patterns: reject raw pointers that are not just integers

1 files changed, 27 insertions, 10 deletions

diff --git a/compiler/rustc_const_eval/src/const_eval/valtrees.rs b/compiler/rustc_const_eval/src/const_eval/valtrees.rs
index d6dc1a62f4d..76bd9a82836 100644
--- a/compiler/rustc_const_eval/src/const_eval/valtrees.rs
+++ b/compiler/rustc_const_eval/src/const_eval/valtrees.rs
@@ -97,11 +97,27 @@ pub(crate) fn const_to_valtree_inner<'tcx>(
             Ok(ty::ValTree::Leaf(val.assert_int()))
         }
 
-        // Raw pointers are not allowed in type level constants, as we cannot properly test them for
-        // equality at compile-time (see `ptr_guaranteed_cmp`).
+        ty::RawPtr(_) => {
+            // Not all raw pointers are allowed, as we cannot properly test them for
+            // equality at compile-time (see `ptr_guaranteed_cmp`).
+            // However we allow those that are just integers in disguise.
+            // (We could allow wide raw pointers where both sides are integers in the future,
+            // but for now we reject them.)
+            let Ok(val) = ecx.read_scalar(place) else {
+                return Err(ValTreeCreationError::Other);
+            };
+            // We are in the CTFE machine, so ptr-to-int casts will fail.
+            // This can only be `Ok` if `val` already is an integer.
+            let Ok(val) = val.try_to_int() else {
+                return Err(ValTreeCreationError::Other);
+            };
+            // It's just a ScalarInt!
+            Ok(ty::ValTree::Leaf(val))
+        }
+
         // Technically we could allow function pointers (represented as `ty::Instance`), but this is not guaranteed to
         // agree with runtime equality tests.
-        ty::FnPtr(_) | ty::RawPtr(_) => Err(ValTreeCreationError::NonSupportedType),
+        ty::FnPtr(_) => Err(ValTreeCreationError::NonSupportedType),
 
         ty::Ref(_, _, _)  => {
             let Ok(derefd_place)= ecx.deref_pointer(place) else {
@@ -222,12 +238,14 @@ pub fn valtree_to_const_value<'tcx>(
             assert!(valtree.unwrap_branch().is_empty());
             mir::ConstValue::ZeroSized
         }
-        ty::Bool | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Char => match valtree {
-            ty::ValTree::Leaf(scalar_int) => mir::ConstValue::Scalar(Scalar::Int(scalar_int)),
-            ty::ValTree::Branch(_) => bug!(
-                "ValTrees for Bool, Int, Uint, Float or Char should have the form ValTree::Leaf"
-            ),
-        },
+        ty::Bool | ty::Int(_) | ty::Uint(_) | ty::Float(_) | ty::Char | ty::RawPtr(_) => {
+            match valtree {
+                ty::ValTree::Leaf(scalar_int) => mir::ConstValue::Scalar(Scalar::Int(scalar_int)),
+                ty::ValTree::Branch(_) => bug!(
+                    "ValTrees for Bool, Int, Uint, Float, Char or RawPtr should have the form ValTree::Leaf"
+                ),
+            }
+        }
         ty::Ref(_, inner_ty, _) => {
             let mut ecx = mk_eval_cx(tcx, DUMMY_SP, param_env, CanAccessStatics::No);
             let imm = valtree_to_ref(&mut ecx, valtree, *inner_ty);
@@ -281,7 +299,6 @@ pub fn valtree_to_const_value<'tcx>(
         | ty::Coroutine(..)
         | ty::CoroutineWitness(..)
         | ty::FnPtr(_)
-        | ty::RawPtr(_)
         | ty::Str
         | ty::Slice(_)
         | ty::Dynamic(..) => bug!("no ValTree should have been created for type {:?}", ty.kind()),