6 files changed, 83 insertions, 17 deletions

diff --git a/crates/ra_hir/src/nameres.rs b/crates/ra_hir/src/nameres.rs
index 7ec6512b6..04cc693b3 100644
--- a/crates/ra_hir/src/nameres.rs
+++ b/crates/ra_hir/src/nameres.rs
@@ -251,10 +251,14 @@ where
             };
         }
         for (import_id, import_data) in input.imports.iter() {
-            if let Some(segment) = import_data.path.segments.iter().last() {
+            if let Some(last_segment) = import_data.path.segments.iter().last() {
                 if !import_data.is_glob {
+                    let name = import_data
+                        .alias
+                        .clone()
+                        .unwrap_or_else(|| last_segment.name.clone());
                     module_items.items.insert(
-                        segment.name.clone(),
+                        name,
                         Resolution {
                             def: PerNs::none(),
                             import: Some(import_id),
@@ -319,19 +323,18 @@ where
 
         if reached_fixedpoint == ReachedFixedPoint::Yes {
             let last_segment = import.path.segments.last().unwrap();
+            let name = import
+                .alias
+                .clone()
+                .unwrap_or_else(|| last_segment.name.clone());
+            log::debug!("resolved import {:?} ({:?}) to {:?}", name, import, def,);
             self.update(module_id, |items| {
                 let res = Resolution {
                     def,
                     import: Some(import_id),
                 };
-                items.items.insert(last_segment.name.clone(), res);
+                items.items.insert(name, res);
             });
-            log::debug!(
-                "resolved import {:?} ({:?}) cross-source root to {:?}",
-                last_segment.name,
-                import,
-                def,
-            );
         }
         reached_fixedpoint
     }
diff --git a/crates/ra_hir/src/nameres/lower.rs b/crates/ra_hir/src/nameres/lower.rs
index 9a45fa61c..df87f520f 100644
--- a/crates/ra_hir/src/nameres/lower.rs
+++ b/crates/ra_hir/src/nameres/lower.rs
@@ -21,6 +21,7 @@ impl_arena_id!(ImportId);
 #[derive(Debug, PartialEq, Eq)]
 pub(super) struct ImportData {
     pub(super) path: Path,
+    pub(super) alias: Option<Name>,
     pub(super) is_glob: bool,
 }
 
@@ -209,9 +210,10 @@ impl LoweredModule {
     }
 
     fn add_use_item(&mut self, source_map: &mut ImportSourceMap, item: &ast::UseItem) {
-        Path::expand_use_item(item, |path, segment| {
+        Path::expand_use_item(item, |path, segment, alias| {
             let import = self.imports.alloc(ImportData {
                 path,
+                alias,
                 is_glob: segment.is_none(),
             });
             if let Some(segment) = segment {
diff --git a/crates/ra_hir/src/nameres/tests.rs b/crates/ra_hir/src/nameres/tests.rs
index 0e0683db7..81c8a4f12 100644
--- a/crates/ra_hir/src/nameres/tests.rs
+++ b/crates/ra_hir/src/nameres/tests.rs
@@ -91,6 +91,30 @@ fn item_map_smoke_test() {
 }
 
 #[test]
+fn use_as() {
+    let (item_map, module_id) = item_map(
+        "
+        //- /lib.rs
+        mod foo;
+
+        use crate::foo::Baz as Foo;
+        <|>
+
+        //- /foo/mod.rs
+        pub struct Baz;
+    ",
+    );
+    check_module_item_map(
+        &item_map,
+        module_id,
+        "
+            Foo: t v
+            foo: t
+        ",
+    );
+}
+
+#[test]
 fn use_trees() {
     let (item_map, module_id) = item_map(
         "
diff --git a/crates/ra_hir/src/path.rs b/crates/ra_hir/src/path.rs
index e13d84c57..cb0a04500 100644
--- a/crates/ra_hir/src/path.rs
+++ b/crates/ra_hir/src/path.rs
@@ -1,6 +1,6 @@
 use std::sync::Arc;
 
-use ra_syntax::{ast, AstNode};
+use ra_syntax::{ast::{self, NameOwner}, AstNode};
 
 use crate::{Name, AsName, type_ref::TypeRef};
 
@@ -46,7 +46,7 @@ impl Path {
     /// Calls `cb` with all paths, represented by this use item.
     pub fn expand_use_item<'a>(
         item: &'a ast::UseItem,
-        mut cb: impl FnMut(Path, Option<&'a ast::PathSegment>),
+        mut cb: impl FnMut(Path, Option<&'a ast::PathSegment>, Option<Name>),
     ) {
         if let Some(tree) = item.use_tree() {
             expand_use_tree(None, tree, &mut cb);
@@ -164,7 +164,7 @@ impl From<Name> for Path {
 fn expand_use_tree<'a>(
     prefix: Option<Path>,
     tree: &'a ast::UseTree,
-    cb: &mut impl FnMut(Path, Option<&'a ast::PathSegment>),
+    cb: &mut impl FnMut(Path, Option<&'a ast::PathSegment>, Option<Name>),
 ) {
     if let Some(use_tree_list) = tree.use_tree_list() {
         let prefix = match tree.path() {
@@ -181,6 +181,7 @@ fn expand_use_tree<'a>(
             expand_use_tree(prefix.clone(), child_tree, cb);
         }
     } else {
+        let alias = tree.alias().and_then(|a| a.name()).map(|a| a.as_name());
         if let Some(ast_path) = tree.path() {
             // Handle self in a path.
             // E.g. `use something::{self, <...>}`
@@ -188,7 +189,7 @@ fn expand_use_tree<'a>(
                 if let Some(segment) = ast_path.segment() {
                     if segment.kind() == Some(ast::PathSegmentKind::SelfKw) {
                         if let Some(prefix) = prefix {
-                            cb(prefix, Some(segment));
+                            cb(prefix, Some(segment), alias);
                             return;
                         }
                     }
@@ -196,9 +197,9 @@ fn expand_use_tree<'a>(
             }
             if let Some(path) = convert_path(prefix, ast_path) {
                 if tree.has_star() {
-                    cb(path, None)
+                    cb(path, None, alias)
                 } else if let Some(segment) = ast_path.segment() {
-                    cb(path, Some(segment))
+                    cb(path, Some(segment), alias)
                 };
             }
             // TODO: report errors somewhere
diff --git a/crates/ra_syntax/src/ast/generated.rs b/crates/ra_syntax/src/ast/generated.rs
index d0561c495..60480c699 100644
--- a/crates/ra_syntax/src/ast/generated.rs
+++ b/crates/ra_syntax/src/ast/generated.rs
@@ -17,6 +17,35 @@ use crate::{
     ast::{self, AstNode},
 };
 
+// Alias
+#[derive(Debug, PartialEq, Eq, Hash)]
+#[repr(transparent)]
+pub struct Alias {
+    pub(crate) syntax: SyntaxNode,
+}
+unsafe impl TransparentNewType for Alias {
+    type Repr = rowan::SyntaxNode<RaTypes>;
+}
+
+impl AstNode for Alias {
+    fn cast(syntax: &SyntaxNode) -> Option<&Self> {
+        match syntax.kind() {
+            ALIAS => Some(Alias::from_repr(syntax.into_repr())),
+            _ => None,
+        }
+    }
+    fn syntax(&self) -> &SyntaxNode { &self.syntax }
+}
+
+impl ToOwned for Alias {
+    type Owned = TreeArc<Alias>;
+    fn to_owned(&self) -> TreeArc<Alias> { TreeArc::cast(self.syntax.to_owned()) }
+}
+
+
+impl ast::NameOwner for Alias {}
+impl Alias {}
+
 // ArgList
 #[derive(Debug, PartialEq, Eq, Hash)]
 #[repr(transparent)]
@@ -4176,6 +4205,10 @@ impl UseTree {
     pub fn use_tree_list(&self) -> Option<&UseTreeList> {
         super::child_opt(self)
     }
+
+    pub fn alias(&self) -> Option<&Alias> {
+        super::child_opt(self)
+    }
 }
 
 // UseTreeList
diff --git a/crates/ra_syntax/src/grammar.ron b/crates/ra_syntax/src/grammar.ron
index 47334bdf0..a2ccd7cb9 100644
--- a/crates/ra_syntax/src/grammar.ron
+++ b/crates/ra_syntax/src/grammar.ron
@@ -593,7 +593,10 @@ Grammar(
             options: [ "UseTree" ]
         ),
         "UseTree": (
-            options: [ "Path", "UseTreeList" ]
+            options: [ "Path", "UseTreeList", "Alias" ]
+        ),
+        "Alias": (
+            traits: ["NameOwner"],
         ),
         "UseTreeList": (
             collections: [["use_trees", "UseTree"]]