Add tests

tests/ui/async-await/async-fn/dyn-pos.rs

@@ -0,0 +1,14 @@
+// edition:2018
+
+#![feature(async_closure)]
+
+fn foo(x: &dyn async Fn()) {}
+//~^ ERROR the trait `AsyncFn` cannot be made into an object
+//~| ERROR the trait `AsyncFn` cannot be made into an object
+//~| ERROR the trait `AsyncFn` cannot be made into an object
+//~| ERROR the trait `AsyncFn` cannot be made into an object
+//~| ERROR the trait `AsyncFnMut` cannot be made into an object
+//~| ERROR the trait `AsyncFnMut` cannot be made into an object
+//~| ERROR the trait `AsyncFnMut` cannot be made into an object
+
+fn main() {}

tests/ui/async-await/async-fn/dyn-pos.stderr

@@ -0,0 +1,87 @@
+error[E0038]: the trait `AsyncFn` cannot be made into an object
+  --> $DIR/dyn-pos.rs:5:16
+   |
+LL | fn foo(x: &dyn async Fn()) {}
+   |                ^^^^^^^^^^ `AsyncFn` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $SRC_DIR/core/src/ops/async_function.rs:LL:COL
+   |
+   = note: the trait cannot be made into an object because it contains the generic associated type `CallFuture`
+
+error[E0038]: the trait `AsyncFnMut` cannot be made into an object
+  --> $DIR/dyn-pos.rs:5:16
+   |
+LL | fn foo(x: &dyn async Fn()) {}
+   |                ^^^^^^^^^^ `AsyncFnMut` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $SRC_DIR/core/src/ops/async_function.rs:LL:COL
+   |
+   = note: the trait cannot be made into an object because it contains the generic associated type `CallMutFuture`
+
+error[E0038]: the trait `AsyncFn` cannot be made into an object
+  --> $DIR/dyn-pos.rs:5:16
+   |
+LL | fn foo(x: &dyn async Fn()) {}
+   |                ^^^^^^^^^^ `AsyncFn` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $SRC_DIR/core/src/ops/async_function.rs:LL:COL
+   |
+   = note: the trait cannot be made into an object because it contains the generic associated type `CallFuture`
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0038]: the trait `AsyncFnMut` cannot be made into an object
+  --> $DIR/dyn-pos.rs:5:16
+   |
+LL | fn foo(x: &dyn async Fn()) {}
+   |                ^^^^^^^^^^ `AsyncFnMut` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $SRC_DIR/core/src/ops/async_function.rs:LL:COL
+   |
+   = note: the trait cannot be made into an object because it contains the generic associated type `CallMutFuture`
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0038]: the trait `AsyncFn` cannot be made into an object
+  --> $DIR/dyn-pos.rs:5:16
+   |
+LL | fn foo(x: &dyn async Fn()) {}
+   |                ^^^^^^^^^^ `AsyncFn` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $SRC_DIR/core/src/ops/async_function.rs:LL:COL
+   |
+   = note: the trait cannot be made into an object because it contains the generic associated type `CallFuture`
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0038]: the trait `AsyncFnMut` cannot be made into an object
+  --> $DIR/dyn-pos.rs:5:16
+   |
+LL | fn foo(x: &dyn async Fn()) {}
+   |                ^^^^^^^^^^ `AsyncFnMut` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $SRC_DIR/core/src/ops/async_function.rs:LL:COL
+   |
+   = note: the trait cannot be made into an object because it contains the generic associated type `CallMutFuture`
+   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0038]: the trait `AsyncFn` cannot be made into an object
+  --> $DIR/dyn-pos.rs:5:12
+   |
+LL | fn foo(x: &dyn async Fn()) {}
+   |            ^^^^^^^^^^^^^^ `AsyncFn` cannot be made into an object
+   |
+note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
+  --> $SRC_DIR/core/src/ops/async_function.rs:LL:COL
+   |
+   = note: the trait cannot be made into an object because it contains the generic associated type `CallFuture`
+  ::: $SRC_DIR/core/src/ops/async_function.rs:LL:COL
+   |
+   = note: the trait cannot be made into an object because it contains the generic associated type `CallMutFuture`
+
+error: aborting due to 7 previous errors
+
+For more information about this error, try `rustc --explain E0038`.

tests/ui/async-await/async-fn/edition-2015.rs

@@ -0,0 +1,8 @@
+// FIXME(async_closures): This error message could be made better.
+
+fn foo(x: impl async Fn()) -> impl async Fn() {}
+//~^ ERROR expected
+//~| ERROR expected
+//~| ERROR expected
+
+fn main() {}

tests/ui/async-await/async-fn/edition-2015.stderr

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+error: expected one of `:` or `|`, found `)`
+  --> $DIR/edition-2015.rs:3:26
+   |
+LL | fn foo(x: impl async Fn()) -> impl async Fn() {}
+   |                          ^ expected one of `:` or `|`
+
+error: expected one of `(`, `)`, `+`, `,`, `::`, or `<`, found `Fn`
+  --> $DIR/edition-2015.rs:3:22
+   |
+LL | fn foo(x: impl async Fn()) -> impl async Fn() {}
+   |                     -^^ expected one of `(`, `)`, `+`, `,`, `::`, or `<`
+   |                     |
+   |                     help: missing `,`
+
+error: expected one of `(`, `+`, `::`, `<`, `where`, or `{`, found `Fn`
+  --> $DIR/edition-2015.rs:3:42
+   |
+LL | fn foo(x: impl async Fn()) -> impl async Fn() {}
+   |                                          ^^ expected one of `(`, `+`, `::`, `<`, `where`, or `{`
+
+error: aborting due to 3 previous errors
+

tests/ui/async-await/async-fn/impl-header.rs

@@ -0,0 +1,8 @@
+// edition:2018
+
+struct F;
+
+impl async Fn<()> for F {}
+//~^ ERROR expected type, found keyword `async`
+
+fn main() {}

tests/ui/async-await/async-fn/impl-header.stderr

@@ -0,0 +1,8 @@
+error: expected type, found keyword `async`
+  --> $DIR/impl-header.rs:5:6
+   |
+LL | impl async Fn<()> for F {}
+   |      ^^^^^ expected type
+
+error: aborting due to 1 previous error
+

tests/ui/async-await/async-fn/impl-trait.rs

@@ -0,0 +1,15 @@
+// edition:2018
+// check-pass
+
+#![feature(async_closure, type_alias_impl_trait)]
+
+type Tait = impl async Fn();
+fn tait() -> Tait {
+    || async {}
+}
+
+fn foo(x: impl async Fn()) -> impl async Fn() { x }
+
+fn param<T: async Fn()>() {}
+
+fn main() {}

tests/ui/async-await/async-fn/method-call-pos.rs

@@ -0,0 +1,7 @@
+// edition:2018
+
+fn main() {
+    <_ as async Fn()>(|| async {});
+    //~^ ERROR expected identifier, found keyword `async`
+    //~| ERROR expected one of
+}

tests/ui/async-await/async-fn/method-call-pos.stderr

@@ -0,0 +1,14 @@
+error: expected identifier, found keyword `async`
+  --> $DIR/method-call-pos.rs:4:11
+   |
+LL |     <_ as async Fn()>(|| async {});
+   |           ^^^^^ expected identifier, found keyword
+
+error: expected one of `(`, `::`, `<`, or `>`, found `Fn`
+  --> $DIR/method-call-pos.rs:4:17
+   |
+LL |     <_ as async Fn()>(|| async {});
+   |                 ^^ expected one of `(`, `::`, `<`, or `>`
+
+error: aborting due to 2 previous errors
+