From 84bbb7b732504ca1cff6152073ac0d244c6c0ce7 Mon Sep 17 00:00:00 2001
From: Nick Tobey <nick@dolthub.com>
Date: Mon, 7 Apr 2025 18:03:57 -0700
Subject: [PATCH] converting a nil value should return nil, not a panic.

Most uses of `convertValue` checked if the input was nil, but `Binary.Eval` didn't. This is always the desired behavior, so just put the check here.
---
 enginetest/queries/queries.go               | 11 ++++++++++
 enginetest/scriptgen/setup/scripts/niltable | 23 +++++++++++++++++++++
 enginetest/scriptgen/setup/setup_data.sg.go |  8 +++++++
 sql/expression/convert.go                   |  3 +++
 4 files changed, 45 insertions(+)

diff --git a/enginetest/queries/queries.go b/enginetest/queries/queries.go
index cc9aaa28e2..e64b4a916e 100644
--- a/enginetest/queries/queries.go
+++ b/enginetest/queries/queries.go
@@ -5206,6 +5206,17 @@ SELECT * FROM cte WHERE  d = 2;`,
 		Query:    "SELECT CAST(-3 AS DOUBLE) FROM dual",
 		Expected: []sql.Row{{-3.0}},
 	},
+	{
+		Query: "SELECT BINARY c, BINARY vc, BINARY t, BINARY b, BINARY vb, BINARY bl FROM niltexttable",
+		Expected: []sql.Row{
+			{nil, nil, nil, nil, nil, nil},
+			{[]byte("2"), nil, []byte("2"), nil, []byte("2"), nil},
+			{nil, []byte("3"), []byte("3"), nil, nil, []byte("3")},
+			{[]byte("4"), []byte("4"), nil, []byte("4\x00"), nil, nil},
+			{nil, nil, nil, []byte("5\x00"), []byte("5"), []byte("5")},
+			{[]byte("6"), []byte("6"), []byte("6"), []byte("6\x00"), []byte("6"), []byte("6")},
+		},
+	},
 	{
 		Query:    `SELECT CONVERT("-3.9876", FLOAT) FROM dual`,
 		Expected: []sql.Row{{float32(-3.9876)}},
diff --git a/enginetest/scriptgen/setup/scripts/niltable b/enginetest/scriptgen/setup/scripts/niltable
index 8ebe370c59..2ab65b016d 100644
--- a/enginetest/scriptgen/setup/scripts/niltable
+++ b/enginetest/scriptgen/setup/scripts/niltable
@@ -21,3 +21,26 @@ insert into niltable values
 exec
 create index niltable_i2 on niltable (i2)
 ----
+
+exec
+CREATE TABLE `niltexttable` (
+  `i` bigint NOT NULL,
+  `c` char(2),
+  `vc` varchar(2),
+  `t` text,
+  `b` binary(2),
+  `vb` varbinary(2),
+  `bl` blob,
+  PRIMARY KEY (`i`)
+)
+----
+
+exec
+insert into niltexttable values
+    (1, null, null, null, null, null, null),
+    (2, '2',  null, '2',  null, '2',  null),
+    (3, null, '3',  '3',  null, null, '3'),
+    (4, '4',  '4',  null, '4',  null, null),
+    (5, null, null, null, '5',  '5',  '5'),
+    (6, '6',  '6',  '6',  '6',  '6',  '6')
+----
\ No newline at end of file
diff --git a/enginetest/scriptgen/setup/setup_data.sg.go b/enginetest/scriptgen/setup/setup_data.sg.go
index b986162c4c..b7d8c8dab9 100755
--- a/enginetest/scriptgen/setup/setup_data.sg.go
+++ b/enginetest/scriptgen/setup/setup_data.sg.go
@@ -3028,6 +3028,14 @@ var NiltableData = []SetupScript{{
     (5,null,1,5.0),
     (6,6,0,6.0)`,
 	`create index niltable_i2 on niltable (i2)`,
+	"CREATE TABLE `niltexttable` (   `i` bigint NOT NULL,   `c` char(2),   `vc` varchar(2),   `t` text,   `b` binary(2),   `vb` varbinary(2),   `bl` blob,   PRIMARY KEY (`i`) )",
+	`insert into niltexttable values
+    (1, null, null, null, null, null, null),
+    (2, '2',  null, '2',  null, '2',  null),
+    (3, null, '3',  '3',  null, null, '3'),
+    (4, '4',  '4',  null, '4',  null, null),
+    (5, null, null, null, '5',  '5',  '5'),
+    (6, '6',  '6',  '6',  '6',  '6',  '6')`,
 }}
 
 var Null_rangesData = []SetupScript{{
diff --git a/sql/expression/convert.go b/sql/expression/convert.go
index f528ff2a44..022501a212 100644
--- a/sql/expression/convert.go
+++ b/sql/expression/convert.go
@@ -284,6 +284,9 @@ func (c *Convert) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
 // converted type where applicable (e.g. Char conversion supports only |typeLength|, Decimal conversion supports
 // |typeLength| and |typeScale|).
 func convertValue(ctx *sql.Context, val interface{}, castTo string, originType sql.Type, typeLength, typeScale int) (interface{}, error) {
+	if val == nil {
+		return nil, nil
+	}
 	switch strings.ToLower(castTo) {
 	case ConvertToBinary:
 		b, _, err := types.LongBlob.Convert(ctx, val)