register DerefMut bounds for implicit mutable derefs

tests/ui/pattern/deref-patterns/bindings.rs

@@ -51,6 +51,7 @@ fn nested_vec(vecvec: Vec<Vec<u32>>) -> u32 {
     }
 }
 
+#[cfg(explicit)]
 fn ref_mut(val: u32) -> u32 {
     let mut b = Box::new(0u32);
     match &mut b {
@@ -64,6 +65,21 @@ fn ref_mut(val: u32) -> u32 {
     *x
 }
 
+#[cfg(implicit)]
+fn ref_mut(val: u32) -> u32 {
+    let mut b = Box::new((0u32,));
+    match &mut b {
+        (_x,) if false => unreachable!(),
+        (x,) => {
+            *x = val;
+        }
+        _ => unreachable!(),
+    }
+    let (x,) = &b else { unreachable!() };
+    *x
+}
+
+#[cfg(explicit)]
 #[rustfmt::skip]
 fn or_and_guard(tuple: (u32, u32)) -> u32 {
     let mut sum = 0;
@@ -75,6 +91,18 @@ fn or_and_guard(tuple: (u32, u32)) -> u32 {
     sum
 }
 
+#[cfg(implicit)]
+#[rustfmt::skip]
+fn or_and_guard(tuple: (u32, u32)) -> u32 {
+    let mut sum = 0;
+    let b = Box::new(tuple);
+    match b {
+        (x, _) | (_, x) if { sum += x; false } => {},
+        _ => {},
+    }
+    sum
+}
+
 fn main() {
     assert_eq!(simple_vec(vec![1]), 1);
     assert_eq!(simple_vec(vec![1, 2]), 202);

tests/ui/pattern/deref-patterns/fake_borrows.rs

@@ -11,4 +11,11 @@ fn main() {
         deref!(false) => {}
         _ => {},
     }
+    match b {
+        true => {}
+        _ if { *b = true; false } => {}
+        //~^ ERROR cannot assign `*b` in match guard
+        false => {}
+        _ => {},
+    }
 }

tests/ui/pattern/deref-patterns/fake_borrows.stderr

@@ -7,6 +7,15 @@ LL |         deref!(true) => {}
 LL |         _ if { *b = true; false } => {}
    |                ^^^^^^^^^ cannot assign
 
-error: aborting due to 1 previous error
+error[E0510]: cannot assign `*b` in match guard
+  --> $DIR/fake_borrows.rs:16:16
+   |
+LL |     match b {
+   |           - value is immutable in match guard
+LL |         true => {}
+LL |         _ if { *b = true; false } => {}
+   |                ^^^^^^^^^ cannot assign
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0510`.

tests/ui/pattern/deref-patterns/ref-mut.rs

@@ -8,10 +8,19 @@ fn main() {
         deref!(x) => {}
         _ => {}
     }
+    match &mut vec![1] {
+        [x] => {}
+        _ => {}
+    }
 
     match &mut Rc::new(1) {
         deref!(x) => {}
         //~^ ERROR the trait bound `Rc<{integer}>: DerefMut` is not satisfied
         _ => {}
     }
+    match &mut Rc::new((1,)) {
+        (x,) => {}
+        //~^ ERROR the trait bound `Rc<({integer},)>: DerefMut` is not satisfied
+        _ => {}
+    }
 }

tests/ui/pattern/deref-patterns/ref-mut.stderr

@@ -8,13 +8,19 @@ LL | #![feature(deref_patterns)]
    = note: `#[warn(incomplete_features)]` on by default
 
 error[E0277]: the trait bound `Rc<{integer}>: DerefMut` is not satisfied
-  --> $DIR/ref-mut.rs:13:9
+  --> $DIR/ref-mut.rs:17:9
    |
 LL |         deref!(x) => {}
    |         ^^^^^^^^^ the trait `DerefMut` is not implemented for `Rc<{integer}>`
    |
    = note: this error originates in the macro `deref` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 1 previous error; 1 warning emitted
+error[E0277]: the trait bound `Rc<({integer},)>: DerefMut` is not satisfied
+  --> $DIR/ref-mut.rs:22:9
+   |
+LL |         (x,) => {}
+   |         ^^^^ the trait `DerefMut` is not implemented for `Rc<({integer},)>`
+
+error: aborting due to 2 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0277`.