rubenada commented on code in PR #5184:
URL: https://github.com/apache/calcite/pull/5184#discussion_r3802666450
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core/src/test/java/org/apache/calcite/rex/RexProgramTest.java:
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@@ -3024,6 +3024,82 @@ trueLiteral, literal(1),
checkSimplifyUnchanged(div(cast(vVarchar(), tInt(false)), nullInt));
}
+ /** Test cases for peeling {@code IS [NOT] NULL} across a strong outer
+ * operator whose subtree contains a non-lossless {@code CAST}.
+ *
+ * <p>Distributing {@code IS [NOT] NULL} across a strong operator (e.g.
+ * {@code +}, {@code *}) preserves subtree evaluation: each operand is
+ * either recursively simplified or rewrapped verbatim as
+ * {@code IS [NOT] NULL(operand)}, so the presence of a non-lossless
+ * {@code CAST} deeper in the tree must not block the distribution. */
+ @Test void testSimplifyIsNotNullDistributesAcrossStrongOpWithLossyCast() {
+ // "(CAST(?0.varchar0):INTEGER + 1) IS NOT NULL"
+ // ==> "IS NOT NULL(CAST(?0.varchar0):INTEGER)"
+ // The outer PLUS is strong AND shallow-safe; distribution keeps the
+ // non-lossless CAST inside the rewrapped IS NOT NULL.
+ checkSimplify(
+ isNotNull(plus(cast(vVarchar(), tInt(true)), literal(1))),
+ "IS NOT NULL(CAST(?0.varchar0):INTEGER)");
+
+ // Symmetric IS NULL peel:
+ // "(CAST(?0.varchar0):INTEGER + 1) IS NULL"
+ // ==> "IS NULL(CAST(?0.varchar0):INTEGER)"
+ checkSimplify(
+ isNull(plus(cast(vVarchar(), tInt(true)), literal(1))),
+ "IS NULL(CAST(?0.varchar0):INTEGER)");
+
+ // Confirm this is consistent with same expression without CAST
+ checkSimplify(isNotNull(plus(vInt(), literal(1))), "IS NOT NULL(?0.int0)");
+ checkSimplify(isNull(plus(vInt(), literal(1))), "IS NULL(?0.int0)");
+
+ // MULTIPLY is also strong + shallow-safe.
+ checkSimplify(
+ isNotNull(mul(cast(vVarchar(), tInt(true)), literal(2))),
+ "IS NOT NULL(CAST(?0.varchar0):INTEGER)");
+ checkSimplify(
+ isNull(mul(cast(vVarchar(), tInt(true)), literal(2))),
+ "IS NULL(CAST(?0.varchar0):INTEGER)");
+ checkSimplify(isNotNull(mul(vInt(), literal(2))), "IS NOT NULL(?0.int0)");
+ checkSimplify(isNull(mul(vInt(), literal(2))), "IS NULL(?0.int0)");
+
+ // Nested PLUS on both sides: distribution still peels one layer
+ // and stops at the inner CAST, which is not shallow-safe.
+ // "((CAST(?0.varchar0):INTEGER + 1) + 2) IS NOT NULL"
+ // ==> "IS NOT NULL(CAST(?0.varchar0):INTEGER)"
+ checkSimplify(
+ isNotNull(
+ plus(plus(cast(vVarchar(), tInt(true)), literal(1)), literal(2))),
+ "IS NOT NULL(CAST(?0.varchar0):INTEGER)");
+ }
+
+ /** The distribution must still be suppressed when the outer node is
+ * itself not shallow-safe (e.g. DIVIDE by a literal zero) or when an
+ * operand is typed non-nullable yet not fully safe, otherwise
+ * {@link org.apache.calcite.rex.RexCall#isAlwaysTrue()} would collapse
+ * the rewrapped {@code IS NOT NULL(operand)} to {@code TRUE} and hide
+ * the runtime throw. */
+ @Test void testSimplifyIsNotNullDoesNotDistributeAcrossUnsafeOuter() {
+ // The outer PLUS is shallow-safe, but the div(1, 0) operand is typed
+ // non-nullable, so the peel would rewrap it as IS NOT NULL(/(1, 0))
+ // which the trivial isAlwaysTrue() shortcut would collapse to TRUE
+ // and lose the throw. The peel is therefore suppressed.
+ checkSimplifyUnchanged(isNotNull(plus(div(literal(1), literal(0)),
vIntNotNull())));
+ checkSimplifyUnchanged(isNull(plus(div(literal(1), literal(0)),
vIntNotNull())));
+
+ // IS NOT NULL(x/0) itself is not peeled, because DIVIDE with a
+ // literal-zero divisor is not shallow-safe (this branch would
+ // otherwise drop the throwing subexpression).
+ checkSimplifyUnchanged(isNotNull(div(vIntNotNull(), literal(0))));
+ checkSimplifyUnchanged(isNull(div(vIntNotNull(), literal(0))));
+ checkSimplifyUnchanged(isNull(div(cast(vIntNotNull(), tBigInt()),
literal(0))));
+
+ // IS NULL(CAST(10/0 AS BIGINT)) stays as IS NULL(10/0)
+ // after the lossless-CAST strip; the DIVIDE is not
+ // shallow-safe, so no further distribution occurs.
+ checkSimplify(isNull(cast(div(vIntNotNull(), literal(0)), tBigInt())),
Review Comment:
good point; added both cases
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