Rollup merge of #144531 - Urgau:int_to_ptr_transmutes, r=jackh726

Add lint against integer to pointer transmutes

# `integer_to_ptr_transmutes`

*warn-by-default*

The `integer_to_ptr_transmutes` lint detects integer to pointer transmutes where the resulting pointers are undefined behavior to dereference.

### Example

```rust
fn foo(a: usize) -> *const u8 {
    unsafe {
        std::mem::transmute::<usize, *const u8>(a)
    }
}
```

```
warning: transmuting an integer to a pointer creates a pointer without provenance
   --> a.rs:1:9
    |
158 |         std::mem::transmute::<usize, *const u8>(a)
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
    = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
    = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
    = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
    = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
    = note: `#[warn(integer_to_ptr_transmutes)]` on by default
help: use `std::ptr::with_exposed_provenance` instead to use a previously exposed provenance
    |
158 -     std::mem::transmute::<usize, *const u8>(a)
158 +     std::ptr::with_exposed_provenance::<u8>(a)
    |
```

### Explanation

Any attempt to use the resulting pointers are undefined behavior as the resulting pointers won't have any provenance.

Alternatively, `std::ptr::with_exposed_provenance` should be used, as they do not carry the provenance requirement or if the wanting to create pointers without provenance `std::ptr::without_provenance_mut` should be used.

See [std::mem::transmute] in the reference for more details.

[std::mem::transmute]: https://doc.rust-lang.org/std/mem/fn.transmute.html

--------

People are getting tripped up on this, see https://github.com/rust-lang/rust/issues/128409 and https://github.com/rust-lang/rust/issues/141220. There are >90 cases like these on [GitHub search](https://github.com/search?q=lang%3Arust+%2Ftransmute%3A%3A%3Cu%5B0-9%5D*.*%2C+%5C*const%2F&type=code).

Fixes https://github.com/rust-lang/rust-clippy/issues/13140
Fixes https://github.com/rust-lang/rust/issues/141220
Fixes https://github.com/rust-lang/rust/issues/145523

`@rustbot` labels +I-lang-nominated +T-lang
cc `@traviscross`
r? compiler

20 files changed, 490 insertions, 68 deletions

diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl
index 940a07c94df..417e5a97069 100644
--- a/compiler/rustc_lint/messages.ftl
+++ b/compiler/rustc_lint/messages.ftl
@@ -462,6 +462,14 @@ lint_invalid_reference_casting_note_book = for more information, visit <https://
 
 lint_invalid_reference_casting_note_ty_has_interior_mutability = even for types with interior mutability, the only legal way to obtain a mutable pointer from a shared reference is through `UnsafeCell::get`
 
+lint_int_to_ptr_transmutes = transmuting an integer to a pointer creates a pointer without provenance
+    .note = this is dangerous because dereferencing the resulting pointer is undefined behavior
+    .note_exposed_provenance = exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+    .help_transmute = for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+    .help_exposed_provenance = for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+    .suggestion_with_exposed_provenance = use `std::ptr::with_exposed_provenance{$suffix}` instead to use a previously exposed provenance
+    .suggestion_without_provenance_mut = if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+
 lint_legacy_derive_helpers = derive helper attribute is used before it is introduced
     .label = the attribute is introduced here
 
diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
index 6c509734626..426500dda4a 100644
--- a/compiler/rustc_lint/src/lints.rs
+++ b/compiler/rustc_lint/src/lints.rs
@@ -1,3 +1,5 @@
+// ignore-tidy-filelength
+
 #![allow(rustc::untranslatable_diagnostic)]
 use std::num::NonZero;
 
@@ -1542,6 +1544,48 @@ impl<'a> LintDiagnostic<'a, ()> for DropGlue<'_> {
     }
 }
 
+// transmute.rs
+#[derive(LintDiagnostic)]
+#[diag(lint_int_to_ptr_transmutes)]
+#[note]
+#[note(lint_note_exposed_provenance)]
+#[help(lint_suggestion_without_provenance_mut)]
+#[help(lint_help_transmute)]
+#[help(lint_help_exposed_provenance)]
+pub(crate) struct IntegerToPtrTransmutes<'tcx> {
+    #[subdiagnostic]
+    pub suggestion: IntegerToPtrTransmutesSuggestion<'tcx>,
+}
+
+#[derive(Subdiagnostic)]
+pub(crate) enum IntegerToPtrTransmutesSuggestion<'tcx> {
+    #[multipart_suggestion(
+        lint_suggestion_with_exposed_provenance,
+        applicability = "machine-applicable",
+        style = "verbose"
+    )]
+    ToPtr {
+        dst: Ty<'tcx>,
+        suffix: &'static str,
+        #[suggestion_part(code = "std::ptr::with_exposed_provenance{suffix}::<{dst}>(")]
+        start_call: Span,
+    },
+    #[multipart_suggestion(
+        lint_suggestion_with_exposed_provenance,
+        applicability = "machine-applicable",
+        style = "verbose"
+    )]
+    ToRef {
+        dst: Ty<'tcx>,
+        suffix: &'static str,
+        ref_mutbl: &'static str,
+        #[suggestion_part(
+            code = "&{ref_mutbl}*std::ptr::with_exposed_provenance{suffix}::<{dst}>("
+        )]
+        start_call: Span,
+    },
+}
+
 // types.rs
 #[derive(LintDiagnostic)]
 #[diag(lint_range_endpoint_out_of_range)]
diff --git a/compiler/rustc_lint/src/transmute.rs b/compiler/rustc_lint/src/transmute.rs
index bc1d4587d07..239c8649041 100644
--- a/compiler/rustc_lint/src/transmute.rs
+++ b/compiler/rustc_lint/src/transmute.rs
@@ -1,3 +1,4 @@
+use rustc_ast::LitKind;
 use rustc_errors::Applicability;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::LocalDefId;
@@ -7,6 +8,7 @@ use rustc_middle::ty::{self, Ty};
 use rustc_session::{declare_lint, impl_lint_pass};
 use rustc_span::sym;
 
+use crate::lints::{IntegerToPtrTransmutes, IntegerToPtrTransmutesSuggestion};
 use crate::{LateContext, LateLintPass};
 
 declare_lint! {
@@ -67,9 +69,44 @@ declare_lint! {
     "detects transmutes that can also be achieved by other operations"
 }
 
+declare_lint! {
+    /// The `integer_to_ptr_transmutes` lint detects integer to pointer
+    /// transmutes where the resulting pointers are undefined behavior to dereference.
+    ///
+    /// ### Example
+    ///
+    /// ```rust
+    /// fn foo(a: usize) -> *const u8 {
+    ///    unsafe {
+    ///        std::mem::transmute::<usize, *const u8>(a)
+    ///    }
+    /// }
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// Any attempt to use the resulting pointers are undefined behavior as the resulting
+    /// pointers won't have any provenance.
+    ///
+    /// Alternatively, [`std::ptr::with_exposed_provenance`] should be used, as they do not
+    /// carry the provenance requirement. If wanting to create pointers without provenance
+    /// [`std::ptr::without_provenance`] should be used instead.
+    ///
+    /// See [`std::mem::transmute`] in the reference for more details.
+    ///
+    /// [`std::mem::transmute`]: https://doc.rust-lang.org/std/mem/fn.transmute.html
+    /// [`std::ptr::with_exposed_provenance`]: https://doc.rust-lang.org/std/ptr/fn.with_exposed_provenance.html
+    /// [`std::ptr::without_provenance`]: https://doc.rust-lang.org/std/ptr/fn.without_provenance.html
+    pub INTEGER_TO_PTR_TRANSMUTES,
+    Warn,
+    "detects integer to pointer transmutes",
+}
+
 pub(crate) struct CheckTransmutes;
 
-impl_lint_pass!(CheckTransmutes => [PTR_TO_INTEGER_TRANSMUTE_IN_CONSTS, UNNECESSARY_TRANSMUTES]);
+impl_lint_pass!(CheckTransmutes => [PTR_TO_INTEGER_TRANSMUTE_IN_CONSTS, UNNECESSARY_TRANSMUTES, INTEGER_TO_PTR_TRANSMUTES]);
 
 impl<'tcx> LateLintPass<'tcx> for CheckTransmutes {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
@@ -94,9 +131,62 @@ impl<'tcx> LateLintPass<'tcx> for CheckTransmutes {
 
         check_ptr_transmute_in_const(cx, expr, body_owner_def_id, const_context, src, dst);
         check_unnecessary_transmute(cx, expr, callee, arg, const_context, src, dst);
+        check_int_to_ptr_transmute(cx, expr, arg, src, dst);
     }
 }
 
+/// Check for transmutes from integer to pointers (*const/*mut and &/&mut).
+///
+/// Using the resulting pointers would be undefined behavior.
+fn check_int_to_ptr_transmute<'tcx>(
+    cx: &LateContext<'tcx>,
+    expr: &'tcx hir::Expr<'tcx>,
+    arg: &'tcx hir::Expr<'tcx>,
+    src: Ty<'tcx>,
+    dst: Ty<'tcx>,
+) {
+    if !matches!(src.kind(), ty::Uint(_) | ty::Int(_)) {
+        return;
+    }
+    let (ty::Ref(_, inner_ty, mutbl) | ty::RawPtr(inner_ty, mutbl)) = dst.kind() else {
+        return;
+    };
+    // bail-out if the argument is literal 0 as we have other lints for those cases
+    if matches!(arg.kind, hir::ExprKind::Lit(hir::Lit { node: LitKind::Int(v, _), .. }) if v == 0) {
+        return;
+    }
+    // bail-out if the inner type is a ZST
+    let Ok(layout_inner_ty) = cx.tcx.layout_of(cx.typing_env().as_query_input(*inner_ty)) else {
+        return;
+    };
+    if layout_inner_ty.is_1zst() {
+        return;
+    }
+
+    let suffix = if mutbl.is_mut() { "_mut" } else { "" };
+    cx.tcx.emit_node_span_lint(
+        INTEGER_TO_PTR_TRANSMUTES,
+        expr.hir_id,
+        expr.span,
+        IntegerToPtrTransmutes {
+            suggestion: if dst.is_ref() {
+                IntegerToPtrTransmutesSuggestion::ToRef {
+                    dst: *inner_ty,
+                    suffix,
+                    ref_mutbl: mutbl.prefix_str(),
+                    start_call: expr.span.shrink_to_lo().until(arg.span),
+                }
+            } else {
+                IntegerToPtrTransmutesSuggestion::ToPtr {
+                    dst: *inner_ty,
+                    suffix,
+                    start_call: expr.span.shrink_to_lo().until(arg.span),
+                }
+            },
+        },
+    );
+}
+
 /// Check for transmutes that exhibit undefined behavior.
 /// For example, transmuting pointers to integers in a const context.
 ///
diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs
index f5c490ca7ce..6fc85a83e17 100644
--- a/library/core/src/ptr/mod.rs
+++ b/library/core/src/ptr/mod.rs
@@ -914,6 +914,7 @@ pub const fn dangling<T>() -> *const T {
 #[must_use]
 #[stable(feature = "strict_provenance", since = "1.84.0")]
 #[rustc_const_stable(feature = "strict_provenance", since = "1.84.0")]
+#[allow(integer_to_ptr_transmutes)] // Expected semantics here.
 pub const fn without_provenance_mut<T>(addr: usize) -> *mut T {
     // An int-to-pointer transmute currently has exactly the intended semantics: it creates a
     // pointer without provenance. Note that this is *not* a stable guarantee about transmute
diff --git a/src/tools/clippy/clippy_lints/src/transmute/useless_transmute.rs b/src/tools/clippy/clippy_lints/src/transmute/useless_transmute.rs
index ec5fb2793f9..b898920baef 100644
--- a/src/tools/clippy/clippy_lints/src/transmute/useless_transmute.rs
+++ b/src/tools/clippy/clippy_lints/src/transmute/useless_transmute.rs
@@ -49,17 +49,7 @@ pub(super) fn check<'tcx>(
             true
         },
         (ty::Int(_) | ty::Uint(_), ty::RawPtr(_, _)) => {
-            span_lint_and_then(
-                cx,
-                USELESS_TRANSMUTE,
-                e.span,
-                "transmute from an integer to a pointer",
-                |diag| {
-                    if let Some(arg) = sugg::Sugg::hir_opt(cx, arg) {
-                        diag.span_suggestion(e.span, "try", arg.as_ty(to_ty.to_string()), Applicability::Unspecified);
-                    }
-                },
-            );
+            // Handled by the upstream rustc `integer_to_ptr_transmutes` lint
             true
         },
         _ => false,
diff --git a/src/tools/clippy/tests/ui/transmute.rs b/src/tools/clippy/tests/ui/transmute.rs
index e968e7a5924..e7099104f94 100644
--- a/src/tools/clippy/tests/ui/transmute.rs
+++ b/src/tools/clippy/tests/ui/transmute.rs
@@ -4,6 +4,7 @@
     dead_code,
     clippy::borrow_as_ptr,
     unnecessary_transmutes,
+    integer_to_ptr_transmutes,
     clippy::needless_lifetimes,
     clippy::missing_transmute_annotations
 )]
@@ -60,12 +61,10 @@ fn useless() {
         //~^ useless_transmute
 
         let _: *const usize = std::mem::transmute(5_isize);
-        //~^ useless_transmute
 
         let _ = std::ptr::dangling::<usize>();
 
         let _: *const usize = std::mem::transmute(1 + 1usize);
-        //~^ useless_transmute
 
         let _ = (1 + 1_usize) as *const usize;
     }
diff --git a/src/tools/clippy/tests/ui/transmute.stderr b/src/tools/clippy/tests/ui/transmute.stderr
index 79528ec06f1..9478db09481 100644
--- a/src/tools/clippy/tests/ui/transmute.stderr
+++ b/src/tools/clippy/tests/ui/transmute.stderr
@@ -1,5 +1,5 @@
 error: transmute from a reference to a pointer
-  --> tests/ui/transmute.rs:33:27
+  --> tests/ui/transmute.rs:34:27
    |
 LL |         let _: *const T = core::mem::transmute(t);
    |                           ^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T`
@@ -8,61 +8,49 @@ LL |         let _: *const T = core::mem::transmute(t);
    = help: to override `-D warnings` add `#[allow(clippy::useless_transmute)]`
 
 error: transmute from a reference to a pointer
-  --> tests/ui/transmute.rs:36:25
+  --> tests/ui/transmute.rs:37:25
    |
 LL |         let _: *mut T = core::mem::transmute(t);
    |                         ^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T as *mut T`
 
 error: transmute from a reference to a pointer
-  --> tests/ui/transmute.rs:39:27
+  --> tests/ui/transmute.rs:40:27
    |
 LL |         let _: *const U = core::mem::transmute(t);
    |                           ^^^^^^^^^^^^^^^^^^^^^^^ help: try: `t as *const T as *const U`
 
 error: transmute from a type (`std::vec::Vec<i32>`) to itself
-  --> tests/ui/transmute.rs:47:27
+  --> tests/ui/transmute.rs:48:27
    |
 LL |         let _: Vec<i32> = core::mem::transmute(my_vec());
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: transmute from a type (`std::vec::Vec<i32>`) to itself
-  --> tests/ui/transmute.rs:50:27
+  --> tests/ui/transmute.rs:51:27
    |
 LL |         let _: Vec<i32> = core::mem::transmute(my_vec());
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: transmute from a type (`std::vec::Vec<i32>`) to itself
-  --> tests/ui/transmute.rs:53:27
+  --> tests/ui/transmute.rs:54:27
    |
 LL |         let _: Vec<i32> = std::mem::transmute(my_vec());
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: transmute from a type (`std::vec::Vec<i32>`) to itself
-  --> tests/ui/transmute.rs:56:27
+  --> tests/ui/transmute.rs:57:27
    |
 LL |         let _: Vec<i32> = std::mem::transmute(my_vec());
    |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: transmute from a type (`std::vec::Vec<i32>`) to itself
-  --> tests/ui/transmute.rs:59:27
+  --> tests/ui/transmute.rs:60:27
    |
 LL |         let _: Vec<i32> = my_transmute(my_vec());
    |                           ^^^^^^^^^^^^^^^^^^^^^^
 
-error: transmute from an integer to a pointer
-  --> tests/ui/transmute.rs:62:31
-   |
-LL |         let _: *const usize = std::mem::transmute(5_isize);
-   |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `5_isize as *const usize`
-
-error: transmute from an integer to a pointer
-  --> tests/ui/transmute.rs:67:31
-   |
-LL |         let _: *const usize = std::mem::transmute(1 + 1usize);
-   |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `(1 + 1usize) as *const usize`
-
 error: transmute from a type (`*const Usize`) to the type that it points to (`Usize`)
-  --> tests/ui/transmute.rs:99:24
+  --> tests/ui/transmute.rs:98:24
    |
 LL |         let _: Usize = core::mem::transmute(int_const_ptr);
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -71,25 +59,25 @@ LL |         let _: Usize = core::mem::transmute(int_const_ptr);
    = help: to override `-D warnings` add `#[allow(clippy::crosspointer_transmute)]`
 
 error: transmute from a type (`*mut Usize`) to the type that it points to (`Usize`)
-  --> tests/ui/transmute.rs:102:24
+  --> tests/ui/transmute.rs:101:24
    |
 LL |         let _: Usize = core::mem::transmute(int_mut_ptr);
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: transmute from a type (`Usize`) to a pointer to that type (`*const Usize`)
-  --> tests/ui/transmute.rs:105:31
+  --> tests/ui/transmute.rs:104:31
    |
 LL |         let _: *const Usize = core::mem::transmute(my_int());
    |                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: transmute from a type (`Usize`) to a pointer to that type (`*mut Usize`)
-  --> tests/ui/transmute.rs:108:29
+  --> tests/ui/transmute.rs:107:29
    |
 LL |         let _: *mut Usize = core::mem::transmute(my_int());
    |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: transmute from a `u8` to a `bool`
-  --> tests/ui/transmute.rs:115:28
+  --> tests/ui/transmute.rs:114:28
    |
 LL |     let _: bool = unsafe { std::mem::transmute(0_u8) };
    |                            ^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `0_u8 != 0`
@@ -98,7 +86,7 @@ LL |     let _: bool = unsafe { std::mem::transmute(0_u8) };
    = help: to override `-D warnings` add `#[allow(clippy::transmute_int_to_bool)]`
 
 error: transmute from a `&[u8]` to a `&str`
-  --> tests/ui/transmute.rs:122:28
+  --> tests/ui/transmute.rs:121:28
    |
 LL |     let _: &str = unsafe { std::mem::transmute(B) };
    |                            ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8(B).unwrap()`
@@ -107,16 +95,16 @@ LL |     let _: &str = unsafe { std::mem::transmute(B) };
    = help: to override `-D warnings` add `#[allow(clippy::transmute_bytes_to_str)]`
 
 error: transmute from a `&mut [u8]` to a `&mut str`
-  --> tests/ui/transmute.rs:125:32
+  --> tests/ui/transmute.rs:124:32
    |
 LL |     let _: &mut str = unsafe { std::mem::transmute(mb) };
    |                                ^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8_mut(mb).unwrap()`
 
 error: transmute from a `&[u8]` to a `&str`
-  --> tests/ui/transmute.rs:128:30
+  --> tests/ui/transmute.rs:127:30
    |
 LL |     const _: &str = unsafe { std::mem::transmute(B) };
    |                              ^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::str::from_utf8_unchecked(B)`
 
-error: aborting due to 18 previous errors
+error: aborting due to 16 previous errors
 
diff --git a/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.fixed b/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.fixed
index e7ad2a1cbbc..02f67f79e2b 100644
--- a/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.fixed
+++ b/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.fixed
@@ -13,9 +13,6 @@ fn main() {
     // We should see an error message for each transmute, and no error messages for
     // the casts, since the casts are the recommended fixes.
 
-    // e is an integer and U is *U_0, while U_0: Sized; addr-ptr-cast
-    let _ptr_i32_transmute = unsafe { usize::MAX as *const i32 };
-    //~^ useless_transmute
     let ptr_i32 = usize::MAX as *const i32;
 
     // e has type *T, U is *U_0, and either U_0: Sized ...
diff --git a/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.rs b/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.rs
index 42a81777a82..c5e156405eb 100644
--- a/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.rs
+++ b/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.rs
@@ -13,9 +13,6 @@ fn main() {
     // We should see an error message for each transmute, and no error messages for
     // the casts, since the casts are the recommended fixes.
 
-    // e is an integer and U is *U_0, while U_0: Sized; addr-ptr-cast
-    let _ptr_i32_transmute = unsafe { transmute::<usize, *const i32>(usize::MAX) };
-    //~^ useless_transmute
     let ptr_i32 = usize::MAX as *const i32;
 
     // e has type *T, U is *U_0, and either U_0: Sized ...
diff --git a/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.stderr b/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.stderr
index 7746f087cc7..f39a64d57eb 100644
--- a/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.stderr
+++ b/src/tools/clippy/tests/ui/transmutes_expressible_as_ptr_casts.stderr
@@ -1,14 +1,5 @@
-error: transmute from an integer to a pointer
-  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:17:39
-   |
-LL |     let _ptr_i32_transmute = unsafe { transmute::<usize, *const i32>(usize::MAX) };
-   |                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `usize::MAX as *const i32`
-   |
-   = note: `-D clippy::useless-transmute` implied by `-D warnings`
-   = help: to override `-D warnings` add `#[allow(clippy::useless_transmute)]`
-
 error: transmute from a pointer to a pointer
-  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:22:38
+  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:19:38
    |
 LL |     let _ptr_i8_transmute = unsafe { transmute::<*const i32, *const i8>(ptr_i32) };
    |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -22,7 +13,7 @@ LL +     let _ptr_i8_transmute = unsafe { ptr_i32.cast::<i8>() };
    |
 
 error: transmute from a pointer to a pointer
-  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:29:46
+  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:26:46
    |
 LL |     let _ptr_to_unsized_transmute = unsafe { transmute::<*const [i32], *const [u32]>(slice_ptr) };
    |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -34,7 +25,7 @@ LL +     let _ptr_to_unsized_transmute = unsafe { slice_ptr as *const [u32] };
    |
 
 error: transmute from `*const i32` to `usize` which could be expressed as a pointer cast instead
-  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:36:50
+  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:33:50
    |
 LL |     let _usize_from_int_ptr_transmute = unsafe { transmute::<*const i32, usize>(ptr_i32) };
    |                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `ptr_i32 as usize`
@@ -43,40 +34,43 @@ LL |     let _usize_from_int_ptr_transmute = unsafe { transmute::<*const i32, us
    = help: to override `-D warnings` add `#[allow(clippy::transmutes_expressible_as_ptr_casts)]`
 
 error: transmute from a reference to a pointer
-  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:43:41
+  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:40:41
    |
 LL |     let _array_ptr_transmute = unsafe { transmute::<&[i32; 4], *const [i32; 4]>(array_ref) };
    |                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `array_ref as *const [i32; 4]`
+   |
+   = note: `-D clippy::useless-transmute` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::useless_transmute)]`
 
 error: transmute from `fn(usize) -> u8` to `*const usize` which could be expressed as a pointer cast instead
-  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:52:41
+  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:49:41
    |
 LL |     let _usize_ptr_transmute = unsafe { transmute::<fn(usize) -> u8, *const usize>(foo) };
    |                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `foo as *const usize`
 
 error: transmute from `fn(usize) -> u8` to `usize` which could be expressed as a pointer cast instead
-  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:57:49
+  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:54:49
    |
 LL |     let _usize_from_fn_ptr_transmute = unsafe { transmute::<fn(usize) -> u8, usize>(foo) };
    |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `foo as usize`
 
 error: transmute from `*const u32` to `usize` which could be expressed as a pointer cast instead
-  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:61:36
+  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:58:36
    |
 LL |     let _usize_from_ref = unsafe { transmute::<*const u32, usize>(&1u32) };
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `&1u32 as *const u32 as usize`
 
 error: transmute from a reference to a pointer
-  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:73:14
+  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:70:14
    |
 LL |     unsafe { transmute::<&[i32; 1], *const u8>(in_param) }
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `in_param as *const [i32; 1] as *const u8`
 
 error: transmute from `fn()` to `*const u8` which could be expressed as a pointer cast instead
-  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:92:28
+  --> tests/ui/transmutes_expressible_as_ptr_casts.rs:89:28
    |
 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
+error: aborting due to 9 previous errors
 
diff --git a/src/tools/miri/tests/fail/branchless-select-i128-pointer.rs b/src/tools/miri/tests/fail/branchless-select-i128-pointer.rs
index 2b861e5447b..7147813c4b6 100644
--- a/src/tools/miri/tests/fail/branchless-select-i128-pointer.rs
+++ b/src/tools/miri/tests/fail/branchless-select-i128-pointer.rs
@@ -1,3 +1,5 @@
+#![allow(integer_to_ptr_transmutes)]
+
 use std::mem::transmute;
 
 #[cfg(target_pointer_width = "32")]
diff --git a/src/tools/miri/tests/fail/provenance/provenance_transmute.rs b/src/tools/miri/tests/fail/provenance/provenance_transmute.rs
index d72f10530d7..60cb9a7f6bf 100644
--- a/src/tools/miri/tests/fail/provenance/provenance_transmute.rs
+++ b/src/tools/miri/tests/fail/provenance/provenance_transmute.rs
@@ -1,5 +1,7 @@
 //@compile-flags: -Zmiri-permissive-provenance
 
+#![allow(integer_to_ptr_transmutes)]
+
 use std::mem;
 
 // This is the example from
diff --git a/src/tools/miri/tests/fail/validity/dangling_ref1.rs b/src/tools/miri/tests/fail/validity/dangling_ref1.rs
index fc3a9f34463..57ba1117e76 100644
--- a/src/tools/miri/tests/fail/validity/dangling_ref1.rs
+++ b/src/tools/miri/tests/fail/validity/dangling_ref1.rs
@@ -1,5 +1,8 @@
 // Make sure we catch this even without Stacked Borrows
 //@compile-flags: -Zmiri-disable-stacked-borrows
+
+#![allow(integer_to_ptr_transmutes)]
+
 use std::mem;
 
 fn main() {
diff --git a/src/tools/miri/tests/panic/transmute_fat2.rs b/src/tools/miri/tests/panic/transmute_fat2.rs
index e695ff2d57b..7441f25d03e 100644
--- a/src/tools/miri/tests/panic/transmute_fat2.rs
+++ b/src/tools/miri/tests/panic/transmute_fat2.rs
@@ -1,3 +1,5 @@
+#![allow(integer_to_ptr_transmutes)]
+
 fn main() {
     #[cfg(all(target_endian = "little", target_pointer_width = "64"))]
     let bad = unsafe { std::mem::transmute::<u128, &[u8]>(42) };
diff --git a/src/tools/miri/tests/pass/binops.rs b/src/tools/miri/tests/pass/binops.rs
index 0aff7acb29d..fcbe6c85b7b 100644
--- a/src/tools/miri/tests/pass/binops.rs
+++ b/src/tools/miri/tests/pass/binops.rs
@@ -32,6 +32,7 @@ fn test_bool() {
     assert_eq!(true ^ true, false);
 }
 
+#[allow(integer_to_ptr_transmutes)]
 fn test_ptr() {
     unsafe {
         let p1: *const u8 = ::std::mem::transmute(0_usize);
diff --git a/src/tools/miri/tests/pass/too-large-primval-write-problem.rs b/src/tools/miri/tests/pass/too-large-primval-write-problem.rs
index f4c418bd78a..00882b7ecca 100644
--- a/src/tools/miri/tests/pass/too-large-primval-write-problem.rs
+++ b/src/tools/miri/tests/pass/too-large-primval-write-problem.rs
@@ -7,6 +7,8 @@
 //
 // This is just intended as a regression test to make sure we don't reintroduce this problem.
 
+#![allow(integer_to_ptr_transmutes)]
+
 #[cfg(target_pointer_width = "32")]
 fn main() {
     use std::mem::transmute;
diff --git a/tests/ui/binop/binops.rs b/tests/ui/binop/binops.rs
index 7142190a45b..702e9a61345 100644
--- a/tests/ui/binop/binops.rs
+++ b/tests/ui/binop/binops.rs
@@ -35,6 +35,7 @@ fn test_bool() {
     assert_eq!(true ^ true, false);
 }
 
+#[allow(integer_to_ptr_transmutes)]
 fn test_ptr() {
     unsafe {
         let p1: *const u8 = ::std::mem::transmute(0_usize);
diff --git a/tests/ui/lint/int_to_ptr.fixed b/tests/ui/lint/int_to_ptr.fixed
new file mode 100644
index 00000000000..8f373492e6f
--- /dev/null
+++ b/tests/ui/lint/int_to_ptr.fixed
@@ -0,0 +1,47 @@
+// Checks for the `integer_to_pointer_transmutes` lint
+
+//@ check-pass
+//@ run-rustfix
+
+#![allow(unused_unsafe)]
+#![allow(dead_code)]
+
+unsafe fn should_lint(a: usize) {
+    let _ptr: *const u8 = unsafe { std::ptr::with_exposed_provenance::<u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ptr: *mut u8 = unsafe { std::ptr::with_exposed_provenance_mut::<u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ref: &'static u8 = unsafe { &*std::ptr::with_exposed_provenance::<u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ref: &'static mut u8 = unsafe { &mut *std::ptr::with_exposed_provenance_mut::<u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+
+    let _ptr = unsafe { std::ptr::with_exposed_provenance::<u8>(42usize) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ptr = unsafe { std::ptr::with_exposed_provenance::<u8>(a + a) };
+    //~^ WARN transmuting an integer to a pointer
+}
+
+const unsafe fn should_lintin_const(a: usize) {
+    let _ptr: *const u8 = unsafe { std::ptr::with_exposed_provenance::<u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ptr: *mut u8 = unsafe { std::ptr::with_exposed_provenance_mut::<u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ref: &'static u8 = unsafe { &*std::ptr::with_exposed_provenance::<u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ref: &'static mut u8 = unsafe { &mut *std::ptr::with_exposed_provenance_mut::<u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+
+    let _ptr = unsafe { std::ptr::with_exposed_provenance::<u8>(42usize) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ptr = unsafe { std::ptr::with_exposed_provenance::<u8>(a + a) };
+    //~^ WARN transmuting an integer to a pointer
+}
+
+unsafe fn should_not_lint(a: usize) {
+    let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(0usize) }; // linted by other lints
+    let _ptr = unsafe { std::mem::transmute::<usize, *const ()>(a) }; // inner type is a ZST
+    let _ptr = unsafe { std::mem::transmute::<usize, fn()>(a) }; // omit fn-ptr for now
+}
+
+fn main() {}
diff --git a/tests/ui/lint/int_to_ptr.rs b/tests/ui/lint/int_to_ptr.rs
new file mode 100644
index 00000000000..7f60da47b85
--- /dev/null
+++ b/tests/ui/lint/int_to_ptr.rs
@@ -0,0 +1,47 @@
+// Checks for the `integer_to_pointer_transmutes` lint
+
+//@ check-pass
+//@ run-rustfix
+
+#![allow(unused_unsafe)]
+#![allow(dead_code)]
+
+unsafe fn should_lint(a: usize) {
+    let _ptr: *const u8 = unsafe { std::mem::transmute::<usize, *const u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ptr: *mut u8 = unsafe { std::mem::transmute::<usize, *mut u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ref: &'static u8 = unsafe { std::mem::transmute::<usize, &'static u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ref: &'static mut u8 = unsafe { std::mem::transmute::<usize, &'static mut u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+
+    let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(42usize) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(a + a) };
+    //~^ WARN transmuting an integer to a pointer
+}
+
+const unsafe fn should_lintin_const(a: usize) {
+    let _ptr: *const u8 = unsafe { std::mem::transmute::<usize, *const u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ptr: *mut u8 = unsafe { std::mem::transmute::<usize, *mut u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ref: &'static u8 = unsafe { std::mem::transmute::<usize, &'static u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ref: &'static mut u8 = unsafe { std::mem::transmute::<usize, &'static mut u8>(a) };
+    //~^ WARN transmuting an integer to a pointer
+
+    let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(42usize) };
+    //~^ WARN transmuting an integer to a pointer
+    let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(a + a) };
+    //~^ WARN transmuting an integer to a pointer
+}
+
+unsafe fn should_not_lint(a: usize) {
+    let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(0usize) }; // linted by other lints
+    let _ptr = unsafe { std::mem::transmute::<usize, *const ()>(a) }; // inner type is a ZST
+    let _ptr = unsafe { std::mem::transmute::<usize, fn()>(a) }; // omit fn-ptr for now
+}
+
+fn main() {}
diff --git a/tests/ui/lint/int_to_ptr.stderr b/tests/ui/lint/int_to_ptr.stderr
new file mode 100644
index 00000000000..4035bda8fb2
--- /dev/null
+++ b/tests/ui/lint/int_to_ptr.stderr
@@ -0,0 +1,207 @@
+warning: transmuting an integer to a pointer creates a pointer without provenance
+  --> $DIR/int_to_ptr.rs:10:36
+   |
+LL |     let _ptr: *const u8 = unsafe { std::mem::transmute::<usize, *const u8>(a) };
+   |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
+   = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+   = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+   = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+   = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+   = note: `#[warn(integer_to_ptr_transmutes)]` on by default
+help: use `std::ptr::with_exposed_provenance` instead to use a previously exposed provenance
+   |
+LL -     let _ptr: *const u8 = unsafe { std::mem::transmute::<usize, *const u8>(a) };
+LL +     let _ptr: *const u8 = unsafe { std::ptr::with_exposed_provenance::<u8>(a) };
+   |
+
+warning: transmuting an integer to a pointer creates a pointer without provenance
+  --> $DIR/int_to_ptr.rs:12:34
+   |
+LL |     let _ptr: *mut u8 = unsafe { std::mem::transmute::<usize, *mut u8>(a) };
+   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
+   = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+   = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+   = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+   = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+help: use `std::ptr::with_exposed_provenance_mut` instead to use a previously exposed provenance
+   |
+LL -     let _ptr: *mut u8 = unsafe { std::mem::transmute::<usize, *mut u8>(a) };
+LL +     let _ptr: *mut u8 = unsafe { std::ptr::with_exposed_provenance_mut::<u8>(a) };
+   |
+
+warning: transmuting an integer to a pointer creates a pointer without provenance
+  --> $DIR/int_to_ptr.rs:14:38
+   |
+LL |     let _ref: &'static u8 = unsafe { std::mem::transmute::<usize, &'static u8>(a) };
+   |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
+   = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+   = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+   = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+   = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+help: use `std::ptr::with_exposed_provenance` instead to use a previously exposed provenance
+   |
+LL -     let _ref: &'static u8 = unsafe { std::mem::transmute::<usize, &'static u8>(a) };
+LL +     let _ref: &'static u8 = unsafe { &*std::ptr::with_exposed_provenance::<u8>(a) };
+   |
+
+warning: transmuting an integer to a pointer creates a pointer without provenance
+  --> $DIR/int_to_ptr.rs:16:42
+   |
+LL |     let _ref: &'static mut u8 = unsafe { std::mem::transmute::<usize, &'static mut u8>(a) };
+   |                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
+   = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+   = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+   = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+   = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+help: use `std::ptr::with_exposed_provenance_mut` instead to use a previously exposed provenance
+   |
+LL -     let _ref: &'static mut u8 = unsafe { std::mem::transmute::<usize, &'static mut u8>(a) };
+LL +     let _ref: &'static mut u8 = unsafe { &mut *std::ptr::with_exposed_provenance_mut::<u8>(a) };
+   |
+
+warning: transmuting an integer to a pointer creates a pointer without provenance
+  --> $DIR/int_to_ptr.rs:19:25
+   |
+LL |     let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(42usize) };
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
+   = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+   = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+   = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+   = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+help: use `std::ptr::with_exposed_provenance` instead to use a previously exposed provenance
+   |
+LL -     let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(42usize) };
+LL +     let _ptr = unsafe { std::ptr::with_exposed_provenance::<u8>(42usize) };
+   |
+
+warning: transmuting an integer to a pointer creates a pointer without provenance
+  --> $DIR/int_to_ptr.rs:21:25
+   |
+LL |     let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(a + a) };
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
+   = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+   = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+   = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+   = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+help: use `std::ptr::with_exposed_provenance` instead to use a previously exposed provenance
+   |
+LL -     let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(a + a) };
+LL +     let _ptr = unsafe { std::ptr::with_exposed_provenance::<u8>(a + a) };
+   |
+
+warning: transmuting an integer to a pointer creates a pointer without provenance
+  --> $DIR/int_to_ptr.rs:26:36
+   |
+LL |     let _ptr: *const u8 = unsafe { std::mem::transmute::<usize, *const u8>(a) };
+   |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
+   = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+   = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+   = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+   = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+help: use `std::ptr::with_exposed_provenance` instead to use a previously exposed provenance
+   |
+LL -     let _ptr: *const u8 = unsafe { std::mem::transmute::<usize, *const u8>(a) };
+LL +     let _ptr: *const u8 = unsafe { std::ptr::with_exposed_provenance::<u8>(a) };
+   |
+
+warning: transmuting an integer to a pointer creates a pointer without provenance
+  --> $DIR/int_to_ptr.rs:28:34
+   |
+LL |     let _ptr: *mut u8 = unsafe { std::mem::transmute::<usize, *mut u8>(a) };
+   |                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
+   = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+   = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+   = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+   = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+help: use `std::ptr::with_exposed_provenance_mut` instead to use a previously exposed provenance
+   |
+LL -     let _ptr: *mut u8 = unsafe { std::mem::transmute::<usize, *mut u8>(a) };
+LL +     let _ptr: *mut u8 = unsafe { std::ptr::with_exposed_provenance_mut::<u8>(a) };
+   |
+
+warning: transmuting an integer to a pointer creates a pointer without provenance
+  --> $DIR/int_to_ptr.rs:30:38
+   |
+LL |     let _ref: &'static u8 = unsafe { std::mem::transmute::<usize, &'static u8>(a) };
+   |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
+   = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+   = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+   = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+   = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+help: use `std::ptr::with_exposed_provenance` instead to use a previously exposed provenance
+   |
+LL -     let _ref: &'static u8 = unsafe { std::mem::transmute::<usize, &'static u8>(a) };
+LL +     let _ref: &'static u8 = unsafe { &*std::ptr::with_exposed_provenance::<u8>(a) };
+   |
+
+warning: transmuting an integer to a pointer creates a pointer without provenance
+  --> $DIR/int_to_ptr.rs:32:42
+   |
+LL |     let _ref: &'static mut u8 = unsafe { std::mem::transmute::<usize, &'static mut u8>(a) };
+   |                                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
+   = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+   = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+   = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+   = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+help: use `std::ptr::with_exposed_provenance_mut` instead to use a previously exposed provenance
+   |
+LL -     let _ref: &'static mut u8 = unsafe { std::mem::transmute::<usize, &'static mut u8>(a) };
+LL +     let _ref: &'static mut u8 = unsafe { &mut *std::ptr::with_exposed_provenance_mut::<u8>(a) };
+   |
+
+warning: transmuting an integer to a pointer creates a pointer without provenance
+  --> $DIR/int_to_ptr.rs:35:25
+   |
+LL |     let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(42usize) };
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
+   = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+   = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+   = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+   = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+help: use `std::ptr::with_exposed_provenance` instead to use a previously exposed provenance
+   |
+LL -     let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(42usize) };
+LL +     let _ptr = unsafe { std::ptr::with_exposed_provenance::<u8>(42usize) };
+   |
+
+warning: transmuting an integer to a pointer creates a pointer without provenance
+  --> $DIR/int_to_ptr.rs:37:25
+   |
+LL |     let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(a + a) };
+   |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: this is dangerous because dereferencing the resulting pointer is undefined behavior
+   = note: exposed provenance semantics can be used to create a pointer based on some previously exposed provenance
+   = help: if you truly mean to create a pointer without provenance, use `std::ptr::without_provenance_mut`
+   = help: for more information about transmute, see <https://doc.rust-lang.org/std/mem/fn.transmute.html#transmutation-between-pointers-and-integers>
+   = help: for more information about exposed provenance, see <https://doc.rust-lang.org/std/ptr/index.html#exposed-provenance>
+help: use `std::ptr::with_exposed_provenance` instead to use a previously exposed provenance
+   |
+LL -     let _ptr = unsafe { std::mem::transmute::<usize, *const u8>(a + a) };
+LL +     let _ptr = unsafe { std::ptr::with_exposed_provenance::<u8>(a + a) };
+   |
+
+warning: 12 warnings emitted
+