Rollup merge of #102161 - compiler-errors:issue-102138, r=tmandry

Resolve async fn signature even without body (e.g., in trait)

Fixes #102138

This "bail if no body" behavior was introduced in #69539 to fix #69401, but that ICE does not reproduce any more. The error message changes a bit, but that's all, and I don't think it's a particularly diagnostic bad regression.

2 files changed, 57 insertions, 0 deletions

diff --git a/src/test/ui/async-await/in-trait/issue-102138.rs b/src/test/ui/async-await/in-trait/issue-102138.rs
new file mode 100644
index 00000000000..f61b34ed99e
--- /dev/null
+++ b/src/test/ui/async-await/in-trait/issue-102138.rs
@@ -0,0 +1,46 @@
+// check-pass
+// edition:2021
+
+#![feature(async_fn_in_trait)]
+#![allow(incomplete_features)]
+
+use std::future::Future;
+
+async fn yield_now() {}
+
+trait AsyncIterator {
+    type Item;
+    async fn next(&mut self) -> Option<Self::Item>;
+}
+
+struct YieldingRange {
+    counter: u32,
+    stop: u32,
+}
+
+impl AsyncIterator for YieldingRange {
+    type Item = u32;
+
+    async fn next(&mut self) -> Option<Self::Item> {
+        if self.counter == self.stop {
+            None
+        } else {
+            let c = self.counter;
+            self.counter += 1;
+            yield_now().await;
+            Some(c)
+        }
+    }
+}
+
+async fn async_main() {
+    let mut x = YieldingRange { counter: 0, stop: 10 };
+
+    while let Some(v) = x.next().await {
+        println!("Hi: {v}");
+    }
+}
+
+fn main() {
+    let _ = async_main();
+}
diff --git a/src/test/ui/resolve/name-collision-in-trait-fn-sig.rs b/src/test/ui/resolve/name-collision-in-trait-fn-sig.rs
new file mode 100644
index 00000000000..fba4ffa1c6e
--- /dev/null
+++ b/src/test/ui/resolve/name-collision-in-trait-fn-sig.rs
@@ -0,0 +1,11 @@
+// check-pass
+// This is currently stable behavior, which was almost accidentally made an
+// error in #102161 since there is no test exercising it. I am not sure if
+// this _should_ be the desired behavior, but at least we should know if it
+// changes.
+
+fn main() {}
+
+trait Foo {
+    fn fn_with_type_named_same_as_local_in_param(b: i32, b: i32);
+}