5 files changed, 98 insertions, 13 deletions

diff --git a/crates/hir/src/code_model.rs b/crates/hir/src/code_model.rs
index fcc42c6bb..42dc35b76 100644
--- a/crates/hir/src/code_model.rs
+++ b/crates/hir/src/code_model.rs
@@ -1250,6 +1250,14 @@ impl LifetimeParam {
         let params = db.generic_params(self.id.parent);
         params.lifetimes[self.id.local_id].name.clone()
     }
+
+    pub fn module(self, db: &dyn HirDatabase) -> Module {
+        self.id.parent.module(db.upcast()).into()
+    }
+
+    pub fn parent(self, _db: &dyn HirDatabase) -> GenericDef {
+        self.id.parent.into()
+    }
 }
 
 // FIXME: rename from `ImplDef` to `Impl`
diff --git a/crates/hir/src/from_id.rs b/crates/hir/src/from_id.rs
index 265ef6d1f..dd3fcfe4a 100644
--- a/crates/hir/src/from_id.rs
+++ b/crates/hir/src/from_id.rs
@@ -41,6 +41,7 @@ from_id![
     (hir_def::FunctionId, crate::Function),
     (hir_def::ImplId, crate::ImplDef),
     (hir_def::TypeParamId, crate::TypeParam),
+    (hir_def::LifetimeParamId, crate::LifetimeParam),
     (hir_expand::MacroDefId, crate::MacroDef)
 ];
 
@@ -154,6 +155,22 @@ impl From<GenericDef> for GenericDefId {
     }
 }
 
+impl From<GenericDefId> for GenericDef {
+    fn from(def: GenericDefId) -> Self {
+        match def {
+            GenericDefId::FunctionId(it) => GenericDef::Function(it.into()),
+            GenericDefId::AdtId(it) => GenericDef::Adt(it.into()),
+            GenericDefId::TraitId(it) => GenericDef::Trait(it.into()),
+            GenericDefId::TypeAliasId(it) => GenericDef::TypeAlias(it.into()),
+            GenericDefId::ImplId(it) => GenericDef::ImplDef(it.into()),
+            GenericDefId::EnumVariantId(it) => {
+                GenericDef::EnumVariant(EnumVariant { parent: it.parent.into(), id: it.local_id })
+            }
+            GenericDefId::ConstId(it) => GenericDef::Const(it.into()),
+        }
+    }
+}
+
 impl From<Adt> for GenericDefId {
     fn from(id: Adt) -> Self {
         match id {
diff --git a/crates/hir/src/has_source.rs b/crates/hir/src/has_source.rs
index c77494152..1e64a1614 100644
--- a/crates/hir/src/has_source.rs
+++ b/crates/hir/src/has_source.rs
@@ -10,8 +10,8 @@ use hir_expand::InFile;
 use syntax::ast;
 
 use crate::{
-    db::HirDatabase, Const, Enum, EnumVariant, Field, FieldSource, Function, ImplDef, MacroDef,
-    Module, Static, Struct, Trait, TypeAlias, TypeParam, Union,
+    db::HirDatabase, Const, Enum, EnumVariant, Field, FieldSource, Function, ImplDef,
+    LifetimeParam, MacroDef, Module, Static, Struct, Trait, TypeAlias, TypeParam, Union,
 };
 
 pub trait HasSource {
@@ -129,6 +129,14 @@ impl HasSource for TypeParam {
     type Ast = Either<ast::Trait, ast::TypeParam>;
     fn source(self, db: &dyn HirDatabase) -> InFile<Self::Ast> {
         let child_source = self.id.parent.child_source(db.upcast());
-        child_source.map(|it| it[self.id.local_id].clone())
+        child_source.map(|it| it.type_params[self.id.local_id].clone())
+    }
+}
+
+impl HasSource for LifetimeParam {
+    type Ast = ast::LifetimeParam;
+    fn source(self, db: &dyn HirDatabase) -> InFile<Self::Ast> {
+        let child_source = self.id.parent.child_source(db.upcast());
+        child_source.map(|it| it.lifetime_params[self.id.local_id].clone())
     }
 }
diff --git a/crates/hir/src/semantics.rs b/crates/hir/src/semantics.rs
index 4bd22ed27..e4fc21ced 100644
--- a/crates/hir/src/semantics.rs
+++ b/crates/hir/src/semantics.rs
@@ -13,7 +13,11 @@ use hir_expand::{hygiene::Hygiene, name::AsName, ExpansionInfo};
 use hir_ty::associated_type_shorthand_candidates;
 use itertools::Itertools;
 use rustc_hash::{FxHashMap, FxHashSet};
-use syntax::{algo::find_node_at_offset, ast, AstNode, SyntaxNode, SyntaxToken, TextSize};
+use syntax::{
+    algo::find_node_at_offset,
+    ast::{self, GenericParamsOwner},
+    match_ast, AstNode, SyntaxNode, SyntaxToken, TextSize,
+};
 
 use crate::{
     code_model::Access,
@@ -21,8 +25,9 @@ use crate::{
     diagnostics::Diagnostic,
     semantics::source_to_def::{ChildContainer, SourceToDefCache, SourceToDefCtx},
     source_analyzer::{resolve_hir_path, SourceAnalyzer},
-    AssocItem, Callable, Crate, Field, Function, HirFileId, ImplDef, InFile, Local, MacroDef,
-    Module, ModuleDef, Name, Path, ScopeDef, Trait, Type, TypeAlias, TypeParam, VariantDef,
+    AssocItem, Callable, Crate, Field, Function, HirFileId, ImplDef, InFile, LifetimeParam, Local,
+    MacroDef, Module, ModuleDef, Name, Path, ScopeDef, Trait, Type, TypeAlias, TypeParam,
+    VariantDef,
 };
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -173,6 +178,11 @@ impl<'db, DB: HirDatabase> Semantics<'db, DB> {
         self.imp.descend_node_at_offset(node, offset).find_map(N::cast)
     }
 
+    // FIXME: Replace the SyntaxToken with a typed ast Node/Token
+    pub fn resolve_lifetime_param(&self, lifetime_token: &SyntaxToken) -> Option<LifetimeParam> {
+        self.imp.resolve_lifetime_param(lifetime_token)
+    }
+
     pub fn type_of_expr(&self, expr: &ast::Expr) -> Option<Type> {
         self.imp.type_of_expr(expr)
     }
@@ -392,16 +402,44 @@ impl<'db> SemanticsImpl<'db> {
             .kmerge_by(|node1, node2| node1.text_range().len() < node2.text_range().len())
     }
 
+    // FIXME: Replace the SyntaxToken with a typed ast Node/Token
+    fn resolve_lifetime_param(&self, lifetime_token: &SyntaxToken) -> Option<LifetimeParam> {
+        if lifetime_token.kind() != syntax::SyntaxKind::LIFETIME {
+            return None;
+        }
+        let lifetime_text = lifetime_token.text();
+        let lifetime_param = lifetime_token.parent().ancestors().find_map(|syn| {
+            let gpl = match_ast! {
+                match syn {
+                    ast::Fn(it) => it.generic_param_list()?,
+                    ast::TypeAlias(it) => it.generic_param_list()?,
+                    ast::Struct(it) => it.generic_param_list()?,
+                    ast::Enum(it) => it.generic_param_list()?,
+                    ast::Union(it) => it.generic_param_list()?,
+                    ast::Trait(it) => it.generic_param_list()?,
+                    ast::Impl(it) => it.generic_param_list()?,
+                    ast::WherePred(it) => it.generic_param_list()?,
+                    ast::ForType(it) => it.generic_param_list()?,
+                    _ => return None,
+                }
+            };
+            gpl.lifetime_params()
+                .find(|tp| tp.lifetime_token().as_ref().map(|lt| lt.text()) == Some(lifetime_text))
+        })?;
+        let src = self.find_file(lifetime_param.syntax().clone()).with_value(lifetime_param);
+        ToDef::to_def(self, src)
+    }
+
     fn type_of_expr(&self, expr: &ast::Expr) -> Option<Type> {
-        self.analyze(expr.syntax()).type_of_expr(self.db, &expr)
+        self.analyze(expr.syntax()).type_of_expr(self.db, expr)
     }
 
     fn type_of_pat(&self, pat: &ast::Pat) -> Option<Type> {
-        self.analyze(pat.syntax()).type_of_pat(self.db, &pat)
+        self.analyze(pat.syntax()).type_of_pat(self.db, pat)
     }
 
     fn type_of_self(&self, param: &ast::SelfParam) -> Option<Type> {
-        self.analyze(param.syntax()).type_of_self(self.db, &param)
+        self.analyze(param.syntax()).type_of_self(self.db, param)
     }
 
     fn resolve_method_call(&self, call: &ast::MethodCallExpr) -> Option<FunctionId> {
@@ -684,6 +722,7 @@ to_def_impls![
     (crate::Field, ast::TupleField, tuple_field_to_def),
     (crate::EnumVariant, ast::Variant, enum_variant_to_def),
     (crate::TypeParam, ast::TypeParam, type_param_to_def),
+    (crate::LifetimeParam, ast::LifetimeParam, lifetime_param_to_def),
     (crate::MacroDef, ast::MacroCall, macro_call_to_def), // this one is dubious, not all calls are macros
     (crate::Local, ast::IdentPat, bind_pat_to_def),
 ];
diff --git a/crates/hir/src/semantics/source_to_def.rs b/crates/hir/src/semantics/source_to_def.rs
index 66fc11611..badcf0ae8 100644
--- a/crates/hir/src/semantics/source_to_def.rs
+++ b/crates/hir/src/semantics/source_to_def.rs
@@ -7,7 +7,8 @@ use hir_def::{
     expr::PatId,
     keys::{self, Key},
     ConstId, DefWithBodyId, EnumId, EnumVariantId, FieldId, FunctionId, GenericDefId, ImplId,
-    ModuleId, StaticId, StructId, TraitId, TypeAliasId, TypeParamId, UnionId, VariantId,
+    LifetimeParamId, ModuleId, StaticId, StructId, TraitId, TypeAliasId, TypeParamId, UnionId,
+    VariantId,
 };
 use hir_expand::{name::AsName, AstId, MacroDefKind};
 use rustc_hash::FxHashMap;
@@ -128,13 +129,25 @@ impl SourceToDefCtx<'_, '_> {
 
     pub(super) fn type_param_to_def(&mut self, src: InFile<ast::TypeParam>) -> Option<TypeParamId> {
         let container: ChildContainer =
-            self.find_type_param_container(src.as_ref().map(|it| it.syntax()))?.into();
+            self.find_generic_param_container(src.as_ref().map(|it| it.syntax()))?.into();
         let db = self.db;
         let dyn_map =
             &*self.cache.entry(container).or_insert_with(|| container.child_by_source(db));
         dyn_map[keys::TYPE_PARAM].get(&src).copied()
     }
 
+    pub(super) fn lifetime_param_to_def(
+        &mut self,
+        src: InFile<ast::LifetimeParam>,
+    ) -> Option<LifetimeParamId> {
+        let container: ChildContainer =
+            self.find_generic_param_container(src.as_ref().map(|it| it.syntax()))?.into();
+        let db = self.db;
+        let dyn_map =
+            &*self.cache.entry(container).or_insert_with(|| container.child_by_source(db));
+        dyn_map[keys::LIFETIME_PARAM].get(&src).copied()
+    }
+
     // FIXME: use DynMap as well?
     pub(super) fn macro_call_to_def(&mut self, src: InFile<ast::MacroCall>) -> Option<MacroDefId> {
         let kind = MacroDefKind::Declarative;
@@ -203,7 +216,7 @@ impl SourceToDefCtx<'_, '_> {
         Some(def.into())
     }
 
-    fn find_type_param_container(&mut self, src: InFile<&SyntaxNode>) -> Option<GenericDefId> {
+    fn find_generic_param_container(&mut self, src: InFile<&SyntaxNode>) -> Option<GenericDefId> {
         for container in src.cloned().ancestors_with_macros(self.db.upcast()).skip(1) {
             let res: GenericDefId = match_ast! {
                 match (container.value) {
@@ -247,7 +260,7 @@ pub(crate) enum ChildContainer {
     VariantId(VariantId),
     TypeAliasId(TypeAliasId),
     /// XXX: this might be the same def as, for example an `EnumId`. However,
-    /// here the children generic parameters, and not, eg enum variants.
+    /// here the children are generic parameters, and not, eg enum variants.
     GenericDefId(GenericDefId),
 }
 impl_from! {