single_match: fix checking of explicitly matched enums

clippy_lints/src/matches/match_wild_enum.rs

@@ -180,9 +180,8 @@ enum CommonPrefixSearcher<'a> {
 }
 impl<'a> CommonPrefixSearcher<'a> {
     fn with_path(&mut self, path: &'a [PathSegment<'a>]) {
-        match path {
-            [path @ .., _] => self.with_prefix(path),
-            [] => (),
+        if let [path @ .., _] = path {
+            self.with_prefix(path);
         }
     }
 

clippy_lints/src/matches/overlapping_arms.rs

@@ -33,19 +33,17 @@ fn all_ranges<'tcx>(cx: &LateContext<'tcx>, arms: &'tcx [Arm<'_>], ty: Ty<'tcx>)
         .filter_map(|arm| {
             if let Arm { pat, guard: None, .. } = *arm {
                 if let PatKind::Range(ref lhs, ref rhs, range_end) = pat.kind {
-                    let lhs_const = match lhs {
-                        Some(lhs) => constant(cx, cx.typeck_results(), lhs)?,
-                        None => {
-                            let min_val_const = ty.numeric_min_val(cx.tcx)?;
-                            mir_to_const(cx, mir::Const::from_ty_const(min_val_const, ty, cx.tcx))?
-                        },
+                    let lhs_const = if let Some(lhs) = lhs {
+                        constant(cx, cx.typeck_results(), lhs)?
+                    } else {
+                        let min_val_const = ty.numeric_min_val(cx.tcx)?;
+                        mir_to_const(cx, mir::Const::from_ty_const(min_val_const, ty, cx.tcx))?
                     };
-                    let rhs_const = match rhs {
-                        Some(rhs) => constant(cx, cx.typeck_results(), rhs)?,
-                        None => {
-                            let max_val_const = ty.numeric_max_val(cx.tcx)?;
-                            mir_to_const(cx, mir::Const::from_ty_const(max_val_const, ty, cx.tcx))?
-                        },
+                    let rhs_const = if let Some(rhs) = rhs {
+                        constant(cx, cx.typeck_results(), rhs)?
+                    } else {
+                        let max_val_const = ty.numeric_max_val(cx.tcx)?;
+                        mir_to_const(cx, mir::Const::from_ty_const(max_val_const, ty, cx.tcx))?
                     };
                     let lhs_val = lhs_const.int_value(cx, ty)?;
                     let rhs_val = rhs_const.int_value(cx, ty)?;

tests/ui-toml/excessive_nesting/excessive_nesting.rs

@@ -1,15 +1,19 @@
 //@aux-build:../../ui/auxiliary/proc_macros.rs
 #![rustfmt::skip]
 #![feature(custom_inner_attributes)]
-#![allow(unused)]
-#![allow(clippy::let_and_return)]
-#![allow(clippy::redundant_closure_call)]
-#![allow(clippy::no_effect)]
-#![allow(clippy::unnecessary_operation)]
-#![allow(clippy::never_loop)]
-#![allow(clippy::needless_if)]
 #![warn(clippy::excessive_nesting)]
-#![allow(clippy::collapsible_if, clippy::blocks_in_conditions)]
+#![allow(
+    unused,
+    clippy::let_and_return,
+    clippy::redundant_closure_call,
+    clippy::no_effect,
+    clippy::unnecessary_operation,
+    clippy::never_loop,
+    clippy::needless_if,
+    clippy::collapsible_if,
+    clippy::blocks_in_conditions,
+    clippy::single_match,
+)]
 
 #[macro_use]
 extern crate proc_macros;

tests/ui-toml/excessive_nesting/excessive_nesting.stderr

@@ -1,5 +1,5 @@
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:21:25
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:25:25
    |
 LL |                 let w = { 3 };
    |                         ^^^^^
@@ -9,7 +9,7 @@ LL |                 let w = { 3 };
    = help: to override `-D warnings` add `#[allow(clippy::excessive_nesting)]`
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:67:17
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:71:17
    |
 LL | /                 impl C {
 LL | |                     pub fn c() {}
@@ -19,15 +19,15 @@ LL | |                 }
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:81:25
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:85:25
    |
 LL |                 let x = { 1 }; // not a warning, but cc is
    |                         ^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:98:17
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:102:17
    |
 LL | /                 pub mod e {
 LL | |                     pub mod f {}
@@ -37,31 +37,31 @@ LL | |                 } // not here
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:111:18
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:115:18
    |
 LL |     a_but_not({{{{{{{{0}}}}}}}});
    |                  ^^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:112:12
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:116:12
    |
 LL |     a.a({{{{{{{{{0}}}}}}}}});
    |            ^^^^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:113:12
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:117:12
    |
 LL |     (0, {{{{{{{1}}}}}}});
    |            ^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:118:25
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:122:25
    |
 LL |                   if true {
    |  _________________________^
@@ -74,7 +74,7 @@ LL | |                 }
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:130:29
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:134:29
    |
 LL |                   let z = (|| {
    |  _____________________________^
@@ -86,207 +86,207 @@ LL | |                 })();
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:149:13
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:153:13
    |
 LL |     y += {{{{{5}}}}};
    |             ^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:150:20
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:154:20
    |
 LL |     let z = y + {{{{{{{{{5}}}}}}}}};
    |                    ^^^^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:151:12
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:155:12
    |
 LL |     [0, {{{{{{{{{{0}}}}}}}}}}];
    |            ^^^^^^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:152:25
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:156:25
    |
 LL |     let mut xx = [0; {{{{{{{{100}}}}}}}}];
    |                         ^^^^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:153:11
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:157:11
    |
 LL |     xx[{{{{{{{{{{{{{{{{{{{{{{{{3}}}}}}}}}}}}}}}}}}}}}}}}];
    |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:154:13
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:158:13
    |
 LL |     &mut {{{{{{{{{{y}}}}}}}}}};
    |             ^^^^^^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:156:17
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:160:17
    |
 LL |     for i in {{{{xx}}}} {{{{{{{{}}}}}}}}
    |                 ^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:156:28
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:160:28
    |
 LL |     for i in {{{{xx}}}} {{{{{{{{}}}}}}}}
    |                            ^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:158:28
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:162:28
    |
 LL |     while let Some(i) = {{{{{{Some(1)}}}}}} {{{{{{{}}}}}}}
    |                            ^^^^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:158:48
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:162:48
    |
 LL |     while let Some(i) = {{{{{{Some(1)}}}}}} {{{{{{{}}}}}}}
    |                                                ^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:160:14
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:164:14
    |
 LL |     while {{{{{{{{true}}}}}}}} {{{{{{{{{}}}}}}}}}
    |              ^^^^^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:160:35
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:164:35
    |
 LL |     while {{{{{{{{true}}}}}}}} {{{{{{{{{}}}}}}}}}
    |                                   ^^^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:162:23
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:166:23
    |
 LL |     let d = D { d: {{{{{{{{{{{{{{{{{{{{{{{3}}}}}}}}}}}}}}}}}}}}}}} };
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:164:8
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:168:8
    |
 LL |     {{{{1;}}}}..{{{{{{3}}}}}};
    |        ^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:164:20
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:168:20
    |
 LL |     {{{{1;}}}}..{{{{{{3}}}}}};
    |                    ^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:165:8
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:169:8
    |
 LL |     {{{{1;}}}}..={{{{{{{{{{{{{{{{{{{{{{{{{{6}}}}}}}}}}}}}}}}}}}}}}}}}};
    |        ^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:165:21
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:169:21
    |
 LL |     {{{{1;}}}}..={{{{{{{{{{{{{{{{{{{{{{{{{{6}}}}}}}}}}}}}}}}}}}}}}}}}};
    |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:166:10
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:170:10
    |
 LL |     ..{{{{{{{5}}}}}}};
    |          ^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:167:11
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:171:11
    |
 LL |     ..={{{{{3}}}}};
    |           ^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:168:8
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:172:8
    |
 LL |     {{{{{1;}}}}}..;
    |        ^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:170:20
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:174:20
    |
 LL |     loop { break {{{{1}}}} };
    |                    ^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:171:13
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:175:13
    |
 LL |     loop {{{{{{}}}}}}
    |             ^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:173:14
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:177:14
    |
 LL |     match {{{{{{true}}}}}} {
    |              ^^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:174:20
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:178:20
    |
 LL |         true => {{{{}}}},
    |                    ^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:175:21
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:179:21
    |
 LL |         false => {{{{}}}},
    |                     ^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:181:17
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:185:17
    |
 LL | /                 {
 LL | |                     println!("warning! :)");
@@ -296,15 +296,15 @@ LL | |                 }
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:190:28
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:194:28
    |
 LL |     async fn c() -> u32 {{{{{{{0}}}}}}}
    |                            ^^^^^^^^^
    |
    = help: try refactoring your code to minimize nesting
 
 error: this block is too nested
-  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:196:8
+  --> tests/ui-toml/excessive_nesting/excessive_nesting.rs:200:8
    |
 LL |     {{{{b().await}}}};
    |        ^^^^^^^^^^^

tests/ui/crashes/ice-6254.rs

@@ -2,7 +2,8 @@
 // panicked at 'assertion failed: rows.iter().all(|r| r.len() == v.len())',
 // compiler/rustc_mir_build/src/thir/pattern/_match.rs:2030:5
 
-#[allow(clippy::derive_partial_eq_without_eq)]
+#![allow(clippy::derive_partial_eq_without_eq, clippy::single_match)]
+
 #[derive(PartialEq)]
 struct Foo(i32);
 const FOO_REF_REF: &&Foo = &&Foo(42);

tests/ui/patterns.fixed

@@ -1,7 +1,7 @@
 //@aux-build:proc_macros.rs
 #![warn(clippy::all)]
 #![allow(unused)]
-#![allow(clippy::uninlined_format_args)]
+#![allow(clippy::uninlined_format_args, clippy::single_match)]
 
 #[macro_use]
 extern crate proc_macros;

tests/ui/patterns.rs

@@ -1,7 +1,7 @@
 //@aux-build:proc_macros.rs
 #![warn(clippy::all)]
 #![allow(unused)]
-#![allow(clippy::uninlined_format_args)]
+#![allow(clippy::uninlined_format_args, clippy::single_match)]
 
 #[macro_use]
 extern crate proc_macros;

tests/ui/single_match.fixed

@@ -253,3 +253,46 @@ mod issue8634 {
         }
     }
 }
+
+fn issue11365() {
+    enum Foo {
+        A,
+        B,
+        C,
+    }
+    use Foo::{A, B, C};
+
+    match Some(A) {
+        Some(A | B | C) => println!(),
+        None => {},
+    }
+
+    match Some(A) {
+        Some(A | B) => println!(),
+        Some { 0: C } | None => {},
+    }
+
+    match [A, A] {
+        [A, _] => println!(),
+        [_, A | B | C] => {},
+    }
+
+    match Ok::<_, u32>(Some(A)) {
+        Ok(Some(A)) => println!(),
+        Err(_) | Ok(None | Some(B | C)) => {},
+    }
+
+    if let Ok(Some(A)) = Ok::<_, u32>(Some(A)) { println!() }
+
+    match &Some(A) {
+        Some(A | B | C) => println!(),
+        None => {},
+    }
+
+    match &Some(A) {
+        &Some(A | B | C) => println!(),
+        None => {},
+    }
+
+    if let Some(A | B) = &Some(A) { println!() }
+}

tests/ui/single_match.rs

@@ -311,3 +311,52 @@ mod issue8634 {
         }
     }
 }
+
+fn issue11365() {
+    enum Foo {
+        A,
+        B,
+        C,
+    }
+    use Foo::{A, B, C};
+
+    match Some(A) {
+        Some(A | B | C) => println!(),
+        None => {},
+    }
+
+    match Some(A) {
+        Some(A | B) => println!(),
+        Some { 0: C } | None => {},
+    }
+
+    match [A, A] {
+        [A, _] => println!(),
+        [_, A | B | C] => {},
+    }
+
+    match Ok::<_, u32>(Some(A)) {
+        Ok(Some(A)) => println!(),
+        Err(_) | Ok(None | Some(B | C)) => {},
+    }
+
+    match Ok::<_, u32>(Some(A)) {
+        Ok(Some(A)) => println!(),
+        Err(_) | Ok(None | Some(_)) => {},
+    }
+
+    match &Some(A) {
+        Some(A | B | C) => println!(),
+        None => {},
+    }
+
+    match &Some(A) {
+        &Some(A | B | C) => println!(),
+        None => {},
+    }
+
+    match &Some(A) {
+        Some(A | B) => println!(),
+        None | Some(_) => {},
+    }
+}

tests/ui/single_match.stderr

@@ -198,5 +198,23 @@ LL +         }
 LL +     }
    |
 
-error: aborting due to 18 previous errors
+error: you seem to be trying to use `match` for destructuring a single pattern. Consider using `if let`
+  --> tests/ui/single_match.rs:343:5
+   |
+LL | /     match Ok::<_, u32>(Some(A)) {
+LL | |         Ok(Some(A)) => println!(),
+LL | |         Err(_) | Ok(None | Some(_)) => {},
+LL | |     }
+   | |_____^ help: try: `if let Ok(Some(A)) = Ok::<_, u32>(Some(A)) { println!() }`
+
+error: you seem to be trying to use `match` for destructuring a single pattern. Consider using `if let`
+  --> tests/ui/single_match.rs:358:5
+   |
+LL | /     match &Some(A) {
+LL | |         Some(A | B) => println!(),
+LL | |         None | Some(_) => {},
+LL | |     }
+   | |_____^ help: try: `if let Some(A | B) = &Some(A) { println!() }`
+
+error: aborting due to 20 previous errors
 

tests/ui/unneeded_field_pattern.rs

@@ -1,6 +1,6 @@
 //@aux-build:proc_macros.rs
 #![warn(clippy::unneeded_field_pattern)]
-#![allow(dead_code, unused)]
+#![allow(dead_code, unused, clippy::single_match)]
 
 #[macro_use]
 extern crate proc_macros;