Bug #5042
closed
xslt3 fails to identify that function with type declaration as="element()" returns an empty sequence
100%
Description
I have a function with a return type declaration as="element()" but a body, that, after a code change and the use of xsl:where-populated, might return the empty sequence.
In this case Saxon Java or Saxon-JS when running a compiled stylesheet from Saxon Java EE give the error "XTTE0780".
However, when I run the stylesheet directly through xslt3, i.e. use the XX compiler, the error is not noticed and the stylesheet incuding the function call returning an empty sequence is executed.
Example function:
<xsl:function name="mf:wrap-if-populated" as="element()" visibility="public">
<xsl:param name="items" as="item()*"/>
<xsl:param name="wrapper-name" as="xs:QName"/>
<xsl:where-populated>
<xsl:element name="{$wrapper-name}" namespace="{namespace-uri-from-QName($wrapper-name)}">
<xsl:apply-templates select="$items"/>
</xsl:element>
</xsl:where-populated>
</xsl:function>
Full test case
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="3.0"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:mf="http://example.com/mf"
exclude-result-prefixes="#all"
expand-text="yes">
<xsl:function name="mf:wrap-if-populated" as="element()" visibility="public">
<xsl:param name="items" as="item()*"/>
<xsl:param name="wrapper-name" as="xs:QName"/>
<xsl:where-populated>
<xsl:element name="{$wrapper-name}" namespace="{namespace-uri-from-QName($wrapper-name)}">
<xsl:apply-templates select="$items"/>
</xsl:element>
</xsl:where-populated>
</xsl:function>
<xsl:template match="list[@type = 'ordered']">
<xsl:sequence select="mf:wrap-if-populated(item, QName('', 'ol'))"/>
</xsl:template>
<xsl:template match="list">
<xsl:sequence select="mf:wrap-if-populated(item, QName('', 'ul'))"/>
</xsl:template>
<xsl:template match="list/item">
<li>
<xsl:apply-templates/>
</li>
</xsl:template>
<xsl:template match="root">
<html>
<head>
<title>Example</title>
</head>
<body>
<xsl:apply-templates/>
</body>
</html>
</xsl:template>
<xsl:output method="xml" indent="yes"/>
<xsl:mode on-no-match="shallow-copy"/>
<xsl:template match="/" name="xsl:initial-template">
<xsl:next-match/>
<xsl:comment xmlns:saxon="http://saxon.sf.net/">Run with {system-property('xsl:product-name')} {system-property('xsl:product-version')} {system-property('Q{http://saxon.sf.net/}platform')}</xsl:comment>
</xsl:template>
</xsl:stylesheet>
Sample input:
<?xml version="1.0" encoding="UTF-8"?>
<root>
<list>
<item>a</item>
<item>b</item>
<item>c</item>
</list>
<list type="ordered"></list>
</root>
Output of xslt3 when running the SEF compiled by Saxon Java EE 10.5:
<?xml version="1.0" encoding="UTF-8"?>
<html>
<head>
<title>Example</title>
</head>
<body>
<ul>
<li>a</li>
<li>b</li>
<li>c</li>
</ul>Transformation failure: Error XTTE0780 at sheet2.xsl#13
Required cardinality of result of call to function mf:wrap-if-populated#2 is exactly one; supplied value is empty
Error XTTE0780 at sheet2.xsl#13
Required cardinality of result of call to function mf:wrap-if-populated#2 is exactly one; supplied value is empty
Output when running the XSLT file through xslt3:
<?xml version="1.0" encoding="UTF-8"?>
<html>
<head>
<title>Example</title>
</head>
<body>
<ul>
<li>a</li>
<li>b</li>
<li>c</li>
</ul>
</body>
</html>
<!--Run with Saxon-JS 2.2 Node.js-->
Updated by Michael Kay over 2 years ago
- Status changed from New to In Progress
Looking at the SEF file, the XX compiler hasn't generated a type checking instruction (by contrast, it does so if we change the function return type to as="element(xxx)"). The probably means that it has wrongly inferred the type of the xsl:where-populated instruction (so it thinks no type check is necessary).
Updated by Michael Kay over 2 years ago
I think the offending code is probably at conditionals.xsl line 202:
<xsl:template match="ex:condCont | ex:onEmpty | ex:onNonEmpty" mode="process-xpath">
<xsl:variable name="source" as="element()">
<xsl:apply-templates select="*" mode="#current"/>
</xsl:variable>
<xsl:copy>
<xsl:sequence select="@*, $source/@sType, $source"/>
</xsl:copy>
</xsl:template>
This is copying the attribute $source/@sType, implying that the inferred static type of the condCont (=wherePopulated) instruction is the same as the inferred type of its operand.
By contrast SaxonJ has
protected int computeCardinality() {
return super.computeCardinality() | StaticProperty.ALLOWS_ZERO;
}
Updated by Michael Kay over 2 years ago
- Status changed from In Progress to Resolved
- Assignee set to Michael Kay
- Fix Committed on JS Branch Trunk added
Updated by Debbie Lockett over 2 years ago
- Fix Committed on JS Branch 2 added
- Fix Committed on JS Branch deleted (
Trunk)
Updated by Debbie Lockett over 2 years ago
- Status changed from Resolved to Closed
- % Done changed from 0 to 100
- Fixed in JS Release set to SaxonJS 2.4
Bug fix applied in the SaxonJS 2.4 maintenance release.
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