fatal error if variable argument length mismatch

* include/ruby/ruby.h (rb_scan_args0): raise fatal error if
  variable argument length does not match, it is a bug in the code
  which uses rb_scan_args, not a runtime error.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55124 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Mon May 23 12:47:09 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* include/ruby/ruby.h (rb_scan_args0): raise fatal error if
+	  variable argument length does not match, it is a bug in the code
+	  which uses rb_scan_args, not a runtime error.
+
 Mon May 23 12:30:29 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* ext/bigdecimal/bigdecimal.c (GetVpValueWithPrec): consider

include/ruby/ruby.h

@@ -2203,6 +2203,12 @@ rb_scan_args0(int argc, const VALUE *argv, const char *fmt, int varc, VALUE *var
     }
     n_mand = n_lead + n_trail;
 
+    vari = n_mand + n_opt + f_var + f_hash + f_block;
+    if (vari != varc) {
+	rb_fatal("variable argument length doesn't match* %d %d", vari, varc);
+    }
+    vari = 0;
+
     if (argc < n_mand)
 	goto argc_error;
 
@@ -2282,9 +2288,6 @@ rb_scan_args0(int argc, const VALUE *argv, const char *fmt, int varc, VALUE *var
       argc_error:
 	rb_error_arity(argc, n_mand, f_var ? UNLIMITED_ARGUMENTS : n_mand + n_opt);
     }
-    if (vari != varc) {
-	rb_raise(rb_eRuntimeError, "variable argument length doesn't match* %d %d", vari, varc);
-    }
 
     return argc;
 }