From: Eric Blake <ebb9@byu.net>
Date: Fri, 24 Oct 2008 22:41:20 +0000 (-0600)
Subject: Speed up AC_CHECK_HEADER.
X-Git-Tag: v2.63b~198
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=89e95fc78b3481deb160488b930b498dfc406c2b;p=thirdparty%2Fautoconf.git

Speed up AC_CHECK_HEADER.

* lib/autoconf/headers.m4 (AC_CHECK_HEADER): Factor out $@.

Signed-off-by: Eric Blake <ebb9@byu.net>
---

diff --git a/ChangeLog b/ChangeLog
index 61b5f3362..a485066ba 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2008-10-24  Eric Blake  <ebb9@byu.net>
+
+	Speed up AC_CHECK_HEADER.
+	* lib/autoconf/headers.m4 (AC_CHECK_HEADER): Factor out $@.
+
 2008-10-24  Paolo Bonzini  <bonzini@gnu.org>
 	and Eric Blake  <ebb9@byu.net>
 
diff --git a/lib/autoconf/headers.m4 b/lib/autoconf/headers.m4
index 40121077e..413be8c15 100644
--- a/lib/autoconf/headers.m4
+++ b/lib/autoconf/headers.m4
@@ -84,11 +84,13 @@
 #
 # If INCLUDES is specified and different from `-', then use the new
 # semantics only.
+#
+# The m4_indir allows for fewer expansions of $@.
 AC_DEFUN([AC_CHECK_HEADER],
-[m4_case([$4],
-	 [],  [_AC_CHECK_HEADER_MONGREL($@)],
-	 [-], [_AC_CHECK_HEADER_OLD($@)],
-	      [_AC_CHECK_HEADER_NEW($@)])
+[m4_indir(m4_case([$4],
+		  [],  [[_AC_CHECK_HEADER_MONGREL]],
+		  [-], [[_AC_CHECK_HEADER_OLD]],
+		       [[_AC_CHECK_HEADER_NEW]]), $@)
 ])# AC_CHECK_HEADER