raise error when no cases matched in pattern matching

lib/back/closure_translator.ml

@@ -74,6 +74,10 @@ let ff_match_constr = C.VARIABLE "ff_match_constr"
 
 let ff_match_tuple = C.VARIABLE "ff_match_tuple"
 
+let ff_match_fail = C.VARIABLE "ff_match_fail"
+
+let ff_match_fail_stmt = C.(COMPUTATION (CALL (ff_match_fail, [])))
+
 let header =
   {|
 #include "fun_rt.hpp"
@@ -315,7 +319,8 @@ and trans_expr ctx e =
       ( res,
         [
           C.DOWHILE
-            (C.CONSTANT (C.CONST_INT "0"), make_stmt_seq (e_stmts @ branches));
+            ( C.CONSTANT (C.CONST_INT "0"),
+              make_stmt_seq (e_stmts @ branches @ [ ff_match_fail_stmt ]) );
         ] )
   | ECmp (op, e0, e1) ->
       let is_eq_v = create_decl "is_eq" ctx in

runtime/include/fun_rt_core.hpp

@@ -177,6 +177,8 @@ bool ff_match_tuple(ff_obj_t cond, ff_obj_t* const (&payloads)[N]) {
     return true;
 }
 
+void ff_match_fail();
+
 ff_obj_t ff_is_equal(ff_obj_t x, ff_obj_t y);
 
 bool ff_is_equal_aux(const ff_obj_t& x, const ff_obj_t& y);

runtime/src/fun_rt_core.cpp

@@ -153,6 +153,10 @@ bool ff_match_constr(int64_t id, ff_obj_t cond, ff_obj_t* payload) {
     return true;
 }
 
+void ff_match_fail() {
+    throw std::runtime_error("Match failure!");
+}
+
 bool ff_is_equal_aux(const ff_obj_t& x, const ff_obj_t& y) {
     if (x.tag != y.tag) {
         return false;