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