Changelog


v2.1.2 ? (Boost 1.72) [release]

Enhancements:

Improved compatibility with cmake tooling
Standalone outcome is now make install-able, and cmake find_package() can find it. Note that you must separately install and find_package() Outcome’s dependency, quickcpplib, else find_package() of Outcome will fail.
Breaking change!
The git submodule mechanism used by standalone Outcome of specifying dependent libraries has been replaced with a cmake superbuild of dependencies mechanism instead. Upon cmake configure, an internal copy of quickcpplib will be git cloned, built and installed into the build directory from where an internal find_package() uses it. This breaks the use of the unconfigured Outcome repo as an implementation of Outcome, one must now do one of:
  1. Add Outcome as subdirectory to cmake build
  2. Use cmake superbuild (i.e. ExternalProject_Add()) to build and install Outcome into a local installation.
  3. Use one of the single header editions.
Breaking change!
For standalone Outcome, the current compiler is now checked for whether it will compile code containing C++ Concepts, and if it does, all cmake consumers of Outcome will enable C++ Concepts. Set the cmake variable CXX_CONCEPTS_FLAGS to an empty string to prevent auto detection and enabling of C++ Concepts support occurring.
OUTCOME_TRY operation now hints to the compiler that operation will be successful
P1886 Error speed benchmarking showed that there is considerable gain in very small functions by hinting to the compiler whether the expression is expected to be successful or not. OUTCOME_TRY previously did not hint to the compiler at all, but now it does. A new suite of macros OUTCOME_TRY_FAILURE_LIKELY hint to the compiler that failure is expected. If you wish to return to the previously unhinted behaviour, define OUTCOME_TRY_LIKELY(expr) to (!!expr).
#199
Support for C++ Coroutines has been added. This comes in two parts, firstly there is now an OUTCOME_CO_TRY() operation suitable for performing the TRY operation from within a C++ Coroutine. Secondly, in the header outcome/coroutine_support.hpp there are implementations of eager<OutcomeType> and lazy<OutcomeType> which let you more naturally and efficiently use basic_result or basic_outcome from within C++ Coroutines – specifically, if the result or outcome will construct from an exception pointer, exceptions thrown in the coroutine return an errored or excepted result with the thrown exception instead of throwing the exception through the coroutine machinery (which in current compilers, has a high likelihood of blowing up the program). Both eager<T> and lazy<T> can accept any T as well. Both have been tested and found working on VS2019 and clang 9.
#210
make_error_code() and make_exception_ptr() are now additionally considered for compatible copy and move conversions for basic_result<>. This lets you construct a basic_result<T, E> into a basic_result<T, error_code>, where E is a custom type which has implemented the ADL discovered free function error_code make_error_code(E), but is otherwise unrelated to error_code. The same availability applies for exception_ptr with make_exception_ptr() being the ADL discovered free function. basic_outcome<> has less support for this than basic_result<> in order to keep constructor count down, but it will accept via this mechanism conversions from basic_result<> and failure_type<>.

Bug fixes:

#184
The detection of [[nodiscard]] support in the compiler was very mildly broken.

v2.1.1 19th August 2019 (Boost 1.71) [release]

Enhancements:

#184
As per request from Boost release managers, relocated version.hpp and revision.hpp into detail, and added the Boost licence boilerplate to the top of every source file which was missing one (I think). Also took the opportunity to run the licence restamping script over all Outcome, so copyright dates are now up to date.
#185
Add FAQ item explaining issue #185, and why we will do nothing to fix it right now.
#189
Refactored the OUTCOME_TRY implementation to use more clarified customisation points capable of accepting very foreign inputs. Removed the std::experimental::expected<T, E> specialisations, as those are no longer necessary. Fixed the documentation for the customisation points which previously claimed that they are ADL discovered, which they are not. Added a recipe describing how to add in support for foreign input types.
#183
Added a separate motivation/plug_error_code specifically for Boost.

Bug fixes:

-
OUTCOME_VERSION_MINOR hadn’t been updated to 1.
#181
Fix issue #181 where Outcome didn’t actually implement the strong swap guarantee, despite being documented as doing so.
#190
Fix issue #190 in Boost edition where unit test suite was not runnable from the Boost release distro.
#182
Fix issue #182 where trait::is_exception_ptr_available<T> was always true, thus causing much weirdness, like not printing diagnostics and trying to feed everything to make_exception_ptr().
#194
Fix issue #192 where the std::basic_outcome_failure_exception_from_error() was being defined twice for translation units which combine standalone and Boost Outcome’s.

v2.1 12th Apr 2019 (Boost 1.70) [release]


v2.0 18th Jan 2018 [release]