by jamespcooper:

What steps will reproduce the problem?

add this test to database/sql/sql_test.go

func TestNullByteSlice(t *testing.T) {
    db := newTestDB(t, "")
    defer closeDB(t, db)
    exec(t, db, "CREATE|t|id=int32,name=string")
    exec(t, db, "INSERT|t|id=10,name=?", nil)

    var name []byte
    err := db.QueryRow("SELECT|t|name|id=?", 10).Scan(&name)
    if err != nil {
        t.Fatal(err)
    }
    if name != nil {
        t.Fatal("name []byte should be nil for null column value, got: %v", name)
    }

    exec(t, db, "INSERT|t|id=10,name=?", "bob")
    err = db.QueryRow("SELECT|t|name|id=?", 10).Scan(&name)
    if err != nil {
        t.Fatal(err)
    }
    if string(name) != "bob" {
        t.Fatal("name []byte should be bob, got: %s", string(name))
    }
}


What is the expected output?
Passing test

What do you see instead?

--- FAIL: sql.TestNullByteSlice (0.00 seconds)
    sql_test.go:354: sql: Scan error on column index 0: unsupported driver -> Scan pair: <nil> -> *[]uint8
FAIL


Which compiler are you using (5g, 6g, 8g, gccgo)?
6g

Which operating system are you using?
Mac OS 10.6.8

Which revision are you using?  (hg identify)
7de66de3961c+ tip

Please provide any additional information below.
This is a follow up to #2699.  We decided to not introduce a NullBytes struct, but we
probably need to modify  convert.go's  convertAssign() to handle this case