Rollup merge of #97653 - RalfJung:int-to-ptr, r=oli-obk

add cast kind of from_exposed_addr (int-to-ptr casts)

This is basically the dual to https://github.com/rust-lang/rust/pull/97582, for int2ptr casts.

Cc `@tmiasko` https://github.com/rust-lang/rust/issues/97649

compiler/rustc_middle/src/mir/mod.rs

@@ -2613,12 +2613,18 @@ impl<'tcx> Rvalue<'tcx> {
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)]
 pub enum CastKind {
-    Misc,
     /// An exposing pointer to address cast. A cast between a pointer and an integer type, or
     /// between a function pointer and an integer type.
     /// See the docs on `expose_addr` for more details.
     PointerExposeAddress,
+    /// An address-to-pointer cast that picks up an exposed provenance.
+    /// See the docs on `from_exposed_addr` for more details.
+    PointerFromExposedAddress,
+    /// All sorts of pointer-to-pointer casts. Note that reference-to-raw-ptr casts are
+    /// translated into `&raw mut/const *r`, i.e., they are not actually casts.
     Pointer(PointerCast),
+    /// Remaining unclassified casts.
+    Misc,
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, Hash, HashStable)]