diesel/type_impls/

tuples.rs

use crate::associations::BelongsTo;
use crate::backend::Backend;
use crate::deserialize::{
    self, FromSqlRow, FromStaticSqlRow, Queryable, SqlTypeOrSelectable, StaticallySizedRow,
};
use crate::expression::{
    AppearsOnTable, Expression, IsContainedInGroupBy, MixedAggregates, QueryMetadata, Selectable,
    SelectableExpression, TypedExpressionType, ValidGrouping, is_contained_in_group_by,
};
use crate::insertable::{CanInsertInSingleQuery, InsertValues, Insertable, InsertableOptionHelper};
#[cfg(any(
    feature = "__sqlite-shared",
    feature = "postgres_backend",
    feature = "mysql_backend"
))]
use crate::query_builder::update_statement::batch_update::{BatchKeyHelper, BatchValueHelper};
use crate::query_builder::*;
use crate::query_dsl::load_dsl::CompatibleType;
use crate::query_source::*;
use crate::result::QueryResult;
use crate::row::*;
use crate::sql_types::{HasSqlType, IntoNullable, Nullable, OneIsNullable, SqlType};
use crate::util::{TupleAppend, TupleSize};
use alloc::vec::Vec;

impl<T> TupleSize for T
where
    T: crate::sql_types::SingleValue,
{
    const SIZE: usize = 1;
}

macro_rules! fake_variadic {
    (1i32 -> $($tt: tt)*) => {
        #[cfg_attr(diesel_docsrs, doc(fake_variadic))]
        $($tt)*
    };
    ($idx:tt -> $($tt: tt)*) => {
        #[cfg_attr(diesel_docsrs, doc(hidden))]
        $($tt)*
    };
}

macro_rules! tuple_impls {
    ($(
        $Tuple:tt {
            $(($idx:tt) -> $T:ident, $ST:ident, $TT:ident,)+
        }
    )+) => {
        $(
            fake_variadic!{
                $Tuple ->
                impl<$($T),+, __DB> HasSqlType<($($T,)+)> for __DB where
                    $(__DB: HasSqlType<$T>),+,
                    __DB: Backend,
                {
                    fn metadata(_: &mut __DB::MetadataLookup) -> __DB::TypeMetadata {
                        unreachable!("Tuples should never implement `ToSql` directly");
                    }
                }
            }

            impl_from_sql_row!(($($T,)+), ($($ST,)+));


            fake_variadic! {
                $Tuple ->
                #[diagnostic::do_not_recommend]
                impl<$($T: Expression),+> Expression for ($($T,)+)
                where ($($T::SqlType, )*): TypedExpressionType
                {
                    type SqlType = ($(<$T as Expression>::SqlType,)+);
                }
            }
            fake_variadic! {
                $Tuple -> impl<$($T: TypedExpressionType,)*> TypedExpressionType for ($($T,)*) {}
            }
            fake_variadic! {
                $Tuple ->
                impl<$($T: SqlType + TypedExpressionType,)*> TypedExpressionType for Nullable<($($T,)*)>
                where ($($T,)*): SqlType
                {
                }
            }
            fake_variadic! {
                $Tuple ->
                impl<$($T: SqlType,)*> IntoNullable for ($($T,)*)
                where Self: SqlType,
                {
                    type Nullable = Nullable<($($T,)*)>;
                }
            }

            fake_variadic! {
                $Tuple ->
                impl<$($T,)+ __DB> Selectable<__DB> for ($($T,)+)
                where
                    __DB: Backend,
                $($T: Selectable<__DB>),+,
                {
                    type SelectExpression = ($($T::SelectExpression,)+);

                    fn construct_selection() -> Self::SelectExpression {
                        ($($T::construct_selection(),)+)
                    }
                }
            }

            fake_variadic! {
                $Tuple ->
                impl<$($T: QueryFragment<__DB>),+, __DB: Backend> QueryFragment<__DB> for ($($T,)+) {
                    #[allow(unused_assignments)]
                    fn walk_ast<'b>(&'b self, mut out: AstPass<'_, 'b, __DB>) -> QueryResult<()>
                    {
                        let mut needs_comma = false;
                        $(
                            if !self.$idx.is_noop(out.backend())? {
                                if needs_comma {
                                    out.push_sql(", ");
                                }
                                self.$idx.walk_ast(out.reborrow())?;
                                needs_comma = true;
                            }
                        )+
                            Ok(())
                    }
                }
            }

            // cannot use `#[diagnostic::do_not_recommend]` here yet to hide tuple impls
            // as this makes the error message worse (not saying which column is problematic)
            impl<$($T,)+ Tab> ColumnList for ($($T,)+)
            where
                $($T: ColumnList<Table = Tab>,)+
            {
                type Table = Tab;

                fn walk_ast<__DB: Backend>(&self, mut out: AstPass<'_, '_, __DB>) -> QueryResult<()> {
                    $(
                        if $idx != 0 {
                            out.push_sql(", ");
                        }
                        self.$idx.walk_ast(out.reborrow())?;
                    )+
                    Ok(())
                }
            }

            fake_variadic! {
                $Tuple ->
                impl<$($T: QueryId),+> QueryId for ($($T,)+) {
                    type QueryId = ($($T::QueryId,)+);

                    const HAS_STATIC_QUERY_ID: bool = $($T::HAS_STATIC_QUERY_ID &&)+ true;
                }
            }

            impl_valid_grouping_for_tuple_of_columns!($($T,)*);

            impl<$($T,)+ Tab> UndecoratedInsertRecord<Tab> for ($($T,)+)
            where
                $($T: UndecoratedInsertRecord<Tab>,)+
            {
            }

            impl<$($T,)+ __DB> CanInsertInSingleQuery<__DB> for ($($T,)+)
            where
                __DB: Backend,
                $($T: CanInsertInSingleQuery<__DB>,)+
            {
                fn rows_to_insert(&self) -> Option<usize> {
                    $(debug_assert_eq!(self.$idx.rows_to_insert(), Some(1));)+
                    Some(1)
                }
            }

            fake_variadic! {
                $Tuple ->
                impl<$($T,)+ $($ST,)+ Tab> Insertable<Tab> for ($($T,)+)
                where
                    $($T: Insertable<Tab, Values = ValuesClause<$ST, Tab>>,)+
                {
                    type Values = ValuesClause<($($ST,)+), Tab>;

                    fn values(self) -> Self::Values {
                        ValuesClause::new(($(self.$idx.values().values,)+))
                    }
                }
            }

            // that isn't supported by the derive yet?
            // fake_variadic! {
            //     $Tuple ->
                impl<'a, $($T,)+ Tab> Insertable<Tab> for &'a ($($T,)+)
                where
                    ($(&'a $T,)+): Insertable<Tab>,
                {
                    type Values = <($(&'a $T,)+) as Insertable<Tab>>::Values;

                    fn values(self) -> Self::Values {
                        ($(&self.$idx,)+).values()
                    }
                }
//            }

            #[allow(unused_assignments)]
            impl<$($T,)+ Tab, __DB> InsertValues<__DB, Tab> for ($($T,)+)
            where
                Tab: Table,
                __DB: Backend,
                $($T: InsertValues<__DB, Tab>,)+
            {
                fn column_names(&self, mut out: AstPass<'_, '_, __DB>) -> QueryResult<()> {
                    let mut needs_comma = false;
                    $(
                        let noop_element = self.$idx.is_noop(out.backend())?;
                        if !noop_element {
                            if needs_comma {
                                out.push_sql(", ");
                            }
                            self.$idx.column_names(out.reborrow())?;
                            needs_comma = true;
                        }
                    )+
                    Ok(())
                }
            }

            impl<__T, $($ST,)* Tab> Insertable<Tab> for InsertableOptionHelper<__T, ($($ST,)*)>
            where
                __T: Insertable<Tab>,
                __T::Values: Default,
            {
                type Values = __T::Values;

                fn values(self) -> Self::Values {
                    self.0.map(|v| v.values()).unwrap_or_default()
                }
            }

            // not possible to use diagnostic::do_not_recommend to hide the tuple impls
            // yet as it gives worse error messages
            // (doesn't show anymore which tuple element doesn't implement the trait)
            impl<$($T,)+ QS> SelectableExpression<QS> for ($($T,)+) where
                $($T: SelectableExpression<QS>,)+
                ($($T,)+): AppearsOnTable<QS>,
            {
            }

            fake_variadic! {
                $Tuple ->
                impl<$($T,)+ QS> AppearsOnTable<QS> for ($($T,)+) where
                    $($T: AppearsOnTable<QS>,)+
                    ($($T,)+): Expression,
                {
                }
            }

            #[cfg(any(feature = "__sqlite-shared", feature = "postgres_backend", feature = "mysql_backend"))]
            impl<$($T,)+  __DB> BatchValueHelper<__DB> for ($($T,)+)
            where
                $($T: BatchValueHelper<__DB>,)+
                __DB: Backend
            {
                fn assign<'b>(&'b self, mut out: AstPass<'_, 'b, __DB>) -> QueryResult<()> {
                     $(
                        if $idx != 0 {
                            out.push_sql(", ");
                        }
                        self.$idx.assign(out.reborrow())?;
                    )+
                    Ok(())
                }
                fn column_name<'b>(&'b self, mut out: AstPass<'_, 'b, __DB>) -> QueryResult<()> {
                     $(
                        if $idx != 0 {
                            out.push_sql(", ");
                        }
                        self.$idx.column_name(out.reborrow())?;
                    )+
                    Ok(())
                }
                fn bind_value<'b>(&'b self, mut out: AstPass<'_, 'b, __DB>) -> QueryResult<()> {
                    $(
                        if $idx != 0 {
                            out.push_sql(", ");
                        }
                        self.$idx.bind_value(out.reborrow())?;
                    )+
                    Ok(())
                }
            }

            #[cfg(any(feature = "__sqlite-shared", feature = "postgres_backend", feature = "mysql_backend"))]
            impl<$($T,)+ $($ST,)+ __DB> BatchKeyHelper<($($ST,)*), __DB> for ($($T,)+)
            where
                __DB: Backend,
               $($T: BatchKeyHelper<$ST, __DB>,)+
            {
                fn bind_value<'b>(&'b self, mut out: AstPass<'_, 'b, __DB>) -> QueryResult<()> {
                    $(
                        if $idx != 0 {
                            out.push_sql(", ");
                        }
                        self.$idx.bind_value(out.reborrow())?;
                    )+
                    Ok(())
                }

                fn column_name<'b>(&'b self, mut out: AstPass<'_, 'b, __DB>) -> QueryResult<()> {
                     $(
                        if $idx != 0 {
                            out.push_sql(", ");
                        }
                        self.$idx.column_name(out.reborrow())?;
                    )+
                    Ok(())
                }

                fn assign<'b>(pk: &'b ($($ST,)+), mut out: AstPass<'_, 'b, __DB>) -> QueryResult<()> {
                    $(
                        if $idx != 0 {
                            out.push_sql(" AND ");
                        }
                        <$T as BatchKeyHelper<$ST, __DB>>::assign(&pk.$idx, out.reborrow())?;
                    )+
                    Ok(())
                }
            }

            impl<$($T,)* W> crate::query_builder::update_statement::private::AllowFilterForUpdate<crate::query_builder::where_clause::WhereClause<W>>
                for ($($T,)*)
            where $($T: crate::query_builder::update_statement::private::AllowFilterForUpdate<crate::query_builder::where_clause::WhereClause<W>>,)* {
            }

            impl<'a, $($T,)* DB> crate::query_builder::update_statement::private::AllowFilterForUpdate<crate::query_builder::where_clause::BoxedWhereClause<'a, DB>>
                for ($($T,)*)
            where
                DB: crate::backend::Backend,
                $($T: crate::query_builder::update_statement::private::AllowFilterForUpdate<crate::query_builder::where_clause::BoxedWhereClause<'a, DB>>,)* {
            }

            impl<'a, $($T,)*> crate::query_builder::update_statement::changeset::IntoOwned for ($(&'a $T,)*)
            where $(&'a $T: crate::query_builder::update_statement::changeset::IntoOwned,)*
            {
                type Owned = ($(<&'a $T as crate::query_builder::update_statement::changeset::IntoOwned>::Owned,)*);

                fn into_owned(self) -> Self::Owned {
                    ($(<&'a $T as crate::query_builder::update_statement::changeset::IntoOwned>::into_owned(&self.$idx),)*)
                }
            }

            fake_variadic! {
                $Tuple ->
                impl<Target, $($T,)+> AsChangeset for ($($T,)+) where
                    $($T: AsChangeset<Target=Target>,)+
                    Target: QuerySource,
                {
                    type Target = Target;
                    type Changeset = ($($T::Changeset,)+);

                    fn as_changeset(self) -> Self::Changeset {
                        ($(self.$idx.as_changeset(),)+)
                    }
                }
            }

            fake_variadic! {
                $Tuple ->
                impl<$($T,)+ Parent> BelongsTo<Parent> for ($($T,)+) where
                    T: BelongsTo<Parent>,
                {
                    type ForeignKey = T::ForeignKey;
                    type ForeignKeyColumn = T::ForeignKeyColumn;

                    fn foreign_key(&self) -> Option<&Self::ForeignKey> {
                        self.0.foreign_key()
                    }

                    fn foreign_key_column() -> Self::ForeignKeyColumn {
                        T::foreign_key_column()
                    }
                }
            }

            impl<$($T,)+ Next> TupleAppend<Next> for ($($T,)+) {
                type Output = ($($T,)+ Next);

                #[allow(non_snake_case)]
                fn tuple_append(self, next: Next) -> Self::Output {
                    let ($($T,)+) = self;
                    ($($T,)+ next)
                }
            }

            impl_sql_type!($($T,)*);

            fake_variadic! {
                $Tuple ->
                impl<$($T,)* __DB, $($ST,)*> Queryable<($($ST,)*), __DB> for ($($T,)*)
                where __DB: Backend,
                      Self: FromStaticSqlRow<($($ST,)*), __DB>,
                {
                    type Row = Self;

                    fn build(row: Self::Row) -> deserialize::Result<Self> {
                        Ok(row)
                    }
                }
            }

            // That's unfortunally not supported yet
            // fake_variadic! {
            //     $Tuple ->
                impl<__T, $($ST,)*  __DB> FromStaticSqlRow<Nullable<($($ST,)*)>, __DB> for Option<__T> where
                    __DB: Backend,
                ($($ST,)*): SqlType,
                    __T: FromSqlRow<($($ST,)*), __DB>,
                {

                    #[allow(non_snake_case, unused_variables, unused_mut)]
                    fn build_from_row<'a>(row: &impl Row<'a, __DB>)
                                          -> deserialize::Result<Self>
                    {
                        match <__T as FromSqlRow<($($ST,)*), __DB>>::build_from_row(row) {
                            Ok(v) => Ok(Some(v)),
                            Err(e) if e.is::<crate::result::UnexpectedNullError>() => Ok(None),
                            Err(e) => Err(e)
                        }
                    }
                }
            //}

            // That's unfortunally not supported yet
            // fake_variadic! {
            //     $Tuple ->
                impl<__T,  __DB, $($ST,)*> Queryable<Nullable<($($ST,)*)>, __DB> for Option<__T>
                where __DB: Backend,
                      Self: FromStaticSqlRow<Nullable<($($ST,)*)>, __DB>,
                ($($ST,)*): SqlType,
                {
                    type Row = Self;

                    fn build(row: Self::Row) -> deserialize::Result<Self> {
                        Ok(row)
                    }
                }
            //}

            impl<$($T,)*> TupleSize for ($($T,)*)
                where $($T: TupleSize,)*
            {
                const SIZE: usize = $($T::SIZE +)* 0;
            }

            impl<$($T,)*> TupleSize for Nullable<($($T,)*)>
            where $($T: TupleSize,)*
                  ($($T,)*): SqlType,
            {
                const SIZE: usize = $($T::SIZE +)* 0;
            }

            fake_variadic! {
                $Tuple ->
                impl<$($T,)* __DB> QueryMetadata<($($T,)*)> for __DB
                where __DB: Backend,
                $(__DB: QueryMetadata<$T>,)*
                {
                    fn row_metadata(lookup: &mut Self::MetadataLookup, row: &mut Vec<Option<__DB::TypeMetadata>>) {
                        $(
                            <__DB as QueryMetadata<$T>>::row_metadata(lookup, row);
                        )*
                    }
                }
            }

            // That's unfortunally not supported yet
            // fake_variadic! {
            //     $Tuple ->
                impl<$($T,)* __DB> QueryMetadata<Nullable<($($T,)*)>> for __DB
                where __DB: Backend,
                $(__DB: QueryMetadata<$T>,)*
                {
                    fn row_metadata(lookup: &mut Self::MetadataLookup, row: &mut Vec<Option<__DB::TypeMetadata>>) {
                        $(
                            <__DB as QueryMetadata<$T>>::row_metadata(lookup, row);
                        )*
                    }
                }
            //}

            fake_variadic! {
                $Tuple ->
                impl<$($T,)* __DB> deserialize::QueryableByName< __DB> for ($($T,)*)
                where __DB: Backend,
                $($T: deserialize::QueryableByName<__DB>,)*
                {
                    fn build<'a>(row: &impl NamedRow<'a, __DB>) -> deserialize::Result<Self> {
                        Ok(($(
                            <$T as deserialize::QueryableByName<__DB>>::build(row)?,
                        )*))
                    }
                }
            }

            #[diagnostic::do_not_recommend]
            impl<__T, $($ST,)* __DB> CompatibleType<__T, __DB> for ($($ST,)*)
            where
                __DB: Backend,
                __T: FromSqlRow<($($ST,)*), __DB>,
            {
                type SqlType = Self;
            }

            impl<__T, $($ST,)* __DB> CompatibleType<Option<__T>, __DB> for Nullable<($($ST,)*)>
            where
                __DB: Backend,
                ($($ST,)*): CompatibleType<__T, __DB>
            {
                type SqlType = Nullable<<($($ST,)*) as CompatibleType<__T, __DB>>::SqlType>;
            }

            impl<$($ST,)*> SqlTypeOrSelectable for ($($ST,)*)
            where $($ST: SqlTypeOrSelectable,)*
            {}

            impl<$($ST,)*> SqlTypeOrSelectable for Nullable<($($ST,)*)>
            where ($($ST,)*): SqlTypeOrSelectable
            {}
        )+
    }
}

macro_rules! impl_from_sql_row {
    (($T1: ident,), ($ST1: ident,)) => {
        #[cfg_attr(diesel_docsrs, doc(fake_variadic))]
        impl<$T1, $ST1, __DB> crate::deserialize::FromStaticSqlRow<($ST1,), __DB> for ($T1,) where
            __DB: Backend,
            $ST1: CompatibleType<$T1, __DB>,
            $T1: FromSqlRow<<$ST1 as CompatibleType<$T1, __DB>>::SqlType, __DB>,
        {

            #[allow(non_snake_case, unused_variables, unused_mut)]
            fn build_from_row<'a>(row: &impl Row<'a, __DB>)
                                                       -> deserialize::Result<Self>
            {
                Ok(($T1::build_from_row(row)?,))
            }
        }
    };
    (($T1: ident, $($T: ident,)*), ($ST1: ident, $($ST: ident,)*)) => {
        #[cfg_attr(diesel_docsrs, doc(hidden))]
        #[diagnostic::do_not_recommend]
        impl<$T1, $($T,)* $($ST,)* __DB> FromSqlRow<($($ST,)* crate::sql_types::Untyped), __DB> for ($($T,)* $T1)
        where __DB: Backend,
              $T1: FromSqlRow<crate::sql_types::Untyped, __DB>,
            $(
                $T: FromSqlRow<$ST, __DB> + StaticallySizedRow<$ST, __DB>,
        )*
        {
            #[allow(non_snake_case, unused_variables, unused_mut)]
            fn build_from_row<'a>(full_row: &impl Row<'a, __DB>)
                -> deserialize::Result<Self>
            {
                let field_count = full_row.field_count();

                let mut static_field_count = 0;
                $(
                    let row = full_row.partial_row(static_field_count..static_field_count + $T::FIELD_COUNT);
                    static_field_count += $T::FIELD_COUNT;
                    let $T = $T::build_from_row(&row)?;
                )*

                let row = full_row.partial_row(static_field_count..field_count);

                Ok(($($T,)* $T1::build_from_row(&row)?,))
            }
        }

        #[cfg_attr(diesel_docsrs, doc(hidden))]
        impl<$T1, $ST1, $($T,)* $($ST,)* __DB> FromStaticSqlRow<($($ST,)* $ST1,), __DB> for ($($T,)* $T1,) where
            __DB: Backend,
            $ST1: CompatibleType<$T1, __DB>,
            $T1: FromSqlRow<<$ST1 as CompatibleType<$T1, __DB>>::SqlType, __DB>,
            $(
                $ST: CompatibleType<$T, __DB>,
                $T: FromSqlRow<<$ST as CompatibleType<$T, __DB>>::SqlType, __DB> + StaticallySizedRow<<$ST as CompatibleType<$T, __DB>>::SqlType, __DB>,
            )*

        {

            #[allow(non_snake_case, unused_variables, unused_mut)]
            fn build_from_row<'a>(full_row: &impl Row<'a, __DB>)
                -> deserialize::Result<Self>
            {
                let field_count = full_row.field_count();

                let mut static_field_count = 0;
                $(
                    let row = full_row.partial_row(static_field_count..static_field_count + $T::FIELD_COUNT);
                    static_field_count += $T::FIELD_COUNT;
                    let $T = <$T as FromSqlRow<<$ST as CompatibleType<$T, __DB>>::SqlType, __DB>>::build_from_row(&row)?;
                )*

                let row = full_row.partial_row(static_field_count..field_count);

                Ok(($($T,)* $T1::build_from_row(&row)?,))
            }
        }
    }
}

macro_rules! impl_valid_grouping_for_tuple_of_columns {
    ($T1: ident, $($T: ident,)+) => {
        #[cfg_attr(diesel_docsrs, doc(hidden))]
        impl<$T1, $($T,)* __GroupByClause> ValidGrouping<__GroupByClause> for ($T1, $($T,)*)
        where
            $T1: ValidGrouping<__GroupByClause>,
            ($($T,)*): ValidGrouping<__GroupByClause>,
            $T1::IsAggregate: MixedAggregates<<($($T,)*) as ValidGrouping<__GroupByClause>>::IsAggregate>,
        {
            type IsAggregate = <$T1::IsAggregate as MixedAggregates<<($($T,)*) as ValidGrouping<__GroupByClause>>::IsAggregate>>::Output;
        }

        impl<$T1, $($T,)* Col> IsContainedInGroupBy<Col> for ($T1, $($T,)*)
        where Col: QueryRelationField,
              ($($T,)*): IsContainedInGroupBy<Col>,
              $T1: IsContainedInGroupBy<Col>,
              $T1::Output: is_contained_in_group_by::IsAny<<($($T,)*) as IsContainedInGroupBy<Col>>::Output>
        {
            type Output = <$T1::Output as is_contained_in_group_by::IsAny<<($($T,)*) as IsContainedInGroupBy<Col>>::Output>>::Output;
        }
    };
    ($T1: ident,) => {
        impl<$T1, Col> IsContainedInGroupBy<Col> for ($T1,)
        where Col: QueryRelationField,
              $T1: IsContainedInGroupBy<Col>
        {
            type Output = <$T1 as IsContainedInGroupBy<Col>>::Output;
        }

        #[cfg_attr(diesel_docsrs, doc(fake_variadic))]
        impl<$T1, __GroupByClause> ValidGrouping<__GroupByClause> for ($T1,)
            where $T1: ValidGrouping<__GroupByClause>
        {
            type IsAggregate = $T1::IsAggregate;
        }
    };
}

macro_rules! impl_sql_type {
    (
        @build
        start_ts = [$($ST: ident,)*],
        ts = [$T1: ident,],
        bounds = [$($bounds: tt)*],
        is_null = [$($is_null: tt)*],
    )=> {
        #[cfg_attr(diesel_docsrs, doc(hidden))]
        impl<$($ST,)*> SqlType for ($($ST,)*)
        where
            $($ST: SqlType,)*
            $($bounds)*
            $T1::IsNull: OneIsNullable<$($is_null)*>,
        {
            type IsNull = <$T1::IsNull as OneIsNullable<$($is_null)*>>::Out;
        }

    };
    (
        @build
        start_ts = [$($ST: ident,)*],
        ts = [$T1: ident, $($T: ident,)+],
        bounds = [$($bounds: tt)*],
        is_null = [$($is_null: tt)*],
    )=> {
        impl_sql_type!{
            @build
            start_ts = [$($ST,)*],
            ts = [$($T,)*],
            bounds = [$($bounds)* $T1::IsNull: OneIsNullable<$($is_null)*>,],
            is_null = [<$T1::IsNull as OneIsNullable<$($is_null)*>>::Out],
        }
    };
    ($T1: ident, $($T: ident,)+) => {
        impl_sql_type!{
            @build
            start_ts = [$T1, $($T,)*],
            ts = [$($T,)*],
            bounds = [],
            is_null = [$T1::IsNull],
        }
    };
    ($T1: ident,) => {
        #[cfg_attr(diesel_docsrs, doc(fake_variadic))]
        impl<$T1> SqlType for ($T1,)
        where $T1: SqlType,
        {
            type IsNull = $T1::IsNull;
        }
    }
}

crate::for_each_tuple!(tuple_impls);