[PATCH v2 5/8] config.guess: manual fixup after previous automated patches

[Jacob Bachmeyer]

This patch provides the special handling for the GNU system.  As these
were two small and unique edits, they were not included in the scripts.

This patch also cleans up other minor issues that must be addressed
before reverting to classic command substitutions and updates
"shellcheck" directives to account for changes in this script and the
change in "shellcheck" towards reporting individual portability issues.
---
 config.guess | 32 +++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/config.guess b/config.guess
index d2bdee7..4bc8157 100755
--- a/config.guess
+++ b/config.guess
@@ -2,6 +2,8 @@
 # Attempt to guess a canonical system name.
 #   Copyright 1992-2021 Free Software Foundation, Inc.
 
+# shellcheck disable=SC2006,SC2268 # see below for rationale
+
 timestamp='2021-05-24'
 
 # This file is free software; you can redistribute it and/or modify it
@@ -32,6 +34,14 @@ timestamp='2021-05-24'
 # Please send patches to <config-patches@gnu.org>.
 
 
+# The "shellcheck disable" line above the timestamp inhibits complaints
+# about features and limitations of the classic Bourne shell that were
+# superseded or lifted in POSIX.  However, this script identifies a wide
+# variety of pre-POSIX systems that do not have POSIX shells at all, and
+# even some reasonably current systems (Solaris 10 as case-in-point) still
+# have a pre-POSIX /bin/sh.
+
+
 me=$(echo "$0" | sed -e 's,.*/,,')
 
 usage="\
@@ -105,7 +115,7 @@ set_cc_for_build() {
     # prevent multiple calls if $tmp is already set
     test "$tmp" && return 0
     : "${TMPDIR=/tmp}"
-    # shellcheck disable=SC2039
+    # shellcheck disable=SC2039,SC3028
     { tmp=$( (umask 077 && mktemp -d "$TMPDIR/cgXXXXXX") 2>/dev/null) && test 
-n "$tmp" && test -d "$tmp" ; } ||
        { test -n "$RANDOM" && tmp=$TMPDIR/cg$$-$RANDOM && (umask 077 && mkdir 
"$tmp" 2>/dev/null) ; } ||
        { tmp=$TMPDIR/cg-$$ && (umask 077 && mkdir "$tmp" 2>/dev/null) && echo 
"Warning: creating insecure temp directory" >&2 ; } ||
@@ -160,7 +170,8 @@ Linux|GNU|GNU/*)
        #endif
        #endif
        EOF
-       eval "$($CC_FOR_BUILD -E "$dummy.c" 2>/dev/null | grep '^LIBC' | sed 
's, ,,g')"
+       cc_set_libc=$($CC_FOR_BUILD -E "$dummy.c" 2>/dev/null | grep '^LIBC' | 
sed 's, ,,g')
+       eval "$cc_set_libc"
 
        # Second heuristic to detect musl libc.
        if [ "$LIBC" = unknown ] &&
@@ -943,11 +954,15 @@ EOF
        ;;
     *:GNU:*:*)
        # the GNU system
-       GUESS="$(echo "$UNAME_MACHINE" | sed -e 
's,[-/].*$,,')-unknown-$LIBC$(echo "$UNAME_RELEASE" | sed -e 's,/.*$,,')"
+       GNU_ARCH=$(echo "$UNAME_MACHINE" | sed -e 's,[-/].*$,,')
+       GNU_REL=$(echo "$UNAME_RELEASE" | sed -e 's,/.*$,,')
+       GUESS=$GNU_ARCH-unknown-$LIBC$GNU_REL
        ;;
     *:GNU/*:*:*)
        # other systems with GNU libc and userland
-       GUESS="$UNAME_MACHINE-unknown-$(echo "$UNAME_SYSTEM" | sed 
's,^[^/]*/,,' | tr "[:upper:]" "[:lower:]")$(echo "$UNAME_RELEASE" | sed -e 
's/[-(].*//')-$LIBC"
+       GNU_SYS=$(echo "$UNAME_SYSTEM" | sed 's,^[^/]*/,,' | tr "[:upper:]" 
"[:lower:]")
+       GNU_REL=$(echo "$UNAME_RELEASE" | sed -e 's/[-(].*//')
+       GUESS=$UNAME_MACHINE-unknown-$GNU_SYS$GNU_REL-$LIBC
        ;;
     *:Minix:*:*)
        GUESS=$UNAME_MACHINE-unknown-minix
@@ -1072,7 +1087,8 @@ EOF
        #endif
        #endif
 EOF
-       eval "$($CC_FOR_BUILD -E "$dummy.c" 2>/dev/null | grep 
'^CPU\|^MIPS_ENDIAN\|^LIBCABI')"
+       cc_set_vars=$($CC_FOR_BUILD -E "$dummy.c" 2>/dev/null | grep 
'^CPU\|^MIPS_ENDIAN\|^LIBCABI')
+       eval "$cc_set_vars"
        test "x$CPU" != x && { echo 
"$CPU${MIPS_ENDIAN}-unknown-linux-$LIBCABI"; exit; }
        ;;
     mips64el:Linux:*:*)
@@ -1688,9 +1704,11 @@ and
   https://git.savannah.gnu.org/cgit/config.git/plain/config.sub
 EOF
 
-year=$(echo $timestamp | sed 's,-.*,,')
+our_year=$(echo $timestamp | sed 's,-.*,,')
+thisyear=$(date +%Y)
 # shellcheck disable=SC2003
-if test "$(expr "$(date +%Y)" - "$year")" -lt 3 ; then
+script_age=$(expr "$thisyear" - "$our_year")
+if test "$script_age" -lt 3 ; then
    cat >&2 <<EOF
 
 If $0 has already been updated, send the following data and any
-- 
2.17.1