Saxon

Reproduced using the command line options

-xsl:Customization/XSL/ConvertToIR.xsl -nogo -jit:off -lib:Core/XSL/pkg.to-ir.xsl:EDK/Scripts/XSL/WordCore/pkg.to-wif.xsl

Switching StylesheetPackage.TRACING on, the last message before the crash is

Doing mode completion for mode towif:document

The crash occurs because the array for new component bindings has length zero (whereas the old component bindings has length 34).

We're in addComponentsFromUsedPackage - it's a long time since I looked at this rather complex code and it's going to require some refamiliarisation.

We have a freestanding stylesheet module ConvertToIR.xsl with use-package dependencies on both to-wif.xsl and to-ir.xsl, in both cases with overriding declarations.

Package to-ir.xsl itself has a use-package dependency on to-wif.xsl, again with overrides.

I think it's this that is causing the problem. I haven't yet established whether the stylesheet is legal or not; either way, of course, Saxon shouldn't be crashing.

At the time of the failure, the freestanding module is copying in the definition of mode towif:document from package to-ir.xsl, which contains this component only because it acquired it from to-wif.xsl.

The problem goes away if we change line 709 of StylesheetPackage from

if (newC.getActor() instanceof Mode && overrides.contains(name)) {

to

if (newC.getActor() instanceof Mode && overrides.contains(name) && !newC.getVisibility().equals(HIDDEN)) {

The thinking behind this is that we only want to do this special code for a mode that we are overriding directly, we don't want to do it because we are overriding the same mode in a different package.

This needs checking. There may be a better way.

The change appears to cause no test regressions.

After quite a bit of effort, I have managed to reproduce the problem in a simplified unit test (TestPackage/testBug6186) which will make it easier to see exactly why it is failing and to confirm that the solution is sound.