Transform the inner expression of yield expressions

async-stream-impl/src/lib.rs

@@ -114,6 +114,8 @@ impl VisitMut for Scrub<'_> {
             syn::Expr::Yield(yield_expr) => {
                 self.has_yielded = true;
 
+                syn::visit_mut::visit_expr_yield_mut(self, yield_expr);
+
                 let value_expr = yield_expr.expr.as_ref().unwrap_or(&self.unit);
 
                 // let ident = &self.yielder;

async-stream/tests/try_stream.rs

@@ -78,3 +78,10 @@ async fn multi_try() {
         values
     );
 }
+
+#[allow(unused)]
+fn issue_65() -> impl Stream<Item = Result<u32, ()>> {
+    try_stream! {
+        yield Err(())?;
+    }
+}

async-stream/tests/ui/yield_in_async.stderr

@@ -22,54 +22,11 @@ error[E0271]: type mismatch resolving `<[static generator@$DIR/src/lib.rs:201:9:
 8  | |
 9  | |         let v = f.await;
 10 | |     };
-   | |______^ expected `()`, found integer
+   | |_____^ expected `()`, found integer
    |
-   = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
-
-error[E0698]: type inside `async` block must be known in this context
- --> $DIR/yield_in_async.rs:6:19
-  |
-6 |             yield 123;
-  |                   ^^^ cannot infer type for type `{integer}`
-  |
-note: the type is part of the `async` block because of this `yield`
- --> $DIR/yield_in_async.rs:6:13
-  |
-6 |             yield 123;
-  |             ^^^^^^^^^
-
-error[E0698]: type inside `async` block must be known in this context
- --> $DIR/yield_in_async.rs:5:13
-  |
-5 |         let f = async {
-  |             ^ cannot infer type for type `{integer}`
-  |
-note: the type is part of the `async` block because of this `await`
- --> $DIR/yield_in_async.rs:9:17
-  |
-9 |         let v = f.await;
-  |                 ^^^^^^^
-
-error[E0698]: type inside `async` block must be known in this context
- --> $DIR/yield_in_async.rs:9:17
-  |
-9 |         let v = f.await;
-  |                 ^ cannot infer type for type `{integer}`
-  |
-note: the type is part of the `async` block because of this `await`
- --> $DIR/yield_in_async.rs:9:17
-  |
-9 |         let v = f.await;
-  |                 ^^^^^^^
-
-error[E0698]: type inside `async` block must be known in this context
- --> $DIR/yield_in_async.rs:9:17
-  |
-9 |         let v = f.await;
-  |                 ^^^^^^^ cannot infer type for type `{integer}`
-  |
-note: the type is part of the `async` block because of this `await`
- --> $DIR/yield_in_async.rs:9:17
-  |
-9 |         let v = f.await;
-  |                 ^^^^^^^
+note: required by a bound in `from_generator`
+  --> $RUST/core/src/future/mod.rs
+   |
+   |     T: Generator<ResumeTy, Yield = ()>,
+   |                            ^^^^^^^^^^ required by this bound in `from_generator`
+   = note: this error originates in the macro `stream` (in Nightly builds, run with -Z macro-backtrace for more info)