sbroeder opened a new pull request, #4959:
URL: https://github.com/apache/calcite/pull/4959
Summary
RexCall.isAlwaysTrue() and isAlwaysFalse() group CAST together with IS_TRUE
/ IS_NOT_FALSE (and IS_FALSE / IS_NOT_TRUE) and simply delegate to the operand.
That is wrong when the cast changes the type: CAST(TRUE AS INTEGER) is an
INTEGER expression that evaluates to 1, not a boolean, so it must report
isAlwaysTrue() == false. Today it returns true.
This is an API-contract violation. RexSimplify happens not to mis-fire on
this expression upstream (its Comparison helper requires a LITERAL-kind
operand, which CAST is not), but any caller that consults isAlwaysTrue/False on
an arbitrary RexNode and trusts the result to be boolean-valued can be misled.
Fix
Split the CAST case out of the fall-through group in both methods and only
delegate to the operand when the result type is BOOLEAN.
- core/src/main/java/org/apache/calcite/rex/RexCall.java
Tests
core/src/test/java/org/apache/calcite/rex/RexProgramTest.java:
- testIsAlwaysTrueCastBooleanToInteger — CAST(TRUE AS
INTEGER).isAlwaysTrue() is false. Fails on unfixed code.
- testIsAlwaysFalseCastBooleanToInteger — CAST(FALSE AS
INTEGER).isAlwaysFalse() is false. Fails on unfixed code.
- testIsAlwaysTrueCastBooleanToBoolean — CAST(TRUE AS
BOOLEAN).isAlwaysTrue() is still true (no regression for same-type casts).
- testIsAlwaysFalseCastBooleanToBoolean — CAST(FALSE AS
BOOLEAN).isAlwaysFalse() is still true.
Repro (against unfixed code)
./gradlew :core:test \
--tests
"org.apache.calcite.rex.RexProgramTest.testIsAlwaysTrueCastBooleanToInteger" \
--tests
"org.apache.calcite.rex.RexProgramTest.testIsAlwaysFalseCastBooleanToInteger"
Both fail with Expected: is <false> but: was <true>. With the fix applied,
all four tests pass.
[CALCITE-7542](https://issues.apache.org/jira/browse/CALCITE-7542)
## Changes Proposed
<!--
Split the CAST case out of the fall-through group in both isAlwaysTrue()
and isAlwaysFalse() and only delegate to the operand when the result type is
BOOLEAN:
- core/src/main/java/org/apache/calcite/rex/RexCall.java
-->
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