add new function mrb_toplevel_run to prevent running through C function...

add new function mrb_toplevel_run to prevent running through C function boudaries on exceptions; close #1942

include/mruby.h

@@ -276,6 +276,7 @@ void mrb_close(mrb_state*);
 
 mrb_value mrb_top_self(mrb_state *);
 mrb_value mrb_run(mrb_state*, struct RProc*, mrb_value);
+mrb_value mrb_toplevel_run(mrb_state*, struct RProc*);
 mrb_value mrb_context_run(mrb_state*, struct RProc*, mrb_value, unsigned int);
 
 void mrb_p(mrb_state*, mrb_value);

src/load.c

@@ -512,7 +512,7 @@ mrb_load_irep_cxt(mrb_state *mrb, const uint8_t *bin, mrbc_context *c)
   proc = mrb_proc_new(mrb, irep);
   mrb_irep_decref(mrb, irep);
   if (c && c->no_exec) return mrb_obj_value(proc);
-  val = mrb_context_run(mrb, proc, mrb_top_self(mrb), 0);
+  val = mrb_toplevel_run(mrb, proc);
   return val;
 }
 
@@ -733,7 +733,7 @@ mrb_load_irep_file_cxt(mrb_state *mrb, FILE* fp, mrbc_context *c)
   proc = mrb_proc_new(mrb, irep);
   mrb_irep_decref(mrb, irep);
   if (c && c->no_exec) return mrb_obj_value(proc);
-  val = mrb_context_run(mrb, proc, mrb_top_self(mrb), 0);
+  val = mrb_toplevel_run(mrb, proc);
   return val;
 }
 

src/parse.y

@@ -5506,7 +5506,7 @@ load_exec(mrb_state *mrb, parser_state *p, mrbc_context *c)
   if (mrb->c->ci) {
     mrb->c->ci->target_class = target;
   }
-  v = mrb_context_run(mrb, proc, mrb_top_self(mrb), 0);
+  v = mrb_toplevel_run(mrb, proc);
   if (mrb->exc) return mrb_nil_value();
   return v;
 }

src/vm.c

@@ -2270,3 +2270,20 @@ mrb_run(mrb_state *mrb, struct RProc *proc, mrb_value self)
 {
   return mrb_context_run(mrb, proc, self, mrb->c->ci->argc + 2); /* argc + 2 (receiver and block) */
 }
+
+mrb_value
+mrb_toplevel_run(mrb_state *mrb, struct RProc *proc)
+{
+  mrb_callinfo *ci;
+  mrb_value v;
+
+  if (!mrb->c->cibase || mrb->c->ci == mrb->c->cibase) {
+    return mrb_context_run(mrb, proc, mrb_top_self(mrb), 0);
+  }
+  ci = cipush(mrb);
+  ci->acc = CI_ACC_SKIP;
+  v = mrb_context_run(mrb, proc, mrb_top_self(mrb), 0);
+  cipop(mrb);
+
+  return v;
+}