From cfd18095199e546d6fd647bc53ade1b0dcdb6da6 Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Wed, 7 Jun 2023 11:20:15 -0700
Subject: [PATCH] Add support for std::coroutine_handle

---
 include/boost/container_hash/hash.hpp | 16 +++++++
 test/Jamfile.v2                       |  2 +
 test/hash_coroutine_handle.cpp        | 65 +++++++++++++++++++++++++++
 3 files changed, 83 insertions(+)
 create mode 100644 test/hash_coroutine_handle.cpp

diff --git a/include/boost/container_hash/hash.hpp b/include/boost/container_hash/hash.hpp
index 605644b3..4013010b 100644
--- a/include/boost/container_hash/hash.hpp
+++ b/include/boost/container_hash/hash.hpp
@@ -69,6 +69,10 @@
 # include <string_view>
 #endif
 
+#if !defined(BOOST_NO_CXX20_HDR_COROUTINE)
+# include <coroutine>
+#endif
+
 namespace boost
 {
 
@@ -551,6 +555,18 @@ namespace boost
         return seed;
     }
 
+#endif
+
+    // std::coroutine_handle
+
+#if !defined(BOOST_NO_CXX20_HDR_COROUTINE)
+
+    template <typename T>
+    std::size_t hash_value( std::coroutine_handle<T> h )
+    {
+      return hash_value( h.address() );
+    }
+
 #endif
 
     //
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 63d9ed35..11be32f0 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -125,3 +125,5 @@ run is_tuple_like_test.cpp ;
 run hash_tuple_like_test.cpp ;
 run hash_tuple_like_test2.cpp
   : : : <warnings>extra ;
+
+run hash_coroutine_handle.cpp ;
diff --git a/test/hash_coroutine_handle.cpp b/test/hash_coroutine_handle.cpp
new file mode 100644
index 00000000..23c696ce
--- /dev/null
+++ b/test/hash_coroutine_handle.cpp
@@ -0,0 +1,65 @@
+// Copyright 2023 Christian Mazakas.
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+#include <boost/config.hpp>
+
+#if defined(BOOST_NO_CXX20_HDR_COROUTINE)
+
+#include <boost/config/pragma_message.hpp>
+
+BOOST_PRAGMA_MESSAGE(
+    "hash_coroutine_handle test requires C++20 and <coroutine> support")
+int main() {}
+#else
+
+#include <boost/container_hash/hash.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+#include <coroutine>
+
+struct promise;
+
+struct task : std::coroutine_handle<promise> {
+  using promise_type = ::promise;
+};
+
+struct promise {
+  task get_return_object() { return {task::from_promise(*this)}; }
+
+  void return_void() {}
+  void unhandled_exception() {}
+  std::suspend_always initial_suspend() { return {}; }
+  std::suspend_always final_suspend() noexcept { return {}; }
+};
+
+task make_task() { co_return; }
+
+namespace {
+
+void coroutine_handle_tests() {
+  task t = make_task();
+  void *p = t.address();
+
+  {
+    auto h = boost::hash<std::coroutine_handle<promise>>()(t);
+    BOOST_TEST_EQ(h, boost::hash<void *>()(p));
+  }
+
+  std::coroutine_handle<> t2 = t;
+  {
+    auto h = boost::hash<std::coroutine_handle<>>()(t2);
+    BOOST_TEST_EQ(h, boost::hash<void *>()(p));
+  }
+
+  t.destroy();
+}
+
+} // namespace
+
+int main() {
+  coroutine_handle_tests();
+  return boost::report_errors();
+}
+
+#endif