diff options
Diffstat (limited to 'compiler/rustc_middle/src/ty/opaque_types.rs')
| -rw-r--r-- | compiler/rustc_middle/src/ty/opaque_types.rs | 112 |
1 files changed, 59 insertions, 53 deletions
diff --git a/compiler/rustc_middle/src/ty/opaque_types.rs b/compiler/rustc_middle/src/ty/opaque_types.rs index 98cd92007..751f3066c 100644 --- a/compiler/rustc_middle/src/ty/opaque_types.rs +++ b/compiler/rustc_middle/src/ty/opaque_types.rs @@ -3,6 +3,7 @@ use crate::ty::fold::{TypeFolder, TypeSuperFoldable}; use crate::ty::subst::{GenericArg, GenericArgKind}; use crate::ty::{self, Ty, TyCtxt, TypeFoldable}; use rustc_data_structures::fx::FxHashMap; +use rustc_span::def_id::DefId; use rustc_span::Span; /// Converts generic params of a TypeFoldable from one @@ -47,10 +48,51 @@ impl<'tcx> ReverseMapper<'tcx> { assert!(!self.do_not_error); kind.fold_with(self) } + + fn fold_closure_substs( + &mut self, + def_id: DefId, + substs: ty::SubstsRef<'tcx>, + ) -> ty::SubstsRef<'tcx> { + // I am a horrible monster and I pray for death. When + // we encounter a closure here, it is always a closure + // from within the function that we are currently + // type-checking -- one that is now being encapsulated + // in an opaque type. Ideally, we would + // go through the types/lifetimes that it references + // and treat them just like we would any other type, + // which means we would error out if we find any + // reference to a type/region that is not in the + // "reverse map". + // + // **However,** in the case of closures, there is a + // somewhat subtle (read: hacky) consideration. The + // problem is that our closure types currently include + // all the lifetime parameters declared on the + // enclosing function, even if they are unused by the + // closure itself. We can't readily filter them out, + // so here we replace those values with `'empty`. This + // can't really make a difference to the rest of the + // compiler; those regions are ignored for the + // outlives relation, and hence don't affect trait + // selection or auto traits, and they are erased + // during codegen. + + let generics = self.tcx.generics_of(def_id); + self.tcx.mk_substs_from_iter(substs.iter().enumerate().map(|(index, kind)| { + if index < generics.parent_count { + // Accommodate missing regions in the parent kinds... + self.fold_kind_no_missing_regions_error(kind) + } else { + // ...but not elsewhere. + self.fold_kind_normally(kind) + } + })) + } } -impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> { - fn tcx(&self) -> TyCtxt<'tcx> { +impl<'tcx> TypeFolder<TyCtxt<'tcx>> for ReverseMapper<'tcx> { + fn interner(&self) -> TyCtxt<'tcx> { self.tcx } @@ -67,6 +109,8 @@ impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> { // them. ty::ReErased => return r, + ty::ReError(_) => return r, + // The regions that we expect from borrow checking. ty::ReEarlyBound(_) | ty::ReFree(_) => {} @@ -83,20 +127,21 @@ impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> { Some(u) => panic!("region mapped to unexpected kind: {:?}", u), None if self.do_not_error => self.tcx.lifetimes.re_static, None => { - self.tcx + let e = self + .tcx .sess .struct_span_err(self.span, "non-defining opaque type use in defining scope") .span_label( self.span, format!( "lifetime `{}` is part of concrete type but not used in \ - parameter list of the `impl Trait` type alias", + parameter list of the `impl Trait` type alias", r ), ) .emit(); - self.tcx().lifetimes.re_static + self.interner().mk_re_error(e) } } } @@ -104,59 +149,20 @@ impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> { fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> { match *ty.kind() { ty::Closure(def_id, substs) => { - // I am a horrible monster and I pray for death. When - // we encounter a closure here, it is always a closure - // from within the function that we are currently - // type-checking -- one that is now being encapsulated - // in an opaque type. Ideally, we would - // go through the types/lifetimes that it references - // and treat them just like we would any other type, - // which means we would error out if we find any - // reference to a type/region that is not in the - // "reverse map". - // - // **However,** in the case of closures, there is a - // somewhat subtle (read: hacky) consideration. The - // problem is that our closure types currently include - // all the lifetime parameters declared on the - // enclosing function, even if they are unused by the - // closure itself. We can't readily filter them out, - // so here we replace those values with `'empty`. This - // can't really make a difference to the rest of the - // compiler; those regions are ignored for the - // outlives relation, and hence don't affect trait - // selection or auto traits, and they are erased - // during codegen. - - let generics = self.tcx.generics_of(def_id); - let substs = self.tcx.mk_substs(substs.iter().enumerate().map(|(index, kind)| { - if index < generics.parent_count { - // Accommodate missing regions in the parent kinds... - self.fold_kind_no_missing_regions_error(kind) - } else { - // ...but not elsewhere. - self.fold_kind_normally(kind) - } - })); - + let substs = self.fold_closure_substs(def_id, substs); self.tcx.mk_closure(def_id, substs) } ty::Generator(def_id, substs, movability) => { - let generics = self.tcx.generics_of(def_id); - let substs = self.tcx.mk_substs(substs.iter().enumerate().map(|(index, kind)| { - if index < generics.parent_count { - // Accommodate missing regions in the parent kinds... - self.fold_kind_no_missing_regions_error(kind) - } else { - // ...but not elsewhere. - self.fold_kind_normally(kind) - } - })); - + let substs = self.fold_closure_substs(def_id, substs); self.tcx.mk_generator(def_id, substs, movability) } + ty::GeneratorWitnessMIR(def_id, substs) => { + let substs = self.fold_closure_substs(def_id, substs); + self.tcx.mk_generator_witness_mir(def_id, substs) + } + ty::Param(param) => { // Look it up in the substitution list. match self.map.get(&ty.into()).map(|k| k.unpack()) { @@ -180,7 +186,7 @@ impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> { .emit(); } - self.tcx().ty_error() + self.interner().ty_error_misc() } } } @@ -208,7 +214,7 @@ impl<'tcx> TypeFolder<'tcx> for ReverseMapper<'tcx> { }); } - self.tcx().const_error(ct.ty()) + self.interner().const_error(ct.ty()) } } } |