#![feature(precise_capturing)] trait Tr { type Assoc; } struct W<'a>(&'a ()); impl Tr for W<'_> { type Assoc = (); } // The normal way of capturing `'a`... impl<'a> W<'a> { fn good1() -> impl Into< as Tr>::Assoc> + use<'a> {} } // This ensures that we don't error when we capture the *parent* copy of `'a`, // since the opaque captures that rather than the duplicated `'a` lifetime // synthesized from mentioning `'a` directly in the bounds. impl<'a> W<'a> { fn good2() -> impl Into<::Assoc> + use<'a> {} } // The normal way of capturing `'a`... but not mentioned in the bounds. impl<'a> W<'a> { fn bad1() -> impl Into< as Tr>::Assoc> + use<> {} //~^ ERROR `impl Trait` captures lifetime parameter, but it is not mentioned in `use<...>` precise captures list } // But also make sure that we error here... impl<'a> W<'a> { fn bad2() -> impl Into<::Assoc> + use<> {} //~^ ERROR `impl Trait` captures lifetime parameter, but it is not mentioned in `use<...>` precise captures list } fn main() {}