4 files changed, 50 insertions, 18 deletions

diff --git a/crates/hir_ty/src/db.rs b/crates/hir_ty/src/db.rs
index 4300680d9..07510ae02 100644
--- a/crates/hir_ty/src/db.rs
+++ b/crates/hir_ty/src/db.rs
@@ -5,7 +5,7 @@ use std::sync::Arc;
 use base_db::{impl_intern_key, salsa, CrateId, Upcast};
 use hir_def::{
     db::DefDatabase, expr::ExprId, ConstParamId, DefWithBodyId, FunctionId, GenericDefId, ImplId,
-    LocalFieldId, TypeParamId, VariantId,
+    LifetimeParamId, LocalFieldId, TypeParamId, VariantId,
 };
 use la_arena::ArenaMap;
 
@@ -86,6 +86,8 @@ pub trait HirDatabase: DefDatabase + Upcast<dyn DefDatabase> {
     #[salsa::interned]
     fn intern_type_param_id(&self, param_id: TypeParamId) -> InternedTypeParamId;
     #[salsa::interned]
+    fn intern_lifetime_param_id(&self, param_id: LifetimeParamId) -> InternedLifetimeParamId;
+    #[salsa::interned]
     fn intern_impl_trait_id(&self, id: ImplTraitId) -> InternedOpaqueTyId;
     #[salsa::interned]
     fn intern_closure(&self, id: (DefWithBodyId, ExprId)) -> InternedClosureId;
@@ -156,6 +158,10 @@ pub struct InternedTypeParamId(salsa::InternId);
 impl_intern_key!(InternedTypeParamId);
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct InternedLifetimeParamId(salsa::InternId);
+impl_intern_key!(InternedLifetimeParamId);
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub struct InternedOpaqueTyId(salsa::InternId);
 impl_intern_key!(InternedOpaqueTyId);
 
diff --git a/crates/hir_ty/src/display.rs b/crates/hir_ty/src/display.rs
index f31e6b108..01c7ef91f 100644
--- a/crates/hir_ty/src/display.rs
+++ b/crates/hir_ty/src/display.rs
@@ -1,8 +1,10 @@
 //! FIXME: write short doc here
 
-use std::{array, fmt};
+use std::{
+    array,
+    fmt::{self, Debug},
+};
 
-use chalk_ir::Mutability;
 use hir_def::{
     db::DefDatabase,
     find_path,
@@ -16,9 +18,10 @@ use hir_def::{
 use hir_expand::name::Name;
 
 use crate::{
-    db::HirDatabase, from_assoc_type_id, from_foreign_def_id, from_placeholder_idx, primitive,
-    to_assoc_type_id, traits::chalk::from_chalk, utils::generics, AdtId, AliasEq, AliasTy,
-    CallableDefId, CallableSig, DomainGoal, GenericArg, ImplTraitId, Interner, Lifetime, OpaqueTy,
+    db::HirDatabase, from_assoc_type_id, from_foreign_def_id, from_placeholder_idx,
+    lt_from_placeholder_idx, primitive, to_assoc_type_id, traits::chalk::from_chalk,
+    utils::generics, AdtId, AliasEq, AliasTy, CallableDefId, CallableSig, DomainGoal, GenericArg,
+    ImplTraitId, Interner, Lifetime, LifetimeData, LifetimeOutlives, Mutability, OpaqueTy,
     ProjectionTy, QuantifiedWhereClause, Scalar, TraitRef, Ty, TyExt, TyKind, WhereClause,
 };
 
@@ -827,15 +830,35 @@ impl HirDisplay for WhereClause {
     }
 }
 
+impl HirDisplay for LifetimeOutlives {
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
+        self.a.hir_fmt(f)?;
+        write!(f, ": ")?;
+        self.b.hir_fmt(f)
+    }
+}
+
 impl HirDisplay for Lifetime {
     fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
+        self.interned().hir_fmt(f)
+    }
+}
+
+impl HirDisplay for LifetimeData {
+    fn hir_fmt(&self, f: &mut HirFormatter) -> Result<(), HirDisplayError> {
         match self {
-            Lifetime::Parameter(id) => {
+            LifetimeData::BoundVar(idx) => write!(f, "?{}.{}", idx.debruijn.depth(), idx.index),
+            LifetimeData::InferenceVar(_) => write!(f, "_"),
+            LifetimeData::Placeholder(idx) => {
+                let id = lt_from_placeholder_idx(f.db, *idx);
                 let generics = generics(f.db.upcast(), id.parent);
                 let param_data = &generics.params.lifetimes[id.local_id];
-                write!(f, "{}", &param_data.name)
+                write!(f, "{}", param_data.name)
             }
-            Lifetime::Static => write!(f, "'static"),
+            LifetimeData::Static => write!(f, "'static"),
+            LifetimeData::Empty(_) => Ok(()),
+            LifetimeData::Erased => Ok(()),
+            LifetimeData::Phantom(_, _) => Ok(()),
         }
     }
 }
diff --git a/crates/hir_ty/src/lib.rs b/crates/hir_ty/src/lib.rs
index daf379ef8..a3addc8e9 100644
--- a/crates/hir_ty/src/lib.rs
+++ b/crates/hir_ty/src/lib.rs
@@ -35,8 +35,8 @@ use smallvec::SmallVec;
 
 use base_db::salsa;
 use hir_def::{
-    expr::ExprId, type_ref::Rawness, AssocContainerId, FunctionId, GenericDefId, HasModule, Lookup,
-    TraitId, TypeAliasId, TypeParamId,
+    expr::ExprId, type_ref::Rawness, AssocContainerId, FunctionId, GenericDefId, HasModule,
+    LifetimeParamId, Lookup, TraitId, TypeAliasId, TypeParamId,
 };
 
 use crate::{db::HirDatabase, display::HirDisplay, utils::generics};
@@ -70,6 +70,10 @@ pub type VariableKind = chalk_ir::VariableKind<Interner>;
 pub type VariableKinds = chalk_ir::VariableKinds<Interner>;
 pub type CanonicalVarKinds = chalk_ir::CanonicalVarKinds<Interner>;
 
+pub type Lifetime = chalk_ir::Lifetime<Interner>;
+pub type LifetimeData = chalk_ir::LifetimeData<Interner>;
+pub type LifetimeOutlives = chalk_ir::LifetimeOutlives<Interner>;
+
 pub type ChalkTraitId = chalk_ir::TraitId<Interner>;
 
 impl ProjectionTy {
@@ -546,6 +550,12 @@ pub fn to_placeholder_idx(db: &dyn HirDatabase, id: TypeParamId) -> PlaceholderI
     }
 }
 
+pub fn lt_from_placeholder_idx(db: &dyn HirDatabase, idx: PlaceholderIndex) -> LifetimeParamId {
+    assert_eq!(idx.ui, chalk_ir::UniverseIndex::ROOT);
+    let interned_id = salsa::InternKey::from_intern_id(salsa::InternId::from(idx.idx));
+    db.lookup_intern_lifetime_param_id(interned_id)
+}
+
 pub fn to_chalk_trait_id(id: TraitId) -> ChalkTraitId {
     chalk_ir::TraitId(salsa::InternKey::as_intern_id(&id))
 }
diff --git a/crates/hir_ty/src/types.rs b/crates/hir_ty/src/types.rs
index 46c705a76..dc64e6e2b 100644
--- a/crates/hir_ty/src/types.rs
+++ b/crates/hir_ty/src/types.rs
@@ -7,7 +7,6 @@ use chalk_ir::{
     cast::{CastTo, Caster},
     BoundVar, Mutability, Scalar, TyVariableKind,
 };
-use hir_def::LifetimeParamId;
 use smallvec::SmallVec;
 
 use crate::{
@@ -16,12 +15,6 @@ use crate::{
 };
 
 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
-pub enum Lifetime {
-    Parameter(LifetimeParamId),
-    Static,
-}
-
-#[derive(Clone, PartialEq, Eq, Debug, Hash)]
 pub struct OpaqueTy {
     pub opaque_ty_id: OpaqueTyId,
     pub substitution: Substitution,