From fb6de052bace5b26346c1624b57d87326a97c7b6 Mon Sep 17 00:00:00 2001
From: Bruno Haible <bruno@clisp.org>
Date: Sun, 13 Nov 2011 21:20:59 +0100
Subject: [PATCH] Silence successful tests that use 'compare' on AIX, HP-UX,
 Solaris.

* tests/init.sh (compare): Remove "No differences encountered" or
synonymous output from the 'diff' program.
---
 ChangeLog     |  7 +++++++
 tests/init.sh | 41 +++++++++++++++++++++++++++++++++++++----
 2 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 59f84c4d5..962b2c4aa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,11 @@
 2011-11-13  Bruno Haible  <bruno@clisp.org>
+	    Jim Meyering  <meyering@redhat.com>
+
+	Silence successful tests that use 'compare' on AIX, HP-UX, Solaris.
+	* tests/init.sh (compare): Remove "No differences encountered" or
+	synonymous output from the 'diff' program.
+
+2011-11-13  Bruno Haible  <bruno@clisp.org>
 
 	Makefile: Tweak indentation.
 	* Makefile: Use tab as first character in every line that contains rule
diff --git a/tests/init.sh b/tests/init.sh
index 373d9d4fe..c78e5b67a 100644
--- a/tests/init.sh
+++ b/tests/init.sh
@@ -221,10 +221,43 @@ export MALLOC_PERTURB_
 # a partition, or to undo any other global state changes.
 cleanup_ () { :; }
 
-if ( diff -u "$0" "$0" < /dev/null ) > /dev/null 2>&1; then
-  compare () { diff -u "$@"; }
-elif ( diff -c "$0" "$0" < /dev/null ) > /dev/null 2>&1; then
-  compare () { diff -c "$@"; }
+if diff_out_=`( diff -u "$0" "$0" < /dev/null ) 2>/dev/null`; then
+  if test -z "$diff_out_"; then
+    compare () { diff -u "$@"; }
+  else
+    compare ()
+    {
+      if diff -u "$@" > diff.out; then
+        # No differences were found, but Solaris 'diff' produces output
+        # "No differences encountered". Hide this output.
+        rm -f diff.out
+        true
+      else
+        cat diff.out
+        rm -f diff.out
+        false
+      fi
+    }
+  fi
+elif diff_out_=`( diff -c "$0" "$0" < /dev/null ) 2>/dev/null`; then
+  if test -z "$diff_out_"; then
+    compare () { diff -c "$@"; }
+  else
+    compare ()
+    {
+      if diff -c "$@" > diff.out; then
+        # No differences were found, but AIX and HP-UX 'diff' produce output
+        # "No differences encountered" or "There are no differences between the
+        # files.". Hide this output.
+        rm -f diff.out
+        true
+      else
+        cat diff.out
+        rm -f diff.out
+        false
+      fi
+    }
+  fi
 elif ( cmp --version < /dev/null 2>&1 | grep GNU ) > /dev/null 2>&1; then
   compare () { cmp -s "$@"; }
 else
-- 
2.11.0