diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_mir_transform/src/shim.rs | 28 |
1 files changed, 27 insertions, 1 deletions
diff --git a/compiler/rustc_mir_transform/src/shim.rs b/compiler/rustc_mir_transform/src/shim.rs index f8b55c86287..aa89ff00381 100644 --- a/compiler/rustc_mir_transform/src/shim.rs +++ b/compiler/rustc_mir_transform/src/shim.rs @@ -176,7 +176,33 @@ fn build_drop_shim<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId, ty: Option<Ty<'tcx>>) if ty.is_some() { // The first argument (index 0), but add 1 for the return value. - let dropee_ptr = Place::from(Local::new(1 + 0)); + let mut dropee_ptr = Place::from(Local::new(1 + 0)); + if tcx.sess.opts.unstable_opts.mir_emit_retag { + // We want to treat the function argument as if it was passed by `&mut`. As such, we + // generate + // ``` + // temp = &mut *arg; + // Retag(temp, FnEntry) + // ``` + // It's important that we do this first, before anything that depends on `dropee_ptr` + // has been put into the body. + let reborrow = Rvalue::Ref( + tcx.lifetimes.re_erased, + BorrowKind::Mut { allow_two_phase_borrow: false }, + tcx.mk_place_deref(dropee_ptr), + ); + let ref_ty = reborrow.ty(body.local_decls(), tcx); + dropee_ptr = body.local_decls.push(LocalDecl::new(ref_ty, span)).into(); + let new_statements = [ + StatementKind::Assign(Box::new((dropee_ptr, reborrow))), + StatementKind::Retag(RetagKind::FnEntry, Box::new(dropee_ptr)), + ]; + for s in new_statements { + body.basic_blocks_mut()[START_BLOCK] + .statements + .push(Statement { source_info, kind: s }); + } + } let patch = { let param_env = tcx.param_env_reveal_all_normalized(def_id); let mut elaborator = |