all: Replace many more http URLs by https URLs. Update stale URLs.

* users.txt: Remove mention of 'newts'.
* lib/localename.c: Update comment about LANG_SOTHO.

26 files changed, 42 insertions, 42 deletions

diff --git a/m4/alloca.m4 b/m4/alloca.m4
index 7f0604cbda..d122431649 100644
--- a/m4/alloca.m4
+++ b/m4/alloca.m4
@@ -44,12 +44,12 @@ AC_DEFUN([gl_FUNC_ALLOCA],
 AC_DEFUN([gl_PREREQ_ALLOCA], [:])
 
 # This works around a bug in autoconf <= 2.68.
-# See <http://lists.gnu.org/archive/html/bug-gnulib/2011-06/msg00277.html>.
+# See <https://lists.gnu.org/archive/html/bug-gnulib/2011-06/msg00277.html>.
 
 m4_version_prereq([2.69], [] ,[
 
 # This is taken from the following Autoconf patch:
-# http://git.savannah.gnu.org/cgit/autoconf.git/commit/?id=6cd9f12520b0d6f76d3230d7565feba1ecf29497
+# https://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commitdiff;h=6cd9f12520b0d6f76d3230d7565feba1ecf29497
 
 # _AC_LIBOBJ_ALLOCA
 # -----------------
diff --git a/m4/duplocale.m4 b/m4/duplocale.m4
index 416742253f..a5eb6cf5bb 100644
--- a/m4/duplocale.m4
+++ b/m4/duplocale.m4
@@ -11,7 +11,7 @@ AC_DEFUN([gl_FUNC_DUPLOCALE],
   AC_CHECK_FUNCS_ONCE([duplocale])
   if test $ac_cv_func_duplocale = yes; then
     dnl Check against glibc bug where duplocale crashes.
-    dnl See <http://sourceware.org/bugzilla/show_bug.cgi?id=10969>.
+    dnl See <https://sourceware.org/bugzilla/show_bug.cgi?id=10969>.
     dnl Also, on AIX 7.1, duplocale(LC_GLOBAL_LOCALE) returns (locale_t)0 with
     dnl errno set to EINVAL.
     dnl Also, on NetBSD 7.0, duplocale(LC_GLOBAL_LOCALE) returns a locale that
diff --git a/m4/extern-inline.m4 b/m4/extern-inline.m4
index 00f960968b..c08af18af6 100644
--- a/m4/extern-inline.m4
+++ b/m4/extern-inline.m4
@@ -11,7 +11,7 @@ AC_DEFUN([gl_EXTERN_INLINE],
 [/* Please see the Gnulib manual for how to use these macros.
 
    Suppress extern inline with HP-UX cc, as it appears to be broken; see
-   <http://lists.gnu.org/archive/html/bug-texinfo/2013-02/msg00030.html>.
+   <https://lists.gnu.org/archive/html/bug-texinfo/2013-02/msg00030.html>.
 
    Suppress extern inline with Sun C in standards-conformance mode, as it
    mishandles inline functions that call each other.  E.g., for 'inline void f
@@ -28,16 +28,16 @@ AC_DEFUN([gl_EXTERN_INLINE],
    from calling static functions.  This bug is known to occur on:
 
      OS X 10.8 and earlier; see:
-     http://lists.gnu.org/archive/html/bug-gnulib/2012-12/msg00023.html
+     https://lists.gnu.org/archive/html/bug-gnulib/2012-12/msg00023.html
 
      DragonFly; see
      http://muscles.dragonflybsd.org/bulk/bleeding-edge-potential/latest-per-pkg/ah-tty-0.3.12.log
 
      FreeBSD; see:
-     http://lists.gnu.org/archive/html/bug-gnulib/2014-07/msg00104.html
+     https://lists.gnu.org/archive/html/bug-gnulib/2014-07/msg00104.html
 
    OS X 10.9 has a macro __header_inline indicating the bug is fixed for C and
-   for clang but remains for g++; see <http://trac.macports.org/ticket/41033>.
+   for clang but remains for g++; see <https://trac.macports.org/ticket/41033>.
    Assume DragonFly and FreeBSD will be similar.  */
 #if (((defined __APPLE__ && defined __MACH__) \
       || defined __DragonFly__ || defined __FreeBSD__) \
diff --git a/m4/fpieee.m4 b/m4/fpieee.m4
index 69579d82a7..3d57112e02 100644
--- a/m4/fpieee.m4
+++ b/m4/fpieee.m4
@@ -33,7 +33,7 @@ AC_DEFUN([gl_FP_IEEE],
     alpha*)
       # On Alpha systems, a compiler option provides the behaviour.
       # See the ieee(3) manual page, also available at
-      # <http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/V51B_HTML/MAN/MAN3/0600____.HTM>
+      # <https://backdrift.org/man/tru64/man3/ieee.3.html>
       if test -n "$GCC"; then
         # GCC has the option -mieee.
         # For full IEEE compliance (rarely needed), use option -mieee-with-inexact.
diff --git a/m4/fstatat.m4 b/m4/fstatat.m4
index 75cf011040..b29ec9258e 100644
--- a/m4/fstatat.m4
+++ b/m4/fstatat.m4
@@ -20,7 +20,7 @@ AC_DEFUN([gl_FUNC_FSTATAT],
     HAVE_FSTATAT=0
   else
     dnl Test for an AIX 7.1 bug; see
-    dnl <http://lists.gnu.org/archive/html/bug-tar/2011-09/msg00015.html>.
+    dnl <https://lists.gnu.org/archive/html/bug-tar/2011-09/msg00015.html>.
     AC_CACHE_CHECK([whether fstatat (..., 0) works],
       [gl_cv_func_fstatat_zero_flag],
       [AC_RUN_IFELSE(
diff --git a/m4/gethostname.m4 b/m4/gethostname.m4
index 89bb04f5c4..fc4d8f99e6 100644
--- a/m4/gethostname.m4
+++ b/m4/gethostname.m4
@@ -48,7 +48,7 @@ AC_DEFUN([gl_PREREQ_HOST_NAME_MAX], [
   dnl - On most Unix systems, use MAXHOSTNAMELEN from <sys/param.h> instead.
   dnl - On Solaris, Cygwin, BeOS, use MAXHOSTNAMELEN from <netdb.h> instead.
   dnl - On mingw, use 256, because
-  dnl   <http://msdn.microsoft.com/en-us/library/ms738527.aspx> says:
+  dnl   <https://msdn.microsoft.com/en-us/library/ms738527.aspx> says:
   dnl   "if a buffer of 256 bytes is passed in the name parameter and
   dnl    the namelen parameter is set to 256, the buffer size will always
   dnl    be adequate."
diff --git a/m4/gnulib-common.m4 b/m4/gnulib-common.m4
index 36f2acc553..36da841287 100644
--- a/m4/gnulib-common.m4
+++ b/m4/gnulib-common.m4
@@ -228,13 +228,13 @@ m4_ifndef([AS_VAR_IF],
 # This is like AC_PROG_CC_C99, except that
 # - AC_PROG_CC_C99 did not exist in Autoconf versions < 2.60,
 # - AC_PROG_CC_C99 does not mix well with AC_PROG_CC_STDC
-#   <http://lists.gnu.org/archive/html/bug-gnulib/2011-09/msg00367.html>,
+#   <https://lists.gnu.org/archive/html/bug-gnulib/2011-09/msg00367.html>,
 #   but many more packages use AC_PROG_CC_STDC than AC_PROG_CC_C99
-#   <http://lists.gnu.org/archive/html/bug-gnulib/2011-09/msg00441.html>.
+#   <https://lists.gnu.org/archive/html/bug-gnulib/2011-09/msg00441.html>.
 # Remaining problems:
 # - When AC_PROG_CC_STDC is invoked twice, it adds the C99 enabling options
 #   to CC twice
-#   <http://lists.gnu.org/archive/html/bug-gnulib/2011-09/msg00431.html>.
+#   <https://lists.gnu.org/archive/html/bug-gnulib/2011-09/msg00431.html>.
 # - AC_PROG_CC_STDC is likely to change now that C11 is an ISO standard.
 AC_DEFUN([gl_PROG_CC_C99],
 [
diff --git a/m4/host-cpu-c-abi.m4 b/m4/host-cpu-c-abi.m4
index 02f7b8a7d4..59b0ebf67e 100644
--- a/m4/host-cpu-c-abi.m4
+++ b/m4/host-cpu-c-abi.m4
@@ -46,7 +46,7 @@ dnl   - Speed of execution of the common instruction set is reasonable across
 dnl     the entire family of CPUs. If you have assembly language source files
 dnl     that are optimized for particular CPU types (like GNU gmp has), you
 dnl     will need to make the distinction.
-dnl   See <http://en.wikipedia.org/wiki/X86_instruction_listings>.
+dnl   See <https://en.wikipedia.org/wiki/X86_instruction_listings>.
 AC_DEFUN([gl_HOST_CPU_C_ABI],
 [
   AC_REQUIRE([AC_CANONICAL_HOST])
diff --git a/m4/javacomp.m4 b/m4/javacomp.m4
index d010baea86..d0914ef284 100644
--- a/m4/javacomp.m4
+++ b/m4/javacomp.m4
@@ -20,7 +20,7 @@ dnl with or without modifications, as long as this notice is preserved.
 #           1.8             lambdas
 # Instead of source-version 1.6, use 1.5, since Java 6 did not introduce any
 # language changes. See
-# http://docs.oracle.com/javase/8/docs/technotes/guides/language/enhancements.html
+# https://docs.oracle.com/javase/8/docs/technotes/guides/language/enhancements.html
 #
 # target-version can be:  classfile version:
 #           1.1                 45.3
diff --git a/m4/lib-ignore.m4 b/m4/lib-ignore.m4
index eb2b8e2257..d90926dae8 100644
--- a/m4/lib-ignore.m4
+++ b/m4/lib-ignore.m4
@@ -53,7 +53,7 @@ AC_DEFUN([gl_IGNORE_UNUSED_LIBRARIES],
      gl_saved_ldflags=$LDFLAGS
      gl_saved_libs=$LIBS
      # Link with -lm to detect binutils 2.16 bug with --as-needed; see
-     # <http://lists.gnu.org/archive/html/bug-gnulib/2006-06/msg00131.html>.
+     # <https://lists.gnu.org/archive/html/bug-gnulib/2006-06/msg00131.html>.
      LIBS="$LIBS -lm"
      # Use long option sequences like '-z ignore' to test for the feature,
      # to forestall problems with linkers that have -z, -i, -g, -n, etc. flags.
diff --git a/m4/lib-prefix.m4 b/m4/lib-prefix.m4
index a5d56c8d78..0d03dc22ba 100644
--- a/m4/lib-prefix.m4
+++ b/m4/lib-prefix.m4
@@ -182,7 +182,7 @@ AC_DEFUN([AC_LIB_PREPARE_MULTILIB],
      case "$host_os" in
        solaris*)
          dnl See Solaris 10 Software Developer Collection > Solaris 64-bit Developer's Guide > The Development Environment
-         dnl <http://docs.sun.com/app/docs/doc/816-5138/dev-env?l=en&a=view>.
+         dnl <https://docs.oracle.com/cd/E19253-01/816-5138/dev-env/index.html>.
          dnl "Portable Makefiles should refer to any library directories using the 64 symbolic link."
          dnl But we want to recognize the sparcv9 or amd64 subdirectory also if the
          dnl symlink is missing, so we set acl_libdirstem2 too.
diff --git a/m4/memchr.m4 b/m4/memchr.m4
index 62ce770c88..0cca69d6f3 100644
--- a/m4/memchr.m4
+++ b/m4/memchr.m4
@@ -25,10 +25,10 @@ AC_DEFUN_ONCE([gl_FUNC_MEMCHR],
   if test $HAVE_MEMCHR = 1; then
     # Detect platform-specific bugs in some versions of glibc:
     # memchr should not dereference anything with length 0
-    #   http://bugzilla.redhat.com/499689
+    #   https://bugzilla.redhat.com/show_bug.cgi?id=499689
     # memchr should not dereference overestimated length after a match
-    #   http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737
-    #   http://sourceware.org/bugzilla/show_bug.cgi?id=10162
+    #   https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=521737
+    #   https://sourceware.org/bugzilla/show_bug.cgi?id=10162
     # Assume that memchr works on platforms that lack mprotect.
     AC_CACHE_CHECK([whether memchr works], [gl_cv_func_memchr_works],
       [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
diff --git a/m4/memmem.m4 b/m4/memmem.m4
index 334cb665e7..df7a119a79 100644
--- a/m4/memmem.m4
+++ b/m4/memmem.m4
@@ -21,7 +21,7 @@ AC_DEFUN([gl_FUNC_MEMMEM_SIMPLE],
   if test $ac_cv_have_decl_memmem = no; then
     HAVE_DECL_MEMMEM=0
   else
-    dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092.
+    dnl Detect https://sourceware.org/bugzilla/show_bug.cgi?id=12092.
     dnl Also check that we handle empty needles correctly.
     AC_CACHE_CHECK([whether memmem works],
       [gl_cv_func_memmem_works_always],
diff --git a/m4/printf.m4 b/m4/printf.m4
index d3ee2531de..5b4a50bae1 100644
--- a/m4/printf.m4
+++ b/m4/printf.m4
@@ -528,7 +528,7 @@ int main ()
           && strcmp (buf, "0xcp-3 33") != 0))
     result |= 4;
   /* This catches a FreeBSD 6.1 bug.  See
-     <http://lists.gnu.org/archive/html/bug-gnulib/2007-04/msg00107.html> */
+     <https://lists.gnu.org/archive/html/bug-gnulib/2007-04/msg00107.html> */
   if (sprintf (buf, "%010a %d", 1.0 / zero, 33, 44, 55) < 0
       || buf[0] == '0')
     result |= 8;
@@ -540,7 +540,7 @@ int main ()
           && strcmp (buf, "0x8.0p-2") != 0))
     result |= 16;
   /* This catches the same Mac OS X 10.3.9 (Darwin 7.9) bug and also a
-     glibc 2.4 bug <http://sourceware.org/bugzilla/show_bug.cgi?id=2908>.  */
+     glibc 2.4 bug <https://sourceware.org/bugzilla/show_bug.cgi?id=2908>.  */
   if (sprintf (buf, "%.1La", 1.999L) < 0
       || (strcmp (buf, "0x1.0p+1") != 0
           && strcmp (buf, "0x2.0p+0") != 0
@@ -862,7 +862,7 @@ changequote([,])dnl
 
 dnl Test whether the *printf family of functions supports the - flag correctly.
 dnl (ISO C99.) See
-dnl <http://lists.gnu.org/archive/html/bug-coreutils/2008-02/msg00035.html>
+dnl <https://lists.gnu.org/archive/html/bug-coreutils/2008-02/msg00035.html>
 dnl Result is gl_cv_func_printf_flag_leftadjust.
 
 AC_DEFUN([gl_PRINTF_FLAG_LEFTADJUST],
@@ -906,7 +906,7 @@ changequote([,])dnl
 
 dnl Test whether the *printf family of functions supports padding of non-finite
 dnl values with the 0 flag correctly. (ISO C99 + TC1 + TC2.) See
-dnl <http://lists.gnu.org/archive/html/bug-gnulib/2007-04/msg00107.html>
+dnl <https://lists.gnu.org/archive/html/bug-gnulib/2007-04/msg00107.html>
 dnl Result is gl_cv_func_printf_flag_zero.
 
 AC_DEFUN([gl_PRINTF_FLAG_ZERO],
diff --git a/m4/regex.m4 b/m4/regex.m4
index 23fe46a16c..ba8d6bb643 100644
--- a/m4/regex.m4
+++ b/m4/regex.m4
@@ -76,7 +76,7 @@ AC_DEFUN([gl_REGEX],
             if (setlocale (LC_ALL, "en_US.UTF-8"))
               {
                 {
-                  /* http://sourceware.org/ml/libc-hacker/2006-09/msg00008.html
+                  /* https://sourceware.org/ml/libc-hacker/2006-09/msg00008.html
                      This test needs valgrind to catch the bug on Debian
                      GNU/Linux 3.1 x86, but it might catch the bug better
                      on other platforms and it shouldn't hurt to try the
@@ -100,7 +100,7 @@ AC_DEFUN([gl_REGEX],
                 {
                   /* This test is from glibc bug 15078.
                      The test case is from Andreas Schwab in
-                     <http://www.sourceware.org/ml/libc-alpha/2013-01/msg00967.html>.
+                     <https://sourceware.org/ml/libc-alpha/2013-01/msg00967.html>.
                      */
                   static char const pat[] = "[^x]x";
                   static char const data[] =
@@ -198,7 +198,7 @@ AC_DEFUN([gl_REGEX],
               result |= 16;
 
             /* Catch a bug reported by Vin Shelton in
-               http://lists.gnu.org/archive/html/bug-coreutils/2007-06/msg00089.html
+               https://lists.gnu.org/archive/html/bug-coreutils/2007-06/msg00089.html
                */
             re_set_syntax (RE_SYNTAX_POSIX_BASIC
                            & ~RE_CONTEXT_INVALID_DUP
diff --git a/m4/stat-size.m4 b/m4/stat-size.m4
index 43dc6e9010..9a95628a04 100644
--- a/m4/stat-size.m4
+++ b/m4/stat-size.m4
@@ -9,6 +9,6 @@
 AC_DEFUN([gl_STAT_SIZE],
 [
   # Don't call AC_STRUCT_ST_BLOCKS because it causes bugs.  Details at
-  # http://lists.gnu.org/archive/html/bug-gnulib/2011-06/msg00051.html
+  # https://lists.gnu.org/archive/html/bug-gnulib/2011-06/msg00051.html
   AC_CHECK_HEADERS_ONCE([sys/param.h])
 ])
diff --git a/m4/std-gnu11.m4 b/m4/std-gnu11.m4
index bd34aa1a26..3c2f26f466 100644
--- a/m4/std-gnu11.m4
+++ b/m4/std-gnu11.m4
@@ -369,7 +369,7 @@ dnl		just the module.  Instead, define the (private) symbol
 dnl		_STDC_C99, which suppresses a bogus failure in <stdbool.h>.
 dnl		The resulting compiler passes the test case here, and that's
 dnl		good enough.  For more, please see the thread starting at:
-dnl            http://lists.gnu.org/archive/html/autoconf/2010-12/msg00059.html
+dnl            https://lists.gnu.org/archive/html/autoconf/2010-12/msg00059.html
 dnl Tru64	-c99
 dnl with extended modes being tried first.
 [[-std=gnu99 -std=c99 -c99 -AC99 -D_STDC_C99= -qlanglvl=extc1x -qlanglvl=extc99]], [$1], [$2])[]dnl
@@ -458,7 +458,7 @@ dnl preferably extc11.
 # --------------
 # Do not use AU_ALIAS here and in AC_PROG_CC_C99 and AC_PROG_CC_STDC,
 # as that'd be incompatible with how Automake redefines AC_PROG_CC.  See
-# <http://lists.gnu.org/archive/html/autoconf/2012-10/msg00048.html>.
+# <https://lists.gnu.org/archive/html/autoconf/2012-10/msg00048.html>.
 AU_DEFUN([AC_PROG_CC_C89],
   [AC_REQUIRE([AC_PROG_CC])],
   [$0 is obsolete; use AC_PROG_CC]
diff --git a/m4/stdbool.m4 b/m4/stdbool.m4
index 2bfbc6fee7..974ca5f4ab 100644
--- a/m4/stdbool.m4
+++ b/m4/stdbool.m4
@@ -88,7 +88,7 @@ AC_DEFUN([AC_CHECK_HEADER_STDBOOL],
              char p[-1 - (Bool) 0 < 0 && -1 - (bool) 0 < 0 ? 1 : -1];
              /* Catch a bug in an HP-UX C compiler.  See
                 https://gcc.gnu.org/ml/gcc-patches/2003-12/msg02303.html
-                http://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html
+                https://lists.gnu.org/archive/html/bug-coreutils/2005-11/msg00161.html
               */
              Bool q = true;
              Bool *pq = &q;
diff --git a/m4/strcasestr.m4 b/m4/strcasestr.m4
index d454ad947d..ca76b85d24 100644
--- a/m4/strcasestr.m4
+++ b/m4/strcasestr.m4
@@ -20,7 +20,7 @@ AC_DEFUN([gl_FUNC_STRCASESTR_SIMPLE],
     if test $HAVE_MEMCHR = 0 || test $REPLACE_MEMCHR = 1; then
       REPLACE_STRCASESTR=1
     else
-      dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092.
+      dnl Detect https://sourceware.org/bugzilla/show_bug.cgi?id=12092.
       AC_CACHE_CHECK([whether strcasestr works],
         [gl_cv_func_strcasestr_works_always],
         [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
diff --git a/m4/strstr.m4 b/m4/strstr.m4
index c6b7d649b8..f48a6cd803 100644
--- a/m4/strstr.m4
+++ b/m4/strstr.m4
@@ -12,7 +12,7 @@ AC_DEFUN([gl_FUNC_STRSTR_SIMPLE],
   if test $HAVE_MEMCHR = 0 || test $REPLACE_MEMCHR = 1; then
     REPLACE_STRSTR=1
   else
-    dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092.
+    dnl Detect https://sourceware.org/bugzilla/show_bug.cgi?id=12092.
     AC_CACHE_CHECK([whether strstr works],
       [gl_cv_func_strstr_works_always],
       [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
diff --git a/m4/strtok_r.m4 b/m4/strtok_r.m4
index 65c2148c45..008bdc472e 100644
--- a/m4/strtok_r.m4
+++ b/m4/strtok_r.m4
@@ -19,7 +19,7 @@ AC_DEFUN([gl_FUNC_STRTOK_R],
     dnl when the second argument to strtok_r is a constant string that has
     dnl exactly one byte and compiling with optimization.  This bug is, for
     dnl example, present in the glibc 2.7-18 package in Debian "lenny".
-    dnl See <http://sources.redhat.com/bugzilla/show_bug.cgi?id=5614>.
+    dnl See <https://sourceware.org/bugzilla/show_bug.cgi?id=5614>.
     AC_CACHE_CHECK([whether strtok_r works], [gl_cv_func_strtok_r_works],
       [AC_RUN_IFELSE(
          [AC_LANG_PROGRAM([[
diff --git a/m4/sys_types_h.m4 b/m4/sys_types_h.m4
index ec0860be90..06268cfb2d 100644
--- a/m4/sys_types_h.m4
+++ b/m4/sys_types_h.m4
@@ -40,7 +40,7 @@ AC_DEFUN([gl_SYS_TYPES_H_DEFAULTS],
 m4_version_prereq([2.70], [], [
 
 # This is taken from the following Autoconf patch:
-# http://git.sv.gnu.org/cgit/autoconf.git/commit/?id=e17a30e98
+# http://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commitdiff;h=e17a30e987d7ee695fb4294a82d987ec3dc9b974
 
 m4_undefine([AC_HEADER_MAJOR])
 AC_DEFUN([AC_HEADER_MAJOR],
diff --git a/m4/threadlib.m4 b/m4/threadlib.m4
index 6fd1b9e87a..f69c4039f2 100644
--- a/m4/threadlib.m4
+++ b/m4/threadlib.m4
@@ -66,7 +66,7 @@ changequote(,)dnl
          dnl child process gets an endless segmentation fault inside execvp().
          dnl Disable multithreading by default on Cygwin 1.5.x, because it has
          dnl bugs that lead to endless loops or crashes. See
-         dnl <http://cygwin.com/ml/cygwin/2009-08/msg00283.html>.
+         dnl <https://cygwin.com/ml/cygwin/2009-08/msg00283.html>.
          osf*) gl_use_threads=no ;;
          cygwin*)
                case `uname -r` in
@@ -169,7 +169,7 @@ int main ()
         #
         # If -pthread works, prefer it to -lpthread, since Ubuntu 14.04
         # needs -pthread for some reason.  See:
-        # http://lists.gnu.org/archive/html/bug-gnulib/2014-09/msg00023.html
+        # https://lists.gnu.org/archive/html/bug-gnulib/2014-09/msg00023.html
         save_LIBS=$LIBS
         for gl_pthread in '' '-pthread'; do
           LIBS="$LIBS $gl_pthread"
diff --git a/m4/vararrays.m4 b/m4/vararrays.m4
index 8391121ad3..38a3ed2354 100644
--- a/m4/vararrays.m4
+++ b/m4/vararrays.m4
@@ -27,7 +27,7 @@ AC_DEFUN([AC_C_VARARRAYS],
 	     [[/* Test for VLA support.  This test is partly inspired
 		  from examples in the C standard.  Use at least two VLA
 		  functions to detect the GCC 3.4.3 bug described in:
-		  http://lists.gnu.org/archive/html/bug-gnulib/2014-08/msg00014.html
+		  https://lists.gnu.org/archive/html/bug-gnulib/2014-08/msg00014.html
 		  */
 	       #ifdef __STDC_NO_VLA__
 		syntax error;
diff --git a/m4/wchar_h.m4 b/m4/wchar_h.m4
index f660ae15b2..d09ea08cb0 100644
--- a/m4/wchar_h.m4
+++ b/m4/wchar_h.m4
@@ -63,7 +63,7 @@ dnl Check whether <wchar.h> is usable at all.
 AC_DEFUN([gl_WCHAR_H_INLINE_OK],
 [
   dnl Test whether <wchar.h> suffers due to the transition from '__inline' to
-  dnl 'gnu_inline'. See <http://sourceware.org/bugzilla/show_bug.cgi?id=4022>
+  dnl 'gnu_inline'. See <https://sourceware.org/bugzilla/show_bug.cgi?id=4022>
   dnl and <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42440>. In summary,
   dnl glibc version 2.5 or older, together with gcc version 4.3 or newer and
   dnl the option -std=c99 or -std=gnu99, leads to a broken <wchar.h>.
@@ -122,7 +122,7 @@ This is a known interoperability problem of glibc <= 2.5 with gcc >= 4.3 in
 C99 mode. You have four options:
   - Add the flag -fgnu89-inline to CC and reconfigure, or
   - Fix your include files, using parts of
-    <http://sourceware.org/git/?p=glibc.git;a=commitdiff;h=b037a293a48718af30d706c2e18c929d0e69a621>, or
+    <https://sourceware.org/git/?p=glibc.git;a=commitdiff;h=b037a293a48718af30d706c2e18c929d0e69a621>, or
   - Use a gcc version older than 4.3, or
   - Don't use the flags -std=c99 or -std=gnu99.
 Configuration aborted.])
diff --git a/m4/wctob.m4 b/m4/wctob.m4
index 9de4960149..7b7d462657 100644
--- a/m4/wctob.m4
+++ b/m4/wctob.m4
@@ -17,7 +17,7 @@ AC_DEFUN([gl_FUNC_WCTOB],
 
     dnl Solaris 9 has the wctob() function but it does not work.
     dnl Cygwin 1.7.2 has the wctob() function but it clobbers caller-owned
-    dnl registers, see <http://cygwin.com/ml/cygwin/2010-05/msg00015.html>.
+    dnl registers, see <https://cygwin.com/ml/cygwin/2010-05/msg00015.html>.
     AC_REQUIRE([AC_PROG_CC])
     AC_REQUIRE([gt_LOCALE_FR])
     AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles