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Merge pull request #3490 from phansch/extract_single_match_else_ui_test

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Extract single_match_else UI test
This commit is contained in:
Philipp Krones 2018-12-04 14:57:19 +01:00 committed by GitHub
commit 3f24cdf10f
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5 changed files with 177 additions and 158 deletions
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17
clippy_lints/src/matches.rs
View File

@ -45,7 +45,7 @@ declare_clippy_lint! {
"a match statement with a single nontrivial arm (i.e. where the other arm is `_ => {}`) instead of `if let`" "a match statement with a single nontrivial arm (i.e. where the other arm is `_ => {}`) instead of `if let`"
} }
/// **What it does:** Checks for matches with a two arms where an `if let` will /// **What it does:** Checks for matches with a two arms where an `if let else` will
/// usually suffice. /// usually suffice.
/// ///
/// **Why is this bad?** Just readability – `if let` nests less than a `match`. /// **Why is this bad?** Just readability – `if let` nests less than a `match`.
@ -53,16 +53,29 @@ declare_clippy_lint! {
/// **Known problems:** Personal style preferences may differ. /// **Known problems:** Personal style preferences may differ.
/// ///
/// **Example:** /// **Example:**
///
/// Using `match`:
///
/// ```rust /// ```rust
/// match x { /// match x {
/// Some(ref foo) => bar(foo), /// Some(ref foo) => bar(foo),
/// _ => bar(other_ref), /// _ => bar(other_ref),
/// } /// }
/// ``` /// ```
///
/// Using `if let` with `else`:
///
/// ```rust
/// if let Some(ref foo) = x {
/// bar(foo);
/// } else {
/// bar(other_ref);
/// }
/// ```
declare_clippy_lint! { declare_clippy_lint! {
pub SINGLE_MATCH_ELSE, pub SINGLE_MATCH_ELSE,
pedantic, pedantic,
"a match statement with a two arms where the second arm's pattern is a wildcard instead of `if let`" "a match statement with a two arms where the second arm's pattern is a placeholder instead of a specific match pattern"
} }
/// **What it does:** Checks for matches where all arms match a reference, /// **What it does:** Checks for matches where all arms match a reference,

16
tests/ui/matches.rs
View File

@ -14,26 +14,12 @@
#![warn(clippy::all)] #![warn(clippy::all)]
#![allow(unused, clippy::redundant_pattern_matching)] #![allow(unused, clippy::redundant_pattern_matching)]
#![warn(clippy::single_match_else, clippy::match_same_arms)] #![warn(clippy::match_same_arms)]
enum ExprNode {
ExprAddrOf,
Butterflies,
Unicorns,
}
static NODE: ExprNode = ExprNode::Unicorns;
fn dummy() { fn dummy() {
} }
fn unwrap_addr() -> Option<&'static ExprNode> {
match ExprNode::Butterflies {
ExprNode::ExprAddrOf => Some(&NODE),
_ => { let x = 5; None },
}
}
fn ref_pats() { fn ref_pats() {
{ {
let v = &Some(0); let v = &Some(0);

262
tests/ui/matches.stderr
View File

@ -1,155 +1,171 @@
error: you seem to be trying to use match for destructuring a single pattern. Consider using `if let`
--> $DIR/matches.rs:31:5
|
31 | / match ExprNode::Butterflies {
32 | | ExprNode::ExprAddrOf => Some(&NODE),
33 | | _ => { let x = 5; None },
34 | | }
| |_____^ 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: you don't need to add `&` to all patterns error: you don't need to add `&` to all patterns
--> $DIR/matches.rs:40:9 --> $DIR/matches.rs:26:9
| |
40 | / match v { 26 | / match v {
41 | | &Some(v) => println!("{:?}", v), 27 | | &Some(v) => println!("{:?}", v),
42 | | &None => println!("none"), 28 | | &None => println!("none"),
43 | | } 29 | | }
| |_________^ | |_________^
| |
= note: `-D clippy::match-ref-pats` implied by `-D warnings` = note: `-D clippy::match-ref-pats` implied by `-D warnings`
help: instead of prefixing all patterns with `&`, you can dereference the expression help: instead of prefixing all patterns with `&`, you can dereference the expression
| |
40 | match *v { 26 | match *v {
41 | Some(v) => println!("{:?}", v), 27 | Some(v) => println!("{:?}", v),
42 | None => println!("none"), 28 | None => println!("none"),
| |
error: you seem to be trying to use match for destructuring a single pattern. Consider using `if let`
--> $DIR/matches.rs:50:5
|
50 | / match tup {
51 | | &(v, 1) => println!("{}", v),
52 | | _ => println!("none"),
53 | | }
| |_____^ help: try this: `if let &(v, 1) = tup { println!("{}", v) } else { println!("none") }`
error: you don't need to add `&` to all patterns error: you don't need to add `&` to all patterns
--> $DIR/matches.rs:50:5 --> $DIR/matches.rs:36:5
| |
50 | / match tup { 36 | / match tup {
51 | | &(v, 1) => println!("{}", v), 37 | | &(v, 1) => println!("{}", v),
52 | | _ => println!("none"), 38 | | _ => println!("none"),
53 | | } 39 | | }
| |_____^ | |_____^
help: instead of prefixing all patterns with `&`, you can dereference the expression help: instead of prefixing all patterns with `&`, you can dereference the expression
| |
50 | match *tup { 36 | match *tup {
51 | (v, 1) => println!("{}", v), 37 | (v, 1) => println!("{}", v),
| |
error: you don't need to add `&` to both the expression and the patterns error: you don't need to add `&` to both the expression and the patterns
--> $DIR/matches.rs:56:5 --> $DIR/matches.rs:42:5
| |
56 | / match &w { 42 | / match &w {
57 | | &Some(v) => println!("{:?}", v), 43 | | &Some(v) => println!("{:?}", v),
58 | | &None => println!("none"), 44 | | &None => println!("none"),
59 | | } 45 | | }
| |_____^ | |_____^
help: try help: try
| |
56 | match w { 42 | match w {
57 | Some(v) => println!("{:?}", v), 43 | Some(v) => println!("{:?}", v),
58 | None => println!("none"), 44 | None => println!("none"),
| |
error: you don't need to add `&` to all patterns error: you don't need to add `&` to all patterns
--> $DIR/matches.rs:67:5 --> $DIR/matches.rs:53:5
| |
67 | / if let &None = a { 53 | / if let &None = a {
68 | | println!("none"); 54 | | println!("none");
69 | | } 55 | | }
| |_____^ | |_____^
help: instead of prefixing all patterns with `&`, you can dereference the expression help: instead of prefixing all patterns with `&`, you can dereference the expression
| |
67 | if let None = *a { 53 | if let None = *a {
| ^^^^ ^^ | ^^^^ ^^
error: you don't need to add `&` to both the expression and the patterns error: you don't need to add `&` to both the expression and the patterns
--> $DIR/matches.rs:72:5 --> $DIR/matches.rs:58:5
| |
72 | / if let &None = &b { 58 | / if let &None = &b {
73 | | println!("none"); 59 | | println!("none");
74 | | } 60 | | }
| |_____^ | |_____^
help: try help: try
| |
72 | if let None = b { 58 | if let None = b {
| ^^^^ ^ | ^^^^ ^
error: Err(_) will match all errors, maybe not a good idea error: Err(_) will match all errors, maybe not a good idea
--> $DIR/matches.rs:83:9 --> $DIR/matches.rs:69:9
| |
83 | Err(_) => panic!("err") 69 | Err(_) => panic!("err")
| ^^^^^^ | ^^^^^^
| |
= note: `-D clippy::match-wild-err-arm` implied by `-D warnings` = note: `-D clippy::match-wild-err-arm` implied by `-D warnings`
= note: to remove this warning, match each error separately or use unreachable macro = note: to remove this warning, match each error separately or use unreachable macro
error: this `match` has identical arm bodies error: this `match` has identical arm bodies
--> $DIR/matches.rs:82:18 --> $DIR/matches.rs:68:18
| |
82 | Ok(_) => println!("ok"), 68 | Ok(_) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
| |
= note: `-D clippy::match-same-arms` implied by `-D warnings` = note: `-D clippy::match-same-arms` implied by `-D warnings`
note: same as this note: same as this
--> $DIR/matches.rs:81:18 --> $DIR/matches.rs:67:18
| |
81 | Ok(3) => println!("ok"), 67 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
note: consider refactoring into `Ok(3) | Ok(_)` note: consider refactoring into `Ok(3) | Ok(_)`
--> $DIR/matches.rs:81:18 --> $DIR/matches.rs:67:18
| |
81 | Ok(3) => println!("ok"), 67 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info) = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
error: Err(_) will match all errors, maybe not a good idea error: Err(_) will match all errors, maybe not a good idea
--> $DIR/matches.rs:89:9 --> $DIR/matches.rs:75:9
| |
89 | Err(_) => {panic!()} 75 | Err(_) => {panic!()}
| ^^^^^^ | ^^^^^^
| |
= note: to remove this warning, match each error separately or use unreachable macro = note: to remove this warning, match each error separately or use unreachable macro
error: this `match` has identical arm bodies error: this `match` has identical arm bodies
--> $DIR/matches.rs:88:18 --> $DIR/matches.rs:74:18
| |
88 | Ok(_) => println!("ok"), 74 | Ok(_) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
| |
note: same as this note: same as this
--> $DIR/matches.rs:87:18 --> $DIR/matches.rs:73:18
| |
87 | Ok(3) => println!("ok"), 73 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
note: consider refactoring into `Ok(3) | Ok(_)` note: consider refactoring into `Ok(3) | Ok(_)`
--> $DIR/matches.rs:87:18 --> $DIR/matches.rs:73:18
| |
87 | Ok(3) => println!("ok"), 73 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info) = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
error: Err(_) will match all errors, maybe not a good idea error: Err(_) will match all errors, maybe not a good idea
--> $DIR/matches.rs:95:9 --> $DIR/matches.rs:81:9
| |
95 | Err(_) => {panic!();} 81 | Err(_) => {panic!();}
| ^^^^^^ | ^^^^^^
| |
= note: to remove this warning, match each error separately or use unreachable macro = note: to remove this warning, match each error separately or use unreachable macro
error: this `match` has identical arm bodies
--> $DIR/matches.rs:80:18
|
80 | Ok(_) => println!("ok"),
| ^^^^^^^^^^^^^^
|
note: same as this
--> $DIR/matches.rs:79:18
|
79 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^
note: consider refactoring into `Ok(3) | Ok(_)`
--> $DIR/matches.rs:79:18
|
79 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
error: this `match` has identical arm bodies
--> $DIR/matches.rs:87:18
|
87 | Ok(_) => println!("ok"),
| ^^^^^^^^^^^^^^
|
note: same as this
--> $DIR/matches.rs:86:18
|
86 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^
note: consider refactoring into `Ok(3) | Ok(_)`
--> $DIR/matches.rs:86:18
|
86 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
error: this `match` has identical arm bodies error: this `match` has identical arm bodies
--> $DIR/matches.rs:94:18 --> $DIR/matches.rs:94:18
| |
@ -169,134 +185,98 @@ note: consider refactoring into `Ok(3) | Ok(_)`
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info) = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
error: this `match` has identical arm bodies error: this `match` has identical arm bodies
--> $DIR/matches.rs:101:18
|
101 | Ok(_) => println!("ok"),
| ^^^^^^^^^^^^^^
|
note: same as this
--> $DIR/matches.rs:100:18 --> $DIR/matches.rs:100:18
| |
100 | Ok(3) => println!("ok"), 100 | Ok(_) => println!("ok"),
| ^^^^^^^^^^^^^^
note: consider refactoring into `Ok(3) | Ok(_)`
--> $DIR/matches.rs:100:18
|
100 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
error: this `match` has identical arm bodies
--> $DIR/matches.rs:108:18
|
108 | Ok(_) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
| |
note: same as this note: same as this
--> $DIR/matches.rs:107:18 --> $DIR/matches.rs:99:18
| |
107 | Ok(3) => println!("ok"), 99 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
note: consider refactoring into `Ok(3) | Ok(_)` note: consider refactoring into `Ok(3) | Ok(_)`
--> $DIR/matches.rs:107:18 --> $DIR/matches.rs:99:18
| |
107 | Ok(3) => println!("ok"), 99 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info) = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
error: this `match` has identical arm bodies error: this `match` has identical arm bodies
--> $DIR/matches.rs:114:18 --> $DIR/matches.rs:106:18
| |
114 | Ok(_) => println!("ok"), 106 | Ok(_) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
| |
note: same as this note: same as this
--> $DIR/matches.rs:113:18 --> $DIR/matches.rs:105:18
| |
113 | Ok(3) => println!("ok"), 105 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
note: consider refactoring into `Ok(3) | Ok(_)` note: consider refactoring into `Ok(3) | Ok(_)`
--> $DIR/matches.rs:113:18 --> $DIR/matches.rs:105:18
| |
113 | Ok(3) => println!("ok"), 105 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info) = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
error: this `match` has identical arm bodies error: this `match` has identical arm bodies
--> $DIR/matches.rs:120:18 --> $DIR/matches.rs:127:29
| |
120 | Ok(_) => println!("ok"), 127 | (Ok(_), Some(x)) => println!("ok {}", x),
| ^^^^^^^^^^^^^^
|
note: same as this
--> $DIR/matches.rs:119:18
|
119 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^
note: consider refactoring into `Ok(3) | Ok(_)`
--> $DIR/matches.rs:119:18
|
119 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
error: this `match` has identical arm bodies
--> $DIR/matches.rs:141:29
|
141 | (Ok(_), Some(x)) => println!("ok {}", x),
| ^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^
| |
note: same as this note: same as this
--> $DIR/matches.rs:140:29 --> $DIR/matches.rs:126:29
| |
140 | (Ok(x), Some(_)) => println!("ok {}", x), 126 | (Ok(x), Some(_)) => println!("ok {}", x),
| ^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^
note: consider refactoring into `(Ok(x), Some(_)) | (Ok(_), Some(x))` note: consider refactoring into `(Ok(x), Some(_)) | (Ok(_), Some(x))`
--> $DIR/matches.rs:140:29 --> $DIR/matches.rs:126:29
| |
140 | (Ok(x), Some(_)) => println!("ok {}", x), 126 | (Ok(x), Some(_)) => println!("ok {}", x),
| ^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info) = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
error: this `match` has identical arm bodies error: this `match` has identical arm bodies
--> $DIR/matches.rs:156:18 --> $DIR/matches.rs:142:18
| |
156 | Ok(_) => println!("ok"), 142 | Ok(_) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
| |
note: same as this note: same as this
--> $DIR/matches.rs:155:18 --> $DIR/matches.rs:141:18
| |
155 | Ok(3) => println!("ok"), 141 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
note: consider refactoring into `Ok(3) | Ok(_)` note: consider refactoring into `Ok(3) | Ok(_)`
--> $DIR/matches.rs:155:18 --> $DIR/matches.rs:141:18
| |
155 | Ok(3) => println!("ok"), 141 | Ok(3) => println!("ok"),
| ^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^
= note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info) = note: this error originates in a macro outside of the current crate (in Nightly builds, run with -Z external-macro-backtrace for more info)
error: use as_ref() instead error: use as_ref() instead
--> $DIR/matches.rs:163:33 --> $DIR/matches.rs:149:33
| |
163 | let borrowed: Option<&()> = match owned { 149 | let borrowed: Option<&()> = match owned {
| _________________________________^ | _________________________________^
164 | | None => None, 150 | | None => None,
165 | | Some(ref v) => Some(v), 151 | | Some(ref v) => Some(v),
166 | | }; 152 | | };
| |_____^ help: try this: `owned.as_ref()` | |_____^ help: try this: `owned.as_ref()`
| |
= note: `-D clippy::match-as-ref` implied by `-D warnings` = note: `-D clippy::match-as-ref` implied by `-D warnings`
error: use as_mut() instead 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, 156 | | None => None,
171 | | Some(ref mut v) => Some(v), 157 | | Some(ref mut v) => Some(v),
172 | | }; 158 | | };
| |_____^ help: try this: `mut_owned.as_mut()` | |_____^ 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
View 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
View 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