Update from Gnulib

This incorporates:
2020-07-07 dup2: remove support for some very old platforms
2020-07-07 memchr: remove support for some very old platforms
2020-07-04 getumask: new module
2020-07-03 getrandom: fix compilation error on native Windows
2020-07-03 lchmod: simplify after 2020-02-22 change
2020-07-01 manywarnings: improve port to GCC 10.1
2020-06-28 getrandom: fix compilation errors on older versions of mingw
2020-06-29 alloca-opt: fix warning on mingw
* lib/alloca.in.h, lib/dup2.c, lib/getrandom.c, lib/string.in.h:
* lib/sys_stat.in.h, lib/unistd.in.h, m4/dup2.m4, m4/getrandom.m4:
* m4/lchmod.m4, m4/manywarnings.m4, m4/string_h.m4, m4/sys_stat_h.m4:
* m4/unistd_h.m4: Copy from Gnulib.
* lib/gnulib.mk.in, m4/gnulib-comp.m4: Regenerate.

8 files changed, 129 insertions, 284 deletions

diff --git a/m4/dup2.m4 b/m4/dup2.m4
index 21b1ecc26b8..462bfd0e526 100644
--- a/m4/dup2.m4
+++ b/m4/dup2.m4
@@ -1,4 +1,4 @@
-#serial 25
+#serial 26
 dnl Copyright (C) 2002, 2005, 2007, 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -8,107 +8,94 @@ AC_DEFUN([gl_FUNC_DUP2],
 [
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
   AC_REQUIRE([AC_CANONICAL_HOST])
-  m4_ifdef([gl_FUNC_DUP2_OBSOLETE], [
-    AC_CHECK_FUNCS_ONCE([dup2])
-    if test $ac_cv_func_dup2 = no; then
-      HAVE_DUP2=0
-    fi
-  ], [
-    AC_DEFINE([HAVE_DUP2], [1], [Define to 1 if you have the 'dup2' function.])
-  ])
-  if test $HAVE_DUP2 = 1; then
-    AC_CACHE_CHECK([whether dup2 works], [gl_cv_func_dup2_works],
-      [AC_RUN_IFELSE([
-         AC_LANG_PROGRAM(
-           [[#include <errno.h>
-             #include <fcntl.h>
-             #include <limits.h>
-             #include <sys/resource.h>
-             #include <unistd.h>
-             #ifndef RLIM_SAVED_CUR
-             # define RLIM_SAVED_CUR RLIM_INFINITY
-             #endif
-             #ifndef RLIM_SAVED_MAX
-             # define RLIM_SAVED_MAX RLIM_INFINITY
-             #endif
-           ]],
-           [[int result = 0;
-             int bad_fd = INT_MAX;
-             struct rlimit rlim;
-             if (getrlimit (RLIMIT_NOFILE, &rlim) == 0
-                 && 0 <= rlim.rlim_cur && rlim.rlim_cur <= INT_MAX
-                 && rlim.rlim_cur != RLIM_INFINITY
-                 && rlim.rlim_cur != RLIM_SAVED_MAX
-                 && rlim.rlim_cur != RLIM_SAVED_CUR)
-               bad_fd = rlim.rlim_cur;
-             #ifdef FD_CLOEXEC
-               if (fcntl (1, F_SETFD, FD_CLOEXEC) == -1)
-                 result |= 1;
-             #endif
-             if (dup2 (1, 1) != 1)
-               result |= 2;
-             #ifdef FD_CLOEXEC
-               if (fcntl (1, F_GETFD) != FD_CLOEXEC)
-                 result |= 4;
-             #endif
-             close (0);
-             if (dup2 (0, 0) != -1)
-               result |= 8;
-             /* Many gnulib modules require POSIX conformance of EBADF.  */
-             if (dup2 (2, bad_fd) == -1 && errno != EBADF)
-               result |= 16;
-             /* Flush out some cygwin core dumps.  */
-             if (dup2 (2, -1) != -1 || errno != EBADF)
-               result |= 32;
-             dup2 (2, 255);
-             dup2 (2, 256);
-             /* On OS/2 kLIBC, dup2() does not work on a directory fd.  */
-             {
-               int fd = open (".", O_RDONLY);
-               if (fd == -1)
-                 result |= 64;
-               else if (dup2 (fd, fd + 1) == -1)
-                 result |= 128;
-
-               close (fd);
-             }
-             return result;]])
-        ],
-        [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
-        [case "$host_os" in
-           mingw*) # on this platform, dup2 always returns 0 for success
-             gl_cv_func_dup2_works="guessing no" ;;
-           cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
-             gl_cv_func_dup2_works="guessing no" ;;
-           aix* | freebsd*)
-                   # on AIX 7.1 and FreeBSD 6.1, dup2 (1,toobig) gives EMFILE,
-                   # not EBADF.
-             gl_cv_func_dup2_works="guessing no" ;;
-           haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC.
-             gl_cv_func_dup2_works="guessing no" ;;
-           *-android*) # implemented using dup3(), which fails if oldfd == newfd
-             gl_cv_func_dup2_works="guessing no" ;;
-           os2*) # on OS/2 kLIBC, dup2() does not work on a directory fd.
-             gl_cv_func_dup2_works="guessing no" ;;
-           *) gl_cv_func_dup2_works="guessing yes" ;;
-         esac])
-      ])
-    case "$gl_cv_func_dup2_works" in
-      *yes) ;;
-      *)
-        REPLACE_DUP2=1
-        AC_CHECK_FUNCS([setdtablesize])
-        ;;
-    esac
-  fi
+  AC_CACHE_CHECK([whether dup2 works], [gl_cv_func_dup2_works],
+    [AC_RUN_IFELSE([
+       AC_LANG_PROGRAM(
+         [[#include <errno.h>
+           #include <fcntl.h>
+           #include <limits.h>
+           #include <sys/resource.h>
+           #include <unistd.h>
+           #ifndef RLIM_SAVED_CUR
+           # define RLIM_SAVED_CUR RLIM_INFINITY
+           #endif
+           #ifndef RLIM_SAVED_MAX
+           # define RLIM_SAVED_MAX RLIM_INFINITY
+           #endif
+         ]],
+         [[int result = 0;
+           int bad_fd = INT_MAX;
+           struct rlimit rlim;
+           if (getrlimit (RLIMIT_NOFILE, &rlim) == 0
+               && 0 <= rlim.rlim_cur && rlim.rlim_cur <= INT_MAX
+               && rlim.rlim_cur != RLIM_INFINITY
+               && rlim.rlim_cur != RLIM_SAVED_MAX
+               && rlim.rlim_cur != RLIM_SAVED_CUR)
+             bad_fd = rlim.rlim_cur;
+           #ifdef FD_CLOEXEC
+             if (fcntl (1, F_SETFD, FD_CLOEXEC) == -1)
+               result |= 1;
+           #endif
+           if (dup2 (1, 1) != 1)
+             result |= 2;
+           #ifdef FD_CLOEXEC
+             if (fcntl (1, F_GETFD) != FD_CLOEXEC)
+               result |= 4;
+           #endif
+           close (0);
+           if (dup2 (0, 0) != -1)
+             result |= 8;
+           /* Many gnulib modules require POSIX conformance of EBADF.  */
+           if (dup2 (2, bad_fd) == -1 && errno != EBADF)
+             result |= 16;
+           /* Flush out some cygwin core dumps.  */
+           if (dup2 (2, -1) != -1 || errno != EBADF)
+             result |= 32;
+           dup2 (2, 255);
+           dup2 (2, 256);
+           /* On OS/2 kLIBC, dup2() does not work on a directory fd.  */
+           {
+             int fd = open (".", O_RDONLY);
+             if (fd == -1)
+               result |= 64;
+             else if (dup2 (fd, fd + 1) == -1)
+               result |= 128;
+             close (fd);
+           }
+           return result;]])
+      ],
+      [gl_cv_func_dup2_works=yes], [gl_cv_func_dup2_works=no],
+      [case "$host_os" in
+         mingw*) # on this platform, dup2 always returns 0 for success
+           gl_cv_func_dup2_works="guessing no" ;;
+         cygwin*) # on cygwin 1.5.x, dup2(1,1) returns 0
+           gl_cv_func_dup2_works="guessing no" ;;
+         aix* | freebsd*)
+                 # on AIX 7.1 and FreeBSD 6.1, dup2 (1,toobig) gives EMFILE,
+                 # not EBADF.
+           gl_cv_func_dup2_works="guessing no" ;;
+         haiku*) # on Haiku alpha 2, dup2(1, 1) resets FD_CLOEXEC.
+           gl_cv_func_dup2_works="guessing no" ;;
+         *-android*) # implemented using dup3(), which fails if oldfd == newfd
+           gl_cv_func_dup2_works="guessing no" ;;
+         os2*) # on OS/2 kLIBC, dup2() does not work on a directory fd.
+           gl_cv_func_dup2_works="guessing no" ;;
+         *) gl_cv_func_dup2_works="guessing yes" ;;
+       esac])
+    ])
+  case "$gl_cv_func_dup2_works" in
+    *yes) ;;
+    *)
+      REPLACE_DUP2=1
+      AC_CHECK_FUNCS([setdtablesize])
+      ;;
+  esac
   dnl Replace dup2() for supporting the gnulib-defined fchdir() function,
   dnl to keep fchdir's bookkeeping up-to-date.
   m4_ifdef([gl_FUNC_FCHDIR], [
     gl_TEST_FCHDIR
     if test $HAVE_FCHDIR = 0; then
-      if test $HAVE_DUP2 = 1; then
-        REPLACE_DUP2=1
-      fi
+      REPLACE_DUP2=1
     fi
   ])
 ])
diff --git a/m4/getrandom.m4 b/m4/getrandom.m4
index 2a0034bf76c..424c2fad3e3 100644
--- a/m4/getrandom.m4
+++ b/m4/getrandom.m4
@@ -1,4 +1,4 @@
-# getrandom.m4 serial 6
+# getrandom.m4 serial 7
 dnl Copyright 2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -36,7 +36,9 @@ AC_DEFUN([gl_FUNC_GETRANDOM],
 
   case "$host_os" in
     mingw*)
-      AC_CHECK_HEADERS([bcrypt.h])
+      AC_CHECK_HEADERS([bcrypt.h], [], [],
+        [[#include <windows.h>
+        ]])
       AC_CACHE_CHECK([whether the bcrypt library is guaranteed to be present],
         [gl_cv_lib_assume_bcrypt],
         [AC_COMPILE_IFELSE(
diff --git a/m4/gnulib-comp.m4 b/m4/gnulib-comp.m4
index 5c92a0768a4..3a0fae11c44 100644
--- a/m4/gnulib-comp.m4
+++ b/m4/gnulib-comp.m4
@@ -240,7 +240,7 @@ AC_DEFUN([gl_INIT],
   gl_DIRENT_H
   gl_DOUBLE_SLASH_ROOT
   gl_FUNC_DUP2
-  if test $HAVE_DUP2 = 0 || test $REPLACE_DUP2 = 1; then
+  if test $REPLACE_DUP2 = 1; then
     AC_LIBOBJ([dup2])
     gl_PREREQ_DUP2
   fi
@@ -465,6 +465,7 @@ AC_DEFUN([gl_INIT],
   gl_SYS_TYPES_H
   AC_PROG_MKDIR_P
   gl_FUNC_GEN_TEMPNAME
+  gl_MODULE_INDICATOR([tempname])
   gl_HEADER_TIME_H
   gl_TIME_R
   if test $HAVE_LOCALTIME_R = 0 || test $REPLACE_LOCALTIME_R = 1; then
diff --git a/m4/lchmod.m4 b/m4/lchmod.m4
index b9e8a97cb31..a86a304f5f1 100644
--- a/m4/lchmod.m4
+++ b/m4/lchmod.m4
@@ -1,4 +1,4 @@
-#serial 7
+#serial 8
 
 dnl Copyright (C) 2005-2006, 2008-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
@@ -26,6 +26,5 @@ AC_DEFUN([gl_FUNC_LCHMOD],
 # Prerequisites of lib/lchmod.c.
 AC_DEFUN([gl_PREREQ_LCHMOD],
 [
-  AC_REQUIRE([AC_C_INLINE])
   :
 ])
diff --git a/m4/manywarnings.m4 b/m4/manywarnings.m4
index 719bafb2909..d18da048d9e 100644
--- a/m4/manywarnings.m4
+++ b/m4/manywarnings.m4
@@ -1,4 +1,4 @@
-# manywarnings.m4 serial 19
+# manywarnings.m4 serial 20
 dnl Copyright (C) 2008-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -21,7 +21,7 @@ AC_DEFUN([gl_MANYWARN_COMPLEMENT],
       *" $gl_warn_item "*)
         ;;
       *)
-        gl_warn_set="$gl_warn_set $gl_warn_item"
+        gl_AS_VAR_APPEND([gl_warn_set], [" $gl_warn_item"])
         ;;
     esac
   done
@@ -49,12 +49,12 @@ m4_defun([gl_MANYWARN_ALL_GCC(C)],
   AC_REQUIRE([AC_PROG_CC])
   if test -n "$GCC"; then
 
-    dnl Check if -W -Werror -Wno-missing-field-initializers is supported
+    dnl Check if -Wextra -Werror -Wno-missing-field-initializers is supported
     dnl with the current $CC $CFLAGS $CPPFLAGS.
     AC_CACHE_CHECK([whether -Wno-missing-field-initializers is supported],
       [gl_cv_cc_nomfi_supported],
       [gl_save_CFLAGS="$CFLAGS"
-       CFLAGS="$CFLAGS -W -Werror -Wno-missing-field-initializers"
+       CFLAGS="$CFLAGS -Wextra -Werror -Wno-missing-field-initializers"
        AC_COMPILE_IFELSE(
          [AC_LANG_PROGRAM([[]], [[]])],
          [gl_cv_cc_nomfi_supported=yes],
@@ -68,7 +68,7 @@ m4_defun([gl_MANYWARN_ALL_GCC(C)],
       AC_CACHE_CHECK([whether -Wno-missing-field-initializers is needed],
         [gl_cv_cc_nomfi_needed],
         [gl_save_CFLAGS="$CFLAGS"
-         CFLAGS="$CFLAGS -W -Werror"
+         CFLAGS="$CFLAGS -Wextra -Werror"
          AC_COMPILE_IFELSE(
            [AC_LANG_PROGRAM(
               [[int f (void)
@@ -105,153 +105,41 @@ m4_defun([gl_MANYWARN_ALL_GCC(C)],
   # To compare this list to your installed GCC's, run this Bash command:
   #
   # comm -3 \
-  #  <((sed -n 's/^  *\(-[^ 0-9][^ ]*\) .*/\1/p' manywarnings.m4; \
+  #  <((sed -n 's/^  *\(-[^ 0-9][^ ]*\).*/\1/p' manywarnings.m4; \
   #     awk '/^[^#]/ {print $1}' ../build-aux/gcc-warning.spec) | sort) \
   #  <(LC_ALL=C gcc --help=warnings | sed -n 's/^  \(-[^ ]*\) .*/\1/p' | sort)
 
-  gl_manywarn_set=
-  for gl_manywarn_item in -fno-common \
-    -W \
-    -Wabsolute-value \
-    -Waddress \
-    -Waddress-of-packed-member \
-    -Waggressive-loop-optimizations \
+  $1=
+  for gl_manywarn_item in -fanalyzer -fno-common \
     -Wall \
-    -Wanalyzer-double-fclose \
-    -Wanalyzer-double-free \
-    -Wanalyzer-exposure-through-output-file \
-    -Wanalyzer-file-leak \
-    -Wanalyzer-free-of-non-heap \
-    -Wanalyzer-malloc-leak \
-    -Wanalyzer-null-argument \
-    -Wanalyzer-null-dereference \
-    -Wanalyzer-possible-null-argument \
-    -Wanalyzer-possible-null-dereference \
-    -Wanalyzer-stale-setjmp-buffer \
-    -Wanalyzer-tainted-array-index \
-    -Wanalyzer-too-complex \
-    -Wanalyzer-unsafe-call-within-signal-handler \
-    -Wanalyzer-use-after-free \
-    -Wanalyzer-use-of-pointer-in-stale-stack-frame \
     -Warith-conversion \
-    -Wattribute-warning \
-    -Wattributes \
     -Wbad-function-cast \
-    -Wbool-compare \
-    -Wbool-operation \
-    -Wbuiltin-declaration-mismatch \
-    -Wbuiltin-macro-redefined \
-    -Wcannot-profile \
-    -Wcast-align \
     -Wcast-align=strict \
-    -Wcast-function-type \
-    -Wchar-subscripts \
-    -Wclobbered \
-    -Wcomment \
-    -Wcomments \
-    -Wcoverage-mismatch \
-    -Wcpp \
-    -Wdangling-else \
     -Wdate-time \
-    -Wdeprecated \
-    -Wdeprecated-declarations \
-    -Wdesignated-init \
     -Wdisabled-optimization \
-    -Wdiscarded-array-qualifiers \
-    -Wdiscarded-qualifiers \
-    -Wdiv-by-zero \
     -Wdouble-promotion \
     -Wduplicated-branches \
     -Wduplicated-cond \
-    -Wduplicate-decl-specifier \
-    -Wempty-body \
-    -Wendif-labels \
-    -Wenum-compare \
-    -Wenum-conversion \
-    -Wexpansion-to-defined \
     -Wextra \
-    -Wformat-contains-nul \
-    -Wformat-diag \
-    -Wformat-extra-args \
-    -Wformat-nonliteral \
-    -Wformat-security \
     -Wformat-signedness \
-    -Wformat-y2k \
-    -Wformat-zero-length \
-    -Wframe-address \
-    -Wfree-nonheap-object \
-    -Whsa \
-    -Wif-not-aligned \
-    -Wignored-attributes \
-    -Wignored-qualifiers \
-    -Wimplicit \
-    -Wimplicit-function-declaration \
-    -Wimplicit-int \
-    -Wincompatible-pointer-types \
     -Winit-self \
     -Winline \
-    -Wint-conversion \
-    -Wint-in-bool-context \
-    -Wint-to-pointer-cast \
-    -Winvalid-memory-model \
     -Winvalid-pch \
-    -Wlogical-not-parentheses \
     -Wlogical-op \
-    -Wmain \
-    -Wmaybe-uninitialized \
-    -Wmemset-elt-size \
-    -Wmemset-transposed-args \
-    -Wmisleading-indentation \
-    -Wmissing-attributes \
-    -Wmissing-braces \
     -Wmissing-declarations \
-    -Wmissing-field-initializers \
     -Wmissing-include-dirs \
-    -Wmissing-parameter-type \
-    -Wmissing-profile \
     -Wmissing-prototypes \
-    -Wmultichar \
-    -Wmultistatement-macros \
-    -Wnarrowing \
     -Wnested-externs \
-    -Wnonnull \
-    -Wnonnull-compare \
     -Wnull-dereference \
-    -Wodr \
-    -Wold-style-declaration \
     -Wold-style-definition \
     -Wopenmp-simd \
-    -Woverflow \
     -Woverlength-strings \
-    -Woverride-init \
     -Wpacked \
-    -Wpacked-bitfield-compat \
-    -Wpacked-not-aligned \
-    -Wparentheses \
     -Wpointer-arith \
-    -Wpointer-compare \
-    -Wpointer-sign \
-    -Wpointer-to-int-cast \
-    -Wpragmas \
-    -Wpsabi \
-    -Wrestrict \
-    -Wreturn-local-addr \
-    -Wreturn-type \
-    -Wscalar-storage-order \
-    -Wsequence-point \
     -Wshadow \
-    -Wshift-count-negative \
-    -Wshift-count-overflow \
-    -Wshift-negative-value \
-    -Wsizeof-array-argument \
-    -Wsizeof-pointer-div \
-    -Wsizeof-pointer-memaccess \
     -Wstack-protector \
-    -Wstrict-aliasing \
     -Wstrict-overflow \
     -Wstrict-prototypes \
-    -Wstring-compare \
-    -Wstringop-truncation \
     -Wsuggest-attribute=cold \
     -Wsuggest-attribute=const \
     -Wsuggest-attribute=format \
@@ -260,95 +148,63 @@ m4_defun([gl_MANYWARN_ALL_GCC(C)],
     -Wsuggest-attribute=pure \
     -Wsuggest-final-methods \
     -Wsuggest-final-types \
-    -Wswitch \
-    -Wswitch-bool \
-    -Wswitch-outside-range \
-    -Wswitch-unreachable \
     -Wsync-nand \
     -Wsystem-headers \
-    -Wtautological-compare \
     -Wtrampolines \
-    -Wtrigraphs \
-    -Wtype-limits \
     -Wuninitialized \
     -Wunknown-pragmas \
     -Wunsafe-loop-optimizations \
-    -Wunused \
-    -Wunused-but-set-parameter \
-    -Wunused-but-set-variable \
-    -Wunused-function \
-    -Wunused-label \
-    -Wunused-local-typedefs \
     -Wunused-macros \
-    -Wunused-parameter \
-    -Wunused-result \
-    -Wunused-value \
-    -Wunused-variable \
-    -Wvarargs \
     -Wvariadic-macros \
     -Wvector-operation-performance \
     -Wvla \
-    -Wvolatile-register-var \
     -Wwrite-strings \
-    -Wzero-length-bounds \
     \
     ; do
-    gl_manywarn_set="$gl_manywarn_set $gl_manywarn_item"
+    gl_AS_VAR_APPEND([$1], [" $gl_manywarn_item"])
   done
 
   # gcc --help=warnings outputs an unusual form for these options; list
   # them here so that the above 'comm' command doesn't report a false match.
-  # Would prefer "min (PTRDIFF_MAX, SIZE_MAX)", but it must be a literal.
-  # Also, AC_COMPUTE_INT requires it to fit in a long; it is 2**63 on
-  # the only platforms where it does not fit in a long, so make that
-  # a special case.
-  AC_MSG_CHECKING([max safe object size])
-  AC_COMPUTE_INT([gl_alloc_max],
-    [LONG_MAX < (PTRDIFF_MAX < (size_t) -1 ? PTRDIFF_MAX : (size_t) -1)
-     ? -1
-     : PTRDIFF_MAX < (size_t) -1 ? (long) PTRDIFF_MAX : (long) (size_t) -1],
-    [[#include <limits.h>
-      #include <stddef.h>
-      #include <stdint.h>
-    ]],
-    [gl_alloc_max=2147483647])
-  case $gl_alloc_max in
-    -1) gl_alloc_max=9223372036854775807;;
-  esac
-  AC_MSG_RESULT([$gl_alloc_max])
-  gl_manywarn_set="$gl_manywarn_set -Walloc-size-larger-than=$gl_alloc_max"
-  gl_manywarn_set="$gl_manywarn_set -Warray-bounds=2"
-  gl_manywarn_set="$gl_manywarn_set -Wattribute-alias=2"
-  gl_manywarn_set="$gl_manywarn_set -Wformat-overflow=2"
-  gl_manywarn_set="$gl_manywarn_set -Wformat-truncation=2"
-  gl_manywarn_set="$gl_manywarn_set -Wimplicit-fallthrough=5"
-  gl_manywarn_set="$gl_manywarn_set -Wnormalized=nfc"
-  gl_manywarn_set="$gl_manywarn_set -Wshift-overflow=2"
-  gl_manywarn_set="$gl_manywarn_set -Wstringop-overflow=2"
-  gl_manywarn_set="$gl_manywarn_set -Wunused-const-variable=2"
-  gl_manywarn_set="$gl_manywarn_set -Wvla-larger-than=4031"
+  gl_AS_VAR_APPEND([$1], [' -Warray-bounds=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wattribute-alias=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wformat-overflow=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wformat=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wformat-truncation=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wimplicit-fallthrough=5'])
+  gl_AS_VAR_APPEND([$1], [' -Wshift-overflow=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wunused-const-variable=2'])
+  gl_AS_VAR_APPEND([$1], [' -Wvla-larger-than=4031'])
 
   # These are needed for older GCC versions.
   if test -n "$GCC"; then
     case `($CC --version) 2>/dev/null` in
       'gcc (GCC) '[[0-3]].* | \
       'gcc (GCC) '4.[[0-7]].*)
-        gl_manywarn_set="$gl_manywarn_set -fdiagnostics-show-option"
-        gl_manywarn_set="$gl_manywarn_set -funit-at-a-time"
+        gl_AS_VAR_APPEND([$1], [' -fdiagnostics-show-option'])
+        gl_AS_VAR_APPEND([$1], [' -funit-at-a-time'])
           ;;
     esac
   fi
 
   # Disable specific options as needed.
   if test "$gl_cv_cc_nomfi_needed" = yes; then
-    gl_manywarn_set="$gl_manywarn_set -Wno-missing-field-initializers"
+    gl_AS_VAR_APPEND([$1], [' -Wno-missing-field-initializers'])
   fi
 
   if test "$gl_cv_cc_uninitialized_supported" = no; then
-    gl_manywarn_set="$gl_manywarn_set -Wno-uninitialized"
+    gl_AS_VAR_APPEND([$1], [' -Wno-uninitialized'])
   fi
 
-  $1=$gl_manywarn_set
+  # Some warnings have too many false alarms in GCC 10.1.
+  # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93695
+  gl_AS_VAR_APPEND([$1], [' -Wno-analyzer-double-free'])
+  # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94458
+  gl_AS_VAR_APPEND([$1], [' -Wno-analyzer-malloc-leak'])
+  # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94851
+  gl_AS_VAR_APPEND([$1], [' -Wno-analyzer-null-dereference'])
+  # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95758
+  gl_AS_VAR_APPEND([$1], [' -Wno-analyzer-use-after-free'])
 
   AC_LANG_POP([C])
 ])
diff --git a/m4/string_h.m4 b/m4/string_h.m4
index cc51337f0d1..516b346b311 100644
--- a/m4/string_h.m4
+++ b/m4/string_h.m4
@@ -5,7 +5,7 @@
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
-# serial 23
+# serial 24
 
 # Written by Paul Eggert.
 
@@ -87,7 +87,6 @@ AC_DEFUN([gl_HEADER_STRING_H_DEFAULTS],
   HAVE_EXPLICIT_BZERO=1;        AC_SUBST([HAVE_EXPLICIT_BZERO])
   HAVE_FFSL=1;                  AC_SUBST([HAVE_FFSL])
   HAVE_FFSLL=1;                 AC_SUBST([HAVE_FFSLL])
-  HAVE_MEMCHR=1;                AC_SUBST([HAVE_MEMCHR])
   HAVE_DECL_MEMMEM=1;           AC_SUBST([HAVE_DECL_MEMMEM])
   HAVE_MEMPCPY=1;               AC_SUBST([HAVE_MEMPCPY])
   HAVE_DECL_MEMRCHR=1;          AC_SUBST([HAVE_DECL_MEMRCHR])
diff --git a/m4/sys_stat_h.m4 b/m4/sys_stat_h.m4
index 3efba5a7b98..929144d155b 100644
--- a/m4/sys_stat_h.m4
+++ b/m4/sys_stat_h.m4
@@ -1,4 +1,4 @@
-# sys_stat_h.m4 serial 33   -*- Autoconf -*-
+# sys_stat_h.m4 serial 34   -*- Autoconf -*-
 dnl Copyright (C) 2006-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -46,8 +46,8 @@ AC_DEFUN([gl_HEADER_SYS_STAT_H],
   dnl Check for declarations of anything we want to poison if the
   dnl corresponding gnulib module is not in use.
   gl_WARN_ON_USE_PREPARE([[#include <sys/stat.h>
-    ]], [fchmodat fstat fstatat futimens lchmod lstat mkdirat mkfifo mkfifoat
-    mknod mknodat stat utimensat])
+    ]], [fchmodat fstat fstatat futimens getumask lchmod lstat
+    mkdirat mkfifo mkfifoat mknod mknodat stat utimensat])
 
   AC_REQUIRE([AC_C_RESTRICT])
 ])
@@ -68,6 +68,7 @@ AC_DEFUN([gl_SYS_STAT_H_DEFAULTS],
   GNULIB_FSTAT=0;       AC_SUBST([GNULIB_FSTAT])
   GNULIB_FSTATAT=0;     AC_SUBST([GNULIB_FSTATAT])
   GNULIB_FUTIMENS=0;    AC_SUBST([GNULIB_FUTIMENS])
+  GNULIB_GETUMASK=0;    AC_SUBST([GNULIB_GETUMASK])
   GNULIB_LCHMOD=0;      AC_SUBST([GNULIB_LCHMOD])
   GNULIB_LSTAT=0;       AC_SUBST([GNULIB_LSTAT])
   GNULIB_MKDIRAT=0;     AC_SUBST([GNULIB_MKDIRAT])
@@ -82,6 +83,7 @@ AC_DEFUN([gl_SYS_STAT_H_DEFAULTS],
   HAVE_FCHMODAT=1;      AC_SUBST([HAVE_FCHMODAT])
   HAVE_FSTATAT=1;       AC_SUBST([HAVE_FSTATAT])
   HAVE_FUTIMENS=1;      AC_SUBST([HAVE_FUTIMENS])
+  HAVE_GETUMASK=1;      AC_SUBST([HAVE_GETUMASK])
   HAVE_LCHMOD=1;        AC_SUBST([HAVE_LCHMOD])
   HAVE_LSTAT=1;         AC_SUBST([HAVE_LSTAT])
   HAVE_MKDIRAT=1;       AC_SUBST([HAVE_MKDIRAT])
diff --git a/m4/unistd_h.m4 b/m4/unistd_h.m4
index dfa38f85d60..b4734daf603 100644
--- a/m4/unistd_h.m4
+++ b/m4/unistd_h.m4
@@ -1,4 +1,4 @@
-# unistd_h.m4 serial 80
+# unistd_h.m4 serial 81
 dnl Copyright (C) 2006-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -120,7 +120,6 @@ AC_DEFUN([gl_UNISTD_H_DEFAULTS],
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_CHOWN=1;           AC_SUBST([HAVE_CHOWN])
   HAVE_COPY_FILE_RANGE=1; AC_SUBST([HAVE_COPY_FILE_RANGE])
-  HAVE_DUP2=1;            AC_SUBST([HAVE_DUP2])
   HAVE_DUP3=1;            AC_SUBST([HAVE_DUP3])
   HAVE_EUIDACCESS=1;      AC_SUBST([HAVE_EUIDACCESS])
   HAVE_FACCESSAT=1;       AC_SUBST([HAVE_FACCESSAT])