From c52ad849eacd7c3e087065839f314d8e6cdfc9cd Mon Sep 17 00:00:00 2001
From: Christian Mazakas <christian.mazakas@gmail.com>
Date: Mon, 1 May 2023 11:04:50 -0700
Subject: [PATCH] Add policy check that excludes unsequenced policies

It's technically UB for the callable in an unsequenced policy to acquire a lock so we add static_assert()s to catch potential user error.
---
 include/boost/unordered/concurrent_flat_map.hpp | 13 +++++++++++++
 test/cfoa/erase_tests.cpp                       |  2 +-
 test/cfoa/visit_tests.cpp                       |  6 +++---
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/include/boost/unordered/concurrent_flat_map.hpp b/include/boost/unordered/concurrent_flat_map.hpp
index 12778f64..c3cf5aeb 100644
--- a/include/boost/unordered/concurrent_flat_map.hpp
+++ b/include/boost/unordered/concurrent_flat_map.hpp
@@ -37,6 +37,14 @@
     boost::unordered::detail::is_invocable<F, value_type const&>::value,       \
     "The provided Callable must be invocable with `value_type const&`");
 
+#define BOOST_UNORDERED_STATIC_ASSERT_EXEC_POLICY(P)                           \
+  static_assert(!std::is_base_of<std::execution::parallel_unsequenced_policy,  \
+                  ExecPolicy>::value,                                          \
+    "ExecPolicy must be sequenced.");                                          \
+  static_assert(                                                               \
+    !std::is_base_of<std::execution::unsequenced_policy, ExecPolicy>::value,   \
+    "ExecPolicy must be sequenced.");
+
 #define BOOST_UNORDERED_COMMA ,
 
 #define BOOST_UNORDERED_LAST_ARG(Arg, Args)                                    \
@@ -357,6 +365,7 @@ namespace boost {
         visit_all(ExecPolicy p, F f)
       {
         BOOST_UNORDERED_STATIC_ASSERT_INVOCABLE(F)
+        BOOST_UNORDERED_STATIC_ASSERT_EXEC_POLICY(ExecPolicy)
         table_.visit_all(p, f);
       }
 
@@ -367,6 +376,7 @@ namespace boost {
         visit_all(ExecPolicy p, F f) const
       {
         BOOST_UNORDERED_STATIC_ASSERT_CONST_INVOCABLE(F)
+        BOOST_UNORDERED_STATIC_ASSERT_EXEC_POLICY(ExecPolicy)
         table_.visit_all(p, f);
       }
 
@@ -377,6 +387,7 @@ namespace boost {
         cvisit_all(ExecPolicy p, F f) const
       {
         BOOST_UNORDERED_STATIC_ASSERT_CONST_INVOCABLE(F)
+        BOOST_UNORDERED_STATIC_ASSERT_EXEC_POLICY(ExecPolicy)
         table_.cvisit_all(p, f);
       }
 #endif
@@ -663,6 +674,8 @@ namespace boost {
           void>::type
         erase_if(ExecPolicy p, F f)
       {
+        BOOST_UNORDERED_STATIC_ASSERT_EXEC_POLICY(ExecPolicy)
+        BOOST_UNORDERED_STATIC_ASSERT_EXEC_POLICY(ExecPolicy)
         table_.erase_if(p, f);
       }
 #endif
diff --git a/test/cfoa/erase_tests.cpp b/test/cfoa/erase_tests.cpp
index 2066e07e..3bffb8a2 100644
--- a/test/cfoa/erase_tests.cpp
+++ b/test/cfoa/erase_tests.cpp
@@ -281,7 +281,7 @@ namespace {
       thread_runner(values, [&num_invokes, &x, threshold](boost::span<T> s) {
         (void)s;
         x.erase_if(
-          std::execution::par_unseq, [&num_invokes, threshold](value_type& v) {
+          std::execution::par, [&num_invokes, threshold](value_type& v) {
             ++num_invokes;
             return v.second.x_ > threshold;
           });
diff --git a/test/cfoa/visit_tests.cpp b/test/cfoa/visit_tests.cpp
index 4c22782c..d49be2df 100644
--- a/test/cfoa/visit_tests.cpp
+++ b/test/cfoa/visit_tests.cpp
@@ -299,7 +299,7 @@ namespace {
         thread_runner(values, [&x, &mut_visitor](boost::span<T>) {
           std::atomic<std::uint64_t> num_visits{0};
 
-          x.visit_all(std::execution::par_unseq, mut_visitor(num_visits));
+          x.visit_all(std::execution::par, mut_visitor(num_visits));
           BOOST_TEST_EQ(x.size(), num_visits);
         });
       }
@@ -309,7 +309,7 @@ namespace {
           std::atomic<std::uint64_t> num_visits{0};
           auto const& y = x;
 
-          y.visit_all(std::execution::par_unseq, const_visitor(num_visits));
+          y.visit_all(std::execution::par, const_visitor(num_visits));
           BOOST_TEST_EQ(x.size(), num_visits);
         });
       }
@@ -317,7 +317,7 @@ namespace {
       {
         thread_runner(values, [&x, &const_visitor](boost::span<T>) {
           std::atomic<std::uint64_t> num_visits{0};
-          x.cvisit_all(std::execution::par_unseq, const_visitor(num_visits));
+          x.cvisit_all(std::execution::par, const_visitor(num_visits));
           BOOST_TEST_EQ(x.size(), num_visits);
         });
       }