Add barest-bones deref patterns · rust-lang/rust@120d357 (original) (raw)
`@@ -18,8 +18,7 @@ use rustc_span::edit_distance::find_best_match_for_name;
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`use rustc_span:🪥:DesugaringKind;
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`use rustc_span::source_map::Spanned;
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`use rustc_span::symbol::{kw, sym, Ident};
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``
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use rustc_span::Span;
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``
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use rustc_span::{BytePos, DUMMY_SP};
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use rustc_span::{BytePos, Span, DUMMY_SP};
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`use rustc_target::abi::FieldIdx;
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`use rustc_trait_selection::traits::{ObligationCause, Pattern};
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`use ty::VariantDef;
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`@@ -211,6 +210,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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`PatKind::Tuple(elements, ddpos) => {
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`self.check_pat_tuple(pat.span, elements, ddpos, expected, pat_info)
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`}
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PatKind::Box(inner) if self.tcx.features().deref_patterns => {
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self.check_pat_deref(pat.span, inner, expected, pat_info)
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}
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`PatKind::Box(inner) => self.check_pat_box(pat.span, inner, expected, pat_info),
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`PatKind::Ref(inner, mutbl) => self.check_pat_ref(pat, inner, mutbl, expected, pat_info),
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`PatKind::Slice(before, slice, after) => {
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`@@ -1975,6 +1977,28 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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` box_ty
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`}
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fn check_pat_deref(
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&self,
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span: Span,
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inner: &'tcx Pat<'tcx>,
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expected: Ty<'tcx>,
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pat_info: PatInfo<'tcx, '_>,
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) -> Ty<'tcx> {
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let tcx = self.tcx;
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// FIXME(deref_patterns): use DerefPure for soundness
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// FIXME(deref_patterns): use DerefMut when required
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// ::Target
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let ty = Ty::new_projection(
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tcx,
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tcx.require_lang_item(hir::LangItem::DerefTarget, Some(span)),
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[expected],
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);
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let ty = self.normalize(span, ty);
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let ty = self.try_structurally_resolve_type(span, ty);
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self.check_pat(inner, ty, pat_info);
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expected
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}
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`// Precondition: Pat is Ref(inner)
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`fn check_pat_ref(
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`&self,
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