Add an intrinsic for `ptr::metadata`

3 files changed, 28 insertions, 1 deletions

diff --git a/compiler/rustc_mir_transform/src/lower_intrinsics.rs b/compiler/rustc_mir_transform/src/lower_intrinsics.rs
index 221301b2ceb..3ffc447217d 100644
--- a/compiler/rustc_mir_transform/src/lower_intrinsics.rs
+++ b/compiler/rustc_mir_transform/src/lower_intrinsics.rs
@@ -316,6 +316,23 @@ impl<'tcx> MirPass<'tcx> for LowerIntrinsics {
 
                         terminator.kind = TerminatorKind::Goto { target };
                     }
+                    sym::ptr_metadata => {
+                        let Ok([ptr]) = <[_; 1]>::try_from(std::mem::take(args)) else {
+                            span_bug!(
+                                terminator.source_info.span,
+                                "Wrong number of arguments for ptr_metadata intrinsic",
+                            );
+                        };
+                        let target = target.unwrap();
+                        block.statements.push(Statement {
+                            source_info: terminator.source_info,
+                            kind: StatementKind::Assign(Box::new((
+                                *destination,
+                                Rvalue::UnaryOp(UnOp::PtrMetadata, ptr.node),
+                            ))),
+                        });
+                        terminator.kind = TerminatorKind::Goto { target };
+                    }
                     _ => {}
                 }
             }
diff --git a/compiler/rustc_mir_transform/src/promote_consts.rs b/compiler/rustc_mir_transform/src/promote_consts.rs
index e37f90ae7f4..7ec59cc983f 100644
--- a/compiler/rustc_mir_transform/src/promote_consts.rs
+++ b/compiler/rustc_mir_transform/src/promote_consts.rs
@@ -464,7 +464,7 @@ impl<'tcx> Validator<'_, 'tcx> {
             Rvalue::UnaryOp(op, operand) => {
                 match op {
                     // These operations can never fail.
-                    UnOp::Neg | UnOp::Not => {}
+                    UnOp::Neg | UnOp::Not | UnOp::PtrMetadata => {}
                 }
 
                 self.validate_operand(operand)?;
diff --git a/compiler/rustc_mir_transform/src/validate.rs b/compiler/rustc_mir_transform/src/validate.rs
index 6df32169eec..d9166d2fcd0 100644
--- a/compiler/rustc_mir_transform/src/validate.rs
+++ b/compiler/rustc_mir_transform/src/validate.rs
@@ -1109,6 +1109,16 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                             ty::Int(..) | ty::Uint(..) | ty::Bool
                         );
                     }
+                    UnOp::PtrMetadata => {
+                        if !matches!(self.mir_phase, MirPhase::Runtime(_)) {
+                            // It would probably be fine to support this in earlier phases,
+                            // but at the time of writing it's only ever introduced from intrinsic lowering,
+                            // so earlier things can just `bug!` on it.
+                            self.fail(location, "PtrMetadata should be in runtime MIR only");
+                        }
+
+                        check_kinds!(a, "Cannot PtrMetadata non-pointer type {:?}", ty::RawPtr(..));
+                    }
                 }
             }
             Rvalue::ShallowInitBox(operand, _) => {