diff --git a/src/test/ui/inference/issue-80816.rs b/src/test/ui/inference/issue-80816.rs new file mode 100644 index 0000000000000..ead320a4fe42c --- /dev/null +++ b/src/test/ui/inference/issue-80816.rs @@ -0,0 +1,54 @@ +#![allow(unreachable_code)] + +use std::marker::PhantomData; +use std::ops::Deref; +use std::sync::Arc; + +pub struct Guard { + _phantom: PhantomData, +} +impl Deref for Guard { + type Target = T; + fn deref(&self) -> &T { + unimplemented!() + } +} + +pub struct DirectDeref(T); +impl Deref for DirectDeref> { + type Target = T; + fn deref(&self) -> &T { + unimplemented!() + } +} + +pub trait Access { + type Guard: Deref; + fn load(&self) -> Self::Guard { + unimplemented!() + } +} +impl, P: Deref> Access for P { + //~^ NOTE: required for `Arc>>` to implement `Access<_>` + type Guard = A::Guard; +} +impl Access for ArcSwapAny { + //~^ NOTE: multiple `impl`s satisfying `ArcSwapAny>: Access<_>` found + type Guard = Guard; +} +impl Access for ArcSwapAny> { + type Guard = DirectDeref>; +} + +pub struct ArcSwapAny { + _phantom_arc: PhantomData, +} + +pub fn foo() { + let s: Arc>> = unimplemented!(); + let guard: Guard> = s.load(); + //~^ ERROR: type annotations needed + //~| HELP: try using a fully qualified path to specify the expected types +} + +fn main() {} diff --git a/src/test/ui/inference/issue-80816.stderr b/src/test/ui/inference/issue-80816.stderr new file mode 100644 index 0000000000000..bd833340df4ce --- /dev/null +++ b/src/test/ui/inference/issue-80816.stderr @@ -0,0 +1,27 @@ +error[E0283]: type annotations needed + --> $DIR/issue-80816.rs:49:38 + | +LL | let guard: Guard> = s.load(); + | ^^^^ + | +note: multiple `impl`s satisfying `ArcSwapAny>: Access<_>` found + --> $DIR/issue-80816.rs:35:1 + | +LL | impl Access for ArcSwapAny { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +... +LL | impl Access for ArcSwapAny> { + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +note: required for `Arc>>` to implement `Access<_>` + --> $DIR/issue-80816.rs:31:45 + | +LL | impl, P: Deref> Access for P { + | ^^^^^^^^^ ^ +help: try using a fully qualified path to specify the expected types + | +LL | let guard: Guard> = >> as Access>::load(&s); + | ++++++++++++++++++++++++++++++++++++++++++++++++++ ~ + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0283`.