I'm using AM_CONFIG_HEADER to insert a couple of configure-time
defines into headers which will be installed. This works well, except
that I want to have one literal #undef pass through, rather than be
commented out like normally happens.
Perhaps a special marker could stop selected #undef's from getting
transformed, for instance,
#define __need_size_t
#include <stddef.h>
#undef __need_size_t /*NOTATEMPLATE*/
--- acgeneral.m4.old Thu Mar 8 06:59:40 2001
+++ acgeneral.m4 Thu Mar 8 07:02:01 2001
@@ -4199,7 +4199,7 @@
# example, in the case of _POSIX_SOURCE, which is predefined and required
# on some systems where configure will not decide to define it.
cat >>conftest.undefs <<\EOF
-[s,^[ ]*#[ ]*undef[ ][ ]*[a-zA-Z_][a-zA-Z_0-9]*,/* & */,]
+[/[*]NOTATEMPLATE[*]/!s,^[ ]*#[ ]*undef[ ][ ]*[a-zA-Z_][a-zA-Z_0-9]*,/* & */,]
EOF
# Break up conftest.defines because some shells have a limit on the size
