| use rustc_hir as hir; |
| use rustc_hir::Expr; |
| use rustc_hir_typeck::{cast, FnCtxt, Inherited}; |
| use rustc_lint::LateContext; |
| use rustc_middle::ty::cast::CastKind; |
| use rustc_middle::ty::Ty; |
| use rustc_span::DUMMY_SP; |
| |
| // check if the component types of the transmuted collection and the result have different ABI, |
| // size or alignment |
| pub(super) fn is_layout_incompatible<'tcx>(cx: &LateContext<'tcx>, from: Ty<'tcx>, to: Ty<'tcx>) -> bool { |
| if let Ok(from) = cx.tcx.try_normalize_erasing_regions(cx.param_env, from) |
| && let Ok(to) = cx.tcx.try_normalize_erasing_regions(cx.param_env, to) |
| && let Ok(from_layout) = cx.tcx.layout_of(cx.param_env.and(from)) |
| && let Ok(to_layout) = cx.tcx.layout_of(cx.param_env.and(to)) |
| { |
| from_layout.size != to_layout.size || from_layout.align.abi != to_layout.align.abi |
| } else { |
| // no idea about layout, so don't lint |
| false |
| } |
| } |
| |
| /// If a cast from `from_ty` to `to_ty` is valid, returns an Ok containing the kind of |
| /// the cast. In certain cases, including some invalid casts from array references |
| /// to pointers, this may cause additional errors to be emitted and/or ICE error |
| /// messages. This function will panic if that occurs. |
| pub(super) fn check_cast<'tcx>( |
| cx: &LateContext<'tcx>, |
| e: &'tcx Expr<'_>, |
| from_ty: Ty<'tcx>, |
| to_ty: Ty<'tcx>, |
| ) -> Option<CastKind> { |
| let hir_id = e.hir_id; |
| let local_def_id = hir_id.owner.def_id; |
| |
| let inherited = Inherited::new(cx.tcx, local_def_id); |
| let fn_ctxt = FnCtxt::new(&inherited, cx.param_env, local_def_id); |
| |
| // If we already have errors, we can't be sure we can pointer cast. |
| assert!( |
| !fn_ctxt.errors_reported_since_creation(), |
| "Newly created FnCtxt contained errors" |
| ); |
| |
| if let Ok(check) = cast::CastCheck::new( |
| &fn_ctxt, |
| e, |
| from_ty, |
| to_ty, |
| // We won't show any error to the user, so we don't care what the span is here. |
| DUMMY_SP, |
| DUMMY_SP, |
| hir::Constness::NotConst, |
| ) { |
| let res = check.do_check(&fn_ctxt); |
| |
| // do_check's documentation says that it might return Ok and create |
| // errors in the fcx instead of returning Err in some cases. Those cases |
| // should be filtered out before getting here. |
| assert!( |
| !fn_ctxt.errors_reported_since_creation(), |
| "`fn_ctxt` contained errors after cast check!" |
| ); |
| |
| res.ok() |
| } else { |
| None |
| } |
| } |