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//@ revisions: current next
//@ ignore-compare-mode-next-solver (explicit revisions)
//@[next] compile-flags: -Znext-solver
//@ reference: attributes.diagnostic.do_not_recommend.intro
pub trait Expression {
type SqlType;
}
pub trait AsExpression<ST> {
type Expression: Expression<SqlType = ST>;
}
pub struct Text;
pub struct Integer;
pub struct Bound<T>(T);
pub struct SelectInt;
impl Expression for SelectInt {
type SqlType = Integer;
}
impl<T> Expression for Bound<T> {
type SqlType = T;
}
#[diagnostic::do_not_recommend]
impl<T, ST> AsExpression<ST> for T
where
T: Expression<SqlType = ST>,
{
type Expression = T;
}
impl AsExpression<Integer> for i32 {
type Expression = Bound<Integer>;
}
impl AsExpression<Text> for &'_ str {
type Expression = Bound<Text>;
}
trait Foo: Expression + Sized {
fn check<T>(&self, _: T) -> <T as AsExpression<<Self as Expression>::SqlType>>::Expression
where
T: AsExpression<Self::SqlType>,
{
todo!()
}
}
impl<T> Foo for T where T: Expression {}
fn main() {
SelectInt.check("bar");
//[current]~^ ERROR the trait bound `&str: AsExpression<Integer>` is not satisfied
//[next]~^^ the trait bound `&str: AsExpression<<SelectInt as Expression>::SqlType>` is not satisfied
//[next]~| type mismatch
}
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