Auto merge of #11196 - c410-f3r:let-chain, r=xFrednet

[significant_drop_tightening] Fix #11189

Fix #11189

```
changelog: FP: [`significant_drop_tightening`]: Consider tuples in drop calls
```

clippy_lints/src/significant_drop_tightening.rs

@@ -331,13 +331,13 @@ impl<'ap, 'lc, 'others, 'stmt, 'tcx> Visitor<'tcx> for StmtsChecker<'ap, 'lc, 'o
                             apa.last_method_span = span;
                         }
                     },
-                    hir::StmtKind::Semi(expr) => {
+                    hir::StmtKind::Semi(semi_expr) => {
-                        if has_drop(expr, &apa.first_bind_ident, self.cx) {
+                        if has_drop(semi_expr, &apa.first_bind_ident, self.cx) {
                             apa.has_expensive_expr_after_last_attr = false;
                             apa.last_stmt_span = DUMMY_SP;
                             return;
                         }
-                        if let hir::ExprKind::MethodCall(_, _, _, span) = expr.kind {
+                        if let hir::ExprKind::MethodCall(_, _, _, span) = semi_expr.kind {
                             apa.last_method_span = span;
                         }
                     },
@@ -435,14 +435,26 @@ fn has_drop(expr: &hir::Expr<'_>, first_bind_ident: &Ident, lcx: &LateContext<'_
         && let Res::Def(DefKind::Fn, did) = fun_path.res
         && lcx.tcx.is_diagnostic_item(sym::mem_drop, did)
         && let [first_arg, ..] = args
-        && let hir::ExprKind::Path(hir::QPath::Resolved(_, arg_path)) = &first_arg.kind
-        && let [first_arg_ps, .. ] = arg_path.segments
     {
-        &first_arg_ps.ident == first_bind_ident
+        let has_ident = |local_expr: &hir::Expr<'_>| {
+            if let hir::ExprKind::Path(hir::QPath::Resolved(_, arg_path)) = &local_expr.kind
+                && let [first_arg_ps, .. ] = arg_path.segments
+                && &first_arg_ps.ident == first_bind_ident
+            {
+                true
             }
             else {
                 false
             }
+        };
+        if has_ident(first_arg) {
+            return true;
+        }
+        if let hir::ExprKind::Tup(value) = &first_arg.kind && value.iter().any(has_ident) {
+            return true;
+        }
+    }
+    false
 }
 
 fn is_inexpensive_expr(expr: &hir::Expr<'_>) -> bool {

tests/ui/significant_drop_tightening.fixed

@@ -58,6 +58,26 @@ pub fn issue_11160() -> bool {
     true
 }
 
+pub fn issue_11189() {
+    struct Number {
+        pub value: u32,
+    }
+
+    fn do_something() -> Result<(), ()> {
+        let number = Mutex::new(Number { value: 1 });
+        let number2 = Mutex::new(Number { value: 2 });
+        let number3 = Mutex::new(Number { value: 3 });
+        let mut lock = number.lock().unwrap();
+        let mut lock2 = number2.lock().unwrap();
+        let mut lock3 = number3.lock().unwrap();
+        lock.value += 1;
+        lock2.value += 1;
+        lock3.value += 1;
+        drop((lock, lock2, lock3));
+        Ok(())
+    }
+}
+
 pub fn path_return_can_be_ignored() -> i32 {
     let mutex = Mutex::new(1);
     let lock = mutex.lock().unwrap();

tests/ui/significant_drop_tightening.rs

@@ -57,6 +57,26 @@ pub fn issue_11160() -> bool {
     true
 }
 
+pub fn issue_11189() {
+    struct Number {
+        pub value: u32,
+    }
+
+    fn do_something() -> Result<(), ()> {
+        let number = Mutex::new(Number { value: 1 });
+        let number2 = Mutex::new(Number { value: 2 });
+        let number3 = Mutex::new(Number { value: 3 });
+        let mut lock = number.lock().unwrap();
+        let mut lock2 = number2.lock().unwrap();
+        let mut lock3 = number3.lock().unwrap();
+        lock.value += 1;
+        lock2.value += 1;
+        lock3.value += 1;
+        drop((lock, lock2, lock3));
+        Ok(())
+    }
+}
+
 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:86:13
+  --> $DIR/significant_drop_tightening.rs:106:13
    |
 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:107:13
+  --> $DIR/significant_drop_tightening.rs:127:13
    |
 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:113:17
+  --> $DIR/significant_drop_tightening.rs:133:17
    |
 LL | /     {
 LL | |         let mutex = Mutex::new(vec![1i32]);