Compile failure in bernoulli_details.hpp when BOOST_MATH_NO_ATOMIC_INT

[heinemml]

I'm currently integrating boost 1.77 into buildroot.

The boost-math build is now failing for the NIOSII Platform.
The Platform does not support atomic ints. So BOOST_MATH_NO_ATOMIC_INT is defined in tools/atomic.hpp.

Since 1.77 this yields the following build error:

In file included from ./boost/math/special_functions/bernoulli.hpp:16,
                 from ./boost/math/special_functions/gamma.hpp:35,
                 from ./boost/math/special_functions/detail/bessel_jy.hpp:14,
                 from ./boost/math/special_functions/bessel.hpp:20,
                 from ./boost/math/special_functions/airy.hpp:12,
                 from ./boost/math/special_functions.hpp:15,
                 from libs/math/build/../src/tr1/pch.hpp:9:
./boost/math/special_functions/detail/bernoulli_details.hpp:560:4: error: 'atomic_counter_type' does not name a type
  560 |    atomic_counter_type m_counter, m_current_precision;
      |    ^~~~~~~~~~~~~~~~~~~
./boost/math/special_functions/detail/bernoulli_details.hpp: In constructor 'boost::math::detail::bernoulli_numbers_cache<T, Policy>::bernoulli_numbers_cache()':
./boost/math/special_functions/detail/bernoulli_details.hpp:212:9: error: class 'boost::math::detail::bernoulli_numbers_cache<T, Policy>' does not have any field named 'm_counter'
  212 |       , m_counter(0)
      |         ^~~~~~~~~
./boost/math/special_functions/detail/bernoulli_details.hpp:213:9: error: class 'boost::math::detail::bernoulli_numbers_cache<T, Policy>' does not have any field named 'm_current_precision'
  213 |       , m_current_precision(boost::math::tools::digits<T>())
      |         ^~~~~~~~~~~~~~~~~~~
./boost/math/special_functions/detail/bernoulli_details.hpp: In member function 'OutputIterator boost::math::detail::bernoulli_numbers_cache<T, Policy>::copy_bernoulli_numbers(OutputIterator, std::size_t, std::size_t, const Policy&)':
./boost/math/special_functions/detail/bernoulli_details.hpp:392:36: error: 'm_counter' was not declared in this scope
  392 |       if((static_cast<std::size_t>(m_counter.load(std::memory_order_consume)) < start + n)
      |                                    ^~~~~~~~~
./boost/math/special_functions/detail/bernoulli_details.hpp:393:31: error: 'm_current_precision' was not declared in this scope; did you mean 'double_precision'?
  393 |          || (static_cast<int>(m_current_precision.load(std::memory_order_consume)) < boost::math::tools::digits<T>()))
      |                               ^~~~~~~~~~~~~~~~~~~
      |                               double_precision
./boost/math/special_functions/detail/bernoulli_details.hpp:413:41: error: 'atomic_integer_type' does not name a type
  413 |             m_counter.store(static_cast<atomic_integer_type>(bn.size()), std::memory_order_release);
      |                                         ^~~~~~~~~~~~~~~~~~~
./boost/math/special_functions/detail/bernoulli_details.hpp: In member function 'OutputIterator boost::math::detail::bernoulli_numbers_cache<T, Policy>::copy_tangent_numbers(OutputIterator, std::size_t, std::size_t, const Policy&)':
./boost/math/special_functions/detail/bernoulli_details.hpp:504:36: error: 'm_counter' was not declared in this scope
  504 |       if((static_cast<std::size_t>(m_counter.load(std::memory_order_consume)) < start + n)
      |                                    ^~~~~~~~~
./boost/math/special_functions/detail/bernoulli_details.hpp:505:31: error: 'm_current_precision' was not declared in this scope; did you mean 'double_precision'?
  505 |          || (static_cast<int>(m_current_precision.load(std::memory_order_consume)) < boost::math::tools::digits<T>()))
      |                               ^~~~~~~~~~~~~~~~~~~
      |                               double_precision
./boost/math/special_functions/detail/bernoulli_details.hpp:525:41: error: 'atomic_integer_type' does not name a type
  525 |             m_counter.store(static_cast<atomic_integer_type>(bn.size()), std::memory_order_release);
      |                                         ^~~~~~~~~~~~~~~~~~~

Since 1.77 special_functions/detail/bernoulli_details.hpp has no special handling for BOOST_MATH_NO_ATOMIC_INT anymore. Is this intentional or an oversight?

For now I would disable the math build for NIOSII Platform.

[mborland]

Does the NIOSII platform offer any of the other threading headers (e.g. <mutex>, <thread>, etc.), or is this strictly limited to no hardware implementation of atomics?

[heinemml]

Dislaimer: I'm not really involved into the nios2 toolchain. I just check the packages against the different buildroot support platforms when updating.

The nios2 toolchain currently used by buildroot is this one: https://toolchains.bootlin.com/downloads/releases/toolchains/nios2/tarballs/nios2--glibc--stable-2020.08-1.tar.bz2
The threading headers are all there.

I think the issue is similar to one we had with boost-atomic (boostorg/atomic#42) since 1.74.

[jzmaddock]

Confirmed as an issue.

This will continue to be unsupported, but we should fail much more gracefully so that only the small number of use cases that are unsupported cause issues. I have a few thoughts about that.

[jzmaddock]

I wonder if I can I get you to verify that #684 fixes this your end?

[heinemml]

With this patchset applied I can compile boost-math for niosII again.

So the Bernoulli code is now not available anymore since 1.77.0 on platforms with no atomic ints right?

[jzmaddock]

It is available for float/double/long double, or without thread safety for user-defined (multiprecision) types.