add paren before '?' when suggesting deref

Author: macovedj

clippy_lints/src/methods/clone_on_copy.rs

@@ -4,7 +4,7 @@ use clippy_utils::source::snippet_with_context;
 use clippy_utils::sugg;
 use clippy_utils::ty::is_copy;
 use rustc_errors::Applicability;
-use rustc_hir::{BindingAnnotation, Expr, ExprKind, MatchSource, Node, PatKind};
+use rustc_hir::{BindingAnnotation, Expr, ExprKind, MatchSource, Node, PatKind, QPath};
 use rustc_lint::LateContext;
 use rustc_middle::ty::{self, adjustment::Adjust};
 use rustc_span::symbol::{sym, Symbol};
@@ -86,6 +86,10 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, method_name: Symbol,
                 {
                     return;
                 },
+                ExprKind::Call(hir_callee, _) => match hir_callee.kind {
+                    ExprKind::Path(QPath::LangItem(rustc_hir::LangItem::TryTraitBranch, _, _)) => true,
+                    _ => false,
+                },
                 ExprKind::MethodCall(_, [self_arg, ..], _) if expr.hir_id == self_arg.hir_id => true,
                 ExprKind::Match(_, _, MatchSource::TryDesugar | MatchSource::AwaitDesugar)
                 | ExprKind::Field(..)

tests/ui/clone_on_copy.fixed

@@ -21,7 +21,7 @@ fn is_ascii(ch: char) -> bool {
     ch.is_ascii()
 }
 
-fn clone_on_copy() {
+fn clone_on_copy() -> Option<(i32)> {
     42;
 
     vec![1].clone(); // ok, not a Copy type
@@ -71,4 +71,8 @@ fn clone_on_copy() {
     // Issue #5436
     let mut vec = Vec::new();
     vec.push(42);
+
+    let opt: &Option<i32> = &None;
+    let value = (*opt)?;
+    None
 }

tests/ui/clone_on_copy.rs

@@ -21,7 +21,7 @@ fn is_ascii(ch: char) -> bool {
     ch.is_ascii()
 }
 
-fn clone_on_copy() {
+fn clone_on_copy() -> Option<(i32)> {
     42.clone();
 
     vec![1].clone(); // ok, not a Copy type
@@ -71,4 +71,8 @@ fn clone_on_copy() {
     // Issue #5436
     let mut vec = Vec::new();
     vec.push(42.clone());
+
+    let opt: &Option<i32> = &None;
+    let value = opt.clone()?;
+    None
 }

tests/ui/clone_on_copy.stderr

@@ -48,5 +48,11 @@ error: using `clone` on type `i32` which implements the `Copy` trait
 LL |     vec.push(42.clone());
    |              ^^^^^^^^^^ help: try removing the `clone` call: `42`
 
-error: aborting due to 8 previous errors
+error: using `clone` on type `std::option::Option<i32>` which implements the `Copy` trait
+  --> $DIR/clone_on_copy.rs:76:17
+   |
+LL |     let value = opt.clone()?;
+   |                 ^^^^^^^^^^^ help: try dereferencing it: `(*opt)`
+
+error: aborting due to 9 previous errors