Cleanup for 'be' statement and comments about future typestate

2 files changed, 18 insertions, 1 deletions

diff --git a/src/comp/front/ast.rs b/src/comp/front/ast.rs
index 756a7ad1..61a7bdc1 100644
--- a/src/comp/front/ast.rs
+++ b/src/comp/front/ast.rs
@@ -315,6 +315,17 @@ fn index_native_item(native_mod_index index, @native_item it) {
     }
 }
 
+fn is_call_expr(@expr e) -> bool {
+    alt (e.node) {
+        case (expr_call(_, _, _)) {
+            ret true;
+        }
+        case (_) {
+            ret false;
+        }
+    }
+}
+
 //
 // Local Variables:
 // mode: rust
diff --git a/src/comp/front/parser.rs b/src/comp/front/parser.rs
index a1b519ba..ea4cf12c 100644
--- a/src/comp/front/parser.rs
+++ b/src/comp/front/parser.rs
@@ -1203,7 +1203,13 @@ impure fn parse_stmt(parser p) -> @ast.stmt {
         case (token.BE) {
             p.bump();
             auto e = parse_expr(p);
-            ret @spanned(lo, e.span, ast.stmt_be(e));
+            // FIXME: Is this the right place for this check?
+            if /*check*/ (ast.is_call_expr(e)) {
+                ret @spanned(lo, e.span, ast.stmt_be(e));
+            }
+            else {
+                p.err("Non-call expression in tail call");
+            }
         }
 
         case (token.LET) {