--- a/sed/execute.c	2015-12-28 07:36:47.000000000 +0100

+++ b/sed/execute.c	2019-07-30 10:37:49.369052072 +0200

@@ -213,58 +220,42 @@

   while (length)

     {

       wchar_t wc;

-      size_t n = MBRTOWC (&wc, string, length, &from_stat);

+      int n = MBRTOWC (&wc, string, length, &from_stat);

-      /* Treat an invalid sequence like a single-byte character.  */

-      if (n == (size_t) -1)

+      /* An invalid sequence is treated like a singlebyte character. */

+      if (n == -1)

         {

-          type &= ~(REPL_LOWERCASE_FIRST | REPL_UPPERCASE_FIRST);

-          if (type == REPL_ASIS)

-            {

-              str_append(to, string, length);

-              return;

-            }

-

-          str_append (to, string, 1);

           memset (&to->mbstate, 0, sizeof (from_stat));

           n = 1;

-          string += n, length -= n;

-          continue;

-        }

-

-      if (n == 0 || n == (size_t) -2)

-        {

-          /* L'\0' or an incomplete sequence: copy it manually.  */

-          str_append(to, string, length);

-          return;

         }

-      string += n, length -= n;

+      if (n > 0)

+        string += n, length -= n;

+      else

+	{

+	  /* Incomplete sequence, copy it manually.  */

+	  str_append(to, string, length);

+	  return;

+	}

       /* Convert the first character specially... */

       if (type & (REPL_UPPERCASE_FIRST | REPL_LOWERCASE_FIRST))

-        {

+	{

           if (type & REPL_UPPERCASE_FIRST)

             wc = towupper(wc);

           else

             wc = towlower(wc);

           type &= ~(REPL_LOWERCASE_FIRST | REPL_UPPERCASE_FIRST);

-          if (type == REPL_ASIS)

-            {

-              /* Copy the new wide character to the end of the string. */

-              n = WCRTOMB (to->active + to->length, wc, &to->mbstate);

-              to->length += n;

-              if (n == (size_t) -1 || n == (size_t) -2)

-                {

-                  fprintf (stderr,

-                           _("case conversion produced an invalid character"));

-                  abort ();

-                }

-              str_append(to, string, length);

-              return;

-            }

+	  if (type == REPL_ASIS)

+	    {

+	      n = WCRTOMB (to->active + to->length, wc, &to->mbstate);

+	      to->length += n;

+	      str_append(to, string, length);

+	      return;

+	    }

         }

+

       else if (type & REPL_UPPERCASE)

         wc = towupper(wc);

       else

@@ -274,10 +265,10 @@

       n = WCRTOMB (to->active + to->length, wc, &to->mbstate);

       to->length += n;

       if (n == -1 || n == -2)

-        {

-          fprintf (stderr, _("case conversion produced an invalid character"));

-          abort ();

-        }

+	{

+	  fprintf (stderr, "Case conversion produced an invalid character!");

+	  abort ();

+	}

     }

 }