From: Akim Demaille <akim@epita.fr>
Date: Fri, 18 Feb 2000 13:44:17 +0000 (+0000)
Subject: Some `diff' refuse to diff with /dev/null, such as Tru64's.
X-Git-Tag: autoconf-2.50~1129
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c34897ff86704bbd30224eabbe6bb24a52f4d150;p=thirdparty%2Fautoconf.git

Some `diff' refuse to diff with /dev/null, such as Tru64's.
Reported by Nicolas Joly.

* tests/atgeneral.m4 (empty): New dummy file.
Changed various `diff /dev/null' as `diff empty'.
---

diff --git a/ChangeLog b/ChangeLog
index fd53c65c1..dbb9fa64d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2000-02-18  Akim Demaille  <akim@epita.fr>
+
+	Some `diff' refuse to diff with /dev/null, such as Tru64's.
+	Reported by Nicolas Joly.
+
+	* tests/atgeneral.m4 (empty): New dummy file.
+	Changed various `diff /dev/null' as `diff empty'.
+
 2000-02-18  Akim Demaille  <akim@epita.fr>
 
 	* tests/atspecific.m4 (TEST_MACRO): Don't run AC_PATH_TOOL and
diff --git a/lib/autotest/general.m4 b/lib/autotest/general.m4
index ce6c6cf15..3d4b4cadf 100644
--- a/lib/autotest/general.m4
+++ b/lib/autotest/general.m4
@@ -139,9 +139,12 @@ done
 # environments, `diff' considers that two files are equal included
 # when there are only differences on the coding of new lines. `cmp'
 # does not.
-# Finally, not all the `diff' support `-u'.
+#
+# Finally, not all the `diff' support `-u', and some, like Tru64, even
+# refuse to `diff' /dev/null.
+: >empty
 
-if diff -u /dev/null /dev/null >/dev/null 2>&1; then
+if diff -u empty empty >/dev/null 2>&1; then
   at_diff='diff -u'
 else
   at_diff='diff'
@@ -370,13 +373,13 @@ if test -z "$at_no_redirs"; then
           ignore, [test -n "$at_verbose" && cat stdout;:],
           expout, [AT_DEFINE([AT_data_expout], [ expout])dnl
 $at_diff expout stdout || exit 1],
-          [], [$at_diff /dev/null stdout || exit 1],
+          [], [$at_diff empty stdout || exit 1],
           [echo $at_n "patsubst([$3], [\([\"`$]\)], \\\1)$at_c" | $at_diff - stdout || exit 1])
   AT_CASE([$4],
           ignore, [test -n "$at_verbose" && cat stderr;:],
           experr, [AT_DEFINE([AT_data_experr], [ experr])dnl
 $at_diff experr stderr || exit 1],
-          [], [$at_diff /dev/null stderr || exit 1],
+          [], [$at_diff empty stderr || exit 1],
           [echo $at_n "patsubst([$4], [\([\"`$]\)], \\\1)$at_c" | $at_diff - stderr || exit 1])
 fi
 $at_traceon
diff --git a/tests/atgeneral.m4 b/tests/atgeneral.m4
index ce6c6cf15..3d4b4cadf 100644
--- a/tests/atgeneral.m4
+++ b/tests/atgeneral.m4
@@ -139,9 +139,12 @@ done
 # environments, `diff' considers that two files are equal included
 # when there are only differences on the coding of new lines. `cmp'
 # does not.
-# Finally, not all the `diff' support `-u'.
+#
+# Finally, not all the `diff' support `-u', and some, like Tru64, even
+# refuse to `diff' /dev/null.
+: >empty
 
-if diff -u /dev/null /dev/null >/dev/null 2>&1; then
+if diff -u empty empty >/dev/null 2>&1; then
   at_diff='diff -u'
 else
   at_diff='diff'
@@ -370,13 +373,13 @@ if test -z "$at_no_redirs"; then
           ignore, [test -n "$at_verbose" && cat stdout;:],
           expout, [AT_DEFINE([AT_data_expout], [ expout])dnl
 $at_diff expout stdout || exit 1],
-          [], [$at_diff /dev/null stdout || exit 1],
+          [], [$at_diff empty stdout || exit 1],
           [echo $at_n "patsubst([$3], [\([\"`$]\)], \\\1)$at_c" | $at_diff - stdout || exit 1])
   AT_CASE([$4],
           ignore, [test -n "$at_verbose" && cat stderr;:],
           experr, [AT_DEFINE([AT_data_experr], [ experr])dnl
 $at_diff experr stderr || exit 1],
-          [], [$at_diff /dev/null stderr || exit 1],
+          [], [$at_diff empty stderr || exit 1],
           [echo $at_n "patsubst([$4], [\([\"`$]\)], \\\1)$at_c" | $at_diff - stderr || exit 1])
 fi
 $at_traceon