Bug #6051: Bug on exist() with non-existing attribute - Saxon - Saxonica Developer Community

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Bug #6051

open

Bug on exist() with non-existing attribute

Added by Christian Grün 11 days ago. Updated 10 days ago.

Status:

In Progress

Priority:

Normal

Assignee:

Michael Kay

Category:

XPath conformance

Sprint/Milestone:

Start date:

2023-05-25

Due date:

% Done:

Estimated time:

Legacy ID:

Applies to branch:

Fix Committed on Branch:

Fixed in Maintenance Release:

Platforms:

.NET, Java

Description

Maybe that's interesting:

https://github.com/BaseXdb/basex/issues/2212

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Updated by Michael Kay 11 days ago

Status changed from New to Rejected
Assignee set to Michael Kay

Thanks.

But Saxon appears to give the correct result.

Test case fn-exists-101 added to qt4tests.

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Updated by Michael Kay 11 days ago

Status changed from Rejected to In Progress

Reopening. ~~The test is working from the command line but not in the test driver.~~

The test is working in 12.x but not in 11.x. In 11.x, the predicate is being rewritten to [exists(data(@n1) ge -1)] which is incorrect; the ge operator returns () when one of the operands is ().

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Updated by Michael Kay 11 days ago

In 11.x, GeneralComparison.typeCheck() line 305 rewrites the comparison to a value comparison like this:

                    Expression vun = makeCompareUntypedToNumeric(getLhsExpression(), getRhsExpression(), singletonOperator);
                    return vun.typeCheck(visitor, contextInfo);

In 12.x this has been changed to:

                    setAtomicComparer(new UntypedNumericComparer());
                    return this;

Git Blame dates this as 19/08/22 and attributes it to bytecode changes, I suspect a bug fix mixed into the same commit as something else.

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Updated by Michael Kay 11 days ago

I've done a fair bit of digging in the history and I can't find any record of what motivated this code change on 2022-08-19. So I'm going to have to deal with it from first principles.

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