v2.0.0a1

This is a draft of version 2.0.0. Bumping the major version number is due to the breaking changes mentioned below. I'm in the process of updating the documentation to use Hyde 2.0 and moving to use GitHub Actions to build the Jekyll pages. The final release will be done when those tasks are completed. This release is for those who "just need the code".

Breaking Changes

• C++17 or later is now required. The was done to make the executors and task<> noexcept aware. Executors now require the tasks being passed to them are noexcept. package<>() can be used to create noexcept packaged_task<>s. The task<> interface can now require that a captured task is noexcept. For example, task<int(double) noexcept> will accept a type invocable with a double, where the result is convertible to int, and is declared noexcept. This is statically checked. If noexceptis ommited, the task will except either a function with a matching signature, noexcept or not.
• As part of moving to C++17, the ability to configure the library to use boost::optional and boost::variant has been removed.

Bug fixes and other changes are listed below.

What's Changed

• Adds a call to pre_exit() on each example using default_executor by @fpelliccioni in #500
• new API: bool packaged_task::canceled() const by @KevinHopps in #498
• Changes to support C++14 and fixed missing include file (#501) by @sean-parent in #503
• Fix name conflict with boost math in Boost <= 1.76 by @fpelliccioni in #499
• Changed CMake paths to be robust to subprojects by @laserallan in #507
• Fixes to futures by @sean-parent in #505
• Fix typo from main_scheduler_type to main_executor_type by @nickpdemarco in #516
• Revisit Reduce by @sean-parent in #521
• Add check for C++20, make ambiguous case assume 23 by @nickpdemarco in #522
• Restore Qt5 compatibility by @touraill-adobe in #524
• Minor comment fix by @sean-parent in #526
• Requiring executor tasks are noexcept. by @sean-parent in #528
• Removing use of boost::variant and optional from stlab now that it has moved to C++17 by @thinlang in #531

New Contributors

• @KevinHopps made their first contribution in #498
• @laserallan made their first contribution in #507
• @touraill-adobe made their first contribution in #524
• @thinlang made their first contribution in #531

Full Changelog: v1.7.1...v2.0.0a1