
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68 | Ok(_) => println!("ok"),
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| ^^^^^^^^^^^^^^
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= note: `-D clippy::match-same-arms` implied by `-D warnings`
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note: same as this
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--> $DIR/matches.rs:81:18
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--> $DIR/matches.rs:67:18
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81 | Ok(3) => println!("ok"),
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67 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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note: consider refactoring into `Ok(3) | Ok(_)`
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--> $DIR/matches.rs:81:18
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--> $DIR/matches.rs:67:18
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81 | Ok(3) => println!("ok"),
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67 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error: Err(_) will match all errors, maybe not a good idea
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--> $DIR/matches.rs:89:9
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--> $DIR/matches.rs:75:9
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89 | Err(_) => {panic!()}
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75 | Err(_) => {panic!()}
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| ^^^^^^
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= note: to remove this warning, match each error separately or use unreachable macro
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error: this `match` has identical arm bodies
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--> $DIR/matches.rs:88:18
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--> $DIR/matches.rs:74:18
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88 | Ok(_) => println!("ok"),
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74 | Ok(_) => println!("ok"),
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| ^^^^^^^^^^^^^^
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note: same as this
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--> $DIR/matches.rs:87:18
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--> $DIR/matches.rs:73:18
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87 | Ok(3) => println!("ok"),
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73 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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note: consider refactoring into `Ok(3) | Ok(_)`
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--> $DIR/matches.rs:87:18
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--> $DIR/matches.rs:73:18
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87 | Ok(3) => println!("ok"),
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73 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error: Err(_) will match all errors, maybe not a good idea
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--> $DIR/matches.rs:95:9
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--> $DIR/matches.rs:81:9
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95 | Err(_) => {panic!();}
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81 | Err(_) => {panic!();}
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| ^^^^^^
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= note: to remove this warning, match each error separately or use unreachable macro
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error: this `match` has identical arm bodies
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--> $DIR/matches.rs:80:18
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80 | Ok(_) => println!("ok"),
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| ^^^^^^^^^^^^^^
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note: same as this
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--> $DIR/matches.rs:79:18
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79 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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note: consider refactoring into `Ok(3) | Ok(_)`
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--> $DIR/matches.rs:79:18
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79 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error: this `match` has identical arm bodies
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--> $DIR/matches.rs:87:18
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87 | Ok(_) => println!("ok"),
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| ^^^^^^^^^^^^^^
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|
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note: same as this
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--> $DIR/matches.rs:86:18
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86 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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note: consider refactoring into `Ok(3) | Ok(_)`
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--> $DIR/matches.rs:86:18
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86 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error: this `match` has identical arm bodies
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--> $DIR/matches.rs:94:18
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@ -169,134 +185,98 @@ note: consider refactoring into `Ok(3) | Ok(_)`
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error: this `match` has identical arm bodies
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--> $DIR/matches.rs:101:18
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101 | Ok(_) => println!("ok"),
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| ^^^^^^^^^^^^^^
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|
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note: same as this
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--> $DIR/matches.rs:100:18
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100 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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note: consider refactoring into `Ok(3) | Ok(_)`
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--> $DIR/matches.rs:100:18
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|
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100 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error: this `match` has identical arm bodies
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--> $DIR/matches.rs:108:18
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108 | Ok(_) => println!("ok"),
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100 | Ok(_) => println!("ok"),
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| ^^^^^^^^^^^^^^
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|
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note: same as this
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--> $DIR/matches.rs:107:18
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--> $DIR/matches.rs:99:18
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107 | Ok(3) => println!("ok"),
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99 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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note: consider refactoring into `Ok(3) | Ok(_)`
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--> $DIR/matches.rs:107:18
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--> $DIR/matches.rs:99:18
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|
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107 | Ok(3) => println!("ok"),
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99 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error: this `match` has identical arm bodies
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--> $DIR/matches.rs:114:18
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--> $DIR/matches.rs:106:18
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114 | Ok(_) => println!("ok"),
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106 | Ok(_) => println!("ok"),
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| ^^^^^^^^^^^^^^
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|
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note: same as this
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--> $DIR/matches.rs:113:18
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--> $DIR/matches.rs:105:18
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113 | Ok(3) => println!("ok"),
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105 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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note: consider refactoring into `Ok(3) | Ok(_)`
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--> $DIR/matches.rs:113:18
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--> $DIR/matches.rs:105:18
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113 | Ok(3) => println!("ok"),
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105 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error: this `match` has identical arm bodies
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--> $DIR/matches.rs:120:18
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--> $DIR/matches.rs:127:29
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120 | Ok(_) => println!("ok"),
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| ^^^^^^^^^^^^^^
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|
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note: same as this
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--> $DIR/matches.rs:119:18
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119 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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note: consider refactoring into `Ok(3) | Ok(_)`
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--> $DIR/matches.rs:119:18
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|
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119 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error: this `match` has identical arm bodies
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--> $DIR/matches.rs:141:29
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141 | (Ok(_), Some(x)) => println!("ok {}", x),
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127 | (Ok(_), Some(x)) => println!("ok {}", x),
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| ^^^^^^^^^^^^^^^^^^^^
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|
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note: same as this
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--> $DIR/matches.rs:140:29
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--> $DIR/matches.rs:126:29
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|
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140 | (Ok(x), Some(_)) => println!("ok {}", x),
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126 | (Ok(x), Some(_)) => println!("ok {}", x),
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| ^^^^^^^^^^^^^^^^^^^^
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note: consider refactoring into `(Ok(x), Some(_)) | (Ok(_), Some(x))`
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--> $DIR/matches.rs:140:29
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--> $DIR/matches.rs:126:29
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140 | (Ok(x), Some(_)) => println!("ok {}", x),
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126 | (Ok(x), Some(_)) => println!("ok {}", x),
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| ^^^^^^^^^^^^^^^^^^^^
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error: this `match` has identical arm bodies
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--> $DIR/matches.rs:156:18
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--> $DIR/matches.rs:142:18
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156 | Ok(_) => println!("ok"),
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142 | Ok(_) => println!("ok"),
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| ^^^^^^^^^^^^^^
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|
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note: same as this
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--> $DIR/matches.rs:155:18
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--> $DIR/matches.rs:141:18
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155 | Ok(3) => println!("ok"),
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141 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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note: consider refactoring into `Ok(3) | Ok(_)`
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--> $DIR/matches.rs:155:18
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--> $DIR/matches.rs:141:18
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|
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155 | Ok(3) => println!("ok"),
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141 | Ok(3) => println!("ok"),
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| ^^^^^^^^^^^^^^
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= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
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error: use as_ref() instead
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--> $DIR/matches.rs:163:33
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--> $DIR/matches.rs:149:33
|
||||
|
|
||||
163 | let borrowed: Option<&()> = match owned {
|
||||
149 | let borrowed: Option<&()> = match owned {
|
||||
| _________________________________^
|
||||
164 | | None => None,
|
||||
165 | | Some(ref v) => Some(v),
|
||||
166 | | };
|
||||
150 | | None => None,
|
||||
151 | | Some(ref v) => Some(v),
|
||||
152 | | };
|
||||
| |_____^ help: try this: `owned.as_ref()`
|
||||
|
|
||||
= note: `-D clippy::match-as-ref` implied by `-D warnings`
|
||||
|
||||
error: use as_mut() instead
|
||||
--> $DIR/matches.rs:169:39
|
||||
--> $DIR/matches.rs:155:39
|
||||
|
|
||||
169 | let borrow_mut: Option<&mut ()> = match mut_owned {
|
||||
155 | let borrow_mut: Option<&mut ()> = match mut_owned {
|
||||
| _______________________________________^
|
||||
170 | | None => None,
|
||||
171 | | Some(ref mut v) => Some(v),
|
||||
172 | | };
|
||||
156 | | None => None,
|
||||
157 | | Some(ref mut v) => Some(v),
|
||||
158 | | };
|
||||
| |_____^ help: try this: `mut_owned.as_mut()`
|
||||
|
||||
error: aborting due to 21 previous errors
|
||||
error: aborting due to 19 previous errors
|
||||
|
||||
|
||||
27
tests/ui/single_match_else.rs
Normal file
27
tests/ui/single_match_else.rs
Normal file
@ -0,0 +1,27 @@
|
||||
// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
|
||||
// file at the top-level directory of this distribution.
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
|
||||
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
|
||||
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
|
||||
// option. This file may not be copied, modified, or distributed
|
||||
// except according to those terms.
|
||||
|
||||
#![warn(clippy::single_match_else)]
|
||||
|
||||
enum ExprNode {
|
||||
ExprAddrOf,
|
||||
Butterflies,
|
||||
Unicorns,
|
||||
}
|
||||
|
||||
static NODE: ExprNode = ExprNode::Unicorns;
|
||||
|
||||
fn unwrap_addr() -> Option<&'static ExprNode> {
|
||||
match ExprNode::Butterflies {
|
||||
ExprNode::ExprAddrOf => Some(&NODE),
|
||||
_ => { let x = 5; None },
|
||||
}
|
||||
}
|
||||
|
||||
fn main() {}
|
||||
13
tests/ui/single_match_else.stderr
Normal file
13
tests/ui/single_match_else.stderr
Normal file
@ -0,0 +1,13 @@
|
||||
error: you seem to be trying to use match for destructuring a single pattern. Consider using `if let`
|
||||
--> $DIR/single_match_else.rs:21:5
|
||||
|
|
||||
21 | / match ExprNode::Butterflies {
|
||||
22 | | ExprNode::ExprAddrOf => Some(&NODE),
|
||||
23 | | _ => { let x = 5; None },
|
||||
24 | | }
|
||||
| |_____^ help: try this: `if let ExprNode::ExprAddrOf = ExprNode::Butterflies { Some(&NODE) } else { let x = 5; None }`
|
||||
|
|
||||
= note: `-D clippy::single-match-else` implied by `-D warnings`
|
||||
|
||||
error: aborting due to previous error
|
||||
|
||||
Loading…
Reference in New Issue
Block a user