boost/website
2
0
Fork 0
mirror of https://github.com/boostorg/website.git synced 2026-01-26 19:12:15 +00:00
Code Issues Projects Releases Wiki Activity

Merge pull request #452 from ned14/master

Browse Source 
Add release notes for Outcome v2.1.2.
This commit is contained in:
Glen Fernandes
2019-11-04 21:58:59 -05:00
committed by GitHub
parent 1ea950bc9a 3e7c437188
commit fa768f0a8f
1 changed files with 16 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
feed/history/boost_1_72_0.qbk
View File

@@ -64,6 +64,22 @@ Please keep the list of libraries sorted in lexicographical order.
* Using `boost::none_t` in place of `void` through
`BOOST_FUNCTIONAL_FACTORY_SUPPORT_NONE_T`
* [phrase library..[@/libs/outcome/ Outcome]:]
* Enhancements:
* 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.
* 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.
* 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*](https://wg21.link/P1886) 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)`.
* [@https://github.com/ned14/outcome/issues/199 #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.
* [@https://github.com/ned14/outcome/issues/210 #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:
* [@https://github.com/ned14/outcome/issues/184 #184] The detection of `[[nodiscard]]` support in the compiler was very mildly broken.
* [phrase library..[@/libs/poly_collection/ PolyCollection]:]
* Maintenance work.