Auto merge of #16805 - dfireBird:lifetime_lowering, r=Veykril

feat: Implement resolving and lowering of Lifetimes (no inference yet)

Author: bors

crates/hir-def/src/generics.rs

@@ -22,8 +22,8 @@ use crate::{
     lower::LowerCtx,
     nameres::{DefMap, MacroSubNs},
     type_ref::{ConstRef, LifetimeRef, TypeBound, TypeRef},
-    AdtId, ConstParamId, GenericDefId, HasModule, ItemTreeLoc, LocalTypeOrConstParamId, Lookup,
-    TypeOrConstParamId, TypeParamId,
+    AdtId, ConstParamId, GenericDefId, HasModule, ItemTreeLoc, LifetimeParamId,
+    LocalTypeOrConstParamId, Lookup, TypeOrConstParamId, TypeParamId,
 };
 
 /// Data about a generic type parameter (to a function, struct, impl, ...).
@@ -102,6 +102,52 @@ impl TypeOrConstParamData {
 
 impl_from!(TypeParamData, ConstParamData for TypeOrConstParamData);
 
+#[derive(Clone, PartialEq, Eq, Debug, Hash)]
+pub enum GenericParamData {
+    TypeParamData(TypeParamData),
+    ConstParamData(ConstParamData),
+    LifetimeParamData(LifetimeParamData),
+}
+
+impl GenericParamData {
+    pub fn name(&self) -> Option<&Name> {
+        match self {
+            GenericParamData::TypeParamData(it) => it.name.as_ref(),
+            GenericParamData::ConstParamData(it) => Some(&it.name),
+            GenericParamData::LifetimeParamData(it) => Some(&it.name),
+        }
+    }
+
+    pub fn type_param(&self) -> Option<&TypeParamData> {
+        match self {
+            GenericParamData::TypeParamData(it) => Some(it),
+            _ => None,
+        }
+    }
+
+    pub fn const_param(&self) -> Option<&ConstParamData> {
+        match self {
+            GenericParamData::ConstParamData(it) => Some(it),
+            _ => None,
+        }
+    }
+
+    pub fn lifetime_param(&self) -> Option<&LifetimeParamData> {
+        match self {
+            GenericParamData::LifetimeParamData(it) => Some(it),
+            _ => None,
+        }
+    }
+}
+
+impl_from!(TypeParamData, ConstParamData, LifetimeParamData for GenericParamData);
+
+pub enum GenericParamDataRef<'a> {
+    TypeParamData(&'a TypeParamData),
+    ConstParamData(&'a ConstParamData),
+    LifetimeParamData(&'a LifetimeParamData),
+}
+
 /// Data about the generic parameters of a function, struct, impl, etc.
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub struct GenericParams {
@@ -365,6 +411,13 @@ impl GenericParams {
         self.type_or_consts.iter()
     }
 
+    /// Iterator of lifetimes field
+    pub fn iter_lt(
+        &self,
+    ) -> impl DoubleEndedIterator<Item = (Idx<LifetimeParamData>, &LifetimeParamData)> {
+        self.lifetimes.iter()
+    }
+
     pub(crate) fn generic_params_query(
         db: &dyn DefDatabase,
         def: GenericDefId,
@@ -507,4 +560,18 @@ impl GenericParams {
             .then(|| id)
         })
     }
+
+    pub fn find_lifetime_by_name(
+        &self,
+        name: &Name,
+        parent: GenericDefId,
+    ) -> Option<LifetimeParamId> {
+        self.lifetimes.iter().find_map(|(id, p)| {
+            if &p.name == name {
+                Some(LifetimeParamId { local_id: id, parent })
+            } else {
+                None
+            }
+        })
+    }
 }

crates/hir-def/src/resolver.rs

@@ -24,6 +24,7 @@ use crate::{
     nameres::{DefMap, MacroSubNs},
     path::{ModPath, Path, PathKind},
     per_ns::PerNs,
+    type_ref::LifetimeRef,
     visibility::{RawVisibility, Visibility},
     AdtId, ConstId, ConstParamId, CrateRootModuleId, DefWithBodyId, EnumId, EnumVariantId,
     ExternBlockId, ExternCrateId, FunctionId, GenericDefId, GenericParamId, HasModule, ImplId,
@@ -120,6 +121,12 @@ pub enum ValueNs {
     GenericParam(ConstParamId),
 }
 
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+pub enum LifetimeNs {
+    Static,
+    LifetimeParam(LifetimeParamId),
+}
+
 impl Resolver {
     /// Resolve known trait from std, like `std::futures::Future`
     pub fn resolve_known_trait(&self, db: &dyn DefDatabase, path: &ModPath) -> Option<TraitId> {
@@ -418,6 +425,19 @@ impl Resolver {
         self.resolve_path_as_macro(db, path, expected_macro_kind).map(|(it, _)| db.macro_def(it))
     }
 
+    pub fn resolve_lifetime(&self, lifetime: &LifetimeRef) -> Option<LifetimeNs> {
+        if lifetime.name == name::known::STATIC_LIFETIME {
+            return Some(LifetimeNs::Static);
+        }
+
+        self.scopes().find_map(|scope| match scope {
+            Scope::GenericParams { def, params } => {
+                params.find_lifetime_by_name(&lifetime.name, *def).map(LifetimeNs::LifetimeParam)
+            }
+            _ => None,
+        })
+    }
+
     /// Returns a set of names available in the current scope.
     ///
     /// Note that this is a somewhat fuzzy concept -- internally, the compiler

crates/hir-ty/src/builder.rs

@@ -9,21 +9,21 @@ use chalk_ir::{
     AdtId, DebruijnIndex, Scalar,
 };
 use hir_def::{
-    builtin_type::BuiltinType, generics::TypeOrConstParamData, ConstParamId, DefWithBodyId,
-    GenericDefId, TraitId, TypeAliasId,
+    builtin_type::BuiltinType, DefWithBodyId, GenericDefId, GenericParamId, TraitId, TypeAliasId,
 };
 use smallvec::SmallVec;
 
 use crate::{
-    consteval::unknown_const_as_generic, db::HirDatabase, infer::unify::InferenceTable, primitive,
-    to_assoc_type_id, to_chalk_trait_id, utils::generics, Binders, BoundVar, CallableSig,
-    GenericArg, GenericArgData, Interner, ProjectionTy, Substitution, TraitRef, Ty, TyDefId, TyExt,
-    TyKind,
+    consteval::unknown_const_as_generic, db::HirDatabase, error_lifetime,
+    infer::unify::InferenceTable, primitive, to_assoc_type_id, to_chalk_trait_id, utils::generics,
+    Binders, BoundVar, CallableSig, GenericArg, GenericArgData, Interner, ProjectionTy,
+    Substitution, TraitRef, Ty, TyDefId, TyExt, TyKind,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum ParamKind {
     Type,
+    Lifetime,
     Const(Ty),
 }
 
@@ -107,6 +107,9 @@ impl<D> TyBuilder<D> {
             ParamKind::Const(ty) => {
                 BoundVar::new(debruijn, idx).to_const(Interner, ty.clone()).cast(Interner)
             }
+            ParamKind::Lifetime => {
+                BoundVar::new(debruijn, idx).to_lifetime(Interner).cast(Interner)
+            }
         });
         this.vec.extend(filler.take(this.remaining()).casted(Interner));
         assert_eq!(this.remaining(), 0);
@@ -119,6 +122,7 @@ impl<D> TyBuilder<D> {
         let filler = this.param_kinds[this.vec.len()..].iter().map(|x| match x {
             ParamKind::Type => TyKind::Error.intern(Interner).cast(Interner),
             ParamKind::Const(ty) => unknown_const_as_generic(ty.clone()),
+            ParamKind::Lifetime => error_lifetime().cast(Interner),
         });
         this.vec.extend(filler.casted(Interner));
         assert_eq!(this.remaining(), 0);
@@ -130,6 +134,7 @@ impl<D> TyBuilder<D> {
         self.fill(|x| match x {
             ParamKind::Type => table.new_type_var().cast(Interner),
             ParamKind::Const(ty) => table.new_const_var(ty.clone()).cast(Interner),
+            ParamKind::Lifetime => table.new_lifetime_var().cast(Interner),
         })
     }
 
@@ -142,7 +147,8 @@ impl<D> TyBuilder<D> {
     fn assert_match_kind(&self, a: &chalk_ir::GenericArg<Interner>, e: &ParamKind) {
         match (a.data(Interner), e) {
             (GenericArgData::Ty(_), ParamKind::Type)
-            | (GenericArgData::Const(_), ParamKind::Const(_)) => (),
+            | (GenericArgData::Const(_), ParamKind::Const(_))
+            | (GenericArgData::Lifetime(_), ParamKind::Lifetime) => (),
             _ => panic!("Mismatched kinds: {a:?}, {:?}, {:?}", self.vec, self.param_kinds),
         }
     }
@@ -201,10 +207,11 @@ impl TyBuilder<()> {
         Substitution::from_iter(
             Interner,
             params.iter_id().map(|id| match id {
-                either::Either::Left(_) => TyKind::Error.intern(Interner).cast(Interner),
-                either::Either::Right(id) => {
+                GenericParamId::TypeParamId(_) => TyKind::Error.intern(Interner).cast(Interner),
+                GenericParamId::ConstParamId(id) => {
                     unknown_const_as_generic(db.const_param_ty(id)).cast(Interner)
                 }
+                GenericParamId::LifetimeParamId(_) => error_lifetime().cast(Interner),
             }),
         )
     }
@@ -219,11 +226,10 @@ impl TyBuilder<()> {
         assert!(generics.parent_generics().is_some() == parent_subst.is_some());
         let params = generics
             .iter_self()
-            .map(|(id, data)| match data {
-                TypeOrConstParamData::TypeParamData(_) => ParamKind::Type,
-                TypeOrConstParamData::ConstParamData(_) => {
-                    ParamKind::Const(db.const_param_ty(ConstParamId::from_unchecked(id)))
-                }
+            .map(|(id, _data)| match id {
+                GenericParamId::TypeParamId(_) => ParamKind::Type,
+                GenericParamId::ConstParamId(id) => ParamKind::Const(db.const_param_ty(id)),
+                GenericParamId::LifetimeParamId(_) => ParamKind::Lifetime,
             })
             .collect();
         TyBuilder::new((), params, parent_subst)

crates/hir-ty/src/display.rs

@@ -938,18 +938,32 @@ impl HirDisplay for Ty {
                 f.end_location_link();
                 if parameters.len(Interner) > 0 {
                     let generics = generics(db.upcast(), def.into());
-                    let (parent_params, self_param, type_params, const_params, _impl_trait_params) =
-                        generics.provenance_split();
-                    let total_len = parent_params + self_param + type_params + const_params;
+                    let (
+                        parent_params,
+                        self_param,
+                        type_params,
+                        const_params,
+                        _impl_trait_params,
+                        lifetime_params,
+                    ) = generics.provenance_split();
+                    let total_len =
+                        parent_params + self_param + type_params + const_params + lifetime_params;
                     // We print all params except implicit impl Trait params. Still a bit weird; should we leave out parent and self?
                     if total_len > 0 {
-                        // `parameters` are in the order of fn's params (including impl traits),
+                        // `parameters` are in the order of fn's params (including impl traits), fn's lifetimes
                         // parent's params (those from enclosing impl or trait, if any).
                         let parameters = parameters.as_slice(Interner);
                         let fn_params_len = self_param + type_params + const_params;
+                        // This will give slice till last type or const
                         let fn_params = parameters.get(..fn_params_len);
+                        let fn_lt_params =
+                            parameters.get(fn_params_len..(fn_params_len + lifetime_params));
                         let parent_params = parameters.get(parameters.len() - parent_params..);
-                        let params = parent_params.into_iter().chain(fn_params).flatten();
+                        let params = parent_params
+                            .into_iter()
+                            .chain(fn_lt_params)
+                            .chain(fn_params)
+                            .flatten();
                         write!(f, "<")?;
                         f.write_joined(params, ", ")?;
                         write!(f, ">")?;
@@ -1308,8 +1322,17 @@ fn hir_fmt_generics(
     generic_def: Option<hir_def::GenericDefId>,
 ) -> Result<(), HirDisplayError> {
     let db = f.db;
-    let lifetime_args_count = generic_def.map_or(0, |g| db.generic_params(g).lifetimes.len());
-    if parameters.len(Interner) + lifetime_args_count > 0 {
+    if parameters.len(Interner) > 0 {
+        use std::cmp::Ordering;
+        let param_compare =
+            |a: &GenericArg, b: &GenericArg| match (a.data(Interner), b.data(Interner)) {
+                (crate::GenericArgData::Lifetime(_), crate::GenericArgData::Lifetime(_)) => {
+                    Ordering::Equal
+                }
+                (crate::GenericArgData::Lifetime(_), _) => Ordering::Less,
+                (_, crate::GenericArgData::Lifetime(_)) => Ordering::Less,
+                (_, _) => Ordering::Equal,
+            };
         let parameters_to_write = if f.display_target.is_source_code() || f.omit_verbose_types() {
             match generic_def
                 .map(|generic_def_id| db.generic_defaults(generic_def_id))
@@ -1335,6 +1358,11 @@ fn hir_fmt_generics(
                                 return true;
                             }
                         }
+                        if parameter.lifetime(Interner).map(|it| it.data(Interner))
+                            == Some(&crate::LifetimeData::Static)
+                        {
+                            return true;
+                        }
                         let default_parameter = match default_parameters.get(i) {
                             Some(it) => it,
                             None => return true,
@@ -1355,16 +1383,12 @@ fn hir_fmt_generics(
         } else {
             parameters.as_slice(Interner)
         };
-        if !parameters_to_write.is_empty() || lifetime_args_count != 0 {
+        //FIXME: Should handle the ordering of lifetimes when creating substitutions
+        let mut parameters_to_write = parameters_to_write.to_vec();
+        parameters_to_write.sort_by(param_compare);
+        if !parameters_to_write.is_empty() {
             write!(f, "<")?;
             let mut first = true;
-            for _ in 0..lifetime_args_count {
-                if !first {
-                    write!(f, ", ")?;
-                }
-                first = false;
-                write!(f, "'_")?;
-            }
             for generic_arg in parameters_to_write {
                 if !first {
                     write!(f, ", ")?;

crates/hir-ty/src/infer.rs

@@ -42,7 +42,7 @@ use hir_def::{
     layout::Integer,
     path::{ModPath, Path},
     resolver::{HasResolver, ResolveValueResult, Resolver, TypeNs, ValueNs},
-    type_ref::TypeRef,
+    type_ref::{LifetimeRef, TypeRef},
     AdtId, AssocItemId, DefWithBodyId, FieldId, FunctionId, ItemContainerId, Lookup, TraitId,
     TupleFieldId, TupleId, TypeAliasId, VariantId,
 };
@@ -1037,6 +1037,12 @@ impl<'a> InferenceContext<'a> {
         self.result.standard_types.unknown.clone()
     }
 
+    fn make_lifetime(&mut self, lifetime_ref: &LifetimeRef) -> Lifetime {
+        let ctx = crate::lower::TyLoweringContext::new(self.db, &self.resolver, self.owner.into());
+        let lt = ctx.lower_lifetime(lifetime_ref);
+        self.insert_type_vars(lt)
+    }
+
     /// Replaces `Ty::Error` by a new type var, so we can maybe still infer it.
     fn insert_type_vars_shallow(&mut self, ty: Ty) -> Ty {
         self.table.insert_type_vars_shallow(ty)