From c6448c8a27e164c32ad6a94679beb04afd0cecb7 Mon Sep 17 00:00:00 2001
From: John Gilmore <gnu@toad.com>
Date: Sat, 18 Mar 1995 04:42:05 +0000
Subject: [PATCH] * acgeneral.m4:  Report the update status of the cache
 better; show diffs if an unwriteable cache gets updated, for manually
 configuring the Mac config.cache. * configure:  Update with this
 acgeneral.m4.

[This change, or one very close to it, was submitted for autoconf 2.2.]

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@5168 dc483132-0cff-0310-8789-dd5450dbe970
---
 src/util/autoconf/acgeneral.m4 | 17 ++++++++++++-----
 src/util/autoconf/configure    | 17 ++++++++++++-----
 2 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/src/util/autoconf/acgeneral.m4 b/src/util/autoconf/acgeneral.m4
index b7e6bc3fd..102b0bdd0 100644
--- a/src/util/autoconf/acgeneral.m4
+++ b/src/util/autoconf/acgeneral.m4
@@ -881,9 +881,7 @@ fi
 
 dnl AC_CACHE_SAVE()
 define(AC_CACHE_SAVE,
-[if test -w $cache_file; then
-echo "updating cache $cache_file"
-cat > $cache_file <<\EOF
+[cat > $cache_file.$$ <<\EOF
 # This file is a shell script that caches the results of configure
 # tests run on this system so they can be shared between configure
 # scripts and configure runs.  It is not useful on other systems.
@@ -906,11 +904,20 @@ dnl Allow a site initialization script to override cache values.
 # with their high bit set.
 (set) 2>&1 | tr '\201-\377' '\001-\177' |
   sed -n "s/^\([a-zA-Z0-9_]*_cv_[a-zA-Z0-9_]*\)=\(.*\)/: \${\1='\2'}/p" \
-  >> $cache_file
+  >> $cache_file.$$
 changequote([, ])dnl
+if cmp -s $cache_file $cache_file.$$; then
+  true
 else
-echo "not updating unwritable cache $cache_file"
+  if test -w $cache_file; then
+    echo "updating cache $cache_file"
+    cat $cache_file.$$ > $cache_file
+  else
+    echo "not updating unwritable cache $cache_file"
+    diff $cache_file $cache_file.$$
+  fi
 fi
+rm -f $cache_file.$$
 ])
 
 dnl The name of shell var CACHE-ID must contain `_cv_' in order to get saved.
diff --git a/src/util/autoconf/configure b/src/util/autoconf/configure
index 97345c99e..adff411cc 100644
--- a/src/util/autoconf/configure
+++ b/src/util/autoconf/configure
@@ -549,9 +549,7 @@ if test -f $srcdir/standards.texi; then
 fi
 
 trap '' 1 2 15
-if test -w $cache_file; then
-echo "updating cache $cache_file"
-cat > $cache_file <<\EOF
+cat > $cache_file.$$ <<\EOF
 # This file is a shell script that caches the results of configure
 # tests run on this system so they can be shared between configure
 # scripts and configure runs.  It is not useful on other systems.
@@ -572,10 +570,19 @@ EOF
 # with their high bit set.
 (set) 2>&1 | tr '\201-\377' '\001-\177' |
   sed -n "s/^\([a-zA-Z0-9_]*_cv_[a-zA-Z0-9_]*\)=\(.*\)/: \${\1='\2'}/p" \
-  >> $cache_file
+  >> $cache_file.$$
+if cmp -s $cache_file $cache_file.$$; then
+  true
 else
-echo "not updating unwritable cache $cache_file"
+  if test -w $cache_file; then
+    echo "updating cache $cache_file"
+    cat $cache_file.$$ > $cache_file
+  else
+    echo "not updating unwritable cache $cache_file"
+    diff $cache_file $cache_file.$$
+  fi
 fi
+rm -f $cache_file.$$
 
 trap 'rm -fr conftest* confdefs* core $ac_clean_files; exit 1' 1 2 15
 
-- 
2.26.2