Saxon

On both platforms we are evaluating the xsl:with-param (unnecessarily). But for some reason on SaxonJ the select expression has been promoted to a global variable, which is evaluated eagerly, triggering the type error; but on SaxonCS this promotion has not taken place, so the value is evaluated lazily, and since it is never used, the type error is not triggered.

So the question becomes: why is the promotion to global happening in SaxonJ but not in SaxonCS?

It seems the SaxonCS test driver is running with JIT compilation of template rules enabled, while the SaxonJ test driver is running with this option disabled. When JIT compilation is enabled, we don't attempt to extract global variables from templates (because we don't want to create new global variables dynamically). Both paths are legitimate, and it does no harm that we're exercising different options...

The real issue is, we shouldn't be evaluating xsl:with-param instructions that aren't needed because they are overridden by dynamic params.

Which in turn means that the test case shouldn't be expecting the type error to be reported.

I've now

(a) updated the code (12.x branch) so it doesn't evaluate the xsl:with-param if there's a dynamic parameter with the same name

(b) modified the test so it forces the xsl:with-param to be evaluated