diff --git a/configure b/configure
index 23d14bc07..4838888f7 100755
--- a/configure
+++ b/configure
@@ -1,9 +1,9 @@
 #! /bin/sh
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.71.
+# Generated by GNU Autoconf 2.72.
 #
 #
-# Copyright (C) 1992-1996, 1998-2017, 2020-2021 Free Software Foundation,
+# Copyright (C) 1992-1996, 1998-2017, 2020-2023 Free Software Foundation,
 # Inc.
 #
 #
@@ -15,7 +15,6 @@
 
 # Be more Bourne compatible
 DUALCASE=1; export DUALCASE # for MKS sh
-as_nop=:
 if test ${ZSH_VERSION+y} && (emulate sh) >/dev/null 2>&1
 then :
   emulate sh
@@ -24,12 +23,13 @@ then :
   # is contrary to our usage.  Disable this feature.
   alias -g '${1+"$@"}'='"$@"'
   setopt NO_GLOB_SUBST
-else $as_nop
-  case `(set -o) 2>/dev/null` in #(
+else case e in #(
+  e) case `(set -o) 2>/dev/null` in #(
   *posix*) :
     set -o posix ;; #(
   *) :
      ;;
+esac ;;
 esac
 fi
 
@@ -101,7 +101,7 @@ IFS=$as_save_IFS
 
      ;;
 esac
-# We did not find ourselves, most probably we were run as `sh COMMAND'
+# We did not find ourselves, most probably we were run as 'sh COMMAND'
 # in which case we are not to be found in the path.
 if test "x$as_myself" = x; then
   as_myself=$0
@@ -131,15 +131,14 @@ case $- in # ((((
 esac
 exec $CONFIG_SHELL $as_opts "$as_myself" ${1+"$@"}
 # Admittedly, this is quite paranoid, since all the known shells bail
-# out after a failed `exec'.
+# out after a failed 'exec'.
 printf "%s\n" "$0: could not re-execute with $CONFIG_SHELL" >&2
 exit 255
   fi
   # We don't want this to propagate to other subprocesses.
           { _as_can_reexec=; unset _as_can_reexec;}
 if test "x$CONFIG_SHELL" = x; then
-  as_bourne_compatible="as_nop=:
-if test \${ZSH_VERSION+y} && (emulate sh) >/dev/null 2>&1
+  as_bourne_compatible="if test \${ZSH_VERSION+y} && (emulate sh) >/dev/null 2>&1
 then :
   emulate sh
   NULLCMD=:
@@ -147,12 +146,13 @@ then :
   # is contrary to our usage.  Disable this feature.
   alias -g '\${1+\"\$@\"}'='\"\$@\"'
   setopt NO_GLOB_SUBST
-else \$as_nop
-  case \`(set -o) 2>/dev/null\` in #(
+else case e in #(
+  e) case \`(set -o) 2>/dev/null\` in #(
   *posix*) :
     set -o posix ;; #(
   *) :
      ;;
+esac ;;
 esac
 fi
 "
@@ -170,8 +170,9 @@ as_fn_ret_failure && { exitcode=1; echo as_fn_ret_failure succeeded.; }
 if ( set x; as_fn_ret_success y && test x = \"\$1\" )
 then :
 
-else \$as_nop
-  exitcode=1; echo positional parameters were not saved.
+else case e in #(
+  e) exitcode=1; echo positional parameters were not saved. ;;
+esac
 fi
 test x\$exitcode = x0 || exit 1
 blah=\$(echo \$(echo blah))
@@ -184,14 +185,15 @@ test -x / || exit 1"
   if (eval "$as_required") 2>/dev/null
 then :
   as_have_required=yes
-else $as_nop
-  as_have_required=no
+else case e in #(
+  e) as_have_required=no ;;
+esac
 fi
   if test x$as_have_required = xyes && (eval "$as_suggested") 2>/dev/null
 then :
 
-else $as_nop
-  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+else case e in #(
+  e) as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
 as_found=false
 for as_dir in /bin$PATH_SEPARATOR/usr/bin$PATH_SEPARATOR$PATH
 do
@@ -224,12 +226,13 @@ IFS=$as_save_IFS
 if $as_found
 then :
 
-else $as_nop
-  if { test -f "$SHELL" || test -f "$SHELL.exe"; } &&
+else case e in #(
+  e) if { test -f "$SHELL" || test -f "$SHELL.exe"; } &&
 	      as_run=a "$SHELL" -c "$as_bourne_compatible""$as_required" 2>/dev/null
 then :
   CONFIG_SHELL=$SHELL as_have_required=yes
-fi
+fi ;;
+esac
 fi
 
 
@@ -251,7 +254,7 @@ case $- in # ((((
 esac
 exec $CONFIG_SHELL $as_opts "$as_myself" ${1+"$@"}
 # Admittedly, this is quite paranoid, since all the known shells bail
-# out after a failed `exec'.
+# out after a failed 'exec'.
 printf "%s\n" "$0: could not re-execute with $CONFIG_SHELL" >&2
 exit 255
 fi
@@ -270,7 +273,8 @@ $0: message. Then install a modern shell, or manually run
 $0: the script under such a shell if you do have one."
   fi
   exit 1
-fi
+fi ;;
+esac
 fi
 fi
 SHELL=${CONFIG_SHELL-/bin/sh}
@@ -309,14 +313,6 @@ as_fn_exit ()
   as_fn_set_status $1
   exit $1
 } # as_fn_exit
-# as_fn_nop
-# ---------
-# Do nothing but, unlike ":", preserve the value of $?.
-as_fn_nop ()
-{
-  return $?
-}
-as_nop=as_fn_nop
 
 # as_fn_mkdir_p
 # -------------
@@ -385,11 +381,12 @@ then :
   {
     eval $1+=\$2
   }'
-else $as_nop
-  as_fn_append ()
+else case e in #(
+  e) as_fn_append ()
   {
     eval $1=\$$1\$2
-  }
+  } ;;
+esac
 fi # as_fn_append
 
 # as_fn_arith ARG...
@@ -403,21 +400,14 @@ then :
   {
     as_val=$(( $* ))
   }'
-else $as_nop
-  as_fn_arith ()
+else case e in #(
+  e) as_fn_arith ()
   {
     as_val=`expr "$@" || test $? -eq 1`
-  }
+  } ;;
+esac
 fi # as_fn_arith
 
-# as_fn_nop
-# ---------
-# Do nothing but, unlike ":", preserve the value of $?.
-as_fn_nop ()
-{
-  return $?
-}
-as_nop=as_fn_nop
 
 # as_fn_error STATUS ERROR [LINENO LOG_FD]
 # ----------------------------------------
@@ -491,6 +481,8 @@ as_cr_alnum=$as_cr_Letters$as_cr_digits
     /[$]LINENO/=
   ' <$as_myself |
     sed '
+      t clear
+      :clear
       s/[$]LINENO.*/&-/
       t lineno
       b
@@ -539,7 +531,6 @@ esac
 as_echo='printf %s\n'
 as_echo_n='printf %s'
 
-
 rm -f conf$$ conf$$.exe conf$$.file
 if test -d conf$$.dir; then
   rm -f conf$$.dir/conf$$.file
@@ -551,9 +542,9 @@ if (echo >conf$$.file) 2>/dev/null; then
   if ln -s conf$$.file conf$$ 2>/dev/null; then
     as_ln_s='ln -s'
     # ... but there are two gotchas:
-    # 1) On MSYS, both `ln -s file dir' and `ln file dir' fail.
-    # 2) DJGPP < 2.04 has no symlinks; `ln -s' creates a wrapper executable.
-    # In both cases, we have to default to `cp -pR'.
+    # 1) On MSYS, both 'ln -s file dir' and 'ln file dir' fail.
+    # 2) DJGPP < 2.04 has no symlinks; 'ln -s' creates a wrapper executable.
+    # In both cases, we have to default to 'cp -pR'.
     ln -s conf$$.file conf$$.dir 2>/dev/null && test ! -f conf$$.exe ||
       as_ln_s='cp -pR'
   elif ln conf$$.file conf$$ 2>/dev/null; then
@@ -578,10 +569,12 @@ as_test_x='test -x'
 as_executable_p=as_fn_executable_p
 
 # Sed expression to map a string onto a valid CPP name.
-as_tr_cpp="eval sed 'y%*$as_cr_letters%P$as_cr_LETTERS%;s%[^_$as_cr_alnum]%_%g'"
+as_sed_cpp="y%*$as_cr_letters%P$as_cr_LETTERS%;s%[^_$as_cr_alnum]%_%g"
+as_tr_cpp="eval sed '$as_sed_cpp'" # deprecated
 
 # Sed expression to map a string onto a valid variable name.
-as_tr_sh="eval sed 'y%*+%pp%;s%[^_$as_cr_alnum]%_%g'"
+as_sed_sh="y%*+%pp%;s%[^_$as_cr_alnum]%_%g"
+as_tr_sh="eval sed '$as_sed_sh'" # deprecated
 
 
 test -n "$DJDIR" || exec 7<&0 </dev/null
@@ -829,7 +822,7 @@ do
     ac_useropt=`expr "x$ac_option" : 'x-*disable-\(.*\)'`
     # Reject names that are not valid shell variable names.
     expr "x$ac_useropt" : ".*[^-+._$as_cr_alnum]" >/dev/null &&
-      as_fn_error $? "invalid feature name: \`$ac_useropt'"
+      as_fn_error $? "invalid feature name: '$ac_useropt'"
     ac_useropt_orig=$ac_useropt
     ac_useropt=`printf "%s\n" "$ac_useropt" | sed 's/[-+.]/_/g'`
     case $ac_user_opts in
@@ -855,7 +848,7 @@ do
     ac_useropt=`expr "x$ac_option" : 'x-*enable-\([^=]*\)'`
     # Reject names that are not valid shell variable names.
     expr "x$ac_useropt" : ".*[^-+._$as_cr_alnum]" >/dev/null &&
-      as_fn_error $? "invalid feature name: \`$ac_useropt'"
+      as_fn_error $? "invalid feature name: '$ac_useropt'"
     ac_useropt_orig=$ac_useropt
     ac_useropt=`printf "%s\n" "$ac_useropt" | sed 's/[-+.]/_/g'`
     case $ac_user_opts in
@@ -1068,7 +1061,7 @@ do
     ac_useropt=`expr "x$ac_option" : 'x-*with-\([^=]*\)'`
     # Reject names that are not valid shell variable names.
     expr "x$ac_useropt" : ".*[^-+._$as_cr_alnum]" >/dev/null &&
-      as_fn_error $? "invalid package name: \`$ac_useropt'"
+      as_fn_error $? "invalid package name: '$ac_useropt'"
     ac_useropt_orig=$ac_useropt
     ac_useropt=`printf "%s\n" "$ac_useropt" | sed 's/[-+.]/_/g'`
     case $ac_user_opts in
@@ -1084,7 +1077,7 @@ do
     ac_useropt=`expr "x$ac_option" : 'x-*without-\(.*\)'`
     # Reject names that are not valid shell variable names.
     expr "x$ac_useropt" : ".*[^-+._$as_cr_alnum]" >/dev/null &&
-      as_fn_error $? "invalid package name: \`$ac_useropt'"
+      as_fn_error $? "invalid package name: '$ac_useropt'"
     ac_useropt_orig=$ac_useropt
     ac_useropt=`printf "%s\n" "$ac_useropt" | sed 's/[-+.]/_/g'`
     case $ac_user_opts in
@@ -1114,8 +1107,8 @@ do
   | --x-librar=* | --x-libra=* | --x-libr=* | --x-lib=* | --x-li=* | --x-l=*)
     x_libraries=$ac_optarg ;;
 
-  -*) as_fn_error $? "unrecognized option: \`$ac_option'
-Try \`$0 --help' for more information"
+  -*) as_fn_error $? "unrecognized option: '$ac_option'
+Try '$0 --help' for more information"
     ;;
 
   *=*)
@@ -1123,7 +1116,7 @@ Try \`$0 --help' for more information"
     # Reject names that are not valid shell variable names.
     case $ac_envvar in #(
       '' | [0-9]* | *[!_$as_cr_alnum]* )
-      as_fn_error $? "invalid variable name: \`$ac_envvar'" ;;
+      as_fn_error $? "invalid variable name: '$ac_envvar'" ;;
     esac
     eval $ac_envvar=\$ac_optarg
     export $ac_envvar ;;
@@ -1173,7 +1166,7 @@ do
   as_fn_error $? "expected an absolute directory name for --$ac_var: $ac_val"
 done
 
-# There might be people who depend on the old broken behavior: `$host'
+# There might be people who depend on the old broken behavior: '$host'
 # used to hold the argument of --host etc.
 # FIXME: To remove some day.
 build=$build_alias
@@ -1241,7 +1234,7 @@ if test ! -r "$srcdir/$ac_unique_file"; then
   test "$ac_srcdir_defaulted" = yes && srcdir="$ac_confdir or .."
   as_fn_error $? "cannot find sources ($ac_unique_file) in $srcdir"
 fi
-ac_msg="sources are in $srcdir, but \`cd $srcdir' does not work"
+ac_msg="sources are in $srcdir, but 'cd $srcdir' does not work"
 ac_abs_confdir=`(
 	cd "$srcdir" && test -r "./$ac_unique_file" || as_fn_error $? "$ac_msg"
 	pwd)`
@@ -1269,7 +1262,7 @@ if test "$ac_init_help" = "long"; then
   # Omit some internal or obsolete options to make the list less imposing.
   # This message is too long to be a string in the A/UX 3.1 sh.
   cat <<_ACEOF
-\`configure' configures this package to adapt to many kinds of systems.
+'configure' configures this package to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1283,11 +1276,11 @@ Configuration:
       --help=short        display options specific to this package
       --help=recursive    display the short help of all the included packages
   -V, --version           display version information and exit
-  -q, --quiet, --silent   do not print \`checking ...' messages
+  -q, --quiet, --silent   do not print 'checking ...' messages
       --cache-file=FILE   cache test results in FILE [disabled]
-  -C, --config-cache      alias for \`--cache-file=config.cache'
+  -C, --config-cache      alias for '--cache-file=config.cache'
   -n, --no-create         do not create output files
-      --srcdir=DIR        find the sources in DIR [configure dir or \`..']
+      --srcdir=DIR        find the sources in DIR [configure dir or '..']
 
 Installation directories:
   --prefix=PREFIX         install architecture-independent files in PREFIX
@@ -1295,10 +1288,10 @@ Installation directories:
   --exec-prefix=EPREFIX   install architecture-dependent files in EPREFIX
                           [PREFIX]
 
-By default, \`make install' will install all the files in
-\`$ac_default_prefix/bin', \`$ac_default_prefix/lib' etc.  You can specify
-an installation prefix other than \`$ac_default_prefix' using \`--prefix',
-for instance \`--prefix=\$HOME'.
+By default, 'make install' will install all the files in
+'$ac_default_prefix/bin', '$ac_default_prefix/lib' etc.  You can specify
+an installation prefix other than '$ac_default_prefix' using '--prefix',
+for instance '--prefix=\$HOME'.
 
 For better control, use the options below.
 
@@ -1362,7 +1355,7 @@ Some influential environment variables:
   CPPFLAGS    (Objective) C/C++ preprocessor flags, e.g. -I<include dir> if
               you have headers in a nonstandard directory <include dir>
 
-Use these variables to override the choices made by `configure' or to help
+Use these variables to override the choices made by 'configure' or to help
 it to find libraries and programs with nonstandard names/locations.
 
 Report bugs to the package provider.
@@ -1430,9 +1423,9 @@ test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
 configure
-generated by GNU Autoconf 2.71
+generated by GNU Autoconf 2.72
 
-Copyright (C) 2021 Free Software Foundation, Inc.
+Copyright (C) 2023 Free Software Foundation, Inc.
 This configure script is free software; the Free Software Foundation
 gives unlimited permission to copy, distribute and modify it.
 _ACEOF
@@ -1471,11 +1464,12 @@ printf "%s\n" "$ac_try_echo"; } >&5
        } && test -s conftest.$ac_objext
 then :
   ac_retval=0
-else $as_nop
-  printf "%s\n" "$as_me: failed program was:" >&5
+else case e in #(
+  e) printf "%s\n" "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
-	ac_retval=1
+	ac_retval=1 ;;
+esac
 fi
   eval $as_lineno_stack; ${as_lineno_stack:+:} unset as_lineno
   as_fn_set_status $ac_retval
@@ -1494,8 +1488,8 @@ printf %s "checking for $2... " >&6; }
 if eval test \${$3+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+else case e in #(
+  e) cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 $4
 #include <$2>
@@ -1503,10 +1497,12 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
   eval "$3=yes"
-else $as_nop
-  eval "$3=no"
+else case e in #(
+  e) eval "$3=no" ;;
+esac
 fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext ;;
+esac
 fi
 eval ac_res=\$$3
 	       { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
@@ -1546,11 +1542,12 @@ printf "%s\n" "$ac_try_echo"; } >&5
        }
 then :
   ac_retval=0
-else $as_nop
-  printf "%s\n" "$as_me: failed program was:" >&5
+else case e in #(
+  e) printf "%s\n" "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
-	ac_retval=1
+	ac_retval=1 ;;
+esac
 fi
   # Delete the IPA/IPO (Inter Procedural Analysis/Optimization) information
   # created by the PGI compiler (conftest_ipa8_conftest.oo), as it would
@@ -1586,7 +1583,7 @@ This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
 
 It was created by $as_me, which was
-generated by GNU Autoconf 2.71.  Invocation command line was
+generated by GNU Autoconf 2.72.  Invocation command line was
 
   $ $0$ac_configure_args_raw
 
@@ -1832,10 +1829,10 @@ esac
 printf "%s\n" "$as_me: loading site script $ac_site_file" >&6;}
     sed 's/^/| /' "$ac_site_file" >&5
     . "$ac_site_file" \
-      || { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+      || { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
 as_fn_error $? "failed to load site script $ac_site_file
-See \`config.log' for more details" "$LINENO" 5; }
+See 'config.log' for more details" "$LINENO" 5; }
   fi
 done
 
@@ -1871,9 +1868,7 @@ struct stat;
 /* Most of the following tests are stolen from RCS 5.7 src/conf.sh.  */
 struct buf { int x; };
 struct buf * (*rcsopen) (struct buf *, struct stat *, int);
-static char *e (p, i)
-     char **p;
-     int i;
+static char *e (char **p, int i)
 {
   return p[i];
 }
@@ -1887,6 +1882,21 @@ static char *f (char * (*g) (char **, int), char **p, ...)
   return s;
 }
 
+/* C89 style stringification. */
+#define noexpand_stringify(a) #a
+const char *stringified = noexpand_stringify(arbitrary+token=sequence);
+
+/* C89 style token pasting.  Exercises some of the corner cases that
+   e.g. old MSVC gets wrong, but not very hard. */
+#define noexpand_concat(a,b) a##b
+#define expand_concat(a,b) noexpand_concat(a,b)
+extern int vA;
+extern int vbee;
+#define aye A
+#define bee B
+int *pvA = &expand_concat(v,aye);
+int *pvbee = &noexpand_concat(v,bee);
+
 /* OSF 4.0 Compaq cc is some sort of almost-ANSI by default.  It has
    function prototypes and stuff, but not \xHH hex character constants.
    These do not provoke an error unfortunately, instead are silently treated
@@ -1914,16 +1924,19 @@ ok |= (argc == 0 || f (e, argv, 0) != argv[0] || f (e, argv, 1) != argv[1]);
 
 # Test code for whether the C compiler supports C99 (global declarations)
 ac_c_conftest_c99_globals='
-// Does the compiler advertise C99 conformance?
+/* Does the compiler advertise C99 conformance? */
 #if !defined __STDC_VERSION__ || __STDC_VERSION__ < 199901L
 # error "Compiler does not advertise C99 conformance"
 #endif
 
+// See if C++-style comments work.
+
 #include <stdbool.h>
 extern int puts (const char *);
 extern int printf (const char *, ...);
 extern int dprintf (int, const char *, ...);
 extern void *malloc (size_t);
+extern void free (void *);
 
 // Check varargs macros.  These examples are taken from C99 6.10.3.5.
 // dprintf is used instead of fprintf to avoid needing to declare
@@ -1973,7 +1986,6 @@ typedef const char *ccp;
 static inline int
 test_restrict (ccp restrict text)
 {
-  // See if C++-style comments work.
   // Iterate through items via the restricted pointer.
   // Also check for declarations in for loops.
   for (unsigned int i = 0; *(text+i) != '\''\0'\''; ++i)
@@ -2039,6 +2051,8 @@ ac_c_conftest_c99_main='
   ia->datasize = 10;
   for (int i = 0; i < ia->datasize; ++i)
     ia->data[i] = i * 1.234;
+  // Work around memory leak warnings.
+  free (ia);
 
   // Check named initializers.
   struct named_init ni = {
@@ -2060,7 +2074,7 @@ ac_c_conftest_c99_main='
 
 # Test code for whether the C compiler supports C11 (global declarations)
 ac_c_conftest_c11_globals='
-// Does the compiler advertise C11 conformance?
+/* Does the compiler advertise C11 conformance? */
 #if !defined __STDC_VERSION__ || __STDC_VERSION__ < 201112L
 # error "Compiler does not advertise C11 conformance"
 #endif
@@ -2183,12 +2197,12 @@ for ac_var in $ac_precious_vars; do
   eval ac_new_val=\$ac_env_${ac_var}_value
   case $ac_old_set,$ac_new_set in
     set,)
-      { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: \`$ac_var' was set to \`$ac_old_val' in the previous run" >&5
-printf "%s\n" "$as_me: error: \`$ac_var' was set to \`$ac_old_val' in the previous run" >&2;}
+      { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: '$ac_var' was set to '$ac_old_val' in the previous run" >&5
+printf "%s\n" "$as_me: error: '$ac_var' was set to '$ac_old_val' in the previous run" >&2;}
       ac_cache_corrupted=: ;;
     ,set)
-      { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: \`$ac_var' was not set in the previous run" >&5
-printf "%s\n" "$as_me: error: \`$ac_var' was not set in the previous run" >&2;}
+      { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: '$ac_var' was not set in the previous run" >&5
+printf "%s\n" "$as_me: error: '$ac_var' was not set in the previous run" >&2;}
       ac_cache_corrupted=: ;;
     ,);;
     *)
@@ -2197,18 +2211,18 @@ printf "%s\n" "$as_me: error: \`$ac_var' was not set in the previous run" >&2;}
 	ac_old_val_w=`echo x $ac_old_val`
 	ac_new_val_w=`echo x $ac_new_val`
 	if test "$ac_old_val_w" != "$ac_new_val_w"; then
-	  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: \`$ac_var' has changed since the previous run:" >&5
-printf "%s\n" "$as_me: error: \`$ac_var' has changed since the previous run:" >&2;}
+	  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: '$ac_var' has changed since the previous run:" >&5
+printf "%s\n" "$as_me: error: '$ac_var' has changed since the previous run:" >&2;}
 	  ac_cache_corrupted=:
 	else
-	  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: warning: ignoring whitespace changes in \`$ac_var' since the previous run:" >&5
-printf "%s\n" "$as_me: warning: ignoring whitespace changes in \`$ac_var' since the previous run:" >&2;}
+	  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: warning: ignoring whitespace changes in '$ac_var' since the previous run:" >&5
+printf "%s\n" "$as_me: warning: ignoring whitespace changes in '$ac_var' since the previous run:" >&2;}
 	  eval $ac_var=\$ac_old_val
 	fi
-	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}:   former value:  \`$ac_old_val'" >&5
-printf "%s\n" "$as_me:   former value:  \`$ac_old_val'" >&2;}
-	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}:   current value: \`$ac_new_val'" >&5
-printf "%s\n" "$as_me:   current value: \`$ac_new_val'" >&2;}
+	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}:   former value:  '$ac_old_val'" >&5
+printf "%s\n" "$as_me:   former value:  '$ac_old_val'" >&2;}
+	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}:   current value: '$ac_new_val'" >&5
+printf "%s\n" "$as_me:   current value: '$ac_new_val'" >&2;}
       fi;;
   esac
   # Pass precious variables to config.status.
@@ -2224,11 +2238,11 @@ printf "%s\n" "$as_me:   current value: \`$ac_new_val'" >&2;}
   fi
 done
 if $ac_cache_corrupted; then
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: changes in the environment can compromise the build" >&5
 printf "%s\n" "$as_me: error: changes in the environment can compromise the build" >&2;}
-  as_fn_error $? "run \`${MAKE-make} distclean' and/or \`rm $cache_file'
+  as_fn_error $? "run '${MAKE-make} distclean' and/or 'rm $cache_file'
 	    and start over" "$LINENO" 5
 fi
 ## -------------------- ##
@@ -2285,6 +2299,11 @@ printf "%s\n" "$as_me: CXX: ${CXX}" >&6;}
 
 # AC_MSG_NOTICE([${PACKAGE_NAME}: ${PACKAGE_VERSION}])
 
+GENERIC_INSTALL_MESSAGE="
+*** Installing this package from source requires the prior
+*** installation of external software, see for details
+*** https://r-spatial.github.io/sf/#installing"
+
 #GDAL
 GDAL_CONFIG="gdal-config"
 
@@ -2313,8 +2332,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_path_GDAL_CONFIG+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  case $GDAL_CONFIG in
+else case e in #(
+  e) case $GDAL_CONFIG in
   [\\/]* | ?:[\\/]*)
   ac_cv_path_GDAL_CONFIG="$GDAL_CONFIG" # Let the user override the test with a path.
   ;;
@@ -2340,6 +2359,7 @@ IFS=$as_save_IFS
 
   test -z "$ac_cv_path_GDAL_CONFIG" && ac_cv_path_GDAL_CONFIG=""no""
   ;;
+esac ;;
 esac
 fi
 GDAL_CONFIG=$ac_cv_path_GDAL_CONFIG
@@ -2355,7 +2375,7 @@ fi
   if test "$GDAL_CONFIG" = "no" ; then
     { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
 printf "%s\n" "no" >&6; }
-    as_fn_error $? "gdal-config not found or not executable." "$LINENO" 5
+    as_fn_error $? "gdal-config not found or not executable. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
   fi
 else
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking gdal-config exists" >&5
@@ -2366,7 +2386,7 @@ printf "%s\n" "yes" >&6; }
   else
     { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
 printf "%s\n" "no" >&6; }
-    as_fn_error $? "gdal-config not found - configure argument error." "$LINENO" 5
+    as_fn_error $? "gdal-config not found - configure argument error. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
   fi
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking gdal-config executable" >&5
 printf %s "checking gdal-config executable... " >&6; }
@@ -2376,7 +2396,7 @@ printf "%s\n" "yes" >&6; }
   else
     { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
 printf "%s\n" "no" >&6; }
-    as_fn_error $? "gdal-config not executable." "$LINENO" 5
+    as_fn_error $? "gdal-config not executable. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
   fi
 fi
 
@@ -2392,20 +2412,7 @@ then
 	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
 printf "%s\n" "yes" >&6; }
 else
-	{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
-printf "%s\n" "no" >&6; }
-	echo "Error: gdal-config not found"
-	echo "The gdal-config script distributed with GDAL could not be found."
-	echo "If you have not installed the GDAL libraries, you can"
-	echo "download the source from  http://www.gdal.org/"
-	echo "If you have installed the GDAL libraries, then make sure that"
-	echo "gdal-config is in your path. Try typing gdal-config at a"
-	echo "shell prompt and see if it runs. If not, use:"
-	echo " --configure-args='--with-gdal-config=/usr/local/bin/gdal-config'"
-	echo "with appropriate values for your installation."
-	echo ""
-
-	exit 1
+	as_fn_error $? "gdal-config not found. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
 fi
 
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: GDAL: ${GDAL_VERSION}" >&5
@@ -2467,8 +2474,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
+else case e in #(
+  e) if test -n "$CC"; then
   ac_cv_prog_CC="$CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2490,7 +2497,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 CC=$ac_cv_prog_CC
 if test -n "$CC"; then
@@ -2512,8 +2520,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_ac_ct_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$ac_ct_CC"; then
+else case e in #(
+  e) if test -n "$ac_ct_CC"; then
   ac_cv_prog_ac_ct_CC="$ac_ct_CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2535,7 +2543,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 ac_ct_CC=$ac_cv_prog_ac_ct_CC
 if test -n "$ac_ct_CC"; then
@@ -2570,8 +2579,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
+else case e in #(
+  e) if test -n "$CC"; then
   ac_cv_prog_CC="$CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2593,7 +2602,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 CC=$ac_cv_prog_CC
 if test -n "$CC"; then
@@ -2615,8 +2625,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
+else case e in #(
+  e) if test -n "$CC"; then
   ac_cv_prog_CC="$CC" # Let the user override the test.
 else
   ac_prog_rejected=no
@@ -2655,7 +2665,8 @@ if test $ac_prog_rejected = yes; then
     ac_cv_prog_CC="$as_dir$ac_word${1+' '}$@"
   fi
 fi
-fi
+fi ;;
+esac
 fi
 CC=$ac_cv_prog_CC
 if test -n "$CC"; then
@@ -2679,8 +2690,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
+else case e in #(
+  e) if test -n "$CC"; then
   ac_cv_prog_CC="$CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2702,7 +2713,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 CC=$ac_cv_prog_CC
 if test -n "$CC"; then
@@ -2728,8 +2740,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_ac_ct_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$ac_ct_CC"; then
+else case e in #(
+  e) if test -n "$ac_ct_CC"; then
   ac_cv_prog_ac_ct_CC="$ac_ct_CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2751,7 +2763,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 ac_ct_CC=$ac_cv_prog_ac_ct_CC
 if test -n "$ac_ct_CC"; then
@@ -2789,8 +2802,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$CC"; then
+else case e in #(
+  e) if test -n "$CC"; then
   ac_cv_prog_CC="$CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2812,7 +2825,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 CC=$ac_cv_prog_CC
 if test -n "$CC"; then
@@ -2834,8 +2848,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_prog_ac_ct_CC+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  if test -n "$ac_ct_CC"; then
+else case e in #(
+  e) if test -n "$ac_ct_CC"; then
   ac_cv_prog_ac_ct_CC="$ac_ct_CC" # Let the user override the test.
 else
 as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
@@ -2857,7 +2871,8 @@ done
   done
 IFS=$as_save_IFS
 
-fi
+fi ;;
+esac
 fi
 ac_ct_CC=$ac_cv_prog_ac_ct_CC
 if test -n "$ac_ct_CC"; then
@@ -2886,10 +2901,10 @@ fi
 fi
 
 
-test -z "$CC" && { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+test -z "$CC" && { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
 as_fn_error $? "no acceptable C compiler found in \$PATH
-See \`config.log' for more details" "$LINENO" 5; }
+See 'config.log' for more details" "$LINENO" 5; }
 
 # Provide some information about the compiler.
 printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for C compiler version" >&5
@@ -2961,8 +2976,8 @@ printf "%s\n" "$ac_try_echo"; } >&5
   printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
   test $ac_status = 0; }
 then :
-  # Autoconf-2.13 could set the ac_cv_exeext variable to `no'.
-# So ignore a value of `no', otherwise this would lead to `EXEEXT = no'
+  # Autoconf-2.13 could set the ac_cv_exeext variable to 'no'.
+# So ignore a value of 'no', otherwise this would lead to 'EXEEXT = no'
 # in a Makefile.  We should not override ac_cv_exeext if it was cached,
 # so that the user can short-circuit this test for compilers unknown to
 # Autoconf.
@@ -2982,7 +2997,7 @@ do
 	   ac_cv_exeext=`expr "$ac_file" : '[^.]*\(\..*\)'`
 	fi
 	# We set ac_cv_exeext here because the later test for it is not
-	# safe: cross compilers may not add the suffix if given an `-o'
+	# safe: cross compilers may not add the suffix if given an '-o'
 	# argument, so we may need to know it at that point already.
 	# Even if this section looks crufty: it has the advantage of
 	# actually working.
@@ -2993,8 +3008,9 @@ do
 done
 test "$ac_cv_exeext" = no && ac_cv_exeext=
 
-else $as_nop
-  ac_file=''
+else case e in #(
+  e) ac_file='' ;;
+esac
 fi
 if test -z "$ac_file"
 then :
@@ -3003,13 +3019,14 @@ printf "%s\n" "no" >&6; }
 printf "%s\n" "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
-{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
 as_fn_error 77 "C compiler cannot create executables
-See \`config.log' for more details" "$LINENO" 5; }
-else $as_nop
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
-printf "%s\n" "yes" >&6; }
+See 'config.log' for more details" "$LINENO" 5; }
+else case e in #(
+  e) { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+printf "%s\n" "yes" >&6; } ;;
+esac
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for C compiler default output file name" >&5
 printf %s "checking for C compiler default output file name... " >&6; }
@@ -3033,10 +3050,10 @@ printf "%s\n" "$ac_try_echo"; } >&5
   printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
   test $ac_status = 0; }
 then :
-  # If both `conftest.exe' and `conftest' are `present' (well, observable)
-# catch `conftest.exe'.  For instance with Cygwin, `ls conftest' will
-# work properly (i.e., refer to `conftest.exe'), while it won't with
-# `rm'.
+  # If both 'conftest.exe' and 'conftest' are 'present' (well, observable)
+# catch 'conftest.exe'.  For instance with Cygwin, 'ls conftest' will
+# work properly (i.e., refer to 'conftest.exe'), while it won't with
+# 'rm'.
 for ac_file in conftest.exe conftest conftest.*; do
   test -f "$ac_file" || continue
   case $ac_file in
@@ -3046,11 +3063,12 @@ for ac_file in conftest.exe conftest conftest.*; do
     * ) break;;
   esac
 done
-else $as_nop
-  { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+else case e in #(
+  e) { { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
 as_fn_error $? "cannot compute suffix of executables: cannot compile and link
-See \`config.log' for more details" "$LINENO" 5; }
+See 'config.log' for more details" "$LINENO" 5; } ;;
+esac
 fi
 rm -f conftest conftest$ac_cv_exeext
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_exeext" >&5
@@ -3066,6 +3084,8 @@ int
 main (void)
 {
 FILE *f = fopen ("conftest.out", "w");
+ if (!f)
+  return 1;
  return ferror (f) || fclose (f) != 0;
 
   ;
@@ -3105,26 +3125,27 @@ printf "%s\n" "$ac_try_echo"; } >&5
     if test "$cross_compiling" = maybe; then
 	cross_compiling=yes
     else
-	{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+	{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
 as_fn_error 77 "cannot run C compiled programs.
-If you meant to cross compile, use \`--host'.
-See \`config.log' for more details" "$LINENO" 5; }
+If you meant to cross compile, use '--host'.
+See 'config.log' for more details" "$LINENO" 5; }
     fi
   fi
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $cross_compiling" >&5
 printf "%s\n" "$cross_compiling" >&6; }
 
-rm -f conftest.$ac_ext conftest$ac_cv_exeext conftest.out
+rm -f conftest.$ac_ext conftest$ac_cv_exeext \
+  conftest.o conftest.obj conftest.out
 ac_clean_files=$ac_clean_files_save
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking for suffix of object files" >&5
 printf %s "checking for suffix of object files... " >&6; }
 if test ${ac_cv_objext+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+else case e in #(
+  e) cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 int
@@ -3156,16 +3177,18 @@ then :
        break;;
   esac
 done
-else $as_nop
-  printf "%s\n" "$as_me: failed program was:" >&5
+else case e in #(
+  e) printf "%s\n" "$as_me: failed program was:" >&5
 sed 's/^/| /' conftest.$ac_ext >&5
 
-{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
-printf "%s\n" "$as_me: error: in \`$ac_pwd':" >&2;}
+{ { printf "%s\n" "$as_me:${as_lineno-$LINENO}: error: in '$ac_pwd':" >&5
+printf "%s\n" "$as_me: error: in '$ac_pwd':" >&2;}
 as_fn_error $? "cannot compute suffix of object files: cannot compile
-See \`config.log' for more details" "$LINENO" 5; }
+See 'config.log' for more details" "$LINENO" 5; } ;;
+esac
 fi
-rm -f conftest.$ac_cv_objext conftest.$ac_ext
+rm -f conftest.$ac_cv_objext conftest.$ac_ext ;;
+esac
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_objext" >&5
 printf "%s\n" "$ac_cv_objext" >&6; }
@@ -3176,8 +3199,8 @@ printf %s "checking whether the compiler supports GNU C... " >&6; }
 if test ${ac_cv_c_compiler_gnu+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+else case e in #(
+  e) cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 int
@@ -3194,12 +3217,14 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
   ac_compiler_gnu=yes
-else $as_nop
-  ac_compiler_gnu=no
+else case e in #(
+  e) ac_compiler_gnu=no ;;
+esac
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
 ac_cv_c_compiler_gnu=$ac_compiler_gnu
-
+ ;;
+esac
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_c_compiler_gnu" >&5
 printf "%s\n" "$ac_cv_c_compiler_gnu" >&6; }
@@ -3217,8 +3242,8 @@ printf %s "checking whether $CC accepts -g... " >&6; }
 if test ${ac_cv_prog_cc_g+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  ac_save_c_werror_flag=$ac_c_werror_flag
+else case e in #(
+  e) ac_save_c_werror_flag=$ac_c_werror_flag
    ac_c_werror_flag=yes
    ac_cv_prog_cc_g=no
    CFLAGS="-g"
@@ -3236,8 +3261,8 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
   ac_cv_prog_cc_g=yes
-else $as_nop
-  CFLAGS=""
+else case e in #(
+  e) CFLAGS=""
       cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -3252,8 +3277,8 @@ _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
 
-else $as_nop
-  ac_c_werror_flag=$ac_save_c_werror_flag
+else case e in #(
+  e) ac_c_werror_flag=$ac_save_c_werror_flag
 	 CFLAGS="-g"
 	 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
@@ -3270,12 +3295,15 @@ if ac_fn_c_try_compile "$LINENO"
 then :
   ac_cv_prog_cc_g=yes
 fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext ;;
+esac
 fi
-rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext ;;
+esac
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
-   ac_c_werror_flag=$ac_save_c_werror_flag
+   ac_c_werror_flag=$ac_save_c_werror_flag ;;
+esac
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_g" >&5
 printf "%s\n" "$ac_cv_prog_cc_g" >&6; }
@@ -3302,8 +3330,8 @@ printf %s "checking for $CC option to enable C11 features... " >&6; }
 if test ${ac_cv_prog_cc_c11+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  ac_cv_prog_cc_c11=no
+else case e in #(
+  e) ac_cv_prog_cc_c11=no
 ac_save_CC=$CC
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
@@ -3320,25 +3348,28 @@ rm -f core conftest.err conftest.$ac_objext conftest.beam
   test "x$ac_cv_prog_cc_c11" != "xno" && break
 done
 rm -f conftest.$ac_ext
-CC=$ac_save_CC
+CC=$ac_save_CC ;;
+esac
 fi
 
 if test "x$ac_cv_prog_cc_c11" = xno
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: unsupported" >&5
 printf "%s\n" "unsupported" >&6; }
-else $as_nop
-  if test "x$ac_cv_prog_cc_c11" = x
+else case e in #(
+  e) if test "x$ac_cv_prog_cc_c11" = x
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: none needed" >&5
 printf "%s\n" "none needed" >&6; }
-else $as_nop
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c11" >&5
+else case e in #(
+  e) { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c11" >&5
 printf "%s\n" "$ac_cv_prog_cc_c11" >&6; }
-     CC="$CC $ac_cv_prog_cc_c11"
+     CC="$CC $ac_cv_prog_cc_c11" ;;
+esac
 fi
   ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c11
-  ac_prog_cc_stdc=c11
+  ac_prog_cc_stdc=c11 ;;
+esac
 fi
 fi
 if test x$ac_prog_cc_stdc = xno
@@ -3348,8 +3379,8 @@ printf %s "checking for $CC option to enable C99 features... " >&6; }
 if test ${ac_cv_prog_cc_c99+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  ac_cv_prog_cc_c99=no
+else case e in #(
+  e) ac_cv_prog_cc_c99=no
 ac_save_CC=$CC
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
@@ -3366,25 +3397,28 @@ rm -f core conftest.err conftest.$ac_objext conftest.beam
   test "x$ac_cv_prog_cc_c99" != "xno" && break
 done
 rm -f conftest.$ac_ext
-CC=$ac_save_CC
+CC=$ac_save_CC ;;
+esac
 fi
 
 if test "x$ac_cv_prog_cc_c99" = xno
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: unsupported" >&5
 printf "%s\n" "unsupported" >&6; }
-else $as_nop
-  if test "x$ac_cv_prog_cc_c99" = x
+else case e in #(
+  e) if test "x$ac_cv_prog_cc_c99" = x
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: none needed" >&5
 printf "%s\n" "none needed" >&6; }
-else $as_nop
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c99" >&5
+else case e in #(
+  e) { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c99" >&5
 printf "%s\n" "$ac_cv_prog_cc_c99" >&6; }
-     CC="$CC $ac_cv_prog_cc_c99"
+     CC="$CC $ac_cv_prog_cc_c99" ;;
+esac
 fi
   ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c99
-  ac_prog_cc_stdc=c99
+  ac_prog_cc_stdc=c99 ;;
+esac
 fi
 fi
 if test x$ac_prog_cc_stdc = xno
@@ -3394,8 +3428,8 @@ printf %s "checking for $CC option to enable C89 features... " >&6; }
 if test ${ac_cv_prog_cc_c89+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  ac_cv_prog_cc_c89=no
+else case e in #(
+  e) ac_cv_prog_cc_c89=no
 ac_save_CC=$CC
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
@@ -3412,25 +3446,28 @@ rm -f core conftest.err conftest.$ac_objext conftest.beam
   test "x$ac_cv_prog_cc_c89" != "xno" && break
 done
 rm -f conftest.$ac_ext
-CC=$ac_save_CC
+CC=$ac_save_CC ;;
+esac
 fi
 
 if test "x$ac_cv_prog_cc_c89" = xno
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: unsupported" >&5
 printf "%s\n" "unsupported" >&6; }
-else $as_nop
-  if test "x$ac_cv_prog_cc_c89" = x
+else case e in #(
+  e) if test "x$ac_cv_prog_cc_c89" = x
 then :
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: none needed" >&5
 printf "%s\n" "none needed" >&6; }
-else $as_nop
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c89" >&5
+else case e in #(
+  e) { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_prog_cc_c89" >&5
 printf "%s\n" "$ac_cv_prog_cc_c89" >&6; }
-     CC="$CC $ac_cv_prog_cc_c89"
+     CC="$CC $ac_cv_prog_cc_c89" ;;
+esac
 fi
   ac_cv_prog_cc_stdc=$ac_cv_prog_cc_c89
-  ac_prog_cc_stdc=c89
+  ac_prog_cc_stdc=c89 ;;
+esac
 fi
 fi
 
@@ -3477,13 +3514,14 @@ if test "x$ac_cv_header_gdal_h" = xyes
 then :
   printf "%s\n" "#define HAVE_GDAL_H 1" >>confdefs.h
 
-else $as_nop
-  gdalok=no
+else case e in #(
+  e) gdalok=no ;;
+esac
 fi
 
 done
 if test "${gdalok}" = no; then
-   as_fn_error $? "gdal.h not found in given locations." "$LINENO" 5
+   as_fn_error $? "gdal.h not found in given locations. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
 fi
 
 NEED_DEPS=no
@@ -3536,7 +3574,7 @@ if test "${gdalok}" = no; then
    cat errors.txt
    { printf "%s\n" "$as_me:${as_lineno-$LINENO}: Install failure: compilation and/or linkage problems." >&5
 printf "%s\n" "$as_me: Install failure: compilation and/or linkage problems." >&6;}
-   as_fn_error $? "GDALAllRegister not found in libgdal." "$LINENO" 5
+   as_fn_error $? "GDALAllRegister not found in libgdal. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
 fi
 
 rm -f gdal_test errors.txt gdal_test.cpp
@@ -3770,8 +3808,9 @@ if test "x$ac_cv_header_proj_h" = xyes
 then :
   printf "%s\n" "#define HAVE_PROJ_H 1" >>confdefs.h
 
-else $as_nop
-  PROJH=no
+else case e in #(
+  e) PROJH=no ;;
+esac
 fi
 
 done
@@ -3794,8 +3833,9 @@ if test "x$ac_cv_header_proj_api_h" = xyes
 then :
   printf "%s\n" "#define HAVE_PROJ_API_H 1" >>confdefs.h
 
-else $as_nop
-  proj4ok=no
+else case e in #(
+  e) proj4ok=no ;;
+esac
 fi
 
 done
@@ -3841,16 +3881,22 @@ printf %s "checking for pj_init_plus in -lproj... " >&6; }
 if test ${ac_cv_lib_proj_pj_init_plus+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  ac_check_lib_save_LIBS=$LIBS
+else case e in #(
+  e) ac_check_lib_save_LIBS=$LIBS
 LIBS="-lproj  $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 /* Override any GCC internal prototype to avoid an error.
    Use char because int might match the return type of a GCC
-   builtin and then its argument prototype would still apply.  */
-char pj_init_plus ();
+   builtin and then its argument prototype would still apply.
+   The 'extern "C"' is for builds by C++ compilers;
+   although this is not generally supported in C code supporting it here
+   has little cost and some practical benefit (sr 110532).  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char pj_init_plus (void);
 int
 main (void)
 {
@@ -3862,12 +3908,14 @@ _ACEOF
 if ac_fn_c_try_link "$LINENO"
 then :
   ac_cv_lib_proj_pj_init_plus=yes
-else $as_nop
-  ac_cv_lib_proj_pj_init_plus=no
+else case e in #(
+  e) ac_cv_lib_proj_pj_init_plus=no ;;
+esac
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam \
     conftest$ac_exeext conftest.$ac_ext
-LIBS=$ac_check_lib_save_LIBS
+LIBS=$ac_check_lib_save_LIBS ;;
+esac
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_proj_pj_init_plus" >&5
 printf "%s\n" "$ac_cv_lib_proj_pj_init_plus" >&6; }
@@ -3877,12 +3925,13 @@ then :
 
   LIBS="-lproj $LIBS"
 
-else $as_nop
-  proj4ok=no
+else case e in #(
+  e) proj4ok=no ;;
+esac
 fi
 
   if test "${proj4ok}" = no; then
-     as_fn_error $? "libproj not found in standard or given locations." "$LINENO" 5
+     as_fn_error $? "libproj not found in standard or given locations. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
   fi
 cat > proj_conf_test.c <<_EOCONF
 #include <stdio.h>
@@ -3919,7 +3968,7 @@ printf "%s\n" "no" >&6; }
 printf "%s\n" "yes" >&6; }
   fi
   if test "${proj6ok}" = no; then
-     as_fn_error $? "libproj or sqlite3 not found in standard or given locations." "$LINENO" 5
+     as_fn_error $? "libproj or sqlite3 not found in standard or given locations. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
   fi
 
 cat > proj_conf_test.c <<_EOCONF
@@ -4153,8 +4202,8 @@ printf %s "checking for $ac_word... " >&6; }
 if test ${ac_cv_path_GEOS_CONFIG+y}
 then :
   printf %s "(cached) " >&6
-else $as_nop
-  case $GEOS_CONFIG in
+else case e in #(
+  e) case $GEOS_CONFIG in
   [\\/]* | ?:[\\/]*)
   ac_cv_path_GEOS_CONFIG="$GEOS_CONFIG" # Let the user override the test with a path.
   ;;
@@ -4180,6 +4229,7 @@ IFS=$as_save_IFS
 
   test -z "$ac_cv_path_GEOS_CONFIG" && ac_cv_path_GEOS_CONFIG=""no""
   ;;
+esac ;;
 esac
 fi
 GEOS_CONFIG=$ac_cv_path_GEOS_CONFIG
@@ -4195,7 +4245,7 @@ fi
   if test "$GEOS_CONFIG" = "no" ; then
     { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
 printf "%s\n" "no" >&6; }
-    as_fn_error $? "geos-config not found or not executable." "$LINENO" 5
+    as_fn_error $? "geos-config not found or not executable. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
   fi
 else
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking geos-config exists" >&5
@@ -4206,7 +4256,7 @@ printf "%s\n" "yes" >&6; }
   else
     { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
 printf "%s\n" "no" >&6; }
-    as_fn_error $? "geos-config not found - configure argument error." "$LINENO" 5
+    as_fn_error $? "geos-config not found - configure argument error. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
   fi
   { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking geos-config executable" >&5
 printf %s "checking geos-config executable... " >&6; }
@@ -4216,7 +4266,7 @@ printf "%s\n" "yes" >&6; }
   else
     { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: no" >&5
 printf "%s\n" "no" >&6; }
-    as_fn_error $? "geos-config not executable." "$LINENO" 5
+    as_fn_error $? "geos-config not executable. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
   fi
 fi
 
@@ -4275,13 +4325,14 @@ if test "x$ac_cv_header_geos_c_h" = xyes
 then :
   printf "%s\n" "#define HAVE_GEOS_C_H 1" >>confdefs.h
 
-else $as_nop
-  geosok=no
+else case e in #(
+  e) geosok=no ;;
+esac
 fi
 
 done
 if test "${geosok}" = no; then
-   as_fn_error $? "geos_c.h not found in given locations." "$LINENO" 5
+   as_fn_error $? "geos_c.h not found in given locations. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
 fi
 
 cat > geos_test.cpp <<_EOCONF
@@ -4330,7 +4381,7 @@ printf "%s\n" "no" >&6; }
     cat errors.txt
     { printf "%s\n" "$as_me:${as_lineno-$LINENO}: Install failure: compilation and/or linkage problems." >&5
 printf "%s\n" "$as_me: Install failure: compilation and/or linkage problems." >&6;}
-    as_fn_error $? "initGEOS_r not found in libgeos_c." "$LINENO" 5
+    as_fn_error $? "initGEOS_r not found in libgeos_c. ${GENERIC_INSTALL_MESSAGE}" "$LINENO" 5
   else
     PKG_LIBS="${PKG_LIBS} ${GEOS_DEP_CLIBS}"
 
@@ -4367,8 +4418,8 @@ cat >confcache <<\_ACEOF
 # config.status only pays attention to the cache file if you give it
 # the --recheck option to rerun configure.
 #
-# `ac_cv_env_foo' variables (set or unset) will be overridden when
-# loading this file, other *unset* `ac_cv_foo' will be assigned the
+# 'ac_cv_env_foo' variables (set or unset) will be overridden when
+# loading this file, other *unset* 'ac_cv_foo' will be assigned the
 # following values.
 
 _ACEOF
@@ -4398,14 +4449,14 @@ printf "%s\n" "$as_me: WARNING: cache variable $ac_var contains a newline" >&2;}
   (set) 2>&1 |
     case $as_nl`(ac_space=' '; set) 2>&1` in #(
     *${as_nl}ac_space=\ *)
-      # `set' does not quote correctly, so add quotes: double-quote
+      # 'set' does not quote correctly, so add quotes: double-quote
       # substitution turns \\\\ into \\, and sed turns \\ into \.
       sed -n \
 	"s/'/'\\\\''/g;
 	  s/^\\([_$as_cr_alnum]*_cv_[_$as_cr_alnum]*\\)=\\(.*\\)/\\1='\\2'/p"
       ;; #(
     *)
-      # `set' quotes correctly as required by POSIX, so do not add quotes.
+      # 'set' quotes correctly as required by POSIX, so do not add quotes.
       sed -n "/^[_$as_cr_alnum]*_cv_[_$as_cr_alnum]*=/p"
       ;;
     esac |
@@ -4469,9 +4520,7 @@ s/^[	 ]*#[	 ]*define[	 ][	 ]*\([^	 ][^	 ]*\)[	 ]*\(.*\)/-D\1=\2/g
 t quote
 b any
 :quote
-s/[	 `~#$^&*(){}\\|;'\''"<>?]/\\&/g
-s/\[/\\&/g
-s/\]/\\&/g
+s/[][	 `~#$^&*(){}\\|;'\''"<>?]/\\&/g
 s/\$/$$/g
 H
 :any
@@ -4531,7 +4580,6 @@ cat >>$CONFIG_STATUS <<\_ASEOF || as_write_fail=1
 
 # Be more Bourne compatible
 DUALCASE=1; export DUALCASE # for MKS sh
-as_nop=:
 if test ${ZSH_VERSION+y} && (emulate sh) >/dev/null 2>&1
 then :
   emulate sh
@@ -4540,12 +4588,13 @@ then :
   # is contrary to our usage.  Disable this feature.
   alias -g '${1+"$@"}'='"$@"'
   setopt NO_GLOB_SUBST
-else $as_nop
-  case `(set -o) 2>/dev/null` in #(
+else case e in #(
+  e) case `(set -o) 2>/dev/null` in #(
   *posix*) :
     set -o posix ;; #(
   *) :
      ;;
+esac ;;
 esac
 fi
 
@@ -4617,7 +4666,7 @@ IFS=$as_save_IFS
 
      ;;
 esac
-# We did not find ourselves, most probably we were run as `sh COMMAND'
+# We did not find ourselves, most probably we were run as 'sh COMMAND'
 # in which case we are not to be found in the path.
 if test "x$as_myself" = x; then
   as_myself=$0
@@ -4646,7 +4695,6 @@ as_fn_error ()
 } # as_fn_error
 
 
-
 # as_fn_set_status STATUS
 # -----------------------
 # Set $? to STATUS, without forking.
@@ -4686,11 +4734,12 @@ then :
   {
     eval $1+=\$2
   }'
-else $as_nop
-  as_fn_append ()
+else case e in #(
+  e) as_fn_append ()
   {
     eval $1=\$$1\$2
-  }
+  } ;;
+esac
 fi # as_fn_append
 
 # as_fn_arith ARG...
@@ -4704,11 +4753,12 @@ then :
   {
     as_val=$(( $* ))
   }'
-else $as_nop
-  as_fn_arith ()
+else case e in #(
+  e) as_fn_arith ()
   {
     as_val=`expr "$@" || test $? -eq 1`
-  }
+  } ;;
+esac
 fi # as_fn_arith
 
 
@@ -4791,9 +4841,9 @@ if (echo >conf$$.file) 2>/dev/null; then
   if ln -s conf$$.file conf$$ 2>/dev/null; then
     as_ln_s='ln -s'
     # ... but there are two gotchas:
-    # 1) On MSYS, both `ln -s file dir' and `ln file dir' fail.
-    # 2) DJGPP < 2.04 has no symlinks; `ln -s' creates a wrapper executable.
-    # In both cases, we have to default to `cp -pR'.
+    # 1) On MSYS, both 'ln -s file dir' and 'ln file dir' fail.
+    # 2) DJGPP < 2.04 has no symlinks; 'ln -s' creates a wrapper executable.
+    # In both cases, we have to default to 'cp -pR'.
     ln -s conf$$.file conf$$.dir 2>/dev/null && test ! -f conf$$.exe ||
       as_ln_s='cp -pR'
   elif ln conf$$.file conf$$ 2>/dev/null; then
@@ -4874,10 +4924,12 @@ as_test_x='test -x'
 as_executable_p=as_fn_executable_p
 
 # Sed expression to map a string onto a valid CPP name.
-as_tr_cpp="eval sed 'y%*$as_cr_letters%P$as_cr_LETTERS%;s%[^_$as_cr_alnum]%_%g'"
+as_sed_cpp="y%*$as_cr_letters%P$as_cr_LETTERS%;s%[^_$as_cr_alnum]%_%g"
+as_tr_cpp="eval sed '$as_sed_cpp'" # deprecated
 
 # Sed expression to map a string onto a valid variable name.
-as_tr_sh="eval sed 'y%*+%pp%;s%[^_$as_cr_alnum]%_%g'"
+as_sed_sh="y%*+%pp%;s%[^_$as_cr_alnum]%_%g"
+as_tr_sh="eval sed '$as_sed_sh'" # deprecated
 
 
 exec 6>&1
@@ -4893,7 +4945,7 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 # values after options handling.
 ac_log="
 This file was extended by $as_me, which was
-generated by GNU Autoconf 2.71.  Invocation command line was
+generated by GNU Autoconf 2.72.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
   CONFIG_HEADERS  = $CONFIG_HEADERS
@@ -4920,7 +4972,7 @@ _ACEOF
 
 cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 ac_cs_usage="\
-\`$as_me' instantiates files and other configuration actions
+'$as_me' instantiates files and other configuration actions
 from templates according to the current configuration.  Unless the files
 and actions are specified as TAGs, all are instantiated by default.
 
@@ -4948,10 +5000,10 @@ cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config='$ac_cs_config_escaped'
 ac_cs_version="\\
 config.status
-configured by $0, generated by GNU Autoconf 2.71,
+configured by $0, generated by GNU Autoconf 2.72,
   with options \\"\$ac_cs_config\\"
 
-Copyright (C) 2021 Free Software Foundation, Inc.
+Copyright (C) 2023 Free Software Foundation, Inc.
 This config.status script is free software; the Free Software Foundation
 gives unlimited permission to copy, distribute and modify it."
 
@@ -5008,8 +5060,8 @@ do
     ac_cs_silent=: ;;
 
   # This is an error.
-  -*) as_fn_error $? "unrecognized option: \`$1'
-Try \`$0 --help' for more information." ;;
+  -*) as_fn_error $? "unrecognized option: '$1'
+Try '$0 --help' for more information." ;;
 
   *) as_fn_append ac_config_targets " $1"
      ac_need_defaults=false ;;
@@ -5059,7 +5111,7 @@ do
   case $ac_config_target in
     "src/Makevars") CONFIG_FILES="$CONFIG_FILES src/Makevars" ;;
 
-  *) as_fn_error $? "invalid argument: \`$ac_config_target'" "$LINENO" 5;;
+  *) as_fn_error $? "invalid argument: '$ac_config_target'" "$LINENO" 5;;
   esac
 done
 
@@ -5077,7 +5129,7 @@ fi
 # creating and moving files from /tmp can sometimes cause problems.
 # Hook for its removal unless debugging.
 # Note that there is a small window in which the directory will not be cleaned:
-# after its creation but before its name has been assigned to `$tmp'.
+# after its creation but before its name has been assigned to '$tmp'.
 $debug ||
 {
   tmp= ac_tmp=
@@ -5101,7 +5153,7 @@ ac_tmp=$tmp
 
 # Set up the scripts for CONFIG_FILES section.
 # No need to generate them if there are no CONFIG_FILES.
-# This happens for instance with `./config.status config.h'.
+# This happens for instance with './config.status config.h'.
 if test -n "$CONFIG_FILES"; then
 
 
@@ -5267,7 +5319,7 @@ do
   esac
   case $ac_mode$ac_tag in
   :[FHL]*:*);;
-  :L* | :C*:*) as_fn_error $? "invalid tag \`$ac_tag'" "$LINENO" 5;;
+  :L* | :C*:*) as_fn_error $? "invalid tag '$ac_tag'" "$LINENO" 5;;
   :[FH]-) ac_tag=-:-;;
   :[FH]*) ac_tag=$ac_tag:$ac_tag.in;;
   esac
@@ -5289,19 +5341,19 @@ do
       -) ac_f="$ac_tmp/stdin";;
       *) # Look for the file first in the build tree, then in the source tree
 	 # (if the path is not absolute).  The absolute path cannot be DOS-style,
-	 # because $ac_f cannot contain `:'.
+	 # because $ac_f cannot contain ':'.
 	 test -f "$ac_f" ||
 	   case $ac_f in
 	   [\\/$]*) false;;
 	   *) test -f "$srcdir/$ac_f" && ac_f="$srcdir/$ac_f";;
 	   esac ||
-	   as_fn_error 1 "cannot find input file: \`$ac_f'" "$LINENO" 5;;
+	   as_fn_error 1 "cannot find input file: '$ac_f'" "$LINENO" 5;;
       esac
       case $ac_f in *\'*) ac_f=`printf "%s\n" "$ac_f" | sed "s/'/'\\\\\\\\''/g"`;; esac
       as_fn_append ac_file_inputs " '$ac_f'"
     done
 
-    # Let's still pretend it is `configure' which instantiates (i.e., don't
+    # Let's still pretend it is 'configure' which instantiates (i.e., don't
     # use $as_me), people would be surprised to read:
     #    /* config.h.  Generated by config.status.  */
     configure_input='Generated from '`
@@ -5425,7 +5477,7 @@ cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 esac
 _ACEOF
 
-# Neutralize VPATH when `$srcdir' = `.'.
+# Neutralize VPATH when '$srcdir' = '.'.
 # Shell code in configure.ac might set extrasub.
 # FIXME: do we really want to maintain this feature?
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
@@ -5454,9 +5506,9 @@ test -z "$ac_datarootdir_hack$ac_datarootdir_seen" &&
   { ac_out=`sed -n '/\${datarootdir}/p' "$ac_tmp/out"`; test -n "$ac_out"; } &&
   { ac_out=`sed -n '/^[	 ]*datarootdir[	 ]*:*=/p' \
       "$ac_tmp/out"`; test -z "$ac_out"; } &&
-  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: $ac_file contains a reference to the variable \`datarootdir'
+  { printf "%s\n" "$as_me:${as_lineno-$LINENO}: WARNING: $ac_file contains a reference to the variable 'datarootdir'
 which seems to be undefined.  Please make sure it is defined" >&5
-printf "%s\n" "$as_me: WARNING: $ac_file contains a reference to the variable \`datarootdir'
+printf "%s\n" "$as_me: WARNING: $ac_file contains a reference to the variable 'datarootdir'
 which seems to be undefined.  Please make sure it is defined" >&2;}
 
   rm -f "$ac_tmp/stdin"
diff --git a/configure.ac b/configure.ac
index a21b76edd..77a55224b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -42,6 +42,11 @@ AC_MSG_NOTICE([CXX: ${CXX}])
 
 # AC_MSG_NOTICE([${PACKAGE_NAME}: ${PACKAGE_VERSION}])
 
+GENERIC_INSTALL_MESSAGE="
+*** Installing this package from source requires the prior 
+*** installation of external software, see for details 
+*** https://r-spatial.github.io/sf/#installing"
+
 #GDAL
 GDAL_CONFIG="gdal-config"
 
@@ -60,7 +65,7 @@ if test ["$GDAL_CONFIG_SET" = "no"] ; then
   AC_PATH_PROG([GDAL_CONFIG], ["$GDAL_CONFIG"],["no"])
   if test ["$GDAL_CONFIG" = "no"] ; then
     AC_MSG_RESULT(no)
-    AC_MSG_ERROR([gdal-config not found or not executable.])
+    AC_MSG_ERROR([gdal-config not found or not executable. ${GENERIC_INSTALL_MESSAGE}])
   fi
 else
   AC_MSG_CHECKING(gdal-config exists)
@@ -68,14 +73,14 @@ else
     AC_MSG_RESULT(yes)
   else
     AC_MSG_RESULT(no)
-    AC_MSG_ERROR([gdal-config not found - configure argument error.])
+    AC_MSG_ERROR([gdal-config not found - configure argument error. ${GENERIC_INSTALL_MESSAGE}])
   fi
   AC_MSG_CHECKING(gdal-config executable)
   if test -x "${GDAL_CONFIG}"; then
     AC_MSG_RESULT(yes)
   else
     AC_MSG_RESULT(no)
-    AC_MSG_ERROR([gdal-config not executable.])
+    AC_MSG_ERROR([gdal-config not executable. ${GENERIC_INSTALL_MESSAGE}])
   fi
 fi
 
@@ -89,19 +94,7 @@ then
 	GDAL_DATADIR=`${GDAL_CONFIG} --datadir`
 	AC_MSG_RESULT(yes)
 else
-	AC_MSG_RESULT(no)
-	echo "Error: gdal-config not found"
-	echo "The gdal-config script distributed with GDAL could not be found."
-	echo "If you have not installed the GDAL libraries, you can"
-	echo "download the source from  http://www.gdal.org/"
-	echo "If you have installed the GDAL libraries, then make sure that"
-	echo "gdal-config is in your path. Try typing gdal-config at a"
-	echo "shell prompt and see if it runs. If not, use:"
-	echo " --configure-args='--with-gdal-config=/usr/local/bin/gdal-config'"
-	echo "with appropriate values for your installation."
-	echo ""
-
-	exit 1
+	AC_MSG_ERROR([gdal-config not found. ${GENERIC_INSTALL_MESSAGE}])
 fi
 
 AC_MSG_NOTICE([GDAL: ${GDAL_VERSION}])
@@ -137,7 +130,7 @@ CPPFLAGS="${INCPPFLAGS} ${PKG_CPPFLAGS}"
 gdalok=yes
 AC_CHECK_HEADERS(gdal.h,,gdalok=no)
 if test "${gdalok}" = no; then
-   AC_MSG_ERROR([gdal.h not found in given locations.])
+   AC_MSG_ERROR([gdal.h not found in given locations. ${GENERIC_INSTALL_MESSAGE}])
 fi
 
 NEED_DEPS=no
@@ -183,7 +176,7 @@ fi
 if test "${gdalok}" = no; then
    cat errors.txt
    AC_MSG_NOTICE([Install failure: compilation and/or linkage problems.])
-   AC_MSG_ERROR([GDALAllRegister not found in libgdal.])
+   AC_MSG_ERROR([GDALAllRegister not found in libgdal. ${GENERIC_INSTALL_MESSAGE}])
 fi
 
 rm -f gdal_test errors.txt gdal_test.cpp
@@ -414,7 +407,7 @@ if test "${PROJH}" = no; then
   proj4ok=yes
   AC_CHECK_LIB(proj,pj_init_plus,,proj4ok=no)
   if test "${proj4ok}" = no; then
-     AC_MSG_ERROR([libproj not found in standard or given locations.])
+     AC_MSG_ERROR([libproj not found in standard or given locations. ${GENERIC_INSTALL_MESSAGE}])
   fi
 [cat > proj_conf_test.c <<_EOCONF
 #include <stdio.h>
@@ -448,7 +441,7 @@ _EOCONF]
     AC_MSG_RESULT(yes)
   fi
   if test "${proj6ok}" = no; then
-     AC_MSG_ERROR([libproj or sqlite3 not found in standard or given locations.])
+     AC_MSG_ERROR([libproj or sqlite3 not found in standard or given locations. ${GENERIC_INSTALL_MESSAGE}])
   fi
 
 [cat > proj_conf_test.c <<_EOCONF
@@ -658,7 +651,7 @@ if test ["$GEOS_CONFIG_SET" = "no"] ; then
   AC_PATH_PROG([GEOS_CONFIG], ["$GEOS_CONFIG"],["no"])
   if test ["$GEOS_CONFIG" = "no"] ; then
     AC_MSG_RESULT(no)
-    AC_MSG_ERROR([geos-config not found or not executable.])
+    AC_MSG_ERROR([geos-config not found or not executable. ${GENERIC_INSTALL_MESSAGE}])
   fi
 else
   AC_MSG_CHECKING(geos-config exists)
@@ -666,14 +659,14 @@ else
     AC_MSG_RESULT(yes)
   else
     AC_MSG_RESULT(no)
-    AC_MSG_ERROR([geos-config not found - configure argument error.])
+    AC_MSG_ERROR([geos-config not found - configure argument error. ${GENERIC_INSTALL_MESSAGE}])
   fi
   AC_MSG_CHECKING(geos-config executable)
   if test -x "${GEOS_CONFIG}"; then
     AC_MSG_RESULT(yes)
   else
     AC_MSG_RESULT(no)
-    AC_MSG_ERROR([geos-config not executable.])
+    AC_MSG_ERROR([geos-config not executable. ${GENERIC_INSTALL_MESSAGE}])
   fi
 fi
 
@@ -717,7 +710,7 @@ LIBS="${LIBS} ${PKG_LIBS}"
 geosok=yes
 AC_CHECK_HEADERS(geos_c.h,,geosok=no)
 if test "${geosok}" = no; then
-   AC_MSG_ERROR([geos_c.h not found in given locations.])
+   AC_MSG_ERROR([geos_c.h not found in given locations. ${GENERIC_INSTALL_MESSAGE}])
 fi
 
 [cat > geos_test.cpp <<_EOCONF
@@ -759,7 +752,7 @@ if test "${geosok}" = no; then
     AC_MSG_RESULT(no)
     cat errors.txt
     AC_MSG_NOTICE([Install failure: compilation and/or linkage problems.])
-    AC_MSG_ERROR([initGEOS_r not found in libgeos_c.])
+    AC_MSG_ERROR([initGEOS_r not found in libgeos_c. ${GENERIC_INSTALL_MESSAGE}])
   else
     AC_SUBST([PKG_LIBS], ["${PKG_LIBS} ${GEOS_DEP_CLIBS}"])
     AC_MSG_RESULT(yes)