From d610375fd6fc0e4185a5cab7503622f4b9a8603d Mon Sep 17 00:00:00 2001
From: Rafi Shamim <rafi@cockroachlabs.com>
Date: Thu, 23 May 2019 11:56:29 -0400
Subject: [PATCH] tree: handle null in suboperator expressions

Before this change, a null right operand in a suboperator would cause an
unhandled error. We were receiving stack trace reports from the wild.
Add a test and fix it. Also add a few additional tests to verify correct
behavior with a null left operand.

Release note (bug fix): a null right operand now causes the suboperator
expression to return null
---
 pkg/sql/sem/tree/eval.go                    |  4 +-
 pkg/sql/sem/tree/testdata/eval/any_some_all | 63 +++++++++++++++++++++
 2 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/pkg/sql/sem/tree/eval.go b/pkg/sql/sem/tree/eval.go
index a5bcc688c2f8..ece9dda35235 100644
--- a/pkg/sql/sem/tree/eval.go
+++ b/pkg/sql/sem/tree/eval.go
@@ -3670,7 +3670,9 @@ func (expr *ComparisonExpr) Eval(ctx *EvalContext) (Datum, error) {
 	if op.hasSubOperator() {
 		var datums Datums
 		// Right is either a tuple or an array of Datums.
-		if tuple, ok := AsDTuple(right); ok {
+		if !expr.fn.NullableArgs && right == DNull {
+			return DNull, nil
+		} else if tuple, ok := AsDTuple(right); ok {
 			datums = tuple.D
 		} else if array, ok := AsDArray(right); ok {
 			datums = array.Array
diff --git a/pkg/sql/sem/tree/testdata/eval/any_some_all b/pkg/sql/sem/tree/testdata/eval/any_some_all
index b54420534801..6ff7747072c2 100644
--- a/pkg/sql/sem/tree/testdata/eval/any_some_all
+++ b/pkg/sql/sem/tree/testdata/eval/any_some_all
@@ -70,6 +70,69 @@ eval
 ----
 NULL
 
+# Regression test for #37547 - ensure that null RHS of comparisons with
+# suboperators are correctly handled. A null RHS always results in null.
+eval
+1 = ANY(NULL::int[])
+----
+NULL
+
+eval
+1 = SOME(NULL::int[])
+----
+NULL
+
+eval
+1 = ALL(NULL::int[])
+----
+NULL
+
+eval
+NULL::int = ANY(NULL::int[])
+----
+NULL
+
+eval
+NULL::int = SOME(NULL::int[])
+----
+NULL
+
+eval
+NULL::int = ALL(NULL::int[])
+----
+NULL
+
+# A null LHS has different behavior if the array is empty or not
+eval
+NULL::int = ANY(ARRAY[1,2])
+----
+NULL
+
+eval
+NULL::int = SOME(ARRAY[1,2])
+----
+NULL
+
+eval
+NULL::int = ALL(ARRAY[1,2])
+----
+NULL
+
+eval
+NULL::int = ANY(ARRAY[]::int[])
+----
+false
+
+eval
+NULL::int = SOME(ARRAY[]::int[])
+----
+false
+
+eval
+NULL::int = ALL(ARRAY[]::int[])
+----
+true
+
 eval
 1 = ALL (ARRAY[1, 2, NULL])
 ----