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