Closed
Description
While working on #104321, creating an async generator directly lead to E0720 and E0700 errors.
The "solution" was to put the async generator through an identity function:
pub const fn identity_future<O, Fut: Future<Output = O>>(f: Fut) -> Fut { f }This "magically" solves / hides those errors, but should ideally not be necessary.
Full Error output
---- [ui] src/test/ui/impl-trait/in-trait/default-body-with-rpit.rs stdout ----
error: test compilation failed although it shouldn't!
status: exit status: 1
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/impl-trait/in-trait/default-body-with-rpit.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/impl-trait/in-trait/default-body-with-rpit" "-A" "unused" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/impl-trait/in-trait/default-body-with-rpit/auxiliary" "--edition=2021"
stdout: none
--- stderr -------------------------------
error: concrete type differs from previous defining opaque type use
|
LL | ""
LL | ""
| ^^ expected `impl Debug`, got `&'static str`
note: previous use here
--> /checkout/src/test/ui/impl-trait/in-trait/default-body-with-rpit.rs:10:39
|
|
LL | async fn baz(&self) -> impl Debug {
LL | | ""
LL | | }
Some tests failed in compiletest suite=ui mode=ui host=x86_64-unknown-linux-gnu target=x86_64-unknown-linux-gnu
| |_____^
| |_____^
error[E0720]: cannot resolve opaque type
--> /checkout/src/test/ui/impl-trait/in-trait/default-body-with-rpit.rs:10:28
|
LL | async fn baz(&self) -> impl Debug {
| ^^^^^^^^^^ cannot resolve opaque type
|
= note: these returned values have a concrete "never" type
= help: this error will resolve once the item's body returns a concrete type
error: aborting due to 2 previous errors
For more information about this error, try `rustc --explain E0720`.
------------------------------------------
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---- [ui] src/test/ui/regions/issue-72051-member-region-hang.rs stdout ----
error: test compilation failed although it shouldn't!
status: exit status: 1
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/regions/issue-72051-member-region-hang.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/regions/issue-72051-member-region-hang" "-A" "unused" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/regions/issue-72051-member-region-hang/auxiliary" "--edition=2018"
stdout: none
--- stderr -------------------------------
error[E0700]: hidden type for `impl Future<Output = ()>` captures lifetime that does not appear in bounds
|
|
LL | pub async fn query<'a>(_: &(), _: &(), _: (&(dyn std::any::Any + 'a),) ) {}
| |
| |
| hidden type `impl Future<Output = ()>` captures the lifetime `'a` as defined here
error: aborting due to previous error
For more information about this error, try `rustc --explain E0700`.
------------------------------------------
------------------------------------------
---- [ui] src/test/ui/self/self_lifetime-async.rs stdout ----
error: test compilation failed although it shouldn't!
status: exit status: 1
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/self/self_lifetime-async.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/self/self_lifetime-async" "-A" "unused" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/self/self_lifetime-async/auxiliary" "--edition=2018"
stdout: none
--- stderr -------------------------------
error[E0700]: hidden type for `impl Future<Output = &'a ()>` captures lifetime that does not appear in bounds
|
|
LL | async fn bar<'a>(self: &Alias, arg: &'a ()) -> &() { arg }
|
|
= note: hidden type `impl Future<Output = &'a ()>` captures lifetime '_#17r
error: aborting due to previous error
For more information about this error, try `rustc --explain E0700`.
------------------------------------------