[Qemu-devel] [PATCH] configure: Support empty target list (--target-list=)

[Stefan Weil <sw@weilnetz.de>]

Specifying an empty target list with --target-list= is shorter
than specifying --disable-user --disable-system.

Both variants should give the same result: no targets at all.

This modification implements that feature.

It uses a trick which works with POSIX compliant shells to test whether
target_list is undefined (=> default targets) or empty (=> no targets).

Signed-off-by: Stefan Weil <sw@weilnetz.de>
---
 configure |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 8f99b7b..769ec1a 100755
--- a/configure
+++ b/configure
@@ -125,7 +125,8 @@ cc_i386=i386-pc-linux-gnu-gcc
 libs_qga=""
 debug_info="yes"
 
-target_list=""
+# Don't accept a target_list environment variable.
+unset target_list
 
 # Default value for a variable defining feature "foo".
 #  * foo="no"  feature will only be used if --enable-foo arg is given
@@ -1281,7 +1282,7 @@ if ! "$python" -c 'import sys; sys.exit(sys.version_info < (2,4) or sys.version_
   exit 1
 fi
 
-if test -z "$target_list" ; then
+if test -z "${target_list+xxx}" ; then
     target_list="$default_target_list"
 else
     target_list=`echo "$target_list" | sed -e 's/,/ /g'`
-- 
1.7.10