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 61b5f3362a4e77e224284b4a76cd3248700c9cf9..a485066ba11483f6b92a41151bc6e4b0c0aba8a7 100644 (file)
--- 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 40121077e08cc7065b24ddc4ea91b211ead30fbe..413be8c1574fba048f7df50944c8a6f1a364dc2a 100644 (file)
--- 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