Don't suggest .cast_mut/.cast_const for types with erased lifetimes

Author: Alexendoo

clippy_lints/src/casts/ptr_cast_constness.rs

@@ -4,7 +4,7 @@ use clippy_utils::sugg::Sugg;
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, Mutability};
 use rustc_lint::LateContext;
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::ty::{self, Ty, TypeVisitableExt};
 
 use super::PTR_CAST_CONSTNESS;
 
@@ -24,6 +24,7 @@ pub(super) fn check<'tcx>(
             (Mutability::Not, Mutability::Mut) | (Mutability::Mut, Mutability::Not)
         )
         && from_ty == to_ty
+        && !from_ty.has_erased_regions()
     {
         let sugg = Sugg::hir(cx, cast_expr, "_");
         let constness = match *to_mutbl {

clippy_lints/src/transmute/transmute_ptr_to_ptr.rs

@@ -5,7 +5,7 @@ use clippy_utils::sugg;
 use rustc_errors::Applicability;
 use rustc_hir::Expr;
 use rustc_lint::LateContext;
-use rustc_middle::ty::{self, Ty};
+use rustc_middle::ty::{self, Ty, TypeVisitableExt};
 
 /// Checks for `transmute_ptr_to_ptr` lint.
 /// Returns `true` if it's triggered, otherwise returns `false`.
@@ -42,6 +42,7 @@ pub(super) fn check<'tcx>(
                                 (ty::Mutability::Mut, ty::Mutability::Not) => Some("cast_const"),
                                 _ => None,
                             }
+                            && !from_pointee_ty.has_erased_regions()
                             && msrv.meets(msrvs::POINTER_CAST_CONSTNESS)
                         {
                             diag.span_suggestion_verbose(

tests/ui/ptr_cast_constness.fixed

@@ -46,6 +46,10 @@ fn main() {
     let _ = external!($ptr as *const u32);
 }
 
+fn lifetime_to_static(v: *mut &()) -> *const &'static () {
+    v as _
+}
+
 #[clippy::msrv = "1.64"]
 fn _msrv_1_64() {
     let ptr: *const u32 = &42_u32;

tests/ui/ptr_cast_constness.rs

@@ -46,6 +46,10 @@ fn main() {
     let _ = external!($ptr as *const u32);
 }
 
+fn lifetime_to_static(v: *mut &()) -> *const &'static () {
+    v as _
+}
+
 #[clippy::msrv = "1.64"]
 fn _msrv_1_64() {
     let ptr: *const u32 = &42_u32;

tests/ui/ptr_cast_constness.stderr

@@ -32,13 +32,13 @@ LL |     let _ = mut_ptr as *const u32;
    |             ^^^^^^^^^^^^^^^^^^^^^ help: try `pointer::cast_const`, a safer alternative: `mut_ptr.cast_const()`
 
 error: `as` casting between raw pointers while changing only its constness
-  --> tests/ui/ptr_cast_constness.rs:64:13
+  --> tests/ui/ptr_cast_constness.rs:68:13
    |
 LL |     let _ = ptr as *mut u32;
    |             ^^^^^^^^^^^^^^^ help: try `pointer::cast_mut`, a safer alternative: `ptr.cast_mut()`
 
 error: `as` casting between raw pointers while changing only its constness
-  --> tests/ui/ptr_cast_constness.rs:65:13
+  --> tests/ui/ptr_cast_constness.rs:69:13
    |
 LL |     let _ = mut_ptr as *const u32;
    |             ^^^^^^^^^^^^^^^^^^^^^ help: try `pointer::cast_const`, a safer alternative: `mut_ptr.cast_const()`

tests/ui/transmute_ptr_to_ptr.fixed

@@ -60,6 +60,11 @@ fn transmute_ptr_to_ptr() {
     let _: &GenericParam<&LifetimeParam<'static>> = unsafe { transmute(&GenericParam { t: &lp }) };
 }
 
+fn lifetime_to_static(v: *mut &()) -> *const &'static () {
+    unsafe { v as *const &() }
+    //~^ transmute_ptr_to_ptr
+}
+
 // dereferencing raw pointers in const contexts, should not lint as it's unstable (issue 5959)
 const _: &() = {
     struct Zst;

tests/ui/transmute_ptr_to_ptr.rs

@@ -60,6 +60,11 @@ fn transmute_ptr_to_ptr() {
     let _: &GenericParam<&LifetimeParam<'static>> = unsafe { transmute(&GenericParam { t: &lp }) };
 }
 
+fn lifetime_to_static(v: *mut &()) -> *const &'static () {
+    unsafe { transmute(v) }
+    //~^ transmute_ptr_to_ptr
+}
+
 // dereferencing raw pointers in const contexts, should not lint as it's unstable (issue 5959)
 const _: &() = {
     struct Zst;

tests/ui/transmute_ptr_to_ptr.stderr

@@ -75,7 +75,18 @@ LL |         let _: *mut u32 = ptr.cast_mut();
    |                           ~~~~~~~~~~~~~~
 
 error: transmute from a pointer to a pointer
-  --> tests/ui/transmute_ptr_to_ptr.rs:74:28
+  --> tests/ui/transmute_ptr_to_ptr.rs:64:14
+   |
+LL |     unsafe { transmute(v) }
+   |              ^^^^^^^^^^^^
+   |
+help: use an `as` cast instead
+   |
+LL |     unsafe { v as *const &() }
+   |              ~~~~~~~~~~~~~~~
+
+error: transmute from a pointer to a pointer
+  --> tests/ui/transmute_ptr_to_ptr.rs:79:28
    |
 LL |         let _: *const i8 = transmute(ptr);
    |                            ^^^^^^^^^^^^^^
@@ -86,7 +97,7 @@ LL |         let _: *const i8 = ptr as *const i8;
    |                            ~~~~~~~~~~~~~~~~
 
 error: transmute from a pointer to a pointer
-  --> tests/ui/transmute_ptr_to_ptr.rs:81:28
+  --> tests/ui/transmute_ptr_to_ptr.rs:86:28
    |
 LL |         let _: *const i8 = transmute(ptr);
    |                            ^^^^^^^^^^^^^^
@@ -97,7 +108,7 @@ LL |         let _: *const i8 = ptr.cast::<i8>();
    |                            ~~~~~~~~~~~~~~~~
 
 error: transmute from a pointer to a pointer
-  --> tests/ui/transmute_ptr_to_ptr.rs:88:26
+  --> tests/ui/transmute_ptr_to_ptr.rs:93:26
    |
 LL |         let _: *mut u8 = transmute(ptr);
    |                          ^^^^^^^^^^^^^^
@@ -108,7 +119,7 @@ LL |         let _: *mut u8 = ptr as *mut u8;
    |                          ~~~~~~~~~~~~~~
 
 error: transmute from a pointer to a pointer
-  --> tests/ui/transmute_ptr_to_ptr.rs:89:28
+  --> tests/ui/transmute_ptr_to_ptr.rs:94:28
    |
 LL |         let _: *const u8 = transmute(mut_ptr);
    |                            ^^^^^^^^^^^^^^^^^^
@@ -119,7 +130,7 @@ LL |         let _: *const u8 = mut_ptr as *const u8;
    |                            ~~~~~~~~~~~~~~~~~~~~
 
 error: transmute from a pointer to a pointer
-  --> tests/ui/transmute_ptr_to_ptr.rs:96:26
+  --> tests/ui/transmute_ptr_to_ptr.rs:101:26
    |
 LL |         let _: *mut u8 = transmute(ptr);
    |                          ^^^^^^^^^^^^^^
@@ -130,7 +141,7 @@ LL |         let _: *mut u8 = ptr.cast_mut();
    |                          ~~~~~~~~~~~~~~
 
 error: transmute from a pointer to a pointer
-  --> tests/ui/transmute_ptr_to_ptr.rs:97:28
+  --> tests/ui/transmute_ptr_to_ptr.rs:102:28
    |
 LL |         let _: *const u8 = transmute(mut_ptr);
    |                            ^^^^^^^^^^^^^^^^^^
@@ -140,5 +151,5 @@ help: use `pointer::cast_const` instead
 LL |         let _: *const u8 = mut_ptr.cast_const();
    |                            ~~~~~~~~~~~~~~~~~~~~
 
-error: aborting due to 15 previous errors
+error: aborting due to 16 previous errors