Description:
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In a Windows binary of PHP4, enable DOMXML and look at a phpinfo() page.  DOM/XSLT is listed as enabled, but DOM/EXSLT, a feature built in to libxslt, is not enabled.  There appears to be no way to enable it, short of perhaps fixing the switch in the standard/snapshot Windows build scripts that are disabling the feature.

Reproduce code:
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Ensure that your PHP.ini contains the line:
  extension=php_domxml.dll

Look at a phpinfo() page, in the domxml section, typically about halfway down the page.

Mine contains these settings only:
DOM/XML 	enabled
DOM/XML API Version 	20020815
libxml Version 	20626
HTML Support 	enabled
XPath Support 	enabled
XPointer Support 	enabled
DOM/XSLT 	enabled
libxslt Version 	1.1.17
libxslt compiled against libxml Version 	2.6.26


Expected result:
----------------
Should also contain:
DOM/EXSLT 	enabled
libexslt Version 	x.x.xx

Actual result:
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Consequence: attempting to use the exslt:node-set() function to get past an egregious limitation in XSLT 1.0 gives the warning messages as follows on any Windows build of PHP4:

Warning: process() [function.process]: xmlXPathCompOpEval: function node-set not found in ...
Warning: process() [function.process]: Unregistered function in ...

This indicates that libxslt is working, but access to its EXSLT features has been prevented.  The phpinfo() result indicates that this prevention has occurred at build time, not as a consequence of any PHP script.

On a standard Linux build, this function works perfectly well.  It is therefore a bug in the way PHP is being built.  Note: this is not a bug in libxslt!