Enable completion for indexed value of array

src/racer/core.rs

@@ -1134,7 +1134,7 @@ fn complete_from_file_(filepath: &path::Path, cursor: Location, session: &Sessio
         }
         CompletionType::Field => {
             let context = ast::get_type_of(contextstr.to_owned(), filepath, pos, session);
-            debug!("complete_from_file context is {:?}", context);
+            println!("complete_from_file context is {:?}", context);
             if let Some(ty) = context {
                 out.extend(nameres::get_field_matches_from_ty(
                     ty,

src/racer/typeinf.rs

@@ -549,12 +549,12 @@ pub fn get_return_type_of_function(
 }
 
 pub(crate) fn get_type_of_indexed_value(body: Ty, session: &Session) -> Option<Ty> {
-    // TODO(kngwyu): slice support
     match body.dereference() {
         Ty::Match(m) => nameres::get_index_output(&m, session),
         Ty::PathSearch(p) => p
             .resolve_as_match(session)
             .and_then(|m| nameres::get_index_output(&m, session)),
+        Ty::Array(ty, _) | Ty::Slice(ty) => Some(*ty),
         _ => None,
     }
 }

tests/consts.rs

@@ -12,6 +12,17 @@ fn completes_methods_for_consts() {
     assert_eq!(get_only_completion(src, None).matchstr, "chars");
 }
 
+#[test]
+fn completes_methods_for_const_array() {
+    let src = r#"
+    const VECTOR: [f64; 2] = [0.0, 0.0];
+    fn main() {
+        VECTOR[0].atan2~
+    }
+    "#;
+    assert_eq!(get_only_completion(src, None).matchstr, "atan2");
+}
+
 #[test]
 fn completes_methods_for_static() {
     let src = r#"