style: rename crates to kebab case

crates/hir-ty/src/utils.rs

@@ -0,0 +1,449 @@
+//! Helper functions for working with def, which don't need to be a separate
+//! query, but can't be computed directly from `*Data` (ie, which need a `db`).
+
+use std::iter;
+
+use base_db::CrateId;
+use chalk_ir::{fold::Shift, BoundVar, DebruijnIndex};
+use hir_def::{
+    db::DefDatabase,
+    generics::{
+        GenericParams, TypeOrConstParamData, TypeParamData, TypeParamProvenance, WherePredicate,
+        WherePredicateTypeTarget,
+    },
+    intern::Interned,
+    path::Path,
+    resolver::{HasResolver, TypeNs},
+    type_ref::{TraitBoundModifier, TypeRef},
+    ConstParamId, FunctionId, GenericDefId, ItemContainerId, Lookup, TraitId, TypeAliasId,
+    TypeOrConstParamId, TypeParamId,
+};
+use hir_expand::name::{known, name, Name};
+use itertools::Either;
+use rustc_hash::FxHashSet;
+use smallvec::{smallvec, SmallVec};
+use syntax::SmolStr;
+
+use crate::{
+    db::HirDatabase, ChalkTraitId, ConstData, ConstValue, GenericArgData, Interner, Substitution,
+    TraitRef, TraitRefExt, TyKind, WhereClause,
+};
+
+pub(crate) fn fn_traits(db: &dyn DefDatabase, krate: CrateId) -> impl Iterator<Item = TraitId> {
+    [
+        db.lang_item(krate, SmolStr::new_inline("fn")),
+        db.lang_item(krate, SmolStr::new_inline("fn_mut")),
+        db.lang_item(krate, SmolStr::new_inline("fn_once")),
+    ]
+    .into_iter()
+    .flatten()
+    .flat_map(|it| it.as_trait())
+}
+
+fn direct_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> SmallVec<[TraitId; 4]> {
+    let resolver = trait_.resolver(db);
+    // 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_.into());
+    let trait_self = generic_params.find_trait_self_param();
+    generic_params
+        .where_predicates
+        .iter()
+        .filter_map(|pred| match pred {
+            WherePredicate::ForLifetime { target, bound, .. }
+            | WherePredicate::TypeBound { target, bound } => match target {
+                WherePredicateTypeTarget::TypeRef(type_ref) => match &**type_ref {
+                    TypeRef::Path(p) if p == &Path::from(name![Self]) => bound.as_path(),
+                    _ => None,
+                },
+                WherePredicateTypeTarget::TypeOrConstParam(local_id)
+                    if Some(*local_id) == trait_self =>
+                {
+                    bound.as_path()
+                }
+                _ => None,
+            },
+            WherePredicate::Lifetime { .. } => None,
+        })
+        .filter_map(|(path, bound_modifier)| match bound_modifier {
+            TraitBoundModifier::None => Some(path),
+            TraitBoundModifier::Maybe => None,
+        })
+        .filter_map(|path| match resolver.resolve_path_in_type_ns_fully(db, path.mod_path()) {
+            Some(TypeNs::TraitId(t)) => Some(t),
+            _ => None,
+        })
+        .collect()
+}
+
+fn direct_super_trait_refs(db: &dyn HirDatabase, trait_ref: &TraitRef) -> Vec<TraitRef> {
+    // 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.hir_trait_id().into());
+    let trait_self = match generic_params.find_trait_self_param() {
+        Some(p) => TypeOrConstParamId { parent: trait_ref.hir_trait_id().into(), local_id: p },
+        None => return Vec::new(),
+    };
+    db.generic_predicates_for_param(trait_self.parent, trait_self, None)
+        .iter()
+        .filter_map(|pred| {
+            pred.as_ref().filter_map(|pred| match pred.skip_binders() {
+                // FIXME: how to correctly handle higher-ranked bounds here?
+                WhereClause::Implemented(tr) => Some(
+                    tr.clone()
+                        .shifted_out_to(Interner, DebruijnIndex::ONE)
+                        .expect("FIXME unexpected higher-ranked trait bound"),
+                ),
+                _ => None,
+            })
+        })
+        .map(|pred| pred.substitute(Interner, &trait_ref.substitution))
+        .collect()
+}
+
+/// Returns an iterator over the whole super trait hierarchy (including the
+/// trait itself).
+pub fn all_super_traits(db: &dyn DefDatabase, trait_: TraitId) -> SmallVec<[TraitId; 4]> {
+    // 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 = smallvec![trait_];
+    let mut i = 0;
+    while let Some(&t) = result.get(i) {
+        // yeah this is quadratic, but trait hierarchies should be flat
+        // enough that this doesn't matter
+        for tt in direct_super_traits(db, t) {
+            if !result.contains(&tt) {
+                result.push(tt);
+            }
+        }
+        i += 1;
+    }
+    result
+}
+
+/// Given a trait ref (`Self: Trait`), builds all the implied trait refs for
+/// super traits. The original trait ref will be included. So the difference to
+/// `all_super_traits` is that we keep track of type parameters; for example if
+/// we have `Self: Trait<u32, i32>` and `Trait<T, U>: OtherTrait<U>` we'll get
+/// `Self: OtherTrait<i32>`.
+pub(super) fn all_super_trait_refs(db: &dyn HirDatabase, trait_ref: TraitRef) -> SuperTraits {
+    SuperTraits { db, seen: iter::once(trait_ref.trait_id).collect(), stack: vec![trait_ref] }
+}
+
+pub(super) struct SuperTraits<'a> {
+    db: &'a dyn HirDatabase,
+    stack: Vec<TraitRef>,
+    seen: FxHashSet<ChalkTraitId>,
+}
+
+impl<'a> SuperTraits<'a> {
+    fn elaborate(&mut self, trait_ref: &TraitRef) {
+        let mut trait_refs = direct_super_trait_refs(self.db, trait_ref);
+        trait_refs.retain(|tr| !self.seen.contains(&tr.trait_id));
+        self.stack.extend(trait_refs);
+    }
+}
+
+impl<'a> Iterator for SuperTraits<'a> {
+    type Item = TraitRef;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if let Some(next) = self.stack.pop() {
+            self.elaborate(&next);
+            Some(next)
+        } else {
+            None
+        }
+    }
+}
+
+pub(super) fn associated_type_by_name_including_super_traits(
+    db: &dyn HirDatabase,
+    trait_ref: TraitRef,
+    name: &Name,
+) -> Option<(TraitRef, TypeAliasId)> {
+    all_super_trait_refs(db, trait_ref).find_map(|t| {
+        let assoc_type = db.trait_data(t.hir_trait_id()).associated_type_by_name(name)?;
+        Some((t, assoc_type))
+    })
+}
+
+pub(crate) fn generics(db: &dyn DefDatabase, def: GenericDefId) -> Generics {
+    let parent_generics = parent_generic_def(db, def).map(|def| Box::new(generics(db, def)));
+    if parent_generics.is_some() && matches!(def, GenericDefId::TypeAliasId(_)) {
+        let params = db.generic_params(def);
+        if params
+            .type_or_consts
+            .iter()
+            .any(|(_, x)| matches!(x, TypeOrConstParamData::ConstParamData(_)))
+        {
+            // XXX: treat const generic associated types as not existing to avoid crashes (#11769)
+            //
+            // Chalk expects the inner associated type's parameters to come
+            // *before*, not after the trait's generics as we've always done it.
+            // Adapting to this requires a larger refactoring
+            cov_mark::hit!(ignore_gats);
+            return Generics { def, params: Interned::new(Default::default()), parent_generics };
+        } else {
+            return Generics { def, params, parent_generics };
+        }
+    }
+    Generics { def, params: db.generic_params(def), parent_generics }
+}
+
+#[derive(Debug)]
+pub(crate) struct Generics {
+    def: GenericDefId,
+    pub(crate) params: Interned<GenericParams>,
+    parent_generics: Option<Box<Generics>>,
+}
+
+impl Generics {
+    // FIXME: we should drop this and handle const and type generics at the same time
+    pub(crate) fn type_iter<'a>(
+        &'a self,
+    ) -> impl Iterator<Item = (TypeOrConstParamId, &'a TypeParamData)> + 'a {
+        self.parent_generics
+            .as_ref()
+            .into_iter()
+            .flat_map(|it| {
+                it.params
+                    .type_iter()
+                    .map(move |(local_id, p)| (TypeOrConstParamId { parent: it.def, local_id }, p))
+            })
+            .chain(
+                self.params.type_iter().map(move |(local_id, p)| {
+                    (TypeOrConstParamId { parent: self.def, local_id }, p)
+                }),
+            )
+    }
+
+    pub(crate) fn iter_id<'a>(
+        &'a self,
+    ) -> impl Iterator<Item = Either<TypeParamId, ConstParamId>> + 'a {
+        self.iter().map(|(id, data)| match data {
+            TypeOrConstParamData::TypeParamData(_) => Either::Left(TypeParamId::from_unchecked(id)),
+            TypeOrConstParamData::ConstParamData(_) => {
+                Either::Right(ConstParamId::from_unchecked(id))
+            }
+        })
+    }
+
+    /// Iterator over types and const params of parent, then self.
+    pub(crate) fn iter<'a>(
+        &'a self,
+    ) -> impl DoubleEndedIterator<Item = (TypeOrConstParamId, &'a TypeOrConstParamData)> + 'a {
+        self.parent_generics
+            .as_ref()
+            .into_iter()
+            .flat_map(|it| {
+                it.params
+                    .iter()
+                    .map(move |(local_id, p)| (TypeOrConstParamId { parent: it.def, local_id }, p))
+            })
+            .chain(
+                self.params.iter().map(move |(local_id, p)| {
+                    (TypeOrConstParamId { parent: self.def, local_id }, p)
+                }),
+            )
+    }
+
+    /// Iterator over types and const params of parent.
+    pub(crate) fn iter_parent<'a>(
+        &'a self,
+    ) -> impl Iterator<Item = (TypeOrConstParamId, &'a TypeOrConstParamData)> + 'a {
+        self.parent_generics.as_ref().into_iter().flat_map(|it| {
+            it.params
+                .type_or_consts
+                .iter()
+                .map(move |(local_id, p)| (TypeOrConstParamId { parent: it.def, local_id }, p))
+        })
+    }
+
+    pub(crate) fn len(&self) -> usize {
+        self.len_split().0
+    }
+
+    /// (total, parents, child)
+    pub(crate) fn len_split(&self) -> (usize, usize, usize) {
+        let parent = self.parent_generics.as_ref().map_or(0, |p| p.len());
+        let child = self.params.type_or_consts.len();
+        (parent + child, parent, child)
+    }
+
+    /// (parent total, self param, type param list, const param list, impl trait)
+    pub(crate) fn provenance_split(&self) -> (usize, usize, usize, usize, usize) {
+        let parent = self.parent_generics.as_ref().map_or(0, |p| p.len());
+        let self_params = self
+            .params
+            .iter()
+            .filter_map(|x| x.1.type_param())
+            .filter(|p| p.provenance == TypeParamProvenance::TraitSelf)
+            .count();
+        let type_params = self
+            .params
+            .type_or_consts
+            .iter()
+            .filter_map(|x| x.1.type_param())
+            .filter(|p| p.provenance == TypeParamProvenance::TypeParamList)
+            .count();
+        let const_params = self.params.iter().filter_map(|x| x.1.const_param()).count();
+        let impl_trait_params = self
+            .params
+            .iter()
+            .filter_map(|x| x.1.type_param())
+            .filter(|p| p.provenance == TypeParamProvenance::ArgumentImplTrait)
+            .count();
+        (parent, self_params, type_params, const_params, impl_trait_params)
+    }
+
+    pub(crate) fn param_idx(&self, param: TypeOrConstParamId) -> Option<usize> {
+        Some(self.find_param(param)?.0)
+    }
+
+    fn find_param(&self, param: TypeOrConstParamId) -> Option<(usize, &TypeOrConstParamData)> {
+        if param.parent == self.def {
+            let (idx, (_local_id, data)) = self
+                .params
+                .type_or_consts
+                .iter()
+                .enumerate()
+                .find(|(_, (idx, _))| *idx == param.local_id)
+                .unwrap();
+            let (_total, parent_len, _child) = self.len_split();
+            Some((parent_len + idx, data))
+        } else {
+            self.parent_generics.as_ref().and_then(|g| g.find_param(param))
+        }
+    }
+
+    /// Returns a Substitution that replaces each parameter by a bound variable.
+    pub(crate) fn bound_vars_subst(
+        &self,
+        db: &dyn HirDatabase,
+        debruijn: DebruijnIndex,
+    ) -> Substitution {
+        Substitution::from_iter(
+            Interner,
+            self.iter_id().enumerate().map(|(idx, id)| match id {
+                Either::Left(_) => GenericArgData::Ty(
+                    TyKind::BoundVar(BoundVar::new(debruijn, idx)).intern(Interner),
+                )
+                .intern(Interner),
+                Either::Right(id) => GenericArgData::Const(
+                    ConstData {
+                        value: ConstValue::BoundVar(BoundVar::new(debruijn, idx)),
+                        ty: db.const_param_ty(id),
+                    }
+                    .intern(Interner),
+                )
+                .intern(Interner),
+            }),
+        )
+    }
+
+    /// Returns a Substitution that replaces each parameter by itself (i.e. `Ty::Param`).
+    pub(crate) fn placeholder_subst(&self, db: &dyn HirDatabase) -> Substitution {
+        Substitution::from_iter(
+            Interner,
+            self.iter_id().map(|id| match id {
+                Either::Left(id) => GenericArgData::Ty(
+                    TyKind::Placeholder(crate::to_placeholder_idx(db, id.into())).intern(Interner),
+                )
+                .intern(Interner),
+                Either::Right(id) => GenericArgData::Const(
+                    ConstData {
+                        value: ConstValue::Placeholder(crate::to_placeholder_idx(db, id.into())),
+                        ty: db.const_param_ty(id),
+                    }
+                    .intern(Interner),
+                )
+                .intern(Interner),
+            }),
+        )
+    }
+}
+
+fn parent_generic_def(db: &dyn DefDatabase, def: GenericDefId) -> Option<GenericDefId> {
+    let container = match def {
+        GenericDefId::FunctionId(it) => it.lookup(db).container,
+        GenericDefId::TypeAliasId(it) => it.lookup(db).container,
+        GenericDefId::ConstId(it) => it.lookup(db).container,
+        GenericDefId::EnumVariantId(it) => return Some(it.parent.into()),
+        GenericDefId::AdtId(_) | GenericDefId::TraitId(_) | GenericDefId::ImplId(_) => return None,
+    };
+
+    match container {
+        ItemContainerId::ImplId(it) => Some(it.into()),
+        ItemContainerId::TraitId(it) => Some(it.into()),
+        ItemContainerId::ModuleId(_) | ItemContainerId::ExternBlockId(_) => None,
+    }
+}
+
+pub fn is_fn_unsafe_to_call(db: &dyn HirDatabase, func: FunctionId) -> bool {
+    let data = db.function_data(func);
+    if data.has_unsafe_kw() {
+        return true;
+    }
+
+    match func.lookup(db.upcast()).container {
+        hir_def::ItemContainerId::ExternBlockId(block) => {
+            // Function in an `extern` block are always unsafe to call, except when it has
+            // `"rust-intrinsic"` ABI there are a few exceptions.
+            let id = block.lookup(db.upcast()).id;
+            match id.item_tree(db.upcast())[id.value].abi.as_deref() {
+                Some("rust-intrinsic") => is_intrinsic_fn_unsafe(&data.name),
+                _ => true,
+            }
+        }
+        _ => false,
+    }
+}
+
+/// Returns `true` if the given intrinsic is unsafe to call, or false otherwise.
+fn is_intrinsic_fn_unsafe(name: &Name) -> bool {
+    // Should be kept in sync with https://github.com/rust-lang/rust/blob/532d2b14c05f9bc20b2d27cbb5f4550d28343a36/compiler/rustc_typeck/src/check/intrinsic.rs#L72-L106
+    ![
+        known::abort,
+        known::add_with_overflow,
+        known::bitreverse,
+        known::black_box,
+        known::bswap,
+        known::caller_location,
+        known::ctlz,
+        known::ctpop,
+        known::cttz,
+        known::discriminant_value,
+        known::forget,
+        known::likely,
+        known::maxnumf32,
+        known::maxnumf64,
+        known::min_align_of,
+        known::minnumf32,
+        known::minnumf64,
+        known::mul_with_overflow,
+        known::needs_drop,
+        known::ptr_guaranteed_eq,
+        known::ptr_guaranteed_ne,
+        known::rotate_left,
+        known::rotate_right,
+        known::rustc_peek,
+        known::saturating_add,
+        known::saturating_sub,
+        known::size_of,
+        known::sub_with_overflow,
+        known::type_id,
+        known::type_name,
+        known::unlikely,
+        known::variant_count,
+        known::wrapping_add,
+        known::wrapping_mul,
+        known::wrapping_sub,
+    ]
+    .contains(name)
+}