Update from Gnulib by running admin/merge-gnulib

8 files changed, 219 insertions, 69 deletions

diff --git a/lib/_Noreturn.h b/lib/_Noreturn.h
index 8e63387914c..d42f15eee62 100644
--- a/lib/_Noreturn.h
+++ b/lib/_Noreturn.h
@@ -27,7 +27,8 @@
    This rare bug can be worked around by compiling with 'clang -D_Noreturn=',
    though the workaround may generate many false-alarm warnings.  */
 #ifndef _Noreturn
-# if 201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0)
+# if ((!defined __cplusplus || defined __clang__) \
+      && (201112 <= (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0)))
    /* _Noreturn works as-is.  */
 # elif (2 < __GNUC__ + (8 <= __GNUC_MINOR__) || defined __clang__ \
         || 0x5110 <= __SUNPRO_C)
diff --git a/lib/fpending.c b/lib/fpending.c
index be8a9877349..529bc7f6517 100644
--- a/lib/fpending.c
+++ b/lib/fpending.c
@@ -39,7 +39,7 @@ __fpending (FILE *fp)
 #if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
   /* GNU libc, BeOS, Haiku, Linux libc5 */
   return fp->_IO_write_ptr - fp->_IO_write_base;
-#elif defined __sferror || defined __DragonFly__ || defined __ANDROID__
+#elif defined __sferror || defined __OpenBSD__ || defined __DragonFly__ || defined __ANDROID__
   /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin < 1.7.34, Minix 3, Android */
   return fp_->_p - fp_->_bf._base;
 #elif defined __EMX__                /* emx+gcc */
diff --git a/lib/ftoastr.c b/lib/ftoastr.c
index 250b840365e..2438ffe837f 100644
--- a/lib/ftoastr.c
+++ b/lib/ftoastr.c
@@ -114,10 +114,12 @@ FTOASTR (char *buf, size_t bufsize, int flags, int width, FLOAT x)
   /* The following method is simple but slow.
      For ideas about speeding things up, please see:
 
-     Andrysco M, Jhala R, Lerner S. Printing floating-point numbers:
-     a faster, always correct method. ACM SIGPLAN notices - POPL '16.
-     2016;51(1):555-67 <https://doi.org/10.1145/2914770.2837654>; draft at
-     <https://cseweb.ucsd.edu/~lerner/papers/fp-printing-popl16.pdf>.  */
+     Jeon J. Dragonbox: a new floating-point binary-to-decimal
+     conversion algorithm. 2024. <https://github.com/jk-jeon/dragonbox/>.
+     Used in {fmt} <https://github.com/fmtlib/fmt>.
+
+     Adams U. Ryū: fast float-to-string conversion.
+     PLDI 2018. 270–282. <https://doi.org/10.1145/3192366.3192369>.  */
 
   PROMOTED_FLOAT promoted_x = x;
   char format[sizeof "%-+ 0*.*Lg"];
diff --git a/lib/gnulib.mk.in b/lib/gnulib.mk.in
index bb147b69eed..b3774a648b8 100644
--- a/lib/gnulib.mk.in
+++ b/lib/gnulib.mk.in
@@ -49,6 +49,7 @@
 #  --avoid=iswxdigit \
 #  --avoid=langinfo-h \
 #  --avoid=libgmp-mpq \
+#  --avoid=localcharset \
 #  --avoid=locale-h \
 #  --avoid=localename-unsafe-limited \
 #  --avoid=lock \
@@ -144,7 +145,7 @@
 #  mktime \
 #  nanosleep \
 #  nproc \
-#  nstrftime \
+#  nstrftime-limited \
 #  pathmax \
 #  pipe2 \
 #  pselect \
@@ -2836,17 +2837,17 @@ EXTRA_DIST += nproc.h
 endif
 ## end   gnulib module nproc
 
-## begin gnulib module nstrftime
-ifeq (,$(OMIT_GNULIB_MODULE_nstrftime))
+## begin gnulib module nstrftime-limited
+ifeq (,$(OMIT_GNULIB_MODULE_nstrftime-limited))
 
 libgnu_a_SOURCES += nstrftime.c
 
-EXTRA_DIST += strftime.c strftime.h
+EXTRA_DIST += calendar-ethiopian.h calendar-persian.h calendar-thai.h calendars.h strftime.c strftime.h
 
 EXTRA_libgnu_a_SOURCES += strftime.c
 
 endif
-## end   gnulib module nstrftime
+## end   gnulib module nstrftime-limited
 
 ## begin gnulib module open
 ifeq (,$(OMIT_GNULIB_MODULE_open))
diff --git a/lib/stdio-impl.h b/lib/stdio-impl.h
index 4b4263fe908..4abf9e68b23 100644
--- a/lib/stdio-impl.h
+++ b/lib/stdio-impl.h
@@ -82,7 +82,7 @@
 
 #include <errno.h>                             /* For detecting Plan9.  */
 
-#if defined __sferror || defined __DragonFly__ || defined __ANDROID__
+#if defined __sferror || defined __OpenBSD__ || defined __DragonFly__ || defined __ANDROID__
   /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
 
 # if defined __DragonFly__          /* DragonFly */
@@ -108,13 +108,15 @@
 #  define _flags pub._flags
 #  define _r pub._r
 #  define _w pub._w
-# elif defined __ANDROID__ /* Android */
-#  ifdef __LP64__
+# elif defined __ANDROID__ || defined __OpenBSD__ /* Android, OpenBSD */
+#  if defined __LP64__ && !defined __OpenBSD__
 #   define _gl_flags_file_t int
 #  else
 #   define _gl_flags_file_t short
 #  endif
-#  ifdef __LP64__
+#  if defined __OpenBSD__
+#   define _gl_file_offset_t fpos_t
+#  elif defined __LP64__
 #   define _gl_file_offset_t int64_t
 #  else
     /* see https://android.googlesource.com/platform/bionic/+/master/docs/32-bit-abi.md */
@@ -122,10 +124,12 @@
 #  endif
   /* Up to this commit from 2015-10-12
      <https://android.googlesource.com/platform/bionic.git/+/f0141dfab10a4b332769d52fa76631a64741297a>
-     the innards of FILE were public, and fp_ub could be defined like for OpenBSD,
+     the innards of FILE were public,
      see <https://android.googlesource.com/platform/bionic.git/+/e78392637d5086384a5631ddfdfa8d7ec8326ee3/libc/stdio/fileext.h>
      and <https://android.googlesource.com/platform/bionic.git/+/e78392637d5086384a5631ddfdfa8d7ec8326ee3/libc/stdio/local.h>.
-     After this commit, the innards of FILE are hidden.  */
+     After this commit, the innards of FILE are hidden.  Likewise for OpenBSD
+     up to this commit from 2025-07-16
+     <https://github.com/openbsd/src/commit/b7f6c2eb760a2da367dd51d539ef06f5f3553790>.  */
 #  define fp_ ((struct { unsigned char *_p; \
                          int _r; \
                          int _w; \
@@ -152,9 +156,8 @@
 #  define fp_ fp
 # endif
 
-# if (defined __NetBSD__ && __NetBSD_Version__ >= 105270000) || defined __OpenBSD__ || defined __minix /* NetBSD >= 1.5ZA, OpenBSD, Minix 3 */
+# if (defined __NetBSD__ && __NetBSD_Version__ >= 105270000) || defined __minix /* NetBSD >= 1.5ZA, Minix 3 */
   /* See <https://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/stdio/fileext.h?rev=HEAD&content-type=text/x-cvsweb-markup>
-     and <https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/lib/libc/stdio/fileext.h?rev=HEAD&content-type=text/x-cvsweb-markup>
      and <https://github.com/Stichting-MINIX-Research-Foundation/minix/blob/master/lib/libc/stdio/fileext.h> */
   struct __sfileext
     {
@@ -162,7 +165,7 @@
       /* More fields, not relevant here.  */
     };
 #  define fp_ub ((struct __sfileext *) fp->_ext._base)->_ub
-# elif defined __ANDROID__                     /* Android */
+# elif defined __ANDROID__ || defined __OpenBSD__ /* Android, OpenBSD */
   struct __sfileext
     {
       struct { unsigned char *_base; size_t _size; } _ub; /* ungetc buffer */
@@ -175,9 +178,11 @@
 
 # define HASUB(fp) (fp_ub._base != NULL)
 
-# if defined __ANDROID__ /* Android */
-  /* Needed after this commit from 2016-01-25
-     <https://android.googlesource.com/platform/bionic.git/+/e70e0e9267d069bf56a5078c99307e08a7280de7> */
+# if defined __ANDROID__ || defined __OpenBSD__ /* Android, OpenBSD */
+  /* Needed after this Android commit from 2016-01-25
+     <https://android.googlesource.com/platform/bionic.git/+/e70e0e9267d069bf56a5078c99307e08a7280de7>
+     And after this OpenBSD commit from 2025-07-16
+     <https://github.com/openbsd/src/commit/b7f6c2eb760a2da367dd51d539ef06f5f3553790>.  */
 #  ifndef __SEOF
 #   define __SLBF 1
 #   define __SNBF 2
diff --git a/lib/strftime.c b/lib/strftime.c
index 64a1f0456a2..537172d8be6 100644
--- a/lib/strftime.c
+++ b/lib/strftime.c
@@ -53,7 +53,7 @@
 /* Whether to require GNU behavior for AM and PM indicators, even on
    other platforms.  This matters only in non-C locales.
    The default is to require it; you can override this via
-   AC_DEFINE([REQUIRE_GNUISH_STRFTIME_AM_PM], 1) and if you do that
+   AC_DEFINE([REQUIRE_GNUISH_STRFTIME_AM_PM], [false]) and if you do that
    you may be able to omit Gnulib's localename module and its dependencies.  */
 #ifndef REQUIRE_GNUISH_STRFTIME_AM_PM
 # define REQUIRE_GNUISH_STRFTIME_AM_PM true
@@ -63,6 +63,25 @@
 # define REQUIRE_GNUISH_STRFTIME_AM_PM false
 #endif
 
+/* Whether to include support for non-Gregorian calendars (outside of the scope
+   of ISO C, POSIX, and glibc).  This matters only in non-C locales.
+   The default is to include it, except on platforms where retrieving the locale
+   name drags in too many dependencies
+   (LOCALENAME_ENHANCE_LOCALE_FUNCS || !SETLOCALE_NULL_ONE_MTSAFE).
+   You can override this via
+   AC_DEFINE([SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME], [false])
+   and if you do that you may be able to omit Gnulib's localename module and its
+   dependencies.  */
+#ifndef SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+# define SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME true
+#endif
+#if defined _LIBC || (HAVE_ONLY_C_LOCALE || USE_C_LOCALE) \
+    || ((defined __OpenBSD__ || defined _AIX || defined __ANDROID__) \
+        && !GNULIB_NSTRFTIME)
+# undef SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+# define SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME false
+#endif
+
 #if HAVE_ONLY_C_LOCALE || USE_C_LOCALE
 # include "c-ctype.h"
 #else
@@ -78,14 +97,8 @@
    C library on the various platforms (UTF-8, GB2312, GBK, CP936,
    GB18030, EUC-TW, BIG5, BIG5-HKSCS, CP950, EUC-JP, EUC-KR, CP949,
    SHIFT_JIS, CP932, JOHAB) are safe for formats, because the byte '%'
-   cannot occur in a multibyte character except in the first byte.
-
-   The DEC-HANYU encoding used on OSF/1 is not safe for formats, but
-   this encoding has never been seen in real-life use, so we ignore
-   it.  */
-#if !(defined __osf__ && 0)
-# define MULTIBYTE_IS_FORMAT_SAFE 1
-#endif
+   cannot occur in a multibyte character except in the first byte.  */
+#define MULTIBYTE_IS_FORMAT_SAFE 1
 #define DO_MULTIBYTE (! MULTIBYTE_IS_FORMAT_SAFE)
 
 #if DO_MULTIBYTE
@@ -164,6 +177,16 @@ enum pad_style
   ((year) % 4 == 0 && ((year) % 100 != 0 || (year) % 400 == 0))
 #endif
 
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+/* Support for non-Gregorian calendars.  */
+# include "localcharset.h"
+# include "localename.h"
+# include "calendars.h"
+# define CAL_ARGS(x,y) x, y,
+#else
+# define CAL_ARGS(x,y) /* empty */
+#endif
+
 
 #ifdef _LIBC
 # define mktime_z(tz, tm) mktime (tm)
@@ -873,6 +896,8 @@ static CHAR_T const c_month_names[][sizeof "September"] =
 
 static size_t __strftime_internal (STREAM_OR_CHAR_T *, STRFTIME_ARG (size_t)
                                    const CHAR_T *, const struct tm *,
+                                   CAL_ARGS (const struct calendar *,
+                                             struct calendar_date *)
                                    bool, enum pad_style, int, bool *
                                    extra_args_spec LOCALE_PARAM);
 
@@ -1087,9 +1112,36 @@ my_strftime (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
              const CHAR_T *format,
              const struct tm *tp extra_args_spec LOCALE_PARAM)
 {
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+  /* Recognize whether to use a non-Gregorian calendar.  */
+  const struct calendar *cal = NULL;
+  struct calendar_date caldate;
+  if (strcmp (locale_charset (), "UTF-8") == 0)
+    {
+      const char *loc = gl_locale_name_unsafe (LC_TIME, "LC_TIME");
+      if (strlen (loc) >= 5 && !(loc[5] >= 'A' && loc[5] <= 'Z'))
+        {
+          if (memcmp (loc, "th_TH", 5) == 0)
+            cal = &thai_calendar;
+          else if (memcmp (loc, "fa_IR", 5) == 0)
+            cal = &persian_calendar;
+          else if (memcmp (loc, "am_ET", 5) == 0)
+            cal = &ethiopian_calendar;
+          if (cal != NULL)
+            {
+              if (cal->from_gregorian (&caldate,
+                                       tp->tm_year + 1900,
+                                       tp->tm_mon,
+                                       tp->tm_mday) < 0)
+                cal = NULL;
+            }
+        }
+    }
+#endif
   bool tzset_called = false;
-  return __strftime_internal (s, STRFTIME_ARG (maxsize) format, tp, false,
-                              ZERO_PAD, -1,
+  return __strftime_internal (s, STRFTIME_ARG (maxsize) format, tp,
+                              CAL_ARGS (cal, &caldate)
+                              false, ZERO_PAD, -1,
                               &tzset_called extra_args LOCALE_ARG);
 }
 libc_hidden_def (my_strftime)
@@ -1101,7 +1153,10 @@ libc_hidden_def (my_strftime)
 static size_t
 __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
                      const CHAR_T *format,
-                     const struct tm *tp, bool upcase,
+                     const struct tm *tp,
+                     CAL_ARGS (const struct calendar *cal,
+                               struct calendar_date *caldate)
+                     bool upcase,
                      enum pad_style yr_spec, int width, bool *tzset_called
                      extra_args_spec LOCALE_PARAM)
 {
@@ -1113,7 +1168,7 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
 #endif
 
   int saved_errno = errno;
-  int hour12 = tp->tm_hour;
+
 #ifdef _NL_CURRENT
   /* We cannot make the following values variables since we must delay
      the evaluation of these values until really needed since some
@@ -1173,6 +1228,7 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
   const char *format_end = NULL;
 #endif
 
+  int hour12 = tp->tm_hour;
   if (hour12 > 12)
     hour12 -= 12;
   else
@@ -1189,6 +1245,9 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
       bool negative_number;     /* The number is negative.  */
       bool always_output_a_sign; /* +/- should always be output.  */
       int tz_colon_mask;        /* Bitmask of where ':' should appear.  */
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+      unsigned int digits_base = '0'; /* '0' or some UCS-2 value.  */
+#endif
       const CHAR_T *subfmt;
       CHAR_T *bufp;
       CHAR_T buf[1
@@ -1436,6 +1495,14 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
             }
           if (modifier == L_('E'))
             goto bad_format;
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+          if (cal != NULL)
+            {
+              cpy (STRLEN (caldate->month_names[caldate->month].abbrev),
+                   caldate->month_names[caldate->month].abbrev);
+              break;
+            }
+#endif
 #ifdef _NL_CURRENT
           if (modifier == L_('O'))
             cpy (aam_len, a_altmonth);
@@ -1460,6 +1527,14 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
               to_uppcase = true;
               to_lowcase = false;
             }
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+          if (cal != NULL)
+            {
+              cpy (STRLEN (caldate->month_names[caldate->month].full),
+                   caldate->month_names[caldate->month].full);
+              break;
+            }
+#endif
 #ifdef _NL_CURRENT
           if (modifier == L_('O'))
             cpy (STRLEN (f_altmonth), f_altmonth);
@@ -1511,13 +1586,17 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
         subformat_width:
           {
             size_t len = __strftime_internal (NULL, STRFTIME_ARG ((size_t) -1)
-                                              subfmt, tp, to_uppcase,
-                                              pad, subwidth, tzset_called
+                                              subfmt, tp,
+                                              CAL_ARGS (cal, caldate)
+                                              to_uppcase, pad, subwidth,
+                                              tzset_called
                                               extra_args LOCALE_ARG);
             add (len, __strftime_internal (p,
                                            STRFTIME_ARG (maxsize - i)
-                                           subfmt, tp, to_uppcase,
-                                           pad, subwidth, tzset_called
+                                           subfmt, tp,
+                                           CAL_ARGS (cal, caldate)
+                                           to_uppcase, pad, subwidth,
+                                           tzset_called
                                            extra_args LOCALE_ARG));
           }
           break;
@@ -1639,6 +1718,13 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
         case L_('x'):
           if (modifier == L_('O'))
             goto bad_format;
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+          if (cal != NULL)
+            {
+              subfmt = cal->d_fmt;
+              goto subformat;
+            }
+#endif
 #ifdef _NL_CURRENT
           if (! (modifier == L_('E')
                  && (*(subfmt =
@@ -1652,6 +1738,7 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
 #else
           goto underlying_strftime;
 #endif
+
         case L_('D'):
           if (modifier != 0)
             goto bad_format;
@@ -1662,12 +1749,20 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
           if (modifier == L_('E'))
             goto bad_format;
 
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+          if (cal != NULL)
+            DO_NUMBER (2, caldate->day);
+#endif
           DO_NUMBER (2, tp->tm_mday);
 
         case L_('e'):
           if (modifier == L_('E'))
             goto bad_format;
 
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+          if (cal != NULL)
+            DO_NUMBER_SPACEPAD (2, caldate->day);
+#endif
           DO_NUMBER_SPACEPAD (2, tp->tm_mday);
 
           /* All numeric formats set DIGITS and NUMBER_VALUE (or U_NUMBER_VALUE)
@@ -1709,7 +1804,10 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
              negating it.  */
           if (modifier == L_('O') && !negative_number)
             {
-#ifdef _NL_CURRENT
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+              if (cal != NULL)
+                digits_base = cal->alt_digits_base;
+#elif defined _NL_CURRENT
               /* Get the locale specific alternate representation of
                  the number.  If none exist NULL is returned.  */
               const CHAR_T *cp = nl_get_alt_digit (u_number_value
@@ -1724,9 +1822,6 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
                       break;
                     }
                 }
-#elif HAVE_ONLY_C_LOCALE || (USE_C_LOCALE && !HAVE_STRFTIME_L)
-#else
-              goto underlying_strftime;
 #endif
             }
 
@@ -1740,7 +1835,13 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
               if (tz_colon_mask & 1)
                 *--bufp = ':';
               tz_colon_mask >>= 1;
-              *--bufp = u_number_value % 10 + L_('0');
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+              *--bufp = u_number_value % 10 + (digits_base & 0xFF);
+              if (digits_base >= 0x100)
+                *--bufp = digits_base >> 8;
+#else
+              *--bufp = u_number_value % 10 + '0';
+#endif
               u_number_value /= 10;
             }
           while (u_number_value != 0 || tz_colon_mask != 0);
@@ -1755,8 +1856,13 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
             CHAR_T sign_char = (negative_number ? L_('-')
                                 : always_output_a_sign ? L_('+')
                                 : 0);
-            int numlen = buf + sizeof buf / sizeof buf[0] - bufp;
-            int shortage = width - !!sign_char - numlen;
+            int number_bytes = buf + sizeof buf / sizeof buf[0] - bufp;
+            int number_digits = number_bytes;
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+            if (digits_base >= 0x100)
+              number_digits = number_bytes / 2;
+#endif
+            int shortage = width - !!sign_char - number_digits;
             int padding = pad == NO_PAD || shortage <= 0 ? 0 : shortage;
 
             if (sign_char)
@@ -1772,7 +1878,7 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
                 width--;
               }
 
-            cpy (numlen, bufp);
+            cpy (number_bytes, bufp);
           }
           break;
 
@@ -1833,6 +1939,10 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
           if (modifier == L_('E'))
             goto bad_format;
 
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+          if (cal != NULL)
+            DO_SIGNED_NUMBER (2, false, caldate->month + 1U);
+#endif
           DO_SIGNED_NUMBER (2, tp->tm_mon < -1, tp->tm_mon + 1U);
 
 #ifndef _LIBC
@@ -2070,9 +2180,11 @@ __strftime_internal (STREAM_OR_CHAR_T *s, STRFTIME_ARG (size_t maxsize)
               goto underlying_strftime;
 #endif
             }
-          if (modifier == L_('O'))
-            goto bad_format;
 
+#if SUPPORT_NON_GREG_CALENDARS_IN_STRFTIME
+          if (cal != NULL)
+            DO_YEARISH (4, false, caldate->year);
+#endif
           DO_YEARISH (4, tp->tm_year < -TM_YEAR_BASE,
                       tp->tm_year + (unsigned int) TM_YEAR_BASE);
 
diff --git a/lib/strftime.h b/lib/strftime.h
index 3b7e20f236a..a76c98c9c82 100644
--- a/lib/strftime.h
+++ b/lib/strftime.h
@@ -59,6 +59,15 @@ extern "C" {
      date and time:          %c
      time zone:              %z %Z
      nanosecond              %N
+   In locales with non-Gregorian calendars, the following conversions don't
+   apply in the expected way:
+     date:
+       century               %C
+       year                  %y
+       week-based year       %G %g
+       week in year          %U %W %V
+       day in year           %j
+       year, month, day      %D
 
    Store the result, as a string with a trailing NUL character, at the
    beginning of the array __S[0..__MAXSIZE-1] and return the length of
diff --git a/lib/string.in.h b/lib/string.in.h
index e3d94b76c17..9a039c7ba06 100644
--- a/lib/string.in.h
+++ b/lib/string.in.h
@@ -214,65 +214,85 @@ _GL_EXTERN_C void free (void *);
 
 /* Declarations for ISO C N3322.  */
 #if defined __GNUC__ && __GNUC__ >= 15 && !defined __clang__
+# ifndef memcpy
 _GL_EXTERN_C void *memcpy (void *__dest, const void *__src, size_t __n)
-# if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
+#  if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
   _GL_ATTRIBUTE_NOTHROW
-# endif
+#  endif
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 3)
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (2, 3);
+# endif
+# ifndef memccpy
 _GL_EXTERN_C void *memccpy (void *__dest, const void *__src, int __c, size_t __n)
-# if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
+#  if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
   _GL_ATTRIBUTE_NOTHROW
-# endif
+#  endif
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 4)
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (2, 4);
+# endif
+# ifndef memmove
 _GL_EXTERN_C void *memmove (void *__dest, const void *__src, size_t __n)
-# if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
+#  if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
   _GL_ATTRIBUTE_NOTHROW
-# endif
+#  endif
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 3)
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (2, 3);
+# endif
+# ifndef strncpy
 _GL_EXTERN_C char *strncpy (char *__dest, const char *__src, size_t __n)
-# if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
+#  if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
   _GL_ATTRIBUTE_NOTHROW
-# endif
+#  endif
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 3)
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (2, 3);
+# endif
+# ifndef strndup
 _GL_EXTERN_C char *strndup (const char *__s, size_t __n)
-# if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
+#  if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
   _GL_ATTRIBUTE_NOTHROW
-# endif
+#  endif
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 2);
+# endif
+# ifndef strncat
 _GL_EXTERN_C char *strncat (char *__dest, const char *__src, size_t __n)
-# if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
+#  if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
   _GL_ATTRIBUTE_NOTHROW
-# endif
+#  endif
   _GL_ARG_NONNULL ((1)) _GL_ATTRIBUTE_NONNULL_IF_NONZERO (2, 3);
+# endif
+# ifndef memcmp
 _GL_EXTERN_C int memcmp (const void *__s1, const void *__s2, size_t __n)
-# if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
+#  if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
   _GL_ATTRIBUTE_NOTHROW
-# endif
+#  endif
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 3)
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (2, 3);
+# endif
+# ifndef strncmp
 _GL_EXTERN_C int strncmp (const char *__s1, const char *__s2, size_t __n)
-# if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
+#  if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
   _GL_ATTRIBUTE_NOTHROW
-# endif
+#  endif
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 3)
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (2, 3);
-# ifndef __cplusplus
+# endif
+# if !defined memchr && !defined __cplusplus
 _GL_EXTERN_C void *memchr (const void *__s, int __c, size_t __n)
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 3);
 _GL_EXTERN_C void *memrchr (const void *__s, int __c, size_t __n)
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 3);
 # endif
+# ifndef memset
 _GL_EXTERN_C void *memset (void *__s, int __c, size_t __n)
-# if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
+#  if __GLIBC__ + (__GLIBC_MINOR__ >= 2) > 2
   _GL_ATTRIBUTE_NOTHROW
-# endif
+#  endif
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 3);
+# endif
+# ifndef memset_explicit
 _GL_EXTERN_C void *memset_explicit (void *__s, int __c, size_t __n)
   _GL_ATTRIBUTE_NONNULL_IF_NONZERO (1, 3);
+# endif
 #endif