parser: ensure calls only happen to Variables

src/parser.zig

@@ -694,10 +694,20 @@ pub const Parser = struct {
     }
 
     fn parseCall(self: *@This()) !*Expr {
+        // we parse a primary expression instead of consuming a .Identifier
+        // since parseCall is connected to the rest of the parser. doing
+        // identifiers would break the rest of the rules that want primaries.
+
+        // nothing stops us from ensuring expr is a Variable though ;)
         var expr = try self.parsePrimary();
 
         while (true) {
             if (self.check(.LeftParen)) {
+                if (ast.ExprType(expr.*) != .Variable) {
+                    self.doError("cannot call non-variable{}", ast.ExprType(expr.*));
+                    return Result.CompileError;
+                }
+
                 _ = try self.consumeSingle(.LeftParen);
                 expr = try self.finishCall(expr);
             } else {