Added inference of array length

crates/ra_syntax/src/ast/generated.rs

@@ -108,6 +108,10 @@ impl ArrayExpr {
     pub fn exprs(&self) -> impl Iterator<Item = &Expr> {
         super::children(self)
     }
+
+    pub fn repeat(&self) -> Option<&Expr> {
+        super::child_opt(self)
+    }
 }
 
 // ArrayType

crates/ra_syntax/src/grammar.ron

@@ -395,7 +395,8 @@ Grammar(
             collections: [["exprs", "Expr"]]
         ),
         "ArrayExpr": (
-            collections: [["exprs", "Expr"]]
+            collections: [["exprs", "Expr"]],
+            options:[["repeat","Expr"]]
         ),
         "ParenExpr": (options: ["Expr"]),
         "PathExpr": (options: ["Path"]),