3 files changed, 88 insertions, 54 deletions

diff --git a/crates/ra_hir/src/code_model.rs b/crates/ra_hir/src/code_model.rs
index c49190a0f..b8d48a500 100644
--- a/crates/ra_hir/src/code_model.rs
+++ b/crates/ra_hir/src/code_model.rs
@@ -13,7 +13,7 @@ use hir_def::{
     traits::TraitData,
     type_ref::{Mutability, TypeRef},
     AssocItemId, CrateModuleId, FunctionContainerId, HasModule, ImplId, LocalEnumVariantId,
-    LocalStructFieldId, Lookup, ModuleId, UnionId,
+    LocalStructFieldId, Lookup, ModuleId, TypeAliasContainerId, UnionId,
 };
 use hir_expand::{
     diagnostics::DiagnosticSink,
@@ -954,30 +954,34 @@ pub struct TypeAlias {
 
 impl TypeAlias {
     pub fn module(self, db: &impl DefDatabase) -> Module {
-        Module { id: self.id.module(db) }
+        Module { id: self.id.lookup(db).module(db) }
     }
 
     pub fn krate(self, db: &impl DefDatabase) -> Option<Crate> {
         Some(self.module(db).krate())
     }
 
-    /// The containing impl block, if this is a method.
+    /// The containing impl block, if this is a type alias.
     pub fn impl_block(self, db: &impl DefDatabase) -> Option<ImplBlock> {
-        ImplBlock::containing(db, self.into())
+        match self.container(db) {
+            Some(Container::ImplBlock(it)) => Some(it),
+            _ => None,
+        }
     }
 
-    /// The containing trait, if this is a trait method definition.
+    /// The containing trait, if this is a trait type alias definition.
     pub fn parent_trait(self, db: &impl DefDatabase) -> Option<Trait> {
-        db.trait_items_index(self.module(db).id).get_parent_trait(self.id.into()).map(Trait::from)
+        match self.container(db) {
+            Some(Container::Trait(it)) => Some(it),
+            _ => None,
+        }
     }
 
     pub fn container(self, db: &impl DefDatabase) -> Option<Container> {
-        if let Some(impl_block) = self.impl_block(db) {
-            Some(impl_block.into())
-        } else if let Some(trait_) = self.parent_trait(db) {
-            Some(trait_.into())
-        } else {
-            None
+        match self.id.lookup(db).container {
+            TypeAliasContainerId::TraitId(it) => Some(Container::Trait(it.into())),
+            TypeAliasContainerId::ImplId(it) => Some(Container::ImplBlock(it.into())),
+            TypeAliasContainerId::ModuleId(_) => None,
         }
     }
 
diff --git a/crates/ra_hir/src/code_model/src.rs b/crates/ra_hir/src/code_model/src.rs
index 91cab7414..04675e08e 100644
--- a/crates/ra_hir/src/code_model/src.rs
+++ b/crates/ra_hir/src/code_model/src.rs
@@ -138,7 +138,7 @@ impl HasSource for Trait {
 impl HasSource for TypeAlias {
     type Ast = ast::TypeAliasDef;
     fn source(self, db: &(impl DefDatabase + AstDatabase)) -> Source<ast::TypeAliasDef> {
-        self.id.source(db)
+        self.id.lookup(db).source(db)
     }
 }
 impl HasSource for MacroDef {
diff --git a/crates/ra_hir/src/from_source.rs b/crates/ra_hir/src/from_source.rs
index 303d5f138..f5fdaafa3 100644
--- a/crates/ra_hir/src/from_source.rs
+++ b/crates/ra_hir/src/from_source.rs
@@ -4,7 +4,7 @@ use hir_def::{ModuleId, StructId, StructOrUnionId, UnionId};
 use hir_expand::{name::AsName, AstId, MacroDefId, MacroDefKind};
 use ra_syntax::{
     ast::{self, AstNode, NameOwner},
-    match_ast, AstPtr,
+    match_ast, AstPtr, SyntaxNode,
 };
 
 use crate::{
@@ -52,48 +52,27 @@ impl FromSource for Trait {
 impl FromSource for Function {
     type Ast = ast::FnDef;
     fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
-        // FIXME: this doesn't try to handle nested declarations
-        for container in src.value.syntax().ancestors() {
-            let res = match_ast! {
-                match container {
-                    ast::TraitDef(it) => {
-                        let c = Trait::from_source(db, src.with_value(it))?;
-                        c.items(db)
-                            .into_iter()
-                            .filter_map(|it| match it {
-                                AssocItem::Function(it) => Some(it),
-                                _ => None
-                            })
-                            .find(|it| same_source(&it.source(db), &src))?
-                    },
-                    ast::ImplBlock(it) => {
-                        let c = ImplBlock::from_source(db, src.with_value(it))?;
-                        c.items(db)
-                            .into_iter()
-                            .filter_map(|it| match it {
-                                AssocItem::Function(it) => Some(it),
-                                _ => None
-                            })
-                            .find(|it| same_source(&it.source(db), &src))?
-
-                     },
-                    _ => { continue },
-                }
-            };
-            return Some(res);
-        }
-
-        let module_source = ModuleSource::from_child_node(db, src.as_ref().map(|it| it.syntax()));
-        let c = Module::from_definition(db, src.with_value(module_source))?;
-        let res = c
-            .declarations(db)
+        let items = match Container::find(db, src.as_ref().map(|it| it.syntax()))? {
+            Container::Trait(it) => it.items(db),
+            Container::ImplBlock(it) => it.items(db),
+            Container::Module(m) => {
+                return m
+                    .declarations(db)
+                    .into_iter()
+                    .filter_map(|it| match it {
+                        ModuleDef::Function(it) => Some(it),
+                        _ => None,
+                    })
+                    .find(|it| same_source(&it.source(db), &src))
+            }
+        };
+        items
             .into_iter()
             .filter_map(|it| match it {
-                ModuleDef::Function(it) => Some(it),
+                AssocItem::Function(it) => Some(it),
                 _ => None,
             })
-            .find(|it| same_source(&it.source(db), &src));
-        res
+            .find(|it| same_source(&it.source(db), &src))
     }
 }
 
@@ -114,8 +93,27 @@ impl FromSource for Static {
 impl FromSource for TypeAlias {
     type Ast = ast::TypeAliasDef;
     fn from_source(db: &(impl DefDatabase + AstDatabase), src: Source<Self::Ast>) -> Option<Self> {
-        let id = from_source(db, src)?;
-        Some(TypeAlias { id })
+        let items = match Container::find(db, src.as_ref().map(|it| it.syntax()))? {
+            Container::Trait(it) => it.items(db),
+            Container::ImplBlock(it) => it.items(db),
+            Container::Module(m) => {
+                return m
+                    .declarations(db)
+                    .into_iter()
+                    .filter_map(|it| match it {
+                        ModuleDef::TypeAlias(it) => Some(it),
+                        _ => None,
+                    })
+                    .find(|it| same_source(&it.source(db), &src))
+            }
+        };
+        items
+            .into_iter()
+            .filter_map(|it| match it {
+                AssocItem::TypeAlias(it) => Some(it),
+                _ => None,
+            })
+            .find(|it| same_source(&it.source(db), &src))
     }
 }
 
@@ -258,6 +256,38 @@ where
     Some(DEF::from_ast(ctx, &src.value))
 }
 
+enum Container {
+    Trait(Trait),
+    ImplBlock(ImplBlock),
+    Module(Module),
+}
+
+impl Container {
+    fn find(db: &impl DefDatabase, src: Source<&SyntaxNode>) -> Option<Container> {
+        // FIXME: this doesn't try to handle nested declarations
+        for container in src.value.ancestors() {
+            let res = match_ast! {
+                match container {
+                    ast::TraitDef(it) => {
+                        let c = Trait::from_source(db, src.with_value(it))?;
+                        Container::Trait(c)
+                    },
+                    ast::ImplBlock(it) => {
+                        let c = ImplBlock::from_source(db, src.with_value(it))?;
+                        Container::ImplBlock(c)
+                     },
+                    _ => { continue },
+                }
+            };
+            return Some(res);
+        }
+
+        let module_source = ModuleSource::from_child_node(db, src);
+        let c = Module::from_definition(db, src.with_value(module_source))?;
+        Some(Container::Module(c))
+    }
+}
+
 /// XXX: AST Nodes and SyntaxNodes have identity equality semantics: nodes are
 /// equal if they point to exactly the same object.
 ///