diff options
| -rw-r--r-- | src/librustc_typeck/check/place_op.rs | 37 |
1 files changed, 24 insertions, 13 deletions
diff --git a/src/librustc_typeck/check/place_op.rs b/src/librustc_typeck/check/place_op.rs index b7c8f310a14..cf2a47b59a4 100644 --- a/src/librustc_typeck/check/place_op.rs +++ b/src/librustc_typeck/check/place_op.rs @@ -9,6 +9,7 @@ use rustc_middle::ty::{self, Ty}; use rustc_span::symbol::{sym, Ident}; use rustc_span::Span; use rustc_trait_selection::autoderef::Autoderef; +use std::slice; impl<'a, 'tcx> FnCtxt<'a, 'tcx> { /// Type-check `*oprnd_expr` with `oprnd_expr` type-checked already. @@ -245,19 +246,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } match expr.kind { - hir::ExprKind::Index(ref base_expr, ref index_expr) => { - // We need to get the final type in case dereferences were needed for the trait - // to apply (#72002). - let index_expr_ty = self.tables.borrow().expr_ty_adjusted(index_expr); - self.convert_place_op_to_mutable( - PlaceOp::Index, - expr, - base_expr, - &[index_expr_ty], - ); + hir::ExprKind::Index(ref base_expr, ..) => { + self.convert_place_op_to_mutable(PlaceOp::Index, expr, base_expr); } hir::ExprKind::Unary(hir::UnOp::UnDeref, ref base_expr) => { - self.convert_place_op_to_mutable(PlaceOp::Deref, expr, base_expr, &[]); + self.convert_place_op_to_mutable(PlaceOp::Deref, expr, base_expr); } _ => {} } @@ -269,9 +262,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { op: PlaceOp, expr: &hir::Expr<'_>, base_expr: &hir::Expr<'_>, - arg_tys: &[Ty<'tcx>], ) { - debug!("convert_place_op_to_mutable({:?}, {:?}, {:?}, {:?})", op, expr, base_expr, arg_tys); + debug!("convert_place_op_to_mutable({:?}, {:?}, {:?})", op, expr, base_expr); if !self.tables.borrow().is_method_call(expr) { debug!("convert_place_op_to_mutable - builtin, nothing to do"); return; @@ -286,6 +278,25 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { .expect("place op takes something that is not a ref") .ty; + let arg_ty = match op { + PlaceOp::Deref => None, + PlaceOp::Index => { + // We would need to recover the `T` used when we resolve `<_ as Index<T>>::index` + // in try_index_step. This is the subst at index 1. + // + // Note: we should *not* use `expr_ty` of index_expr here because autoderef + // during coercions can cause type of index_expr to differ from `T` (#72002). + // We also could not use `expr_ty_adjusted` of index_expr because reborrowing + // during coercions can also cause type of index_expr to differ from `T`, + // which can potentially cause regionck failure (#74933). + Some(self.tables.borrow().node_substs(expr.hir_id).type_at(1)) + } + }; + let arg_tys = match arg_ty { + None => &[], + Some(ref ty) => slice::from_ref(ty), + }; + let method = self.try_mutable_overloaded_place_op(expr.span, base_ty, arg_tys, op); let method = match method { Some(ok) => self.register_infer_ok_obligations(ok), |