From 7d482f6ebc356e6ec455ccb5f51a23971bf6ce5b Mon Sep 17 00:00:00 2001
From: jzmaddock <john@johnmaddock.co.uk>
Date: Wed, 1 Sep 2021 20:31:53 +0100
Subject: [PATCH] Make no atomics a soft failure in bernoulli_details.hpp.
 Include an "escape macro" so thread safety can be disabled if certain
 bernoulli features are to be used in a no-atomics environment. Fixes
 https://github.com/boostorg/math/issues/673.

[buildroot@heine.tech:
  - backport from boostorg/math 7d482f6ebc356e6ec455ccb5f51a23971bf6ce5b
  - alter path to match boost release
]
Signed-off-by: Michael Nosthoff <buildroot@heine.tech>
---
Upstream-Status: Backport [https://github.com/boostorg/math/pull/684/commits/7d482f6ebc356e6ec455ccb5f51a23971bf6ce5b]
 .../detail/bernoulli_details.hpp                 | 10 +++++++---
 libs/math/test/Jamfile.v2                        |  3 +++
 test/compile_test/bernoulli_no_atomic_d.cpp      | 14 ++++++++++++++
 test/compile_test/bernoulli_no_atomic_fail.cpp   | 15 +++++++++++++++
 test/compile_test/bernoulli_no_atomic_mp.cpp     | 16 ++++++++++++++++
 5 files changed, 55 insertions(+), 3 deletions(-)
 create mode 100644 test/compile_test/bernoulli_no_atomic_d.cpp
 create mode 100644 test/compile_test/bernoulli_no_atomic_fail.cpp
 create mode 100644 test/compile_test/bernoulli_no_atomic_mp.cpp

diff --git a/boost/math/special_functions/detail/bernoulli_details.hpp b/boost/math/special_functions/detail/bernoulli_details.hpp
index cf35545264..8519b7c89c 100644
--- a/boost/math/special_functions/detail/bernoulli_details.hpp
+++ b/boost/math/special_functions/detail/bernoulli_details.hpp
@@ -360,7 +360,7 @@ class bernoulli_numbers_cache
          return out;
       }
 
-      #ifndef BOOST_HAS_THREADS
+      #if !defined(BOOST_HAS_THREADS) || defined(BOOST_MATH_BERNOULLI_UNTHREADED)
       //
       // Single threaded code, very simple:
       //
@@ -382,6 +382,8 @@ class bernoulli_numbers_cache
          *out = (i >= m_overflow_limit) ? policies::raise_overflow_error<T>("boost::math::bernoulli_b2n<%1%>(std::size_t)", 0, T(i), pol) : bn[i];
          ++out;
       }
+      #elif defined(BOOST_MATH_NO_ATOMIC_INT)
+      static_assert(sizeof(T) == 1, "Unsupported configuration: your platform appears to have no atomic integers.  If you are happy with thread-unsafe code, then you may define BOOST_MATH_BERNOULLI_UNTHREADED to suppress this error.");
       #else
       //
       // Double-checked locking pattern, lets us access cached already cached values
@@ -464,7 +466,7 @@ class bernoulli_numbers_cache
          return out;
       }
 
-      #ifndef BOOST_HAS_THREADS
+      #if !defined(BOOST_HAS_THREADS) || defined(BOOST_MATH_BERNOULLI_UNTHREADED)
       //
       // Single threaded code, very simple:
       //
@@ -494,6 +496,8 @@ class bernoulli_numbers_cache
          }
          ++out;
       }
+      #elif defined(BOOST_MATH_NO_ATOMIC_INT)
+      static_assert(sizeof(T) == 1, "Unsupported configuration: your platform appears to have no atomic integers.  If you are happy with thread-unsafe code, then you may define BOOST_MATH_BERNOULLI_UNTHREADED to suppress this error.");
       #else
       //
       // Double-checked locking pattern, lets us access cached already cached values
@@ -555,7 +559,7 @@ class bernoulli_numbers_cache
    // The value at which we know overflow has already occurred for the Bn:
    std::size_t m_overflow_limit;
 
-   #ifdef BOOST_HAS_THREADS
+   #if defined(BOOST_HAS_THREADS) && !defined(BOOST_MATH_NO_ATOMIC_INT)
    std::mutex m_mutex;
    atomic_counter_type m_counter, m_current_precision;
    #else
diff --git a/libs/math/test/Jamfile.v2 b/libs/math/test/Jamfile.v2
index 52fb87f5e5..3ac63f9279 100644
--- a/libs/math/test/Jamfile.v2
+++ b/libs/math/test/Jamfile.v2
@@ -1137,6 +1137,9 @@ test-suite misc :
 
 #   [ run __temporary_test.cpp test_instances//test_instances : : : <test-info>always_show_run_output <pch>off ]
    [ compile test_no_long_double_policy.cpp ]
+   [ compile compile_test/bernoulli_no_atomic_d.cpp ]
+   [ compile compile_test/bernoulli_no_atomic_mp.cpp ]
+   [ compile-fail compile_test/bernoulli_no_atomic_fail.cpp ]
 ;
 
 test-suite interpolators :
diff --git a/test/compile_test/bernoulli_no_atomic_d.cpp b/test/compile_test/bernoulli_no_atomic_d.cpp
new file mode 100644
index 0000000000..61926f7e1f
--- /dev/null
+++ b/test/compile_test/bernoulli_no_atomic_d.cpp
@@ -0,0 +1,14 @@
+//  (C) Copyright John Maddock 2021.
+//  Use, modification and distribution are subject to 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)
+
+#define BOOST_MATH_NO_ATOMIC_INT
+
+#include <boost/math/special_functions/bernoulli.hpp>
+#include "test_compile_result.hpp"
+
+void compile_and_link_test()
+{
+   check_result<double>(boost::math::bernoulli_b2n<double>(4));
+}
diff --git a/test/compile_test/bernoulli_no_atomic_fail.cpp b/test/compile_test/bernoulli_no_atomic_fail.cpp
new file mode 100644
index 0000000000..bbd7152412
--- /dev/null
+++ b/test/compile_test/bernoulli_no_atomic_fail.cpp
@@ -0,0 +1,15 @@
+//  (C) Copyright John Maddock 2021.
+//  Use, modification and distribution are subject to 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)
+
+#define BOOST_MATH_NO_ATOMIC_INT
+
+#include <boost/math/special_functions/bernoulli.hpp>
+#include <boost/multiprecision/cpp_bin_float.hpp>
+#include "test_compile_result.hpp"
+
+void compile_and_link_test()
+{
+   check_result<boost::multiprecision::cpp_bin_float_50>(boost::math::bernoulli_b2n<boost::multiprecision::cpp_bin_float_50>(4));
+}
diff --git a/test/compile_test/bernoulli_no_atomic_mp.cpp b/test/compile_test/bernoulli_no_atomic_mp.cpp
new file mode 100644
index 0000000000..8d5a6e78e6
--- /dev/null
+++ b/test/compile_test/bernoulli_no_atomic_mp.cpp
@@ -0,0 +1,16 @@
+//  (C) Copyright John Maddock 2021.
+//  Use, modification and distribution are subject to 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)
+
+#define BOOST_MATH_NO_ATOMIC_INT
+#define BOOST_MATH_BERNOULLI_UNTHREADED
+
+#include <boost/math/special_functions/bernoulli.hpp>
+#include <boost/multiprecision/cpp_bin_float.hpp>
+#include "test_compile_result.hpp"
+
+void compile_and_link_test()
+{
+   check_result<boost::multiprecision::cpp_bin_float_50>(boost::math::bernoulli_b2n<boost::multiprecision::cpp_bin_float_50>(4));
+}
