We seem to have discovered a strange bug in libxslt where the value of a 
global variable is being reported incorrectly as an empty string.

This occurs if you have a certain combination of global variables, 
template calls and functions returning result tree fragments.

Here is the output of the test case (just run it against itself), the 
libxslt version information, and the test case itself:

[dev3:pawlowski] ~/xsl/ext/bin [15:27 2009-11-20]
$ ./xsltproc test-case.xsl test-case.xsl 
assert 'success!' == ''

[dev3:pawlowski] ~/xsl/ext/bin [15:27 2009-11-20]
$ ./xsltproc --version
Using libxml 20706, libxslt 10126 and libexslt 815
xsltproc was compiled against libxml 20706, libxslt 10126 and libexslt 815
libxslt 10126 was compiled against libxml 20706
libexslt 815 was compiled against libxml 20706


=== our test case ===

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
  xmlns:xsl='http://www.w3.org/1999/XSL/Transform'
  xmlns:func='http://exslt.org/functions'
  xmlns:foo='http://foo.com/'
  extension-element-prefixes='func'
 >
<xsl:output method="text" />

<!-- $func-value should have the value 'success!' but instead reports an 
empty string -->
<xsl:variable name="func-value" select="foo:get-value()" />
<xsl:variable name="dummy-value" select="$func-value" />
<xsl:variable name="template-value">
   <xsl:call-template name="get-dummy" />
</xsl:variable>

<func:function name="foo:get-value">
   <func:result>success!</func:result>

   <!-- use this func:result instead and $func-value will report the 
expected value
   <func:result select="'success!'" />
   -->

</func:function>

<xsl:template name="get-dummy">
   <xsl:value-of select="$dummy-value" />
</xsl:template>

<xsl:template match="/">
   <xsl:text>assert 'success!' == '</xsl:text>
   <xsl:value-of select="$func-value" />
   <xsl:text>'
</xsl:text>
</xsl:template>

</xsl:stylesheet>

=== end test case ===


It seems obscure, but in our very complex, several thousand line XSL 
transformations, this actually comes up pretty frequently and is 
extremely frustrating to debug -- I hope you might be able to help us fix the problem.