diff options
Diffstat (limited to 'compiler/rustc_middle/src/ty/print/mod.rs')
| -rw-r--r-- | compiler/rustc_middle/src/ty/print/mod.rs | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/compiler/rustc_middle/src/ty/print/mod.rs b/compiler/rustc_middle/src/ty/print/mod.rs new file mode 100644 index 000000000..d57cf8f01 --- /dev/null +++ b/compiler/rustc_middle/src/ty/print/mod.rs @@ -0,0 +1,327 @@ +use crate::ty::subst::{GenericArg, Subst}; +use crate::ty::{self, DefIdTree, Ty, TyCtxt}; + +use rustc_data_structures::fx::FxHashSet; +use rustc_data_structures::sso::SsoHashSet; +use rustc_hir::def_id::{CrateNum, DefId}; +use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData}; + +// `pretty` is a separate module only for organization. +mod pretty; +pub use self::pretty::*; + +// FIXME(eddyb) false positive, the lifetime parameters are used with `P: Printer<...>`. +#[allow(unused_lifetimes)] +pub trait Print<'tcx, P> { + type Output; + type Error; + + fn print(&self, cx: P) -> Result<Self::Output, Self::Error>; +} + +/// Interface for outputting user-facing "type-system entities" +/// (paths, types, lifetimes, constants, etc.) as a side-effect +/// (e.g. formatting, like `PrettyPrinter` implementors do) or by +/// constructing some alternative representation (e.g. an AST), +/// which the associated types allow passing through the methods. +/// +/// For pretty-printing/formatting in particular, see `PrettyPrinter`. +// +// FIXME(eddyb) find a better name; this is more general than "printing". +pub trait Printer<'tcx>: Sized { + type Error; + + type Path; + type Region; + type Type; + type DynExistential; + type Const; + + fn tcx<'a>(&'a self) -> TyCtxt<'tcx>; + + fn print_def_path( + self, + def_id: DefId, + substs: &'tcx [GenericArg<'tcx>], + ) -> Result<Self::Path, Self::Error> { + self.default_print_def_path(def_id, substs) + } + + fn print_impl_path( + self, + impl_def_id: DefId, + substs: &'tcx [GenericArg<'tcx>], + self_ty: Ty<'tcx>, + trait_ref: Option<ty::TraitRef<'tcx>>, + ) -> Result<Self::Path, Self::Error> { + self.default_print_impl_path(impl_def_id, substs, self_ty, trait_ref) + } + + fn print_region(self, region: ty::Region<'tcx>) -> Result<Self::Region, Self::Error>; + + fn print_type(self, ty: Ty<'tcx>) -> Result<Self::Type, Self::Error>; + + fn print_dyn_existential( + self, + predicates: &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>>, + ) -> Result<Self::DynExistential, Self::Error>; + + fn print_const(self, ct: ty::Const<'tcx>) -> Result<Self::Const, Self::Error>; + + fn path_crate(self, cnum: CrateNum) -> Result<Self::Path, Self::Error>; + + fn path_qualified( + self, + self_ty: Ty<'tcx>, + trait_ref: Option<ty::TraitRef<'tcx>>, + ) -> Result<Self::Path, Self::Error>; + + fn path_append_impl( + self, + print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, + disambiguated_data: &DisambiguatedDefPathData, + self_ty: Ty<'tcx>, + trait_ref: Option<ty::TraitRef<'tcx>>, + ) -> Result<Self::Path, Self::Error>; + + fn path_append( + self, + print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, + disambiguated_data: &DisambiguatedDefPathData, + ) -> Result<Self::Path, Self::Error>; + + fn path_generic_args( + self, + print_prefix: impl FnOnce(Self) -> Result<Self::Path, Self::Error>, + args: &[GenericArg<'tcx>], + ) -> Result<Self::Path, Self::Error>; + + // Defaults (should not be overridden): + + #[instrument(skip(self), level = "debug")] + fn default_print_def_path( + self, + def_id: DefId, + substs: &'tcx [GenericArg<'tcx>], + ) -> Result<Self::Path, Self::Error> { + let key = self.tcx().def_key(def_id); + debug!(?key); + + match key.disambiguated_data.data { + DefPathData::CrateRoot => { + assert!(key.parent.is_none()); + self.path_crate(def_id.krate) + } + + DefPathData::Impl => { + let generics = self.tcx().generics_of(def_id); + let self_ty = self.tcx().bound_type_of(def_id); + let impl_trait_ref = self.tcx().bound_impl_trait_ref(def_id); + let (self_ty, impl_trait_ref) = if substs.len() >= generics.count() { + ( + self_ty.subst(self.tcx(), substs), + impl_trait_ref.map(|i| i.subst(self.tcx(), substs)), + ) + } else { + (self_ty.0, impl_trait_ref.map(|i| i.0)) + }; + self.print_impl_path(def_id, substs, self_ty, impl_trait_ref) + } + + _ => { + let parent_def_id = DefId { index: key.parent.unwrap(), ..def_id }; + + let mut parent_substs = substs; + let mut trait_qualify_parent = false; + if !substs.is_empty() { + let generics = self.tcx().generics_of(def_id); + parent_substs = &substs[..generics.parent_count.min(substs.len())]; + + match key.disambiguated_data.data { + // Closures' own generics are only captures, don't print them. + DefPathData::ClosureExpr => {} + // This covers both `DefKind::AnonConst` and `DefKind::InlineConst`. + // Anon consts doesn't have their own generics, and inline consts' own + // generics are their inferred types, so don't print them. + DefPathData::AnonConst => {} + + // If we have any generic arguments to print, we do that + // on top of the same path, but without its own generics. + _ => { + if !generics.params.is_empty() && substs.len() >= generics.count() { + let args = generics.own_substs_no_defaults(self.tcx(), substs); + return self.path_generic_args( + |cx| cx.print_def_path(def_id, parent_substs), + args, + ); + } + } + } + + // FIXME(eddyb) try to move this into the parent's printing + // logic, instead of doing it when printing the child. + trait_qualify_parent = generics.has_self + && generics.parent == Some(parent_def_id) + && parent_substs.len() == generics.parent_count + && self.tcx().generics_of(parent_def_id).parent_count == 0; + } + + self.path_append( + |cx: Self| { + if trait_qualify_parent { + let trait_ref = ty::TraitRef::new( + parent_def_id, + cx.tcx().intern_substs(parent_substs), + ); + cx.path_qualified(trait_ref.self_ty(), Some(trait_ref)) + } else { + cx.print_def_path(parent_def_id, parent_substs) + } + }, + &key.disambiguated_data, + ) + } + } + } + + fn default_print_impl_path( + self, + impl_def_id: DefId, + _substs: &'tcx [GenericArg<'tcx>], + self_ty: Ty<'tcx>, + impl_trait_ref: Option<ty::TraitRef<'tcx>>, + ) -> Result<Self::Path, Self::Error> { + debug!( + "default_print_impl_path: impl_def_id={:?}, self_ty={}, impl_trait_ref={:?}", + impl_def_id, self_ty, impl_trait_ref + ); + + let key = self.tcx().def_key(impl_def_id); + let parent_def_id = DefId { index: key.parent.unwrap(), ..impl_def_id }; + + // Decide whether to print the parent path for the impl. + // Logically, since impls are global, it's never needed, but + // users may find it useful. Currently, we omit the parent if + // the impl is either in the same module as the self-type or + // as the trait. + let in_self_mod = match characteristic_def_id_of_type(self_ty) { + None => false, + Some(ty_def_id) => self.tcx().parent(ty_def_id) == parent_def_id, + }; + let in_trait_mod = match impl_trait_ref { + None => false, + Some(trait_ref) => self.tcx().parent(trait_ref.def_id) == parent_def_id, + }; + + if !in_self_mod && !in_trait_mod { + // If the impl is not co-located with either self-type or + // trait-type, then fallback to a format that identifies + // the module more clearly. + self.path_append_impl( + |cx| cx.print_def_path(parent_def_id, &[]), + &key.disambiguated_data, + self_ty, + impl_trait_ref, + ) + } else { + // Otherwise, try to give a good form that would be valid language + // syntax. Preferably using associated item notation. + self.path_qualified(self_ty, impl_trait_ref) + } + } +} + +/// As a heuristic, when we see an impl, if we see that the +/// 'self type' is a type defined in the same module as the impl, +/// we can omit including the path to the impl itself. This +/// function tries to find a "characteristic `DefId`" for a +/// type. It's just a heuristic so it makes some questionable +/// decisions and we may want to adjust it later. +/// +/// Visited set is needed to avoid full iteration over +/// deeply nested tuples that have no DefId. +fn characteristic_def_id_of_type_cached<'a>( + ty: Ty<'a>, + visited: &mut SsoHashSet<Ty<'a>>, +) -> Option<DefId> { + match *ty.kind() { + ty::Adt(adt_def, _) => Some(adt_def.did()), + + ty::Dynamic(data, ..) => data.principal_def_id(), + + ty::Array(subty, _) | ty::Slice(subty) => { + characteristic_def_id_of_type_cached(subty, visited) + } + + ty::RawPtr(mt) => characteristic_def_id_of_type_cached(mt.ty, visited), + + ty::Ref(_, ty, _) => characteristic_def_id_of_type_cached(ty, visited), + + ty::Tuple(ref tys) => tys.iter().find_map(|ty| { + if visited.insert(ty) { + return characteristic_def_id_of_type_cached(ty, visited); + } + return None; + }), + + ty::FnDef(def_id, _) + | ty::Closure(def_id, _) + | ty::Generator(def_id, _, _) + | ty::Foreign(def_id) => Some(def_id), + + ty::Bool + | ty::Char + | ty::Int(_) + | ty::Uint(_) + | ty::Str + | ty::FnPtr(_) + | ty::Projection(_) + | ty::Placeholder(..) + | ty::Param(_) + | ty::Opaque(..) + | ty::Infer(_) + | ty::Bound(..) + | ty::Error(_) + | ty::GeneratorWitness(..) + | ty::Never + | ty::Float(_) => None, + } +} +pub fn characteristic_def_id_of_type(ty: Ty<'_>) -> Option<DefId> { + characteristic_def_id_of_type_cached(ty, &mut SsoHashSet::new()) +} + +impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for ty::Region<'tcx> { + type Output = P::Region; + type Error = P::Error; + fn print(&self, cx: P) -> Result<Self::Output, Self::Error> { + cx.print_region(*self) + } +} + +impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for Ty<'tcx> { + type Output = P::Type; + type Error = P::Error; + + fn print(&self, cx: P) -> Result<Self::Output, Self::Error> { + cx.print_type(*self) + } +} + +impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> + for &'tcx ty::List<ty::Binder<'tcx, ty::ExistentialPredicate<'tcx>>> +{ + type Output = P::DynExistential; + type Error = P::Error; + fn print(&self, cx: P) -> Result<Self::Output, Self::Error> { + cx.print_dyn_existential(self) + } +} + +impl<'tcx, P: Printer<'tcx>> Print<'tcx, P> for ty::Const<'tcx> { + type Output = P::Const; + type Error = P::Error; + fn print(&self, cx: P) -> Result<Self::Output, Self::Error> { + cx.print_const(*self) + } +} |