Fix: lv6 -exec was raising a spurious runtime error

bin/main.ml

-(* Time-stamp: <modified the 12/03/2020 (at 11:45) by Erwan Jahier> *)
+(* Time-stamp: <modified the 15/03/2021 (at 12:28) by Erwan Jahier> *)
 
 open AstV6
 open Lxm
@@ -324,12 +324,12 @@ could try one the options: -2c, -2c-exec, -exec, -ec, -lic, or -h for more optio
     | Parse_error ->
        print_compile_error (Lxm.last_made ()) "Syntax error"; my_exit opt 1
     | Unknown_var(lxm,id) -> 
-      print_compile_error lxm ("unknown variable (" ^ (Lv6Id.to_string id) ^")");
+      print_runtime_error lxm ("unknown variable (" ^ (Lv6Id.to_string id) ^")");
       my_exit opt 1
     | Unknown_constant(lxm,str) -> 
-      print_compile_error lxm ("unknown constant (" ^ str ^")");
+      print_runtime_error lxm ("unknown constant (" ^ str ^")");
       my_exit opt 1
-    | Compile_error(lxm,msg) -> print_compile_error lxm msg;  my_exit opt 1
+    | Compile_error(lxm,msg) -> print_runtime_error lxm msg;  my_exit opt 1
     | L2lCheckLoops.Error(lxm,msg,lic_prg) -> 
       (* Sometime it helps to see the current state of the faulty program *)
       LicPrg.to_file opt lic_prg main_node;
@@ -337,7 +337,10 @@ could try one the options: -2c, -2c-exec, -exec, -ec, -lic, or -h for more optio
       print_compile_error lxm msg;
       my_exit opt 1
     | SocExec.AssertViolation lxm ->
-       print_compile_error lxm "An assertion is violated in the Lustre program";
+       print_runtime_error lxm "An assertion is violated in the Lustre program";
+       my_exit opt 1
+    | Failure msg ->
+       Printf.eprintf "\nRuntime Error: %s\n" msg;
        my_exit opt 1
     | Assert_failure (file, line, col)  -> 
       prerr_string (

lib/lv6errors.ml

-(* Time-stamp: <modified the 29/08/2019 (at 14:17) by Erwan Jahier> *)
+(* Time-stamp: <modified the 15/03/2021 (at 12:22) by Erwan Jahier> *)
 
 (** *)
 
@@ -105,6 +105,9 @@ Formatage standard des erreurs de compil
 let compile_error_string lxm msg = (
    Printf.sprintf "\nError: %s:\nError: %s\n" (Lxm.details lxm) msg
 )
+let runtime_error_string lxm msg = (
+   Printf.sprintf "\nRuntime Error: %s:\nError: %s\n" (Lxm.details lxm) msg
+)
 
 (** ---------------------------------------------------------------------
 Message d'erreur (associé à un lexeme) sur stderr
@@ -114,6 +117,11 @@ let print_compile_error lxm msg = (
   flush stderr
 )
 
+let print_runtime_error lxm msg = (
+  Printf.eprintf "%s\n" (compile_error_string lxm msg);
+  flush stderr
+)
+
 (** ---------------------------------------------------------------------
 Warning (associé à un lexeme) sur stderr
 ----------------------------------------------------------------------*)

lib/socExecValue.ml

-(* Time-stamp: <modified the 06/03/2020 (at 13:30) by Erwan Jahier> *)
+(* Time-stamp: <modified the 15/03/2021 (at 15:44) by Erwan Jahier> *)
 
 let dbg = (Lv6Verbose.get_flag "exec")
 
@@ -285,11 +285,17 @@ let rec (get_value : ctx -> var_expr -> Data.v) =
       | Field(ve,fn,_t) -> 
         let s = get_value ctx ve in
         (match s with
-          | S fl -> (
-            try List.assoc fn fl
-            with Not_found -> assert false (* should not occur *)
+         | U -> U
+         | S fl -> (
+             try List.assoc fn fl
+             with Not_found -> assert false (* should not occur *)
           )
-          | _ -> assert false (* should not occur *)
+          | _ ->
+            let msg = Printf.sprintf "'%s' is not a struct\n"
+                (SocUtils.string_of_filter ve)
+            in
+            failwith msg
+            (*             assert false (* should not occur *) *)
         )
       | Index(ve,i,_vt) -> (
         let a = get_value ctx ve in