Auto merge of #10454 - Alexendoo:transmutes-expressible-as-ptr-casts-parens, r=Jarcho

Wrap `transmutes_expressible_as_ptr_casts` suggestions in parentheses

changelog: [`transmutes_expressible_as_ptr_casts`]: Fix suggestion missing wrapping parentheses

Fixes #10449

r? `@Jarcho`

Is this the best way to go about this? `unused_parens` will catch the unnecessary ones but emitting them in the first place isn't ideal

3 files changed, 21 insertions, 3 deletions

diff --git a/tests/ui/transmutes_expressible_as_ptr_casts.fixed b/tests/ui/transmutes_expressible_as_ptr_casts.fixed
index 55307506eb3..cc84ba25bd0 100644
--- a/tests/ui/transmutes_expressible_as_ptr_casts.fixed
+++ b/tests/ui/transmutes_expressible_as_ptr_casts.fixed
@@ -4,7 +4,7 @@
 // would otherwise be responsible for
 #![warn(clippy::useless_transmute)]
 #![warn(clippy::transmute_ptr_to_ptr)]
-#![allow(dead_code, unused_unsafe, clippy::borrow_as_ptr)]
+#![allow(unused, clippy::borrow_as_ptr)]
 
 use std::mem::{size_of, transmute};
 
@@ -77,3 +77,9 @@ fn cannot_be_expressed_as_pointer_cast(in_param: Single) -> Pair {
 
     unsafe { transmute::<Single, Pair>(in_param) }
 }
+
+fn issue_10449() {
+    fn f() {}
+
+    let _x: u8 = unsafe { *(f as *const u8) };
+}
diff --git a/tests/ui/transmutes_expressible_as_ptr_casts.rs b/tests/ui/transmutes_expressible_as_ptr_casts.rs
index e7360f3f9dc..aa65ab4dd24 100644
--- a/tests/ui/transmutes_expressible_as_ptr_casts.rs
+++ b/tests/ui/transmutes_expressible_as_ptr_casts.rs
@@ -4,7 +4,7 @@
 // would otherwise be responsible for
 #![warn(clippy::useless_transmute)]
 #![warn(clippy::transmute_ptr_to_ptr)]
-#![allow(dead_code, unused_unsafe, clippy::borrow_as_ptr)]
+#![allow(unused, clippy::borrow_as_ptr)]
 
 use std::mem::{size_of, transmute};
 
@@ -77,3 +77,9 @@ fn cannot_be_expressed_as_pointer_cast(in_param: Single) -> Pair {
 
     unsafe { transmute::<Single, Pair>(in_param) }
 }
+
+fn issue_10449() {
+    fn f() {}
+
+    let _x: u8 = unsafe { *std::mem::transmute::<fn(), *const u8>(f) };
+}
diff --git a/tests/ui/transmutes_expressible_as_ptr_casts.stderr b/tests/ui/transmutes_expressible_as_ptr_casts.stderr
index e862fcb67a4..58f5162c78e 100644
--- a/tests/ui/transmutes_expressible_as_ptr_casts.stderr
+++ b/tests/ui/transmutes_expressible_as_ptr_casts.stderr
@@ -58,5 +58,11 @@ error: transmute from a reference to a pointer
 LL |     unsafe { transmute::<&[i32; 1], *const u8>(in_param) }
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `in_param as *const [i32; 1] as *const u8`
 
-error: aborting due to 9 previous errors
+error: transmute from `fn()` to `*const u8` which could be expressed as a pointer cast instead
+  --> $DIR/transmutes_expressible_as_ptr_casts.rs:84:28
+   |
+LL |     let _x: u8 = unsafe { *std::mem::transmute::<fn(), *const u8>(f) };
+   |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(f as *const u8)`
+
+error: aborting due to 10 previous errors