Update unwrap_get code review suggestions

Author: Michael Wright

clippy_lints/src/methods/mod.rs

@@ -1628,14 +1628,13 @@ fn lint_get_unwrap(cx: &LateContext<'_, '_>, expr: &hir::Expr, get_args: &[hir::
     // Handle the case where the result is immedately dereferenced
     // by not requiring ref and pulling the dereference into the
     // suggestion.
-    if needs_ref {
-        if let Some(parent) = get_parent_expr(cx, expr) {
-            if let hir::ExprKind::Unary(op, _) = parent.node {
-                if op == hir::UnOp::UnDeref {
-                    needs_ref = false;
-                    span = parent.span;
-                }
-            }
+    if_chain! {
+        if needs_ref;
+        if let Some(parent) = get_parent_expr(cx, expr);
+        if let hir::ExprKind::Unary(hir::UnOp::UnDeref, _) = parent.node;
+        then {
+            needs_ref = false;
+            span = parent.span;
         }
     }
 

tests/ui/get_unwrap.fixed

@@ -46,6 +46,8 @@ fn main() {
         let _ = &some_hashmap[&1];
         let _ = &some_btreemap[&1];
         let _ = false_positive.get(0).unwrap();
+        // Test with deref
+        let _: u8 = boxed_slice[1];
     }
 
     {

tests/ui/get_unwrap.rs

@@ -46,6 +46,8 @@ fn main() {
         let _ = some_hashmap.get(&1).unwrap();
         let _ = some_btreemap.get(&1).unwrap();
         let _ = false_positive.get(0).unwrap();
+        // Test with deref
+        let _: u8 = *boxed_slice.get(1).unwrap();
     }
 
     {

tests/ui/get_unwrap.stderr

@@ -36,41 +36,47 @@ error: called `.get().unwrap()` on a BTreeMap. Using `[]` is more clear and more
 LL |         let _ = some_btreemap.get(&1).unwrap();
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&some_btreemap[&1]`
 
+error: called `.get().unwrap()` on a slice. Using `[]` is more clear and more concise
+  --> $DIR/get_unwrap.rs:50:21
+   |
+LL |         let _: u8 = *boxed_slice.get(1).unwrap();
+   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `boxed_slice[1]`
+
 error: called `.get_mut().unwrap()` on a slice. Using `[]` is more clear and more concise
-  --> $DIR/get_unwrap.rs:53:9
+  --> $DIR/get_unwrap.rs:55:9
    |
 LL |         *boxed_slice.get_mut(0).unwrap() = 1;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `boxed_slice[0]`
 
 error: called `.get_mut().unwrap()` on a slice. Using `[]` is more clear and more concise
-  --> $DIR/get_unwrap.rs:54:9
+  --> $DIR/get_unwrap.rs:56:9
    |
 LL |         *some_slice.get_mut(0).unwrap() = 1;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `some_slice[0]`
 
 error: called `.get_mut().unwrap()` on a Vec. Using `[]` is more clear and more concise
-  --> $DIR/get_unwrap.rs:55:9
+  --> $DIR/get_unwrap.rs:57:9
    |
 LL |         *some_vec.get_mut(0).unwrap() = 1;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `some_vec[0]`
 
 error: called `.get_mut().unwrap()` on a VecDeque. Using `[]` is more clear and more concise
-  --> $DIR/get_unwrap.rs:56:9
+  --> $DIR/get_unwrap.rs:58:9
    |
 LL |         *some_vecdeque.get_mut(0).unwrap() = 1;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `some_vecdeque[0]`
 
 error: called `.get().unwrap()` on a Vec. Using `[]` is more clear and more concise
-  --> $DIR/get_unwrap.rs:65:17
+  --> $DIR/get_unwrap.rs:67:17
    |
 LL |         let _ = some_vec.get(0..1).unwrap().to_vec();
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `some_vec[0..1]`
 
 error: called `.get_mut().unwrap()` on a Vec. Using `[]` is more clear and more concise
-  --> $DIR/get_unwrap.rs:66:17
+  --> $DIR/get_unwrap.rs:68:17
    |
 LL |         let _ = some_vec.get_mut(0..1).unwrap().to_vec();
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `some_vec[0..1]`
 
-error: aborting due to 12 previous errors
+error: aborting due to 13 previous errors