Saxon

Demonstrated by QT4 test case function-call-promotion-405 run with -lang:XQ31.

The test turned out to be incorrect. There is a problem, but it's quite hard to find a test case that reveals it.

The ItemChecker is letting an xs:anyURI through where an xs:string is expected, which means that a call that supplies an xs:anyURI to a function expecting an xs:string actually succeeds -- but it arrives as an xs:anyURI, not as an xs:string. How do we detect the difference? The obvious way is by using an "instance of" test, but this will be optimized away because we think we know the type of the value statically. Perhaps we should mix the supplied value into a sequence with other values and then do an instance-of test on a selected item from that sequence...?

I have revised the test function-call-promotion-405 so it now demonstrates the failure.

Because the "treat as" expression is implemented using the ItemChecker class, and ItemChecker treats an xs:anyURI as an xs:string, the expression $x treat as xs:string* can succeed (incorrectly) when the sequence $x contains an xs:anyURI.

I have added QT3 test treat-as-26 to demonstrate this.

I'm now looking at the SEF file output to ensure backwards compatibility in SaxonJS.

For this function (in test as-0152):

<xsl:function name="f:promote" as="xs:double">
      <xsl:param name="p"/>
      <xsl:sequence select="$p"/>
</xsl:function>

we are now generating:

<function name='Q{f}promote' line='10' module='file:/Users/mike/GitHub/xslt30-test/tests/attr/as/as-0152.xsl' flags='pU' as='1AO' slots='1'>
   <arg name='Q{}p' as='*'/>
   <check role='body' baseUri='file:/Users/mike/GitHub/xslt30-test/tests/attr/as/as-0152.xsl' ns='f=f xs=~ xsl=~' line='12' card='1' diag='5|0|XTTE0780|f:promote#1'>
    <convert from='A' to='AO' flags='p' diag='5|0|XTTE0780|f:promote#1'>
     <data diag='5|0|XTTE0780|f:promote#1'>
      <varRef name='Q{}p' slot='0'/>
     </data>
    </convert>
   </check>
  </function>

Specifcally, the varRef is wrapped in data (to do atomisation) then convert which now does both numeric type promotion and conversion from untyped atomic, and then check for a cardinality check.

Saxon 11 generated:

<function name='Q{f}promote' line='10' module='file:/Users/mike/GitHub/xslt30-test/tests/attr/as/as-0152.xsl' eval='16' flags='pU' as='1AO' slots='1'>
   <arg name='Q{}p' as='*'/>
   <check role='body' baseUri='file:/Users/mike/GitHub/xslt30-test/tests/attr/as/as-0152.xsl' ns='f=f xs=~ xsl=~' line='12' card='1' diag='5|0|XTTE0780|f:promote#1'>
    <convert from='A' to='AO' flags='p' diag='5|0|XTTE0780|f:promote#1'>
     <cvUntyped to='AO' diag='5|0|XTTE0780|f:promote#1'>
      <data diag='5|0|XTTE0780|f:promote#1'>
       <varRef name='Q{}p' slot='0'/>
      </data>
     </cvUntyped>
    </convert>
   </check>
  </function>

So the conversion was done in two steps: cvUntyped to convert untypedAtomic to double, and then convert to do promotion from decimal/float to double.

Attempting to run the SEF file from Saxon 12.x using SaxonJS 2.6 results in "Incompatible operands: xs:untypedAtomic (01.123) and xs:double". So we're going to need to adapt the SEF output from 12.x when target=JS.