[jira] [Commented] (CALCITE-2615) When simplifying NOT-AND-OR, RexSimplify incorrectly applies predicates deduced for operands to the same operands

["Julian Hyde (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-2615?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16642383#comment-16642383 ] 

Julian Hyde commented on CALCITE-2615:
--------------------------------------

[~kgyrtkirk], Can you take this one, please?

> When simplifying NOT-AND-OR, RexSimplify incorrectly applies predicates deduced for operands to the same operands
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: CALCITE-2615
>                 URL: https://issues.apache.org/jira/browse/CALCITE-2615
>             Project: Calcite
>          Issue Type: Task
>            Reporter: Julian Hyde
>            Assignee: Julian Hyde
>            Priority: Major
>
> When simplifying NOT-AND-OR, RexSimplify incorrectly applies predicates deduced for operands to the same operands.
> Here is the test case (add it to RexProgramTest):
> {code:java}
>   @Test public void testSimplifyNotAnd() {
>     final RexNode e = not(
>         and(
>             gt(and(vBool(1), literal(true)),
>                 or(literal(true), literal(true), literal(false))),
>             gt(isNotNull(vBool(0)), eq(literal(false), vBool(1))),
>             or(ne(literal(true), literal(false)),
>                 ge(vInt(0), literal((Integer) null)))));
>     final String expected = "TODO";
>    checkSimplify(e, expected);
>   }
> {code}
> When you run it, verify will find a combination of assignments such that the simplified expression returns a different result than the original.
> The test case is not minimal; sorry. Maybe it reproduces with NOT-OR.
> The bug is in [RexSimplify.simplifyAndTerms|https://github.com/apache/calcite/blob/6b3844c0634792263a5073b8ea93565fb3415f41/core/src/main/java/org/apache/calcite/rex/RexSimplify.java#L412]. Put a breakpoint at that line to see the problem. It passes through the operands once, building a list of predicates. Then it passes through the operands again, simplifying each operand. Thus operand1 is simplified using a list of predicates that includes the predicate 'not operand1'. Clearly wrong. [~kgyrtkirk], I warned that this was possible in our discussions.



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