Wrap transmutes_expressible_as_ptr_casts suggestions in parentheses

clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs

@@ -23,17 +23,19 @@ pub(super) fn check<'tcx>(
         Some(PtrPtrCast | AddrPtrCast | ArrayPtrCast | FnPtrPtrCast | FnPtrAddrCast) => {
             Sugg::hir_with_context(cx, arg, e.span.ctxt(), "..", &mut app)
                 .as_ty(to_ty.to_string())
+                .maybe_par()
                 .to_string()
         },
         Some(PtrAddrCast) if !from_ty_adjusted => Sugg::hir_with_context(cx, arg, e.span.ctxt(), "..", &mut app)
             .as_ty(to_ty.to_string())
+            .maybe_par()
             .to_string(),
 
         // The only adjustments here would be ref-to-ptr and unsize coercions. The result of an unsize coercions can't
         // be transmuted to a usize. For ref-to-ptr coercions, borrows need to be cast to a pointer before being cast to
         // a usize.
         Some(PtrAddrCast) => format!(
-            "{} as {to_ty}",
+            "({} as {to_ty})",
             Sugg::hir_with_context(cx, arg, e.span.ctxt(), "..", &mut app).as_ty(from_ty)
         ),
         _ => return false,

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};
 
@@ -31,7 +31,7 @@ fn main() {
     // we should wait until std::raw::TraitObject is stabilized?
 
     // e has type *T and U is a numeric type, while T: Sized; ptr-addr-cast
-    let _usize_from_int_ptr_transmute = unsafe { ptr_i32 as usize };
+    let _usize_from_int_ptr_transmute = unsafe { (ptr_i32 as usize) };
     let _usize_from_int_ptr = ptr_i32 as usize;
 
     let array_ref: &[i32; 4] = &[1, 2, 3, 4];
@@ -45,14 +45,14 @@ fn main() {
     }
 
     // e is a function pointer type and U has type *T, while T: Sized; fptr-ptr-cast
-    let _usize_ptr_transmute = unsafe { foo as *const usize };
+    let _usize_ptr_transmute = unsafe { (foo as *const usize) };
     let _usize_ptr_transmute = foo as *const usize;
 
     // e is a function pointer type and U is an integer; fptr-addr-cast
-    let _usize_from_fn_ptr_transmute = unsafe { foo as usize };
+    let _usize_from_fn_ptr_transmute = unsafe { (foo as usize) };
     let _usize_from_fn_ptr = foo as *const usize;
 
-    let _usize_from_ref = unsafe { &1u32 as *const u32 as usize };
+    let _usize_from_ref = unsafe { (&1u32 as *const u32 as usize) };
 }
 
 // If a ref-to-ptr cast of this form where the pointer type points to a type other
@@ -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) };
+}

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) };
+}

tests/ui/transmutes_expressible_as_ptr_casts.stderr

@@ -24,7 +24,7 @@ error: transmute from `*const i32` to `usize` which could be expressed as a poin
   --> $DIR/transmutes_expressible_as_ptr_casts.rs:34:50
    |
 LL |     let _usize_from_int_ptr_transmute = unsafe { transmute::<*const i32, usize>(ptr_i32) };
-   |                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `ptr_i32 as usize`
+   |                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(ptr_i32 as usize)`
    |
    = note: `-D clippy::transmutes-expressible-as-ptr-casts` implied by `-D warnings`
 
@@ -38,25 +38,31 @@ error: transmute from `fn(usize) -> u8` to `*const usize` which could be express
   --> $DIR/transmutes_expressible_as_ptr_casts.rs:48:41
    |
 LL |     let _usize_ptr_transmute = unsafe { transmute::<fn(usize) -> u8, *const usize>(foo) };
-   |                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `foo as *const usize`
+   |                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(foo as *const usize)`
 
 error: transmute from `fn(usize) -> u8` to `usize` which could be expressed as a pointer cast instead
   --> $DIR/transmutes_expressible_as_ptr_casts.rs:52:49
    |
 LL |     let _usize_from_fn_ptr_transmute = unsafe { transmute::<fn(usize) -> u8, usize>(foo) };
-   |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `foo as usize`
+   |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(foo as usize)`
 
 error: transmute from `*const u32` to `usize` which could be expressed as a pointer cast instead
   --> $DIR/transmutes_expressible_as_ptr_casts.rs:55:36
    |
 LL |     let _usize_from_ref = unsafe { transmute::<*const u32, usize>(&1u32) };
-   |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `&1u32 as *const u32 as usize`
+   |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(&1u32 as *const u32 as usize)`
 
 error: transmute from a reference to a pointer
   --> $DIR/transmutes_expressible_as_ptr_casts.rs:66:14
    |
 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