Add test for needless_pass_by_ref_mut to ensure that the lint is not emitted if variable is used in an unsafe block or function

Author: GuillaumeGomez

tests/ui/needless_pass_by_ref_mut.rs

@@ -1,4 +1,9 @@
-#![allow(clippy::if_same_then_else, clippy::no_effect, clippy::redundant_closure_call)]
+#![allow(
+    clippy::if_same_then_else,
+    clippy::no_effect,
+    clippy::redundant_closure_call,
+    clippy::mut_from_ref
+)]
 #![warn(clippy::needless_pass_by_ref_mut)]
 #![feature(lint_reasons)]
 //@no-rustfix
@@ -270,6 +275,18 @@ pub async fn closure4(n: &mut usize) {
     })();
 }
 
+struct Data<T: ?Sized> {
+    value: T,
+}
+// Unsafe functions should not warn.
+unsafe fn get_mut_unchecked<T>(ptr: &NonNull<Data<T>>) -> &mut T {
+    &mut (*ptr.as_ptr()).value
+}
+// Unsafe blocks should not warn.
+fn get_mut_unchecked2<T>(ptr: &NonNull<Data<T>>) -> &mut T {
+    unsafe { &mut (*ptr.as_ptr()).value }
+}
+
 fn main() {
     let mut u = 0;
     let mut v = vec![0];

tests/ui/needless_pass_by_ref_mut.stderr

@@ -1,5 +1,5 @@
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:7:11
+  --> $DIR/needless_pass_by_ref_mut.rs:12:11
    |
 LL | fn foo(s: &mut Vec<u32>, b: &u32, x: &mut u32) {
    |           ^^^^^^^^^^^^^ help: consider changing to: `&Vec<u32>`
@@ -8,131 +8,131 @@ LL | fn foo(s: &mut Vec<u32>, b: &u32, x: &mut u32) {
    = help: to override `-D warnings` add `#[allow(clippy::needless_pass_by_ref_mut)]`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:32:12
+  --> $DIR/needless_pass_by_ref_mut.rs:37:12
    |
 LL | fn foo6(s: &mut Vec<u32>) {
    |            ^^^^^^^^^^^^^ help: consider changing to: `&Vec<u32>`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:45:29
+  --> $DIR/needless_pass_by_ref_mut.rs:50:29
    |
 LL |     fn mushroom(&self, vec: &mut Vec<i32>) -> usize {
    |                             ^^^^^^^^^^^^^ help: consider changing to: `&Vec<i32>`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:50:31
+  --> $DIR/needless_pass_by_ref_mut.rs:55:31
    |
 LL |     fn badger(&mut self, vec: &mut Vec<i32>) -> usize {
    |                               ^^^^^^^^^^^^^ help: consider changing to: `&Vec<i32>`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:127:16
+  --> $DIR/needless_pass_by_ref_mut.rs:132:16
    |
 LL | async fn a1(x: &mut i32) {
    |                ^^^^^^^^ help: consider changing to: `&i32`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:131:16
+  --> $DIR/needless_pass_by_ref_mut.rs:136:16
    |
 LL | async fn a2(x: &mut i32, y: String) {
    |                ^^^^^^^^ help: consider changing to: `&i32`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:135:16
+  --> $DIR/needless_pass_by_ref_mut.rs:140:16
    |
 LL | async fn a3(x: &mut i32, y: String, z: String) {
    |                ^^^^^^^^ help: consider changing to: `&i32`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:139:16
+  --> $DIR/needless_pass_by_ref_mut.rs:144:16
    |
 LL | async fn a4(x: &mut i32, y: i32) {
    |                ^^^^^^^^ help: consider changing to: `&i32`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:143:24
+  --> $DIR/needless_pass_by_ref_mut.rs:148:24
    |
 LL | async fn a5(x: i32, y: &mut i32) {
    |                        ^^^^^^^^ help: consider changing to: `&i32`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:147:24
+  --> $DIR/needless_pass_by_ref_mut.rs:152:24
    |
 LL | async fn a6(x: i32, y: &mut i32) {
    |                        ^^^^^^^^ help: consider changing to: `&i32`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:151:32
+  --> $DIR/needless_pass_by_ref_mut.rs:156:32
    |
 LL | async fn a7(x: i32, y: i32, z: &mut i32) {
    |                                ^^^^^^^^ help: consider changing to: `&i32`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:155:24
+  --> $DIR/needless_pass_by_ref_mut.rs:160:24
    |
 LL | async fn a8(x: i32, a: &mut i32, y: i32, z: &mut i32) {
    |                        ^^^^^^^^ help: consider changing to: `&i32`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:155:45
+  --> $DIR/needless_pass_by_ref_mut.rs:160:45
    |
 LL | async fn a8(x: i32, a: &mut i32, y: i32, z: &mut i32) {
    |                                             ^^^^^^^^ help: consider changing to: `&i32`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:189:16
+  --> $DIR/needless_pass_by_ref_mut.rs:194:16
    |
 LL | fn cfg_warn(s: &mut u32) {}
    |                ^^^^^^^^ help: consider changing to: `&u32`
    |
    = note: this is cfg-gated and may require further changes
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:195:20
+  --> $DIR/needless_pass_by_ref_mut.rs:200:20
    |
 LL |     fn cfg_warn(s: &mut u32) {}
    |                    ^^^^^^^^ help: consider changing to: `&u32`
    |
    = note: this is cfg-gated and may require further changes
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:209:39
+  --> $DIR/needless_pass_by_ref_mut.rs:214:39
    |
 LL | async fn inner_async2(x: &mut i32, y: &mut u32) {
    |                                       ^^^^^^^^ help: consider changing to: `&u32`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:217:26
+  --> $DIR/needless_pass_by_ref_mut.rs:222:26
    |
 LL | async fn inner_async3(x: &mut i32, y: &mut u32) {
    |                          ^^^^^^^^ help: consider changing to: `&i32`
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:236:34
+  --> $DIR/needless_pass_by_ref_mut.rs:241:34
    |
 LL | pub async fn call_in_closure1(n: &mut str) {
    |                                  ^^^^^^^^ help: consider changing to: `&str`
    |
    = warning: changing this function will impact semver compatibility
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:248:25
+  --> $DIR/needless_pass_by_ref_mut.rs:253:25
    |
 LL | pub async fn closure(n: &mut usize) -> impl '_ + FnMut() {
    |                         ^^^^^^^^^^ help: consider changing to: `&usize`
    |
    = warning: changing this function will impact semver compatibility
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:255:20
+  --> $DIR/needless_pass_by_ref_mut.rs:260:20
    |
 LL | pub fn closure2(n: &mut usize) -> impl '_ + FnMut() -> usize {
    |                    ^^^^^^^^^^ help: consider changing to: `&usize`
    |
    = warning: changing this function will impact semver compatibility
 
 error: this argument is a mutable reference, but not used mutably
-  --> $DIR/needless_pass_by_ref_mut.rs:266:26
+  --> $DIR/needless_pass_by_ref_mut.rs:271:26
    |
 LL | pub async fn closure4(n: &mut usize) {
    |                          ^^^^^^^^^^ help: consider changing to: `&usize`