Auto merge of #11670 - lengyijun:ignored_unit_pattern_ref, r=dswij

[`ignored_unit_patterns`]: check &(), &&(), ...

changelog: [`ignored_unit_patterns`]: check &(), &&(), ...

clippy_lints/src/ignored_unit_patterns.rs

@@ -52,7 +52,7 @@ fn check_pat(&mut self, cx: &LateContext<'tcx>, pat: &'tcx hir::Pat<'tcx>) {
             },
             _ => {},
         }
-        if matches!(pat.kind, PatKind::Wild) && cx.typeck_results().pat_ty(pat).is_unit() {
+        if matches!(pat.kind, PatKind::Wild) && cx.typeck_results().pat_ty(pat).peel_refs().is_unit() {
             span_lint_and_sugg(
                 cx,
                 IGNORED_UNIT_PATTERNS,

tests/ui/ignored_unit_patterns.fixed

@@ -38,3 +38,19 @@ pub fn moo(_: ()) {
     let _: () = foo().unwrap();
     let _: () = ();
 }
+
+fn test_unit_ref_1() {
+    let x: (usize, &&&&&()) = (1, &&&&&&());
+    match x {
+        (1, ()) => unimplemented!(),
+        //~^ ERROR: matching over `()` is more explicit
+        _ => unimplemented!(),
+    };
+}
+
+fn test_unit_ref_2(v: &[(usize, ())]) {
+    for (x, ()) in v {
+        //~^ ERROR: matching over `()` is more explicit
+        let _ = x;
+    }
+}

tests/ui/ignored_unit_patterns.rs

@@ -38,3 +38,19 @@ pub fn moo(_: ()) {
     let _: () = foo().unwrap();
     let _: () = ();
 }
+
+fn test_unit_ref_1() {
+    let x: (usize, &&&&&()) = (1, &&&&&&());
+    match x {
+        (1, _) => unimplemented!(),
+        //~^ ERROR: matching over `()` is more explicit
+        _ => unimplemented!(),
+    };
+}
+
+fn test_unit_ref_2(v: &[(usize, ())]) {
+    for (x, _) in v {
+        //~^ ERROR: matching over `()` is more explicit
+        let _ = x;
+    }
+}

tests/ui/ignored_unit_patterns.stderr

@@ -43,5 +43,17 @@ error: matching over `()` is more explicit
 LL |     let _ = foo().unwrap();
    |         ^ help: use `()` instead of `_`: `()`
 
-error: aborting due to 7 previous errors
+error: matching over `()` is more explicit
+  --> $DIR/ignored_unit_patterns.rs:45:13
+   |
+LL |         (1, _) => unimplemented!(),
+   |             ^ help: use `()` instead of `_`: `()`
+
+error: matching over `()` is more explicit
+  --> $DIR/ignored_unit_patterns.rs:52:13
+   |
+LL |     for (x, _) in v {
+   |             ^ help: use `()` instead of `_`: `()`
+
+error: aborting due to 9 previous errors