Merge pull request #81925 from slavapestov/test-rdar151466803

Add regression test for fixed crasher

Author: slavapestov

validation-test/compiler_crashers_2_fixed/rdar151466803.swift

@@ -0,0 +1,25 @@
+// RUN: not %target-swift-frontend -typecheck
+
+enum E: Error, Equatable {
+    case error1
+}
+
+public struct S {}
+
+public struct S2: AsyncSequence {
+    public typealias Element = S
+    public init() {}
+    public func makeAsyncIterator() -> AsyncIterator { return AsyncIterator() }
+    public struct AsyncIterator: AsyncIteratorProtocol {
+        public func next() async throws -> S? {
+            return nil
+        }
+    }
+}
+
+public struct S3: Sendable {
+    public func f() async throws -> AsyncSequence<S, E> {
+        return S2()
+    }
+}
+