lyne7-sc opened a new pull request, #24248:
URL: https://github.com/apache/datafusion/pull/24248
## Which issue does this PR close?
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- Part of #24246 .
## Rationale for this change
Bitwise XOR simplifications cancelled repeated nullable operands, which
could incorrectly produce a non-NULL result when the operand was NULL.
For example:
```sql
SELECT
i XOR i,
(i XOR 7) XOR i,
i XOR (7 XOR i)
FROM (VALUES (NULL::INT)) AS t(i);
```
These expressions should all return NULL, but simplification could replace
them with 0, 7, and 7.
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## What changes are included in this PR?
Only cancel repeated XOR operands when the removed operand is non-nullable.
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## Are these changes tested?
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Yes. Added sqllogictests covering results.
## Are there any user-facing changes?
Yes. Bitwise XOR expressions with repeated nullable operands now correctly
preserve NULLs.
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