Description:
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Hi. We've just got some bug reports over at Gentoo that I was also able to reproduce (http://bugs.gentoo.org/show_bug.cgi?id=105268). The problem is obvious by the error messages, 'XML_FEATURE_UNICODE' gets declared two times, one time by libxml2 version 2.6.21, and one time by the bundled expat library. Now this happens only if you enable any extension that uses the bundled expat library (wddx, xml, xmlrpc) AND the DOM XML extension. In that case the external libxml2 gets included also and, since it defines 'XML_FEATURE_UNICODE' too it clashes with the 'XML_FEATURE_UNICODE' definition the bundled expat library has. libxml2 2.6.19 works since it does not define 'XML_FEATURE_UNICODE' at all, but 2.6.21 does define it ( /usr/include/libxml2/libxml/parser.h:1196: XML_FEATURE_UNICODE = 21, ), and thus the compile crashes. Now I'm not sure how the bundled expat library can be fixed so that this error goes away, I hope someone knows. :)

Reproduce code:
---------------
a) install libxml2 2.6.21
b) install PHP with --with-dom --enable-wddx
c) see the bug :)

Expected result:
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PHP should compile with the new libxml2 version, and support for both DOM XML and the bundled expat-based library extensions.

Actual result:
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In file included from
/var/tmp/portage/mod_php-4.4.0-r1/work/php-4.4.0/ext/wddx/php_wddx.h:26,
		 from main/internal_functions.c:65:
/var/tmp/portage/mod_php-4.4.0-r1/work/php-4.4.0/ext/xml/expat/expat.h:894:
error: conflicting types for 'XML_FEATURE_UNICODE'
/usr/include/libxml2/libxml/parser.h:1196: error: previous definition of
'XML_FEATURE_UNICODE' was here
make: *** [main/internal_functions.lo] Error 1
make: *** Waiting for unfinished jobs....