diff options
| -rw-r--r-- | compiler/rustc_middle/src/ty/print/pretty.rs | 284 |
1 files changed, 210 insertions, 74 deletions
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs index 3846cf19d91..5a8fc943f9a 100644 --- a/compiler/rustc_middle/src/ty/print/pretty.rs +++ b/compiler/rustc_middle/src/ty/print/pretty.rs @@ -643,81 +643,8 @@ pub trait PrettyPrinter<'tcx>: } return Ok(self); } - // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`, - // by looking up the projections associated with the def_id. - let bounds = self.tcx().explicit_item_bounds(def_id); - - let mut first = true; - let mut is_sized = false; - let mut is_future = false; - let mut future_output_ty = None; - - p!("impl"); - for (predicate, _) in bounds { - let predicate = predicate.subst(self.tcx(), substs); - let bound_predicate = predicate.kind(); - - match bound_predicate.skip_binder() { - ty::PredicateKind::Projection(projection_predicate) => { - let Some(future_trait) = self.tcx().lang_items().future_trait() else { continue }; - let future_output_def_id = - self.tcx().associated_item_def_ids(future_trait)[0]; - - if projection_predicate.projection_ty.item_def_id - == future_output_def_id - { - // We don't account for multiple `Future::Output = Ty` contraints. - is_future = true; - future_output_ty = Some(projection_predicate.ty); - } - } - ty::PredicateKind::Trait(pred) => { - let trait_ref = bound_predicate.rebind(pred.trait_ref); - // Don't print +Sized, but rather +?Sized if absent. - if Some(trait_ref.def_id()) == self.tcx().lang_items().sized_trait() - { - is_sized = true; - continue; - } - - if Some(trait_ref.def_id()) - == self.tcx().lang_items().future_trait() - { - is_future = true; - continue; - } - - p!( - write("{}", if first { " " } else { " + " }), - print(trait_ref.print_only_trait_path()) - ); - - first = false; - } - _ => {} - } - } - if is_future { - p!(write("{}Future", if first { " " } else { " + " })); - first = false; - - if let Some(future_output_ty) = future_output_ty { - // Don't print projection types, which we (unfortunately) see often - // in the error outputs involving async blocks. - if !matches!(future_output_ty.kind(), ty::Projection(_)) { - p!("<Output = ", print(future_output_ty), ">"); - } - } - } - - if !is_sized { - p!(write("{}?Sized", if first { " " } else { " + " })); - } else if first { - p!(" Sized"); - } - - Ok(self) + self.pretty_print_opaque_impl_type(def_id, substs) }); } ty::Str => p!("str"), @@ -826,6 +753,208 @@ pub trait PrettyPrinter<'tcx>: Ok(self) } + fn pretty_print_opaque_impl_type( + mut self, + def_id: DefId, + substs: &'tcx ty::List<ty::GenericArg<'tcx>>, + ) -> Result<Self::Type, Self::Error> { + define_scoped_cx!(self); + + // Grab the "TraitA + TraitB" from `impl TraitA + TraitB`, + // by looking up the projections associated with the def_id. + let bounds = self.tcx().explicit_item_bounds(def_id); + + let mut traits = BTreeMap::new(); + let mut fn_traits = BTreeMap::new(); + let mut is_sized = false; + + for (predicate, _) in bounds { + let predicate = predicate.subst(self.tcx(), substs); + let bound_predicate = predicate.kind(); + + match bound_predicate.skip_binder() { + ty::PredicateKind::Trait(pred) => { + let trait_ref = bound_predicate.rebind(pred.trait_ref); + + // Don't print + Sized, but rather + ?Sized if absent. + if Some(trait_ref.def_id()) == self.tcx().lang_items().sized_trait() { + is_sized = true; + continue; + } + + self.insert_trait_and_projection(trait_ref, None, &mut traits, &mut fn_traits); + } + ty::PredicateKind::Projection(pred) => { + let proj_ref = bound_predicate.rebind(pred); + let trait_ref = proj_ref.required_poly_trait_ref(self.tcx()); + + // Projection type entry -- the def-id for naming, and the ty. + let proj_ty = (proj_ref.projection_def_id(), proj_ref.ty()); + + self.insert_trait_and_projection( + trait_ref, + Some(proj_ty), + &mut traits, + &mut fn_traits, + ); + } + _ => {} + } + } + + let mut first = true; + // Insert parenthesis around (Fn(A, B) -> C) if the opaque ty has more than one other trait + let paren_needed = fn_traits.len() > 1 || traits.len() > 0 || !is_sized; + + p!("impl"); + + for (fn_once_trait_ref, entry) in fn_traits { + // Get the (single) generic ty (the args) of this FnOnce trait ref. + let generics = self.generic_args_to_print( + self.tcx().generics_of(fn_once_trait_ref.def_id()), + fn_once_trait_ref.skip_binder().substs, + ); + + match (entry.return_ty, generics[0].expect_ty()) { + // We can only print `impl Fn() -> ()` if we have a tuple of args and we recorded + // a return type. + (Some(return_ty), arg_tys) if matches!(arg_tys.kind(), ty::Tuple(_)) => { + let name = if entry.fn_trait_ref.is_some() { + "Fn" + } else if entry.fn_mut_trait_ref.is_some() { + "FnMut" + } else { + "FnOnce" + }; + + p!( + write("{}", if first { " " } else { " + " }), + write("{}{}(", if paren_needed { "(" } else { "" }, name) + ); + + for (idx, ty) in arg_tys.tuple_fields().enumerate() { + if idx > 0 { + p!(", "); + } + p!(print(ty)); + } + + p!(") -> ", print(return_ty), write("{}", if paren_needed { ")" } else { "" })); + + first = false; + } + // If we got here, we can't print as a `impl Fn(A, B) -> C`. Just record the + // trait_refs we collected in the OpaqueFnEntry as normal trait refs. + _ => { + traits.entry(fn_once_trait_ref).or_default().extend( + // Group the return ty with its def id, if we had one. + entry + .return_ty + .map(|ty| (self.tcx().lang_items().fn_once_output().unwrap(), ty)), + ); + if let Some(trait_ref) = entry.fn_mut_trait_ref { + traits.entry(trait_ref).or_default(); + } + if let Some(trait_ref) = entry.fn_trait_ref { + traits.entry(trait_ref).or_default(); + } + } + } + } + + // Print the rest of the trait types (that aren't Fn* family of traits) + for (trait_ref, assoc_items) in traits { + p!( + write("{}", if first { " " } else { " + " }), + print(trait_ref.skip_binder().print_only_trait_name()) + ); + + let generics = self.generic_args_to_print( + self.tcx().generics_of(trait_ref.def_id()), + trait_ref.skip_binder().substs, + ); + + if !generics.is_empty() || !assoc_items.is_empty() { + p!("<"); + let mut first = true; + + for ty in generics { + if !first { + p!(", "); + } + p!(print(trait_ref.rebind(*ty))); + first = false; + } + + for (assoc_item_def_id, ty) in assoc_items { + if !first { + p!(", "); + } + p!( + write("{} = ", self.tcx().associated_item(assoc_item_def_id).ident), + print(ty) + ); + first = false; + } + + p!(">"); + } + + first = false; + } + + if !is_sized { + p!(write("{}?Sized", if first { " " } else { " + " })); + } else if first { + p!(" Sized"); + } + + Ok(self) + } + + /// Insert the trait ref and optionally a projection type associated with it into either the + /// traits map or fn_traits map, depending on if the trait is in the Fn* family of traits. + fn insert_trait_and_projection( + &mut self, + trait_ref: ty::PolyTraitRef<'tcx>, + proj_ty: Option<(DefId, ty::Binder<'tcx, Ty<'tcx>>)>, + traits: &mut BTreeMap<ty::PolyTraitRef<'tcx>, BTreeMap<DefId, ty::Binder<'tcx, Ty<'tcx>>>>, + fn_traits: &mut BTreeMap<ty::PolyTraitRef<'tcx>, OpaqueFnEntry<'tcx>>, + ) { + let trait_def_id = trait_ref.def_id(); + + // If our trait_ref is FnOnce or any of its children, project it onto the parent FnOnce + // super-trait ref and record it there. + if let Some(fn_once_trait) = self.tcx().lang_items().fn_once_trait() { + // If we have a FnOnce, then insert it into + if trait_def_id == fn_once_trait { + let entry = fn_traits.entry(trait_ref).or_default(); + // Optionally insert the return_ty as well. + if let Some((_, ty)) = proj_ty { + entry.return_ty = Some(ty); + } + return; + } else if Some(trait_def_id) == self.tcx().lang_items().fn_mut_trait() { + let super_trait_ref = crate::traits::util::supertraits(self.tcx(), trait_ref) + .find(|super_trait_ref| super_trait_ref.def_id() == fn_once_trait) + .unwrap(); + + fn_traits.entry(super_trait_ref).or_default().fn_mut_trait_ref = Some(trait_ref); + return; + } else if Some(trait_def_id) == self.tcx().lang_items().fn_trait() { + let super_trait_ref = crate::traits::util::supertraits(self.tcx(), trait_ref) + .find(|super_trait_ref| super_trait_ref.def_id() == fn_once_trait) + .unwrap(); + + fn_traits.entry(super_trait_ref).or_default().fn_trait_ref = Some(trait_ref); + return; + } + } + + // Otherwise, just group our traits and projection types. + traits.entry(trait_ref).or_default().extend(proj_ty); + } + fn pretty_print_bound_var( &mut self, debruijn: ty::DebruijnIndex, @@ -2553,3 +2682,10 @@ fn trimmed_def_paths(tcx: TyCtxt<'_>, (): ()) -> FxHashMap<DefId, Symbol> { pub fn provide(providers: &mut ty::query::Providers) { *providers = ty::query::Providers { trimmed_def_paths, ..*providers }; } + +#[derive(Default)] +pub struct OpaqueFnEntry<'tcx> { + fn_mut_trait_ref: Option<ty::PolyTraitRef<'tcx>>, + fn_trait_ref: Option<ty::PolyTraitRef<'tcx>>, + return_ty: Option<ty::Binder<'tcx, Ty<'tcx>>>, +} |