Lint significant drop on while let and if let

tests/ui/significant_drop_in_scrutinee.rs

@@ -801,4 +801,30 @@ fn should_not_trigger_lint_with_explicit_drop() {
     }
 }
 
+fn should_trigger_lint_in_if_let() {
+    let mutex = Mutex::new(vec![1]);
+
+    if let Some(val) = mutex.lock().unwrap().first().copied() {
+        //~^ ERROR: temporary with significant `Drop` in `if let` scrutinee will live until the
+        //~| NOTE: this might lead to deadlocks or other unexpected behavior
+        println!("{}", val);
+    }
+
+    // Should not trigger lint without the final `copied()`, because we actually hold a reference
+    // (i.e., the `val`) to the locked data.
+    if let Some(val) = mutex.lock().unwrap().first() {
+        println!("{}", val);
+    };
+}
+
+fn should_trigger_lint_in_while_let() {
+    let mutex = Mutex::new(vec![1]);
+
+    while let Some(val) = mutex.lock().unwrap().pop() {
+        //~^ ERROR: temporary with significant `Drop` in `while let` scrutinee will live until the
+        //~| NOTE: this might lead to deadlocks or other unexpected behavior
+        println!("{}", val);
+    }
+}
+
 fn main() {}

tests/ui/significant_drop_in_scrutinee.stderr

@@ -541,5 +541,32 @@ LL ~     let value = mutex.lock().unwrap()[0];
 LL ~     for val in [value, 2] {
    |
 
-error: aborting due to 27 previous errors
+error: temporary with significant `Drop` in `if let` scrutinee will live until the end of the `if let` expression
+  --> tests/ui/significant_drop_in_scrutinee.rs:807:24
+   |
+LL |     if let Some(val) = mutex.lock().unwrap().first().copied() {
+   |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL |     }
+   |      - temporary lives until here
+   |
+   = note: this might lead to deadlocks or other unexpected behavior
+help: try moving the temporary above the match
+   |
+LL ~     let value = mutex.lock().unwrap().first().copied();
+LL ~     if let Some(val) = value {
+   |
+
+error: temporary with significant `Drop` in `while let` scrutinee will live until the end of the `while let` expression
+  --> tests/ui/significant_drop_in_scrutinee.rs:823:27
+   |
+LL |     while let Some(val) = mutex.lock().unwrap().pop() {
+   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
+...
+LL |     }
+   |      - temporary lives until here
+   |
+   = note: this might lead to deadlocks or other unexpected behavior
+
+error: aborting due to 29 previous errors