andygrove opened a new issue, #4484:
URL: https://github.com/apache/datafusion-comet/issues/4484

   ## Describe the bug
   
   `try_mod` (Spark 4.0+) is `RuntimeReplaceable` and rewrites to 
`Remainder(left, right, EvalMode.TRY)`. Comet's `CometRemainder` serde 
explicitly rejects `EvalMode.TRY` with `withInfo(expr, "Eval mode TRY is not 
supported")` and returns `None`, so the enclosing plan falls back to Spark.
   
   The sibling arithmetic serdes (`CometAdd`, `CometSubtract`, `CometMultiply`, 
`CometDivide`, `CometIntegralDivide`) all accept `EvalMode.TRY` by propagating 
the mode through `evalModeToProto`, and the Rust `spark_modulo` UDF already 
takes a `fail_on_error: bool` flag, so there is no semantic obstacle to letting 
`EvalMode.TRY` through.
   
   Surfaced by the math-expressions audit (collection PR queue).
   
   ## Steps to reproduce
   
   ```sql
   SELECT try_mod(10, 0); -- Spark 4.0+ returns NULL; Comet falls back
   ```
   
   ## Expected behavior
   
   `CometRemainder` should accept `EvalMode.TRY` the same way the other 
arithmetic serdes do (TRY currently behaves identically to LEGACY at the Rust 
layer, returning NULL on divide-by-zero).
   
   ## Additional context
   
   - Comet serde: `CometRemainder` in 
`spark/src/main/scala/org/apache/comet/serde/arithmetic.scala`
   - Rust impl: `native/spark-expr/src/math_funcs/modulo_expr.rs::spark_modulo`
   - Spark reference: `TryMod` in 
`org.apache.spark.sql.catalyst.expressions.tryArithmetic.scala`
   


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