Hennadii Stepanov fc4ceda8b6 Merge bitcoin-core/gui#949: Fix -Wsfinae-incomplete warnings when building with GCC 16.x
51d36dfd07 qt: Fix `-Wsfinae-incomplete` warnings when building with GCC 16.x (Hennadii Stepanov)

Pull request description:

  According to the CMake documentation for [`AUTOMOC`](https://cmake.org/cmake/help/latest/prop_tgt/AUTOMOC.html), all `moc` output files that are not included in a source file are aggregated into the CMake-generated `<AUTOGEN_BUILD_DIR>/mocs_compilation.cpp`, which is added to the target's sources.

  Within that single translation unit, `moc`-generated code checks the completeness of a signal or slot parameter type while it is still only forward-declared, and the type is completed later, when a subsequently included `moc_*.cpp` file pulls in the header that defines it. GCC 16.x diagnoses this pattern with the `-Wsfinae-incomplete` warning, which is enabled by default.

  Including the `moc` output files at the end of the corresponding source files excludes them from `mocs_compilation.cpp`, so each one is compiled in a translation unit where the relevant types are complete.

  FWIW, Qt itself uses the same approach throughout its own codebase. Also see https://www.youtube.com/watch?v=Cx_m-qVnEjo.

  ---

  Steps to reproduce on the master branch @ 18c05d9301  on Fedora 44 (GCC 16.1.1):
  ```console
  $ cmake --preset dev-mode
  $ cmake --build build_dev_mode -t bitcoind
  $ cmake --build build_dev_mode -t bitcoin-qt
  [166/172] Building CXX object src/qt/CMakeFiles/bitcoinqt.dir/bitcoinqt_autogen/mocs_compilation.cpp.o
  In file included from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/EWIEGA46WW/moc_bitcoingui.cpp:9,
                   from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/mocs_compilation.cpp:9:
  /home/hebasto/dev/bitcoin-gui/src/qt/bitcoingui.h:67:7: warning: defining ‘BitcoinGUI’, which previously failed to be complete in a SFINAE context [-Wsfinae-incomplete=]
     67 | class BitcoinGUI : public QMainWindow
        |       ^~~~~~~~~~
  In file included from /usr/include/qt6/QtCore/qobject.h:19,
                   from /usr/include/qt6/QtWidgets/qwidget.h:10,
                   from /usr/include/qt6/QtWidgets/qdialog.h:9,
                   from /usr/include/qt6/QtWidgets/QDialog:1,
                   from /home/hebasto/dev/bitcoin-gui/src/qt/addressbookpage.h:8,
                   from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/EWIEGA46WW/moc_addressbookpage.cpp:9,
                   from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/mocs_compilation.cpp:2:
  /usr/include/qt6/QtCore/qmetatype.h:344:64: note: here.  Use ‘-Wsfinae-incomplete=2’ for a diagnostic at that point
    344 |         static auto check(U *) -> std::integral_constant<bool, sizeof(U) != 0>;
        |                                                                ^~~~~~~~~
  In file included from /home/hebasto/dev/bitcoin-gui/src/qt/paymentserver.h:35,
                   from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/EWIEGA46WW/moc_paymentserver.cpp:9,
                   from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/mocs_compilation.cpp:27:
  /home/hebasto/dev/bitcoin-gui/src/qt/sendcoinsrecipient.h:15:7: warning: defining ‘SendCoinsRecipient’, which previously failed to be complete in a SFINAE context [-Wsfinae-incomplete=]
     15 | class SendCoinsRecipient
        |       ^~~~~~~~~~~~~~~~~~
  /usr/include/qt6/QtCore/qmetatype.h:344:64: note: here.  Use ‘-Wsfinae-incomplete=2’ for a diagnostic at that point
    344 |         static auto check(U *) -> std::integral_constant<bool, sizeof(U) != 0>;
        |                                                                ^~~~~~~~~
  In file included from /home/hebasto/dev/bitcoin-gui/src/qt/psbtoperationsdialog.h:13,
                   from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/EWIEGA46WW/moc_psbtoperationsdialog.cpp:9,
                   from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/mocs_compilation.cpp:30:
  /home/hebasto/dev/bitcoin-gui/src/qt/walletmodel.h:48:7: warning: defining ‘WalletModel’, which previously failed to be complete in a SFINAE context [-Wsfinae-incomplete=]
     48 | class WalletModel : public QObject
        |       ^~~~~~~~~~~
  /usr/include/qt6/QtCore/qmetatype.h:344:64: note: here.  Use ‘-Wsfinae-incomplete=2’ for a diagnostic at that point
    344 |         static auto check(U *) -> std::integral_constant<bool, sizeof(U) != 0>;
        |                                                                ^~~~~~~~~
  In file included from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/EWIEGA46WW/moc_qvalidatedlineedit.cpp:9,
                   from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/mocs_compilation.cpp:32:
  /home/hebasto/dev/bitcoin-gui/src/qt/qvalidatedlineedit.h:13:7: warning: defining ‘QValidatedLineEdit’, which previously failed to be complete in a SFINAE context [-Wsfinae-incomplete=]
     13 | class QValidatedLineEdit : public QLineEdit
        |       ^~~~~~~~~~~~~~~~~~
  /usr/include/qt6/QtCore/qmetatype.h:344:64: note: here.  Use ‘-Wsfinae-incomplete=2’ for a diagnostic at that point
    344 |         static auto check(U *) -> std::integral_constant<bool, sizeof(U) != 0>;
        |                                                                ^~~~~~~~~
  In file included from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/EWIEGA46WW/moc_rpcconsole.cpp:9,
                   from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/mocs_compilation.cpp:37:
  /home/hebasto/dev/bitcoin-gui/src/qt/rpcconsole.h:43:7: warning: defining ‘RPCConsole’, which previously failed to be complete in a SFINAE context [-Wsfinae-incomplete=]
     43 | class RPCConsole: public QWidget
        |       ^~~~~~~~~~
  /usr/include/qt6/QtCore/qmetatype.h:344:64: note: here.  Use ‘-Wsfinae-incomplete=2’ for a diagnostic at that point
    344 |         static auto check(U *) -> std::integral_constant<bool, sizeof(U) != 0>;
        |                                                                ^~~~~~~~~
  In file included from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/EWIEGA46WW/moc_sendcoinsentry.cpp:9,
                   from /home/hebasto/dev/bitcoin-gui/build_dev_mode/src/qt/bitcoinqt_autogen/mocs_compilation.cpp:39:
  /home/hebasto/dev/bitcoin-gui/src/qt/sendcoinsentry.h:26:7: warning: defining ‘SendCoinsEntry’, which previously failed to be complete in a SFINAE context [-Wsfinae-incomplete=]
     26 | class SendCoinsEntry : public QWidget
        |       ^~~~~~~~~~~~~~
  /usr/include/qt6/QtCore/qmetatype.h:344:64: note: here.  Use ‘-Wsfinae-incomplete=2’ for a diagnostic at that point
    344 |         static auto check(U *) -> std::integral_constant<bool, sizeof(U) != 0>;
        |                                                                ^~~~~~~~~
  [172/172] Linking CXX executable bin/bitcoin-qt
  ```

ACKs for top commit:
  maflcko:
    review ACK 51d36dfd07 🦅

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Bitcoin Core integration/staging tree

https://bitcoincore.org

For an immediately usable, binary version of the Bitcoin Core software, see https://bitcoincore.org/en/download/.

What is Bitcoin Core?

Bitcoin Core connects to the Bitcoin peer-to-peer network to download and fully validate blocks and transactions. It also includes a wallet and graphical user interface, which can be optionally built.

Further information about Bitcoin Core is available in the doc folder.

License

Bitcoin Core is released under the terms of the MIT license. See COPYING for more information or see https://opensource.org/license/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 during the generation of the build system) with: ctest. 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. These tests can be run (if the test dependencies are installed) with: build/test/functional/test_runner.py (assuming build is your build directory).

The CI (Continuous Integration) systems make sure that every pull request is tested on Windows, Linux, and macOS. The CI must pass on all commits before merge to avoid unrelated CI failures on new pull requests.

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.

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