Address PR feedback

Author: scottmcm

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -583,17 +583,6 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         Ok(self.read_immediate(op)?.to_scalar())
     }
 
-    pub fn read_mem_place_meta(
-        &self,
-        op: &impl Readable<'tcx, M::Provenance>,
-    ) -> InterpResult<'tcx, MemPlaceMeta<M::Provenance>> {
-        Ok(if op.layout().is_zst() {
-            MemPlaceMeta::None
-        } else {
-            MemPlaceMeta::Meta(self.read_scalar(op)?)
-        })
-    }
-
     // Pointer-sized reads are fairly common and need target layout access, so we wrap them in
     // convenience functions.
 

compiler/rustc_const_eval/src/interpret/step.rs

@@ -9,7 +9,9 @@ use rustc_middle::mir;
 use rustc_middle::ty::layout::LayoutOf;
 use rustc_target::abi::{FieldIdx, FIRST_VARIANT};
 
-use super::{ImmTy, Immediate, InterpCx, InterpResult, Machine, PlaceTy, Projectable, Scalar};
+use super::{
+    ImmTy, Immediate, InterpCx, InterpResult, Machine, MemPlaceMeta, PlaceTy, Projectable, Scalar,
+};
 use crate::util;
 
 impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
@@ -304,15 +306,21 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
                 (variant_index, variant_dest, active_field_index)
             }
             mir::AggregateKind::RawPtr(..) => {
-                // Trying to `project_field` into pointers tends not to work,
-                // so build the `Immediate` from the parts directly.
+                // Pointers don't have "fields" in the normal sense, so the
+                // projection-based code below would either fail in projection
+                // or in type mismatches. Instead, build an `Immediate` from
+                // the parts and write that to the destination.
                 let [data, meta] = &operands.raw else {
                     bug!("{kind:?} should have 2 operands, had {operands:?}");
                 };
                 let data = self.eval_operand(data, None)?;
                 let data = self.read_pointer(&data)?;
                 let meta = self.eval_operand(meta, None)?;
-                let meta = self.read_mem_place_meta(&meta)?;
+                let meta = if meta.layout.is_zst() {
+                    MemPlaceMeta::None
+                } else {
+                    MemPlaceMeta::Meta(self.read_scalar(&meta)?)
+                };
                 let ptr_imm = Immediate::new_pointer_with_meta(data, meta, self);
                 let ptr = ImmTy::from_immediate(ptr_imm, dest.layout);
                 self.copy_op(&ptr, dest)?;