Detect shadowing in pattern field

tests/ui/shadow.rs

@@ -133,4 +133,12 @@ fn shadow_closure() {
         .collect();
 }
 
+struct Issue13795 {
+    value: i32,
+}
+
+fn issue13795(value: Issue13795) {
+    let Issue13795 { value, .. } = value;
+}
+
 fn main() {}

tests/ui/shadow.stderr

@@ -304,5 +304,17 @@ note: previous binding is here
 LL |         .map(|i| i.map(|i| i - 10))
    |               ^
 
-error: aborting due to 25 previous errors
+error: `value` is shadowed by itself in `value`
+  --> tests/ui/shadow.rs:141:22
+   |
+LL |     let Issue13795 { value, .. } = value;
+   |                      ^^^^^
+   |
+note: previous binding is here
+  --> tests/ui/shadow.rs:140:15
+   |
+LL | fn issue13795(value: Issue13795) {
+   |               ^^^^^
+
+error: aborting due to 26 previous errors