typeck: add tests for suggesting -> 2018 on wrong <expr>.await

src/test/ui/async-await/suggest-switching-edition-on-await.rs

@@ -0,0 +1,45 @@
+use std::pin::Pin;
+use std::future::Future;
+
+fn main() {}
+
+fn await_on_struct_missing() {
+    struct S;
+    let x = S;
+    x.await;
+    //~^ ERROR no field `await` on type
+    //~| NOTE unknown field
+    //~| NOTE to `.await` a `Future`, switch to Rust 2018
+    //~| HELP set `edition = "2018"` in `Cargo.toml`
+    //~| NOTE for more on editions, read https://doc.rust-lang.org/edition-guide
+}
+
+fn await_on_struct_similar() {
+    struct S {
+        awai: u8,
+    }
+    let x = S { awai: 42 };
+    x.await;
+    //~^ ERROR no field `await` on type
+    //~| HELP a field with a similar name exists
+    //~| NOTE to `.await` a `Future`, switch to Rust 2018
+    //~| HELP set `edition = "2018"` in `Cargo.toml`
+    //~| NOTE for more on editions, read https://doc.rust-lang.org/edition-guide
+}
+
+fn await_on_63533(x: Pin<&mut dyn Future<Output = ()>>) {
+    x.await;
+    //~^ ERROR no field `await` on type
+    //~| NOTE unknown field
+    //~| NOTE to `.await` a `Future`, switch to Rust 2018
+    //~| HELP set `edition = "2018"` in `Cargo.toml`
+    //~| NOTE for more on editions, read https://doc.rust-lang.org/edition-guide
+}
+
+fn await_on_apit(x: impl Future<Output = ()>) {
+    x.await;
+    //~^ ERROR no field `await` on type
+    //~| NOTE to `.await` a `Future`, switch to Rust 2018
+    //~| HELP set `edition = "2018"` in `Cargo.toml`
+    //~| NOTE for more on editions, read https://doc.rust-lang.org/edition-guide
+}

src/test/ui/async-await/suggest-switching-edition-on-await.stderr

@@ -0,0 +1,43 @@
+error[E0609]: no field `await` on type `await_on_struct_missing::S`
+  --> $DIR/suggest-switching-edition-on-await.rs:9:7
+   |
+LL |     x.await;
+   |       ^^^^^ unknown field
+   |
+   = note: to `.await` a `Future`, switch to Rust 2018
+   = help: set `edition = "2018"` in `Cargo.toml`
+   = note: for more on editions, read https://doc.rust-lang.org/edition-guide
+
+error[E0609]: no field `await` on type `await_on_struct_similar::S`
+  --> $DIR/suggest-switching-edition-on-await.rs:22:7
+   |
+LL |     x.await;
+   |       ^^^^^ help: a field with a similar name exists: `awai`
+   |
+   = note: to `.await` a `Future`, switch to Rust 2018
+   = help: set `edition = "2018"` in `Cargo.toml`
+   = note: for more on editions, read https://doc.rust-lang.org/edition-guide
+
+error[E0609]: no field `await` on type `std::pin::Pin<&mut dyn std::future::Future<Output = ()>>`
+  --> $DIR/suggest-switching-edition-on-await.rs:31:7
+   |
+LL |     x.await;
+   |       ^^^^^ unknown field
+   |
+   = note: to `.await` a `Future`, switch to Rust 2018
+   = help: set `edition = "2018"` in `Cargo.toml`
+   = note: for more on editions, read https://doc.rust-lang.org/edition-guide
+
+error[E0609]: no field `await` on type `impl Future<Output = ()>`
+  --> $DIR/suggest-switching-edition-on-await.rs:40:7
+   |
+LL |     x.await;
+   |       ^^^^^
+   |
+   = note: to `.await` a `Future`, switch to Rust 2018
+   = help: set `edition = "2018"` in `Cargo.toml`
+   = note: for more on editions, read https://doc.rust-lang.org/edition-guide
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0609`.