[PATCH] test-framework-sh: work around AIX 7.2 diff bugs

[Paul Eggert]

* tests/init.sh (compare_dev_null_): Run diff in the C locale.
AIX 7.2 diff messes up in UTF-8 locales; for example,
‘printf '\360\220\200\200\n' | diff - /dev/null’ incorrectly
outputs nothing and exits with status 0 when LC_ALL=en_US.UTF-8.
---
 ChangeLog     | 8 ++++++++
 tests/init.sh | 7 ++++---
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index fb467a3c14..0900c54c1d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2023-01-14  Paul Eggert  <eggert@cs.ucla.edu>
+
+       test-framework-sh: work around AIX 7.2 diff bugs
+       * tests/init.sh (compare_dev_null_): Run diff in the C locale.
+       AIX 7.2 diff messes up in UTF-8 locales; for example,
+       ‘printf '\360\220\200\200\n' | diff - /dev/null’ incorrectly
+       outputs nothing and exits with status 0 when LC_ALL=en_US.UTF-8.
+
 2023-01-14  Bruno Haible  <bruno@clisp.org>
 
        error, verror tests: Fix link error when the package uses libintl.
diff --git a/tests/init.sh b/tests/init.sh
index 6c09392867..0494097e9f 100644
--- a/tests/init.sh
+++ b/tests/init.sh
@@ -646,18 +646,19 @@ compare_dev_null_ ()
 
 for diff_opt_ in -u -U3 -c '' no; do
   test "$diff_opt_" != no &&
-    diff_out_=`exec 2>/dev/null; diff $diff_opt_ "$0" "$0" < /dev/null` &&
+    diff_out_=`exec 2>/dev/null
+      LC_ALL=C diff $diff_opt_ "$0" "$0" < /dev/null` &&
     break
 done
 if test "$diff_opt_" != no; then
   if test -z "$diff_out_"; then
-    compare_ () { diff $diff_opt_ "$@"; }
+    compare_ () { LC_ALL=C diff $diff_opt_ "$@"; }
   else
     compare_ ()
     {
       # If no differences were found, AIX and HP-UX 'diff' produce output
       # like "No differences encountered".  Hide this output.
-      diff $diff_opt_ "$@" > diff.out
+      LC_ALL=C diff $diff_opt_ "$@" > diff.out
       diff_status_=$?
       test $diff_status_ -eq 0 || cat diff.out || diff_status_=2
       rm -f diff.out || diff_status_=2
-- 
2.37.2