e3fa3c7d67
f1d21ef1c370898ae10569f2a8569bd98d71a981 doc: add C++17 release note for 0.21.0 (fanquake) Pull request description: TLDR: Mention that the codebase is now compatible with C++17, and that the intention is to require C++17 starting with 0.22.0. Following some discussion with Cory/Carl, and in #16684, I think this is the next step in the C++17 migration. While #16684 mentions a gitian/Guix release with C++17, it's not yet clear how that would be done. Are we just going to pass `--enable-c++17` in gitian/Guix?. Are we changing our default in configure.ac? According to the [last comment](https://github.com/bitcoin/bitcoin/issues/16684#issuecomment-643778757) in #16684, we wouldn't be changing anything in depends: > No, everything (including depends) will stay at C++11. However I don't think we want to be mixing C++11 built dependencies, with a C++17 built bitcoind, if there is any potential for compatibility issues. Instead, I'd suggest we build the 0.21.0 release as C++11, and do a complete switch to C++17 for 0.22.0. Also, if we actually wanted to use C++17 in depends for 0.21.0, we couldn't without breaking C++11 compat (Qt). See below. Here is a potential timeline/TODOs for the migration: Potential Timeline * 17 / 6 / 2020 - Today * Some time prior to split-off: * Confirm that compiling with C++17 works. * Confirm that C++11 compatibility has not been broken. * 1 / 11 / 2020 * [0.21.0 split off happens](https://github.com/bitcoin/bitcoin/issues/18947). * 2 / 11 / 2020 * Merge an "incompatible with C++11" change into master. * Switch configure to use C++17 mode by default. * Update minimum compiler requirements. At least: * Clang 5: https://clang.llvm.org/cxx_status.html#cxx17 * GCC 7: https://gcc.gnu.org/projects/cxx-status.html#cxx17 * While GCC has some support from 5, it seems a more complete support landed in GCC 7. * https://gcc.gnu.org/gcc-7/changes.html#cxx * Switch depends packages to use C++17 where applicable. * Bump Qt from 5.9.x (no c++17 mode) to, likely, 5.15.x (LTS). * Drop support for macOS < 10.14.x * The c++ dylib shipped with macOS [doesn't support c++17, prior to macOS 10.14](https://github.com/bitcoin/bitcoin/issues/16684#issuecomment-643722538). * Building Qt 5.12 or 5.15 in C++17 mode will also require a minimum macOS deployment target of 10.14. https://codereview.qt-project.org/c/qt/qtbase/+/283832. * Begin merging PRs like #19183 and #19245. * I've left some comments in #19183 if the macOS runtime issue interests anyone. * 3 / 12 / 2020 * 0.21.0 released. * Built as C++11. * Contains warning in release notes that compiling 0.22.0 will require C++17. * 3 / 6 / 2021 * 0.22.0 released. * Full of C++17 code. One thing worth noting, is that we cannot bump our Qt to a newer LTS for 0.21.0, without breaking C++11 compatibility. Qt 5.12 is not compilable in C++11 mode, as the project has started using C++14 features throughout at least the macOS portions of it's codebase, and seemingly "forgotten" that the release is meant to be C++11 compatible. Upstream bug here: https://bugreports.qt.io/browse/QTBUG-77310. > Building Qt requires C+11, at a minimum, but in practice we use later features, usually under a feature define, or with a fallback of some kind. On platforms that support > C11, we've (apparently) not considered the fallback necessary, under the assumption C+14 is always available. ACKs for top commit: MarcoFalke: ACK f1d21ef1c370898ae10569f2a8569bd98d71a981 can't hurt to give an advance warning Sjors: ACK f1d21ef1c370898ae10569f2a8569bd98d71a981 laanwj: ACK f1d21ef1c370898ae10569f2a8569bd98d71a981 theStack: ACK f1d21ef1c370898ae10569f2a8569bd98d71a981 Tree-SHA512: 706baceb07d9584783ba6e437cdf447531c20f586285b9797edc21f3adb1e9d386059d1c543c70eb298d0f8e555dafb6682a55d35c5836979fc12132e8ba06f5
Bitcoin Core integration/staging tree
What is Bitcoin?
Bitcoin is an experimental digital currency that enables instant payments to anyone, anywhere in the world. Bitcoin uses peer-to-peer technology to operate with no central authority: managing transactions and issuing money are carried out collectively by the network. Bitcoin Core is the name of open source software which enables the use of this currency.
For more information, as well as an immediately usable, binary version of the Bitcoin Core software, see https://bitcoincore.org/en/download/, or read the original whitepaper.
License
Bitcoin Core is released under the terms of the MIT license. See COPYING for more information or see https://opensource.org/licenses/MIT.
Development Process
The master branch is regularly built (see doc/build-*.md for instructions) and tested, but it is not guaranteed to be
completely stable. Tags are created
regularly from release branches to indicate new official, stable release versions of Bitcoin Core.
The https://github.com/bitcoin-core/gui repository is used exclusively for the development of the GUI. Its master branch is identical in all monotree repositories. Release branches and tags do not exist, so please do not fork that repository unless it is for development reasons.
The contribution workflow is described in CONTRIBUTING.md and useful hints for developers can be found in doc/developer-notes.md.
Testing
Testing and code review is the bottleneck for development; we get more pull requests than we can review and test on short notice. Please be patient and help out by testing other people's pull requests, and remember this is a security-critical project where any mistake might cost people lots of money.
Automated Testing
Developers are strongly encouraged to write unit tests for new code, and to
submit new unit tests for old code. Unit tests can be compiled and run
(assuming they weren't disabled in configure) with: make check. Further details on running
and extending unit tests can be found in /src/test/README.md.
There are also regression and integration tests, written
in Python, that are run automatically on the build server.
These tests can be run (if the test dependencies are installed) with: test/functional/test_runner.py
The Travis CI system makes sure that every pull request is built for Windows, Linux, and macOS, and that unit/sanity tests are run automatically.
Manual Quality Assurance (QA) Testing
Changes should be tested by somebody other than the developer who wrote the code. This is especially important for large or high-risk changes. It is useful to add a test plan to the pull request description if testing the changes is not straightforward.
Translations
Changes to translations as well as new translations can be submitted to Bitcoin Core's Transifex page.
Translations are periodically pulled from Transifex and merged into the git repository. See the translation process for details on how this works.
Important: We do not accept translation changes as GitHub pull requests because the next pull from Transifex would automatically overwrite them again.
Translators should also subscribe to the mailing list.