Auto merge of #11161 - c410-f3r:let-chain, r=dswij

[significant_drop_tightening] Fix #11160

Fix #11160

```
changelog: [`significant_drop_tightening`]: Ignore literals in function returns
```

tests/ui/significant_drop_tightening.fixed

@@ -51,6 +51,13 @@ pub fn issue_11128() {
     }
 }
 
+pub fn issue_11160() -> bool {
+    let mutex = Mutex::new(1i32);
+    let lock = mutex.lock().unwrap();
+    let _ = lock.abs();
+    true
+}
+
 pub fn path_return_can_be_ignored() -> i32 {
     let mutex = Mutex::new(1);
     let lock = mutex.lock().unwrap();

tests/ui/significant_drop_tightening.rs

@@ -50,6 +50,13 @@ pub fn issue_11128() {
     }
 }
 
+pub fn issue_11160() -> bool {
+    let mutex = Mutex::new(1i32);
+    let lock = mutex.lock().unwrap();
+    let _ = lock.abs();
+    true
+}
+
 pub fn path_return_can_be_ignored() -> i32 {
     let mutex = Mutex::new(1);
     let lock = mutex.lock().unwrap();

tests/ui/significant_drop_tightening.stderr

@@ -23,7 +23,7 @@ LL +     drop(lock);
    |
 
 error: temporary with significant `Drop` can be early dropped
-  --> $DIR/significant_drop_tightening.rs:79:13
+  --> $DIR/significant_drop_tightening.rs:86:13
    |
 LL | /     {
 LL | |         let mutex = Mutex::new(1i32);
@@ -43,7 +43,7 @@ LL +         drop(lock);
    |
 
 error: temporary with significant `Drop` can be early dropped
-  --> $DIR/significant_drop_tightening.rs:100:13
+  --> $DIR/significant_drop_tightening.rs:107:13
    |
 LL | /     {
 LL | |         let mutex = Mutex::new(1i32);
@@ -67,7 +67,7 @@ LL +
    |
 
 error: temporary with significant `Drop` can be early dropped
-  --> $DIR/significant_drop_tightening.rs:106:17
+  --> $DIR/significant_drop_tightening.rs:113:17
    |
 LL | /     {
 LL | |         let mutex = Mutex::new(vec![1i32]);