--- libcpp/include/cpplib.h.jj	2022-08-10 09:06:53.268209449 +0200
+++ libcpp/include/cpplib.h	2022-08-15 19:32:53.743213474 +0200
@@ -519,6 +519,9 @@ struct cpp_options
   /* Nonzero for C++23 size_t literals.  */
   unsigned char size_t_literals;
 
+  /* Nonzero for C++23 delimited escape sequences.  */
+  unsigned char delimited_escape_seqs;
+
   /* Holds the name of the target (execution) character set.  */
   const char *narrow_charset;
 
--- libcpp/init.cc.jj	2022-08-10 09:06:53.268209449 +0200
+++ libcpp/init.cc	2022-08-15 16:09:01.403020485 +0200
@@ -96,34 +96,35 @@ struct lang_flags
   char dfp_constants;
   char size_t_literals;
   char elifdef;
+  char delimited_escape_seqs;
 };
 
 static const struct lang_flags lang_defaults[] =
-{ /*              c99 c++ xnum xid c11 std digr ulit rlit udlit bincst digsep trig u8chlit vaopt scope dfp szlit elifdef */
-  /* GNUC89   */  { 0,  0,  1,  0,  0,  0,  1,   0,   0,   0,    0,     0,     0,   0,      1,   1,     0,   0,   0 },
-  /* GNUC99   */  { 1,  0,  1,  1,  0,  0,  1,   1,   1,   0,    0,     0,     0,   0,      1,   1,     0,   0,   0 },
-  /* GNUC11   */  { 1,  0,  1,  1,  1,  0,  1,   1,   1,   0,    0,     0,     0,   0,      1,   1,     0,   0,   0 },
-  /* GNUC17   */  { 1,  0,  1,  1,  1,  0,  1,   1,   1,   0,    0,     0,     0,   0,      1,   1,     0,   0,   0 },
-  /* GNUC2X   */  { 1,  0,  1,  1,  1,  0,  1,   1,   1,   0,    1,     1,     0,   1,      1,   1,     1,   0,   1 },
-  /* STDC89   */  { 0,  0,  0,  0,  0,  1,  0,   0,   0,   0,    0,     0,     1,   0,      0,   0,     0,   0,   0 },
-  /* STDC94   */  { 0,  0,  0,  0,  0,  1,  1,   0,   0,   0,    0,     0,     1,   0,      0,   0,     0,   0,   0 },
-  /* STDC99   */  { 1,  0,  1,  1,  0,  1,  1,   0,   0,   0,    0,     0,     1,   0,      0,   0,     0,   0,   0 },
-  /* STDC11   */  { 1,  0,  1,  1,  1,  1,  1,   1,   0,   0,    0,     0,     1,   0,      0,   0,     0,   0,   0 },
-  /* STDC17   */  { 1,  0,  1,  1,  1,  1,  1,   1,   0,   0,    0,     0,     1,   0,      0,   0,     0,   0,   0 },
-  /* STDC2X   */  { 1,  0,  1,  1,  1,  1,  1,   1,   0,   0,    1,     1,     1,   1,      0,   1,     1,   0,   1 },
-  /* GNUCXX   */  { 0,  1,  1,  1,  0,  0,  1,   0,   0,   0,    0,     0,     0,   0,      1,   1,     0,   0,   0 },
-  /* CXX98    */  { 0,  1,  0,  1,  0,  1,  1,   0,   0,   0,    0,     0,     1,   0,      0,   1,     0,   0,   0 },
-  /* GNUCXX11 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    0,     0,     0,   0,      1,   1,     0,   0,   0 },
-  /* CXX11    */  { 1,  1,  0,  1,  1,  1,  1,   1,   1,   1,    0,     0,     1,   0,      0,   1,     0,   0,   0 },
-  /* GNUCXX14 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    1,     1,     0,   0,      1,   1,     0,   0,   0 },
-  /* CXX14    */  { 1,  1,  0,  1,  1,  1,  1,   1,   1,   1,    1,     1,     1,   0,      0,   1,     0,   0,   0 },
-  /* GNUCXX17 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    1,     1,     0,   1,      1,   1,     0,   0,   0 },
-  /* CXX17    */  { 1,  1,  1,  1,  1,  1,  1,   1,   1,   1,    1,     1,     0,   1,      0,   1,     0,   0,   0 },
-  /* GNUCXX20 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    1,     1,     0,   1,      1,   1,     0,   0,   0 },
-  /* CXX20    */  { 1,  1,  1,  1,  1,  1,  1,   1,   1,   1,    1,     1,     0,   1,      1,   1,     0,   0,   0 },
-  /* GNUCXX23 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    1,     1,     0,   1,      1,   1,     0,   1,   1 },
-  /* CXX23    */  { 1,  1,  1,  1,  1,  1,  1,   1,   1,   1,    1,     1,     0,   1,      1,   1,     0,   1,   1 },
-  /* ASM      */  { 0,  0,  1,  0,  0,  0,  0,   0,   0,   0,    0,     0,     0,   0,      0,   0,     0,   0,   0 }
+{ /*              c99 c++ xnum xid c11 std digr ulit rlit udlit bincst digsep trig u8chlit vaopt scope dfp szlit elifdef delim */
+  /* GNUC89   */  { 0,  0,  1,  0,  0,  0,  1,   0,   0,   0,    0,     0,     0,   0,      1,   1,     0,   0,   0,      0 },
+  /* GNUC99   */  { 1,  0,  1,  1,  0,  0,  1,   1,   1,   0,    0,     0,     0,   0,      1,   1,     0,   0,   0,      0 },
+  /* GNUC11   */  { 1,  0,  1,  1,  1,  0,  1,   1,   1,   0,    0,     0,     0,   0,      1,   1,     0,   0,   0,      0 },
+  /* GNUC17   */  { 1,  0,  1,  1,  1,  0,  1,   1,   1,   0,    0,     0,     0,   0,      1,   1,     0,   0,   0,      0 },
+  /* GNUC2X   */  { 1,  0,  1,  1,  1,  0,  1,   1,   1,   0,    1,     1,     0,   1,      1,   1,     1,   0,   1,      0 },
+  /* STDC89   */  { 0,  0,  0,  0,  0,  1,  0,   0,   0,   0,    0,     0,     1,   0,      0,   0,     0,   0,   0,      0 },
+  /* STDC94   */  { 0,  0,  0,  0,  0,  1,  1,   0,   0,   0,    0,     0,     1,   0,      0,   0,     0,   0,   0,      0 },
+  /* STDC99   */  { 1,  0,  1,  1,  0,  1,  1,   0,   0,   0,    0,     0,     1,   0,      0,   0,     0,   0,   0,      0 },
+  /* STDC11   */  { 1,  0,  1,  1,  1,  1,  1,   1,   0,   0,    0,     0,     1,   0,      0,   0,     0,   0,   0,      0 },
+  /* STDC17   */  { 1,  0,  1,  1,  1,  1,  1,   1,   0,   0,    0,     0,     1,   0,      0,   0,     0,   0,   0,      0 },
+  /* STDC2X   */  { 1,  0,  1,  1,  1,  1,  1,   1,   0,   0,    1,     1,     1,   1,      0,   1,     1,   0,   1,      0 },
+  /* GNUCXX   */  { 0,  1,  1,  1,  0,  0,  1,   0,   0,   0,    0,     0,     0,   0,      1,   1,     0,   0,   0,      0 },
+  /* CXX98    */  { 0,  1,  0,  1,  0,  1,  1,   0,   0,   0,    0,     0,     1,   0,      0,   1,     0,   0,   0,      0 },
+  /* GNUCXX11 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    0,     0,     0,   0,      1,   1,     0,   0,   0,      0 },
+  /* CXX11    */  { 1,  1,  0,  1,  1,  1,  1,   1,   1,   1,    0,     0,     1,   0,      0,   1,     0,   0,   0,      0 },
+  /* GNUCXX14 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    1,     1,     0,   0,      1,   1,     0,   0,   0,      0 },
+  /* CXX14    */  { 1,  1,  0,  1,  1,  1,  1,   1,   1,   1,    1,     1,     1,   0,      0,   1,     0,   0,   0,      0 },
+  /* GNUCXX17 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    1,     1,     0,   1,      1,   1,     0,   0,   0,      0 },
+  /* CXX17    */  { 1,  1,  1,  1,  1,  1,  1,   1,   1,   1,    1,     1,     0,   1,      0,   1,     0,   0,   0,      0 },
+  /* GNUCXX20 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    1,     1,     0,   1,      1,   1,     0,   0,   0,      0 },
+  /* CXX20    */  { 1,  1,  1,  1,  1,  1,  1,   1,   1,   1,    1,     1,     0,   1,      1,   1,     0,   0,   0,      0 },
+  /* GNUCXX23 */  { 1,  1,  1,  1,  1,  0,  1,   1,   1,   1,    1,     1,     0,   1,      1,   1,     0,   1,   1,      1 },
+  /* CXX23    */  { 1,  1,  1,  1,  1,  1,  1,   1,   1,   1,    1,     1,     0,   1,      1,   1,     0,   1,   1,      1 },
+  /* ASM      */  { 0,  0,  1,  0,  0,  0,  0,   0,   0,   0,    0,     0,     0,   0,      0,   0,     0,   0,   0,      0 }
 };
 
 /* Sets internal flags correctly for a given language.  */
@@ -153,6 +154,7 @@ cpp_set_lang (cpp_reader *pfile, enum c_
   CPP_OPTION (pfile, dfp_constants)		 = l->dfp_constants;
   CPP_OPTION (pfile, size_t_literals)		 = l->size_t_literals;
   CPP_OPTION (pfile, elifdef)			 = l->elifdef;
+  CPP_OPTION (pfile, delimited_escape_seqs)	 = l->delimited_escape_seqs;
 }
 
 /* Initialize library global state.  */
--- libcpp/charset.cc.jj	2022-08-15 12:52:43.213902801 +0200
+++ libcpp/charset.cc	2022-08-16 11:42:27.729948705 +0200
@@ -1081,6 +1081,7 @@ _cpp_valid_ucn (cpp_reader *pfile, const
   unsigned int length;
   const uchar *str = *pstr;
   const uchar *base = str - 2;
+  bool delimited = false;
 
   if (!CPP_OPTION (pfile, cplusplus) && !CPP_OPTION (pfile, c99))
     cpp_error (pfile, CPP_DL_WARNING,
@@ -1095,7 +1096,17 @@ _cpp_valid_ucn (cpp_reader *pfile, const
 	         (int) str[-1]);
 
   if (str[-1] == 'u')
-    length = 4;
+    {
+      length = 4;
+      if (str < limit && *str == '{')
+	{
+	  str++;
+	  length = 32;
+	  delimited = true;
+	  if (loc_reader)
+	    char_range->m_finish = loc_reader->get_next ().m_finish;
+	}
+    }
   else if (str[-1] == 'U')
     length = 8;
   else
@@ -1107,6 +1118,8 @@ _cpp_valid_ucn (cpp_reader *pfile, const
   result = 0;
   do
     {
+      if (str == limit)
+	break;
       c = *str;
       if (!ISXDIGIT (c))
 	break;
@@ -1116,9 +1129,41 @@ _cpp_valid_ucn (cpp_reader *pfile, const
 	  gcc_assert (char_range);
 	  char_range->m_finish = loc_reader->get_next ().m_finish;
 	}
+      if (delimited)
+	{
+	  if (!result)
+	    /* Accept arbitrary number of leading zeros.  */
+	    length = 16;
+	  else if (length == 8)
+	    {
+	      /* Make sure we detect overflows.  */
+	      result |= 0x8000000;
+	      ++length;
+	    }
+	}
+
       result = (result << 4) + hex_value (c);
     }
-  while (--length && str < limit);
+  while (--length);
+
+  if (delimited
+      && str < limit
+      && *str == '}'
+      && (length != 32 || !identifier_pos))
+    {
+      if (length == 32)
+	cpp_error (pfile, CPP_DL_ERROR,
+		   "empty delimited escape sequence");
+      else if (!CPP_OPTION (pfile, delimited_escape_seqs)
+	       && CPP_OPTION (pfile, cpp_pedantic))
+	cpp_error (pfile, CPP_DL_PEDWARN,
+		   "delimited escape sequences are only valid in C++23");
+      str++;
+      length = 0;
+      delimited = false;
+      if (loc_reader)
+	char_range->m_finish = loc_reader->get_next ().m_finish;
+    }
 
   /* Partial UCNs are not valid in strings, but decompose into
      multiple tokens in identifiers, so we can't give a helpful
@@ -1132,9 +1177,14 @@ _cpp_valid_ucn (cpp_reader *pfile, const
   *pstr = str;
   if (length)
     {
-      cpp_error (pfile, CPP_DL_ERROR,
-		 "incomplete universal character name %.*s",
-		 (int) (str - base), base);
+      if (!delimited)
+	cpp_error (pfile, CPP_DL_ERROR,
+		   "incomplete universal character name %.*s",
+		   (int) (str - base), base);
+      else
+	cpp_error (pfile, CPP_DL_ERROR,
+		   "'\\u{' not terminated with '}' after %.*s",
+		   (int) (str - base), base);
       result = 1;
     }
   /* The C99 standard permits $, @ and ` to be specified as UCNs.  We use
@@ -1392,6 +1442,8 @@ convert_hex (cpp_reader *pfile, const uc
   int digits_found = 0;
   size_t width = cvt.width;
   size_t mask = width_to_mask (width);
+  bool delimited = false;
+  const uchar *base = from - 1;
 
   /* loc_reader and ranges must either be both NULL, or both be non-NULL.  */
   gcc_assert ((loc_reader != NULL) == (ranges != NULL));
@@ -1407,6 +1459,14 @@ convert_hex (cpp_reader *pfile, const uc
   if (loc_reader)
     char_range.m_finish = loc_reader->get_next ().m_finish;
 
+  if (from < limit && *from == '{')
+    {
+      delimited = true;
+      from++;
+      if (loc_reader)
+	char_range.m_finish = loc_reader->get_next ().m_finish;
+    }
+
   while (from < limit)
     {
       c = *from;
@@ -1420,12 +1480,37 @@ convert_hex (cpp_reader *pfile, const uc
       digits_found = 1;
     }
 
+  if (delimited && from < limit && *from == '}')
+    {
+      from++;
+      if (!digits_found)
+	{
+	  cpp_error (pfile, CPP_DL_ERROR,
+		     "empty delimited escape sequence");
+	  return from;
+	}
+     else if (!CPP_OPTION (pfile, delimited_escape_seqs)
+	      && CPP_OPTION (pfile, cpp_pedantic))
+	cpp_error (pfile, CPP_DL_PEDWARN,
+		   "delimited escape sequences are only valid in C++23");
+      delimited = false;
+      if (loc_reader)
+	char_range.m_finish = loc_reader->get_next ().m_finish;
+    }
+
   if (!digits_found)
     {
       cpp_error (pfile, CPP_DL_ERROR,
 		 "\\x used with no following hex digits");
       return from;
     }
+  else if (delimited)
+    {
+      cpp_error (pfile, CPP_DL_ERROR,
+		 "'\\x{' not terminated with '}' after %.*s",
+		 (int) (from - base), base);
+      return from;
+    }
 
   if (overflow | (n != (n & mask)))
     {
@@ -1459,13 +1544,31 @@ convert_oct (cpp_reader *pfile, const uc
 	     cpp_substring_ranges *ranges)
 {
   size_t count = 0;
-  cppchar_t c, n = 0;
+  cppchar_t c, n = 0, overflow = 0;
   size_t width = cvt.width;
   size_t mask = width_to_mask (width);
+  bool delimited = false;
+  const uchar *base = from - 1;
 
   /* loc_reader and ranges must either be both NULL, or both be non-NULL.  */
   gcc_assert ((loc_reader != NULL) == (ranges != NULL));
 
+  if (from < limit && *from == 'o')
+    {
+      from++;
+      if (loc_reader)
+	char_range.m_finish = loc_reader->get_next ().m_finish;
+      if (from == limit || *from != '{')
+	cpp_error (pfile, CPP_DL_ERROR, "'\\o' not followed by '{'");
+      else
+	{
+	  from++;
+	  if (loc_reader)
+	    char_range.m_finish = loc_reader->get_next ().m_finish;
+	  delimited = true;
+	}
+    }
+
   while (from < limit && count++ < 3)
     {
       c = *from;
@@ -1474,10 +1577,42 @@ convert_oct (cpp_reader *pfile, const uc
       from++;
       if (loc_reader)
 	char_range.m_finish = loc_reader->get_next ().m_finish;
+      if (delimited)
+	{
+	  count = 2;
+	  overflow |= n ^ (n << 3 >> 3);
+	}
       n = (n << 3) + c - '0';
     }
 
-  if (n != (n & mask))
+  if (delimited)
+    {
+      if (from < limit && *from == '}')
+	{
+	  from++;
+	  if (count == 1)
+	    {
+	      cpp_error (pfile, CPP_DL_ERROR,
+			 "empty delimited escape sequence");
+	      return from;
+	    }
+	  else if (!CPP_OPTION (pfile, delimited_escape_seqs)
+		   && CPP_OPTION (pfile, cpp_pedantic))
+	    cpp_error (pfile, CPP_DL_PEDWARN,
+		       "delimited escape sequences are only valid in C++23");
+	  if (loc_reader)
+	    char_range.m_finish = loc_reader->get_next ().m_finish;
+	}
+      else
+	{
+	  cpp_error (pfile, CPP_DL_ERROR,
+		     "'\\o{' not terminated with '}' after %.*s",
+		     (int) (from - base), base);
+	  return from;
+	}
+    }
+
+  if (overflow | (n != (n & mask)))
     {
       cpp_error (pfile, CPP_DL_PEDWARN,
 		 "octal escape sequence out of range");
@@ -1535,6 +1670,7 @@ convert_escape (cpp_reader *pfile, const
 
     case '0':  case '1':  case '2':  case '3':
     case '4':  case '5':  case '6':  case '7':
+    case 'o':
       return convert_oct (pfile, from, limit, tbuf, cvt,
 			  char_range, loc_reader, ranges);
 
@@ -2119,15 +2255,23 @@ _cpp_interpret_identifier (cpp_reader *p
 	cppchar_t value = 0;
 	size_t bufleft = len - (bufp - buf);
 	int rval;
+	bool delimited = false;
 
 	idp += 2;
+	if (length == 4 && id[idp] == '{')
+	  {
+	    delimited = true;
+	    idp++;
+	  }
 	while (length && idp < len && ISXDIGIT (id[idp]))
 	  {
 	    value = (value << 4) + hex_value (id[idp]);
 	    idp++;
-	    length--;
+	    if (!delimited)
+	      length--;
 	  }
-	idp--;
+	if (!delimited)
+	  idp--;
 
 	/* Special case for EBCDIC: if the identifier contains
 	   a '$' specified using a UCN, translate it to EBCDIC.  */
--- libcpp/lex.cc.jj	2022-05-23 10:59:06.235591348 +0200
+++ libcpp/lex.cc	2022-08-16 11:57:53.772823661 +0200
@@ -1426,19 +1426,35 @@ get_bidi_utf8 (cpp_reader *pfile, const
 /* Parse a UCN where P points just past \u or \U and return its bidi code.  */
 
 static bidi::kind
-get_bidi_ucn_1 (const unsigned char *p, bool is_U)
+get_bidi_ucn_1 (const unsigned char *p, bool is_U, const unsigned char **end)
 {
   /* 6.4.3 Universal Character Names
       \u hex-quad
       \U hex-quad hex-quad
+      \u { simple-hexadecimal-digit-sequence }
      where \unnnn means \U0000nnnn.  */
 
+  *end = p + 4;
   if (is_U)
     {
       if (p[0] != '0' || p[1] != '0' || p[2] != '0' || p[3] != '0')
 	return bidi::kind::NONE;
       /* Skip 4B so we can treat \u and \U the same below.  */
       p += 4;
+      *end += 4;
+    }
+  else if (p[0] == '{')
+    {
+      p++;
+      while (*p == '0')
+	p++;
+      if (p[0] != '2'
+	  || p[1] != '0'
+	  || !ISXDIGIT (p[2])
+	  || !ISXDIGIT (p[3])
+	  || p[4] != '}')
+	return bidi::kind::NONE;
+      *end = p + 5;
     }
 
   /* All code points we are looking for start with 20xx.  */
@@ -1499,14 +1515,15 @@ get_bidi_ucn_1 (const unsigned char *p,
    If the kind is not NONE, write the location to *OUT.*/
 
 static bidi::kind
-get_bidi_ucn (cpp_reader *pfile,  const unsigned char *p, bool is_U,
+get_bidi_ucn (cpp_reader *pfile, const unsigned char *p, bool is_U,
 	      location_t *out)
 {
-  bidi::kind result = get_bidi_ucn_1 (p, is_U);
+  const unsigned char *end;
+  bidi::kind result = get_bidi_ucn_1 (p, is_U, &end);
   if (result != bidi::kind::NONE)
     {
       const unsigned char *start = p - 2;
-      size_t num_bytes = 2 + (is_U ? 8 : 4);
+      size_t num_bytes = end - start;
       *out = get_location_for_byte_range_in_cur_line (pfile, start, num_bytes);
     }
   return result;
--- gcc/testsuite/c-c++-common/cpp/delimited-escape-seq-1.c.jj	2022-08-16 10:47:38.693022740 +0200
+++ gcc/testsuite/c-c++-common/cpp/delimited-escape-seq-1.c	2022-08-16 12:18:42.235477632 +0200
@@ -0,0 +1,92 @@
+/* P2290R3 - Delimited escape sequences */
+/* { dg-do run } */
+/* { dg-require-effective-target wchar } */
+/* { dg-options "-std=gnu99 -Wno-c++-compat" { target c } } */
+/* { dg-options "-std=c++23" { target c++ } } */
+
+#ifndef __cplusplus
+#include <wchar.h>
+typedef __CHAR16_TYPE__ char16_t;
+typedef __CHAR32_TYPE__ char32_t;
+#endif
+
+const char32_t *a = U"\u{1234}\u{10fffd}\u{000000000000000000000000000000000000000000000000000000000001234}\u{10FFFD}";
+const char32_t *b = U"\x{1234}\x{10fffd}\x{000000000000000000000000000000000000000000000000000000000001234}";
+const char32_t *c = U"\o{1234}\o{4177775}\o{000000000000000000000000000000000000000000000000000000000000000000000000004177775}";
+const char16_t *d = u"\u{1234}\u{bFFd}\u{00000000000000000000000000000001234}";
+const char16_t *e = u"\x{1234}\x{BffD}\x{000001234}";
+const char16_t *f = u"\o{1234}\o{137775}\o{000000000000000137775}";
+const wchar_t *g = L"\u{1234}\u{bFFd}\u{00000000000000000000000000000001234}";
+const wchar_t *h = L"\x{1234}\x{bFFd}\x{000001234}";
+const wchar_t *i = L"\o{1234}\o{137775}\o{000000000000000137775}";
+#ifdef __cplusplus
+const char *j = "\u{34}\u{000000000000000003D}";
+#endif
+const char *k = "\x{34}\x{000000000000000003D}";
+const char *l = "\o{34}\o{000000000000000176}";
+
+#if U'\u{1234}' != U'\u1234' || U'\u{10fffd}' != U'\U0010FFFD' \
+    || U'\x{00000001234}' != U'\x1234' || U'\x{010fffd}' != U'\x10FFFD' \
+    || U'\o{1234}' != U'\x29c' || U'\o{004177775}' != U'\x10FFFD' \
+    || u'\u{1234}' != u'\u1234' || u'\u{0bffd}' != u'\uBFFD' \
+    || u'\x{00000001234}' != u'\x1234' || u'\x{0Bffd}' != u'\x0bFFD' \
+    || u'\o{1234}' != u'\x29c' || u'\o{00137775}' != u'\xBFFD' \
+    || L'\u{1234}' != L'\u1234' || L'\u{0bffd}' != L'\uBFFD' \
+    || L'\x{00000001234}' != L'\x1234' || L'\x{0bffd}' != L'\x0bFFD' \
+    || L'\o{1234}' != L'\x29c' || L'\o{00137775}' != L'\xBFFD' \
+    || '\x{34}' != '\x034' || '\x{0003d}' != '\x003D' \
+    || '\o{34}' != '\x1C' || '\o{176}' != '\x007E'
+#error Bad
+#endif
+#ifdef __cplusplus
+#if '\u{0000000034}' != '\u0034' || '\u{3d}' != '\u003D'
+#error Bad
+#endif
+#endif
+
+int
+main ()
+{
+  if (a[0] != U'\u1234' || a[0] != U'\u{1234}'
+      || a[1] != U'\U0010FFFD' || a[1] != U'\u{000010fFfD}'
+      || a[2] != a[0]
+      || a[3] != a[1]
+      || b[0] != U'\x1234' || b[0] != U'\x{001234}'
+      || b[1] != U'\x10FFFD' || b[1] != U'\x{0010fFfD}'
+      || b[2] != b[0]
+      || c[0] != U'\x29c' || c[0] != U'\o{001234}'
+      || c[1] != U'\x10FFFD' || c[1] != U'\o{4177775}'
+      || c[2] != c[1])
+    __builtin_abort ();
+  if (d[0] != u'\u1234' || d[0] != u'\u{1234}'
+      || d[1] != u'\U0000BFFD' || d[1] != u'\u{00000bFfD}'
+      || d[2] != d[0]
+      || e[0] != u'\x1234' || e[0] != u'\x{001234}'
+      || e[1] != u'\xBFFD' || e[1] != u'\x{00bFfD}'
+      || e[2] != e[0]
+      || f[0] != u'\x29c' || f[0] != u'\o{001234}'
+      || f[1] != u'\xbFFD' || f[1] != u'\o{137775}'
+      || f[2] != f[1])
+    __builtin_abort ();
+  if (g[0] != L'\u1234' || g[0] != L'\u{1234}'
+      || g[1] != L'\U0000BFFD' || g[1] != L'\u{00000bFfD}'
+      || g[2] != g[0]
+      || h[0] != L'\x1234' || h[0] != L'\x{001234}'
+      || h[1] != L'\xBFFD' || h[1] != L'\x{00bFfD}'
+      || h[2] != h[0]
+      || i[0] != L'\x29c' || i[0] != L'\o{001234}'
+      || i[1] != L'\xbFFD' || i[1] != L'\o{137775}'
+      || i[2] != i[1])
+    __builtin_abort ();
+#ifdef __cplusplus
+  if (j[0] != '\u0034' || j[0] != '\u{034}'
+      || j[1] != '\U0000003D' || j[1] != '\u{000003d}')
+    __builtin_abort ();
+#endif
+  if (k[0] != '\x034' || k[0] != '\x{0034}'
+      || k[1] != '\x3D' || k[1] != '\x{3d}'
+      || l[0] != '\x1c' || l[0] != '\o{0034}'
+      || l[1] != '\x07e' || l[1] != '\o{176}' || l[1] != '\176')
+    __builtin_abort ();
+  return 0;
+}
--- gcc/testsuite/c-c++-common/cpp/delimited-escape-seq-2.c.jj	2022-08-16 10:47:41.846981390 +0200
+++ gcc/testsuite/c-c++-common/cpp/delimited-escape-seq-2.c	2022-08-16 12:18:58.807260607 +0200
@@ -0,0 +1,18 @@
+/* P2290R3 - Delimited escape sequences */
+/* { dg-do compile } */
+/* { dg-options "-std=gnu99 -Wno-c++-compat" { target c } } */
+/* { dg-options "-std=c++23" { target c++ } } */
+
+int jalape\u{f1}o = 42;
+
+int
+caf\u{000e9} (void)
+{
+  return jalape\u00F1o;
+}
+
+int
+test (void)
+{
+  return caf\u00e9 ();
+}
--- gcc/testsuite/c-c++-common/cpp/delimited-escape-seq-3.c.jj	2022-08-16 12:18:19.308777922 +0200
+++ gcc/testsuite/c-c++-common/cpp/delimited-escape-seq-3.c	2022-08-16 12:41:23.693648138 +0200
@@ -0,0 +1,33 @@
+/* P2290R3 - Delimited escape sequences */
+/* { dg-do compile } */
+/* { dg-require-effective-target wchar } */
+/* { dg-options "-std=gnu99 -Wno-c++-compat" { target c } } */
+/* { dg-options "-std=c++23" { target c++ } } */
+
+#ifndef __cplusplus
+typedef __CHAR32_TYPE__ char32_t;
+#endif
+
+const char32_t *a = U"\u{}";				/* { dg-error "empty delimited escape sequence" } */
+							/* { dg-error "is not a valid universal character" "" { target c } .-1 } */
+const char32_t *b = U"\u{12" "34}";			/* { dg-error "'\\\\u\\{' not terminated with '\\}' after" } */
+const char32_t *c = U"\u{0000ffffffff}";		/* { dg-error "is not a valid universal character" } */
+const char32_t *d = U"\u{010000edcb}";			/* { dg-error "is not a valid universal character" } */
+const char32_t *e = U"\u{02000000000000000000edcb}";	/* { dg-error "is not a valid universal character" } */
+const char32_t *f = U"\u{123ghij}";			/* { dg-error "'\\\\u\\{' not terminated with '\\}' after" } */
+const char32_t *g = U"\u{123.}";			/* { dg-error "'\\\\u\\{' not terminated with '\\}' after" } */
+const char32_t *h = U"\u{.}";				/* { dg-error "'\\\\u\\{' not terminated with '\\}' after" } */
+const char32_t *i = U"\x{}";				/* { dg-error "empty delimited escape sequence" } */
+const char32_t *j = U"\x{12" "34}";			/* { dg-error "'\\\\x\\{' not terminated with '\\}' after" } */
+const char32_t *k = U"\x{0000ffffffff}";
+const char32_t *l = U"\x{010000edcb}";			/* { dg-warning "hex escape sequence out of range" } */
+const char32_t *m = U"\x{02000000000000000000edcb}";	/* { dg-warning "hex escape sequence out of range" } */
+const char32_t *n = U"\x{123ghij}";			/* { dg-error "'\\\\x\\{' not terminated with '\\}' after" } */
+const char32_t *o = U"\x{123.}";			/* { dg-error "'\\\\x\\{' not terminated with '\\}' after" } */
+const char32_t *p = U"\o{}";				/* { dg-error "empty delimited escape sequence" } */
+const char32_t *q = U"\o{12" "34}";			/* { dg-error "'\\\\o\\{' not terminated with '\\}' after" } */
+const char32_t *r = U"\o{0000037777777777}";
+const char32_t *s = U"\o{040000166713}";		/* { dg-warning "octal escape sequence out of range" } */
+const char32_t *t = U"\o{02000000000000000000000166713}";/* { dg-warning "octal escape sequence out of range" } */
+const char32_t *u = U"\o{1238}";			/* { dg-error "'\\\\o\\{' not terminated with '\\}' after" } */
+const char32_t *v = U"\o{.}";				/* { dg-error "'\\\\o\\{' not terminated with '\\}' after" } */
--- gcc/testsuite/c-c++-common/Wbidi-chars-24.c.jj	2022-08-16 12:03:19.350561676 +0200
+++ gcc/testsuite/c-c++-common/Wbidi-chars-24.c	2022-08-16 12:06:46.381851525 +0200
@@ -0,0 +1,28 @@
+/* PR preprocessor/103026 */
+/* { dg-do compile } */
+/* { dg-options "-Wbidi-chars=ucn,unpaired" } */
+/* Test nesting of bidi chars in various contexts.  */
+
+void
+g1 ()
+{
+  const char *s1 = "a b c LRE\u{202a} 1 2 3 PDI\u{00000000000000000000000002069} x y z";
+/* { dg-warning "unpaired" "" { target *-*-* } .-1 } */
+  const char *s2 = "a b c RLE\u{00202b} 1 2 3 PDI\u{2069} x y z";
+/* { dg-warning "unpaired" "" { target *-*-* } .-1 } */
+  const char *s3 = "a b c LRO\u{000000202d} 1 2 3 PDI\u{02069} x y z";
+/* { dg-warning "unpaired" "" { target *-*-* } .-1 } */
+  const char *s4 = "a b c RLO\u{202e} 1 2 3 PDI\u{00000002069} x y z";
+/* { dg-warning "unpaired" "" { target *-*-* } .-1 } */
+  const char *s5 = "a b c LRI\u{002066} 1 2 3 PDF\u{202C} x y z";
+/* { dg-warning "unpaired" "" { target *-*-* } .-1 } */
+  const char *s6 = "a b c RLI\u{02067} 1 2 3 PDF\u{202c} x y z";
+/* { dg-warning "unpaired" "" { target *-*-* } .-1 } */
+  const char *s7 = "a b c FSI\u{0002068} 1 2 3 PDF\u{0202c} x y z";
+/* { dg-warning "unpaired" "" { target *-*-* } .-1 } */
+}
+
+int A\u{202a}B\u{2069}C;
+/* { dg-warning "unpaired" "" { target *-*-* } .-1 } */
+int a\u{00000202b}B\u{000000002069}c;
+/* { dg-warning "unpaired" "" { target *-*-* } .-1 } */
--- gcc/testsuite/gcc.dg/cpp/delimited-escape-seq-1.c.jj	2022-08-16 10:47:38.693022740 +0200
+++ gcc/testsuite/gcc.dg/cpp/delimited-escape-seq-1.c	2022-08-16 12:46:56.508291006 +0200
@@ -0,0 +1,10 @@
+/* P2290R3 - Delimited escape sequences */
+/* { dg-do compile } */
+/* { dg-require-effective-target wchar } */
+/* { dg-options "-std=gnu99 -Wno-c++-compat -pedantic" } */
+
+typedef __CHAR32_TYPE__ char32_t;
+
+const char32_t *a = U"\u{1234}";	/* { dg-warning "delimited escape sequences are only valid in" } */
+const char32_t *b = U"\x{1234}";	/* { dg-warning "delimited escape sequences are only valid in" } */
+const char32_t *c = U"\o{1234}";	/* { dg-warning "delimited escape sequences are only valid in" } */
--- gcc/testsuite/gcc.dg/cpp/delimited-escape-seq-2.c.jj	2022-08-16 10:47:41.846981390 +0200
+++ gcc/testsuite/gcc.dg/cpp/delimited-escape-seq-2.c	2022-08-16 12:47:05.955167423 +0200
@@ -0,0 +1,10 @@
+/* P2290R3 - Delimited escape sequences */
+/* { dg-do compile } */
+/* { dg-require-effective-target wchar } */
+/* { dg-options "-std=gnu99 -Wno-c++-compat -pedantic-errors" } */
+
+typedef __CHAR32_TYPE__ char32_t;
+
+const char32_t *a = U"\u{1234}";	/* { dg-error "delimited escape sequences are only valid in" } */
+const char32_t *b = U"\x{1234}";	/* { dg-error "delimited escape sequences are only valid in" } */
+const char32_t *c = U"\o{1234}";	/* { dg-error "delimited escape sequences are only valid in" } */
--- gcc/testsuite/g++.dg/cpp/delimited-escape-seq-1.C.jj	2022-08-16 12:46:43.368462901 +0200
+++ gcc/testsuite/g++.dg/cpp/delimited-escape-seq-1.C	2022-08-16 12:49:21.532393786 +0200
@@ -0,0 +1,8 @@
+// P2290R3 - Delimited escape sequences
+// { dg-do compile { target c++11 } }
+// { dg-require-effective-target wchar }
+// { dg-options "-pedantic" }
+
+const char32_t *a = U"\u{1234}";	// { dg-warning "delimited escape sequences are only valid in" "" { target c++20_down } }
+const char32_t *b = U"\x{1234}";	// { dg-warning "delimited escape sequences are only valid in" "" { target c++20_down } }
+const char32_t *c = U"\o{1234}";	// { dg-warning "delimited escape sequences are only valid in" "" { target c++20_down } }
--- gcc/testsuite/g++.dg/cpp/delimited-escape-seq-2.C.jj	2022-08-16 12:46:46.281424798 +0200
+++ gcc/testsuite/g++.dg/cpp/delimited-escape-seq-2.C	2022-08-16 12:49:33.761233803 +0200
@@ -0,0 +1,8 @@
+// P2290R3 - Delimited escape sequences
+// { dg-do compile { target c++11 } }
+// { dg-require-effective-target wchar }
+// { dg-options "-pedantic-errors" }
+
+const char32_t *a = U"\u{1234}";	// { dg-error "delimited escape sequences are only valid in" "" { target c++20_down } }
+const char32_t *b = U"\x{1234}";	// { dg-error "delimited escape sequences are only valid in" "" { target c++20_down } }
+const char32_t *c = U"\o{1234}";	// { dg-error "delimited escape sequences are only valid in" "" { target c++20_down } }
