From 497073abc66df21b178c931e91969fccd8afcdc3 Mon Sep 17 00:00:00 2001 From: Florian Diebold Date: Sun, 26 Apr 2020 16:56:25 +0200 Subject: [PATCH] For associated type shorthand (T::Item), use the substs from the where clause So e.g. if we have `fn foo>() -> T::Item`, we want to lower that to `>::Item` and not `>::Item`. --- crates/ra_hir_ty/src/lib.rs | 12 +++++++ crates/ra_hir_ty/src/lower.rs | 42 ++++++++++++++++-------- crates/ra_hir_ty/src/tests/traits.rs | 30 +++++++++++++++++ crates/ra_hir_ty/src/utils.rs | 48 ++++++++++++++++++++++++++++ 4 files changed, 119 insertions(+), 13 deletions(-) diff --git a/crates/ra_hir_ty/src/lib.rs b/crates/ra_hir_ty/src/lib.rs index 279c06d65d1..a8ef32ec597 100644 --- a/crates/ra_hir_ty/src/lib.rs +++ b/crates/ra_hir_ty/src/lib.rs @@ -487,6 +487,18 @@ impl Binders { pub fn new(num_binders: usize, value: T) -> Self { Self { num_binders, value } } + + pub fn as_ref(&self) -> Binders<&T> { + Binders { num_binders: self.num_binders, value: &self.value } + } + + pub fn map(self, f: impl FnOnce(T) -> U) -> Binders { + Binders { num_binders: self.num_binders, value: f(self.value) } + } + + pub fn filter_map(self, f: impl FnOnce(T) -> Option) -> Option> { + Some(Binders { num_binders: self.num_binders, value: f(self.value)? }) + } } impl Binders<&T> { diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs index b5721429661..a6f893037f5 100644 --- a/crates/ra_hir_ty/src/lower.rs +++ b/crates/ra_hir_ty/src/lower.rs @@ -28,11 +28,11 @@ db::HirDatabase, primitive::{FloatTy, IntTy}, utils::{ - all_super_traits, associated_type_by_name_including_super_traits, generics, make_mut_slice, - variant_data, + all_super_trait_refs, associated_type_by_name_including_super_traits, generics, + make_mut_slice, variant_data, }, Binders, BoundVar, DebruijnIndex, FnSig, GenericPredicate, PolyFnSig, ProjectionPredicate, - ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypeCtor, + ProjectionTy, Substs, TraitEnvironment, TraitRef, Ty, TypeCtor, TypeWalk, }; #[derive(Debug)] @@ -256,7 +256,7 @@ pub(crate) fn from_type_relative_path( if remaining_segments.len() == 1 { // resolve unselected assoc types let segment = remaining_segments.first().unwrap(); - (Ty::select_associated_type(ctx, ty, res, segment), None) + (Ty::select_associated_type(ctx, res, segment), None) } else if remaining_segments.len() > 1 { // FIXME report error (ambiguous associated type) (Ty::Unknown, None) @@ -380,21 +380,20 @@ pub(crate) fn from_hir_path(ctx: &TyLoweringContext<'_>, path: &Path) -> (Ty, Op fn select_associated_type( ctx: &TyLoweringContext<'_>, - self_ty: Ty, res: Option, segment: PathSegment<'_>, ) -> Ty { let traits_from_env: Vec<_> = match res { Some(TypeNs::SelfType(impl_id)) => match ctx.db.impl_trait(impl_id) { None => return Ty::Unknown, - Some(trait_ref) => vec![trait_ref.value.trait_], + Some(trait_ref) => vec![trait_ref.value], }, Some(TypeNs::GenericParam(param_id)) => { let predicates = ctx.db.generic_predicates_for_param(param_id); let mut traits_: Vec<_> = predicates .iter() .filter_map(|pred| match &pred.value { - GenericPredicate::Implemented(tr) => Some(tr.trait_), + GenericPredicate::Implemented(tr) => Some(tr.clone()), _ => None, }) .collect(); @@ -404,20 +403,37 @@ fn select_associated_type( if generics.params.types[param_id.local_id].provenance == TypeParamProvenance::TraitSelf { - traits_.push(trait_id); + let trait_ref = TraitRef { + trait_: trait_id, + substs: Substs::bound_vars(&generics, DebruijnIndex::INNERMOST), + }; + traits_.push(trait_ref); } } traits_ } _ => return Ty::Unknown, }; - let traits = traits_from_env.into_iter().flat_map(|t| all_super_traits(ctx.db.upcast(), t)); + let traits = traits_from_env.into_iter().flat_map(|t| all_super_trait_refs(ctx.db, t)); for t in traits { - if let Some(associated_ty) = ctx.db.trait_data(t).associated_type_by_name(&segment.name) + if let Some(associated_ty) = + ctx.db.trait_data(t.trait_).associated_type_by_name(&segment.name) { - let substs = - Substs::build_for_def(ctx.db, t).push(self_ty).fill_with_unknown().build(); - // FIXME handle type parameters on the segment + let substs = match ctx.type_param_mode { + TypeParamLoweringMode::Placeholder => { + // if we're lowering to placeholders, we have to put + // them in now + let s = Substs::type_params( + ctx.db, + ctx.resolver + .generic_def() + .expect("there should be generics if there's a generic param"), + ); + t.substs.subst_bound_vars(&s) + } + TypeParamLoweringMode::Variable => t.substs, + }; + // FIXME handle (forbid) type parameters on the segment return Ty::Projection(ProjectionTy { associated_ty, parameters: substs }); } } diff --git a/crates/ra_hir_ty/src/tests/traits.rs b/crates/ra_hir_ty/src/tests/traits.rs index f51cdd4964b..e555c879a04 100644 --- a/crates/ra_hir_ty/src/tests/traits.rs +++ b/crates/ra_hir_ty/src/tests/traits.rs @@ -1897,6 +1897,36 @@ fn test() { assert_eq!(t, "u32"); } +#[test] +fn unselected_projection_chalk_fold() { + let t = type_at( + r#" +//- /main.rs +trait Interner {} +trait Fold { + type Result; +} + +struct Ty {} +impl Fold for Ty { + type Result = Ty; +} + +fn fold(interner: &I, t: T) -> T::Result +where + T: Fold, +{ + loop {} +} + +fn foo(interner: &I, t: Ty) { + fold(interner, t)<|>; +} +"#, + ); + assert_eq!(t, "Ty"); +} + #[test] fn trait_impl_self_ty() { let t = type_at( diff --git a/crates/ra_hir_ty/src/utils.rs b/crates/ra_hir_ty/src/utils.rs index 1e5022fa4c7..f98350bf921 100644 --- a/crates/ra_hir_ty/src/utils.rs +++ b/crates/ra_hir_ty/src/utils.rs @@ -14,6 +14,8 @@ }; use hir_expand::name::{name, Name}; +use crate::{db::HirDatabase, GenericPredicate, TraitRef}; + fn direct_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> Vec { let resolver = trait_.resolver(db); // returning the iterator directly doesn't easily work because of @@ -41,6 +43,28 @@ fn direct_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> Vec { .collect() } +fn direct_super_trait_refs(db: &dyn HirDatabase, trait_ref: &TraitRef) -> Vec { + // returning the iterator directly doesn't easily work because of + // lifetime problems, but since there usually shouldn't be more than a + // few direct traits this should be fine (we could even use some kind of + // SmallVec if performance is a concern) + let generic_params = db.generic_params(trait_ref.trait_.into()); + let trait_self = match generic_params.find_trait_self_param() { + Some(p) => TypeParamId { parent: trait_ref.trait_.into(), local_id: p }, + None => return Vec::new(), + }; + db.generic_predicates_for_param(trait_self) + .iter() + .filter_map(|pred| { + pred.as_ref().filter_map(|pred| match pred { + GenericPredicate::Implemented(tr) => Some(tr.clone()), + _ => None, + }) + }) + .map(|pred| pred.subst(&trait_ref.substs)) + .collect() +} + /// Returns an iterator over the whole super trait hierarchy (including the /// trait itself). pub(super) fn all_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> Vec { @@ -62,6 +86,30 @@ pub(super) fn all_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> Vec` and `Trait: OtherTrait` we'll get +/// `Self: OtherTrait`. +pub(super) fn all_super_trait_refs(db: &dyn HirDatabase, trait_ref: TraitRef) -> Vec { + // we need to take care a bit here to avoid infinite loops in case of cycles + // (i.e. if we have `trait A: B; trait B: A;`) + let mut result = vec![trait_ref]; + let mut i = 0; + while i < result.len() { + let t = &result[i]; + // yeah this is quadratic, but trait hierarchies should be flat + // enough that this doesn't matter + for tt in direct_super_trait_refs(db, t) { + if !result.iter().any(|tr| tr.trait_ == tt.trait_) { + result.push(tt); + } + } + i += 1; + } + result +} + /// Finds a path from a trait to one of its super traits. Returns an empty /// vector if there is no path. pub(super) fn find_super_trait_path(