diff options
Diffstat (limited to 'compiler/rustc_hir_typeck/src/coercion.rs')
| -rw-r--r-- | compiler/rustc_hir_typeck/src/coercion.rs | 38 |
1 files changed, 21 insertions, 17 deletions
diff --git a/compiler/rustc_hir_typeck/src/coercion.rs b/compiler/rustc_hir_typeck/src/coercion.rs index f0b349f0c..bbf7b81a2 100644 --- a/compiler/rustc_hir_typeck/src/coercion.rs +++ b/compiler/rustc_hir_typeck/src/coercion.rs @@ -13,7 +13,7 @@ //! useful for freezing mut things (that is, when the expected type is &T //! but you have &mut T) and also for avoiding the linearity //! of mut things (when the expected is &mut T and you have &mut T). See -//! the various `src/test/ui/coerce/*.rs` tests for +//! the various `tests/ui/coerce/*.rs` tests for //! examples of where this is useful. //! //! ## Subtle note @@ -118,7 +118,7 @@ fn identity(_: Ty<'_>) -> Vec<Adjustment<'_>> { vec![] } -fn simple<'tcx>(kind: Adjust<'tcx>) -> impl FnOnce(Ty<'tcx>) -> Vec<Adjustment<'tcx>> { +fn simple<'tcx>(kind: Adjust<'tcx>) -> impl FnOnce(Ty<'tcx>) -> Vec<Adjustment<'_>> { move |target| vec![Adjustment { kind, target }] } @@ -171,6 +171,10 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> { // Just ignore error types. if a.references_error() || b.references_error() { + // Best-effort try to unify these types -- we're already on the error path, + // so this will have the side-effect of making sure we have no ambiguities + // due to `[type error]` and `_` not coercing together. + let _ = self.commit_if_ok(|_| self.at(&self.cause, self.param_env).eq(a, b)); return success(vec![], self.fcx.tcx.ty_error(), vec![]); } @@ -309,7 +313,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> { // If we have a parameter of type `&M T_a` and the value // provided is `expr`, we will be adding an implicit borrow, - // meaning that we convert `f(expr)` to `f(&M *expr)`. Therefore, + // meaning that we convert `f(expr)` to `f(&M *expr)`. Therefore, // to type check, we will construct the type that `&M*expr` would // yield. @@ -336,7 +340,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> { continue; } - // At this point, we have deref'd `a` to `referent_ty`. So + // At this point, we have deref'd `a` to `referent_ty`. So // imagine we are coercing from `&'a mut Vec<T>` to `&'b mut [T]`. // In the autoderef loop for `&'a mut Vec<T>`, we would get // three callbacks: @@ -367,7 +371,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> { // - if in sub mode, that means we want to use `'b` (the // region from the target reference) for both // pointers [2]. This is because sub mode (somewhat - // arbitrarily) returns the subtype region. In the case + // arbitrarily) returns the subtype region. In the case // where we are coercing to a target type, we know we // want to use that target type region (`'b`) because -- // for the program to type-check -- it must be the @@ -379,7 +383,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> { // annotate the region of a borrow), and regionck has // code that adds edges from the region of a borrow // (`'b`, here) into the regions in the borrowed - // expression (`*x`, here). (Search for "link".) + // expression (`*x`, here). (Search for "link".) // - if in lub mode, things can get fairly complicated. The // easiest thing is just to make a fresh // region variable [4], which effectively means we defer @@ -453,7 +457,7 @@ impl<'f, 'tcx> Coerce<'f, 'tcx> { if ty == a && mt_a.mutbl.is_not() && autoderef.step_count() == 1 { // As a special case, if we would produce `&'a *x`, that's // a total no-op. We end up with the type `&'a T` just as - // we started with. In that case, just skip it + // we started with. In that case, just skip it // altogether. This is just an optimization. // // Note that for `&mut`, we DO want to reborrow -- @@ -1472,7 +1476,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { // if let Some(x) = ... { } // // we wind up with a second match arm that is like `_ => - // ()`. That is the case we are considering here. We take + // ()`. That is the case we are considering here. We take // a different path to get the right "expected, found" // message and so forth (and because we know that // `expression_ty` will be unit). @@ -1543,12 +1547,12 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { err.span_label(cause.span, "return type is not `()`"); } ObligationCauseCode::BlockTailExpression(blk_id) => { - let parent_id = fcx.tcx.hir().get_parent_node(blk_id); + let parent_id = fcx.tcx.hir().parent_id(blk_id); err = self.report_return_mismatched_types( cause, expected, found, - coercion_error.clone(), + coercion_error, fcx, parent_id, expression, @@ -1567,14 +1571,14 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { cause, expected, found, - coercion_error.clone(), + coercion_error, fcx, id, expression, None, ); if !fcx.tcx.features().unsized_locals { - let id = fcx.tcx.hir().get_parent_node(id); + let id = fcx.tcx.hir().parent_id(id); unsized_return = self.is_return_ty_unsized(fcx, id); } } @@ -1583,7 +1587,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { cause, expected, found, - coercion_error.clone(), + coercion_error, ); } } @@ -1664,7 +1668,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { let mut pointing_at_return_type = false; let mut fn_output = None; - let parent_id = fcx.tcx.hir().get_parent_node(id); + let parent_id = fcx.tcx.hir().parent_id(id); let parent = fcx.tcx.hir().get(parent_id); if let Some(expr) = expression && let hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Closure(&hir::Closure { body, .. }), .. }) = parent @@ -1803,9 +1807,9 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { // Get the return type. && let hir::TyKind::OpaqueDef(..) = ty.kind { - let ty = <dyn AstConv<'_>>::ast_ty_to_ty(fcx, ty); + let ty = fcx.astconv().ast_ty_to_ty( ty); // Get the `impl Trait`'s `DefId`. - if let ty::Opaque(def_id, _) = ty.kind() + if let ty::Alias(ty::Opaque, ty::AliasTy { def_id, .. }) = ty.kind() // Get the `impl Trait`'s `Item` so that we can get its trait bounds and // get the `Trait`'s `DefId`. && let hir::ItemKind::OpaqueTy(hir::OpaqueTy { bounds, .. }) = @@ -1862,7 +1866,7 @@ impl<'tcx, 'exprs, E: AsCoercionSite> CoerceMany<'tcx, 'exprs, E> { fn is_return_ty_unsized<'a>(&self, fcx: &FnCtxt<'a, 'tcx>, blk_id: hir::HirId) -> bool { if let Some((fn_decl, _)) = fcx.get_fn_decl(blk_id) && let hir::FnRetTy::Return(ty) = fn_decl.output - && let ty = <dyn AstConv<'_>>::ast_ty_to_ty(fcx, ty) + && let ty = fcx.astconv().ast_ty_to_ty( ty) && let ty::Dynamic(..) = ty.kind() { return true; |