dialect/sql: report explicit error when trying to SELECT .. FOR UPDAT… (#1847)

* dialect/sql: report explicit error when trying to SELECT .. FOR UPDATE with sqlite

* remove redundant assertion

dialect/sql/builder.go

@@ -2363,6 +2363,9 @@ func WithLockClause(clause string) LockOption {
 // For sets the lock configuration for suffixing the `SELECT`
 // statement with the `FOR [SHARE | UPDATE] ...` clause.
 func (s *Selector) For(l LockStrength, opts ...LockOption) *Selector {
+	if s.Dialect() == dialect.SQLite {
+		s.AddError(errors.New("sql: SELECT .. FOR UPDATE/SHARE not supported in SQLite"))
+	}
 	s.lock = &LockOptions{Strength: l}
 	for _, opt := range opts {
 		opt(s.lock)

dialect/sql/builder_test.go

@@ -1667,6 +1667,14 @@ func TestSelectWithLock(t *testing.T) {
 		Query()
 	require.Equal(t, "SELECT * FROM `users` WHERE `id` = ? LOCK IN SHARE MODE", query)
 	require.Equal(t, 20, args[0])
+
+	s := Dialect(dialect.SQLite).
+		Select().
+		From(Table("users")).
+		Where(EQ("id", 1)).
+		ForUpdate()
+	s.Query()
+	require.EqualError(t, s.Err(), "sql: SELECT .. FOR UPDATE/SHARE not supported in SQLite")
 }
 
 func TestSelector_UnionOrderBy(t *testing.T) {