[WIP] build: Add CMake-based build system

[hebasto]

Benefits of using CMake in the Bitcoin Core project:

• no hacks required to build dll for Windows, even with DEBUG=1 (see build: Cross-compiling libbitcoinconsensus for Windows fails with DEBUG=1 bitcoin/bitcoin#19772)
• better maintainability (say bye to global variables)
• easy integration with Qt 5 (compare src/qt/CMakeLists.txt vs build-aux/m4/bitcoin_qt.m4)
• easy integration with Qt 6
• works fine with installed both Qt 5 and Qt 6 on Linux and macOS

Important notes:

• backward compatibility with Ubuntu Bionic (only CMake 3.10 is required)
• see a new CI task :)
• building in the source tree is not supported.

Done:

• bitcoind executable, could be disabled with -DBUILD_DAEMON=OFF
• bitcoin-cli executable, could be disabled with -DBUILD_CLI=OFF
• libbitcoinconsensus shared library, could be disabled with -DBUILD_BITCOINCONSENSUS_LIB=OFF
• libbitcoinkernel shared library, could be disabled with -DBUILD_BITCOINKERNEL_LIB=OFF
• wallet support, could be disabled with -DENABLE_WALLET=OFF
• bitcoin-qt executable, could be specified with -DWITH_GUI=Qt5 or -DWITH_GUI=Qt6, or disabled with -DWITH_GUI=no (no Android support)
• ccache support, could be disabled with -DUSE_CCACHE=OFF (not working when cross-compiling for macOS, see ci: ccache does not work for macOS cross-compiling builds bitcoin/bitcoin#21552 and build: Fix ccache behavior when cross-compiling for darwin hosts bitcoin/bitcoin#24620)
• cross-compiling, including Windows builds with DEBUG=1
• reduce exported symbols support, could be enabled with -DREDUCE_EXPORTS=ON
• optional packages support

Not implemented yet:

• bitcoin-qt for Android
• ...

Need to be fixed:

• ...

---

Native compiling has been tested on the following OSes:

• Ubuntu 22.04
• macOS Monterey
• FreeBSD 12.3
• OpenBSD 7.1

rm -rf build && cmake -S . -B build
cmake --build build

Native compiling on Ubuntu 22.04 with system Qt 6

sudo apt install qt6-base-dev qt6-l10n-tools qt6-tools-dev qt6-tools-dev-tools libxkbcommon-dev
rm -rf build && cmake -S . -B build
cmake --build build

Native compiling on macOS Monterey with Homebrew's Qt 6

brew install qt
rm -rf build && cmake -S . -B build
cmake --build build

Cross compiling for Windows on Ubuntu 22.04

make -C depends HOST=x86_64-w64-mingw32
rm -rf build && cmake --toolchain depends/x86_64-w64-mingw32/share/toolchain.cmake -S . -B build
cmake --build build

Cross compiling for macOS on Ubuntu 22.04

make -C depends HOST=x86_64-apple-darwin
rm -rf build && cmake --toolchain depends/x86_64-apple-darwin/share/toolchain.cmake -S . -B build
cmake --build build

---

Configuration Options Comparison Table (a draft)

Autotools	CMake
--enable-ccache	-DUSE_CCACHE=auto,yes,no

Optional packages:

Autotools	CMake
--with-gui	-DWITH_GUI=auto,Qt5,Qt6,no
--with-natpmp	-DWITH_NATPMP=auto,yes,no
--enable-natpmp-default	-DENABLE_NATPMP_DEFAULT=ON,OFF
--with-miniupnpc	-DWITH_MINIUPNPC=auto,yes,no
--enable-upnp-default	-DENABLE_UPNP_DEFAULT=ON,OFF
--enable-zmq	-DWITH_ZMQ=auto,yes,no
--enable-usdt	-DWITH_USDT=auto,yes,no
--with-seccomp	-DWITH_SECCOMP=auto,yes,no
--with-qrencode	-DWITH_QRENCODE=auto,yes,no

---

Functional Tests

Functional tests can be run in exactly the same way as when building with Autotools out of the source tree, i.e.:

./build/test/functional/test_runner.py

---

A related brainstorming issue: #4.

[hebasto]

Added config/bitcoin-config.h support.

Fixed macro definitions for macOS.

[fanquake]

The cmake docs say that CMAKE_SYSTEM_VERSION must also be set explicitly when cross-compiling:

When the CMAKE_SYSTEM_NAME variable is set explicitly to enable cross compiling then the value of CMAKE_SYSTEM_VERSION must also be set explicitly to specify the target system version.

[hebasto]

Yes, docs are clear.

FWIW, CMAKE_SYSTEM_VERSION is ignored currently:

bitcoin/depends/funcs.mk

Lines 183 to 185 in 455780b

	$(1)_cmake += -DCMAKE_SYSTEM_NAME=$($(host_os)_cmake_system)
	$(1)_cmake += -DCMAKE_C_COMPILER_TARGET=$(host)
	$(1)_cmake += -DCMAKE_CXX_COMPILER_TARGET=$(host)

[ryanofsky]

Yes, docs are clear.

I think this doc is overgeneralizing. If you look at https://cmake.org/cmake/help/latest/manual/cmake-toolchains.7.html you can see this variable only has meaning when cross compiling for windows and android

[hebasto]

I think this doc is overgeneralizing. If you look at https://cmake.org/cmake/help/latest/manual/cmake-toolchains.7.html you can see this variable only has meaning when cross compiling for windows and android

Looking into CMake sources makes me think you are almost right. I see usage of CMAKE_SYSTEM_VERSION's value in the Modules/Platform/Android-*.cmake and Modules/Platform/Darwin.cmake files.

I'd say this variable only has meaning when cross compiling for darwin and android.

UPDATE: https://gitlab.kitware.com/cmake/cmake/-/blob/master/Modules/CMakeDetermineSystem.cmake#L7:

# CMAKE_SYSTEM_VERSION - on unix this is uname -r, for windows it is empty

[fanquake]

So it might be Android and Windows, or Android and macOS, or Android and Windows and macOS, where this matters. In either case it seems like we should figure out if we need to set this.

[fanquake]

I don't think there's any particular reason for this to be tied to Qts minimum required, so we could drop the comment. I'd also suggest setting this to 3.10, otherwise we wont be able to build on Ubuntu Bionic, which ships with 3.10.0.

[hebasto]

Thanks! Updated.

[hebasto]

Added an initial implementation of qt/CMakeList.txt.

Addressed @fanquake's comment.

[theStack]

Tested building f217df3 on OpenBSD 7.1 via

rm -rf build && cmake -DCMAKE_MAKE_PROGRAM=gmake -S . -B build
cmake --build build

The good news: the previously (via IRC) reported secp256k1 preprocessor failure is gone now and I could successfully build bitcoin-cli and bitcoind 🚀 however, the following patch was needed (could have probably also specified that as argument?):

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 94c2934d7..6fff6093d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -80,7 +80,7 @@ option(BUILD_CLI "Build bitcoin-cli" ON)
 option(BUILD_BITCOINCONSENSUS_LIB "Build bitcoinconsensus shared library" ON)
 option(BUILD_BITCOINKERNEL_LIB "Build experimental bitcoinkernel shared library" ON)
 option(ENABLE_WALLET "Enable wallet" ON)
-option(BUILD_QT5_GUI "Build Qt5 widget-based GUI" ON)
+option(BUILD_QT5_GUI "Build Qt5 widget-based GUI" OFF)

 include(cmake/subtree-crc32c.cmake)
 include(cmake/subtree-leveldb.cmake)

The bad news: building bitcoin-qt fails due to a missing CMake file (qt5 was installed via # pkg_add qt5 which should bring the necessary development files):

CMake Error at src/qt/CMakeLists.txt:14 (find_package):
  By not providing "FindQt5.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "Qt5", but
  CMake did not find one.

  Could not find a package configuration file provided by "Qt5" (requested
  version 5.11.3) with any of the following names:

    Qt5Config.cmake
    qt5-config.cmake

  Add the installation prefix of "Qt5" to CMAKE_PREFIX_PATH or set "Qt5_DIR"
  to a directory containing one of the above files.  If "Qt5" provides a
  separate development package or SDK, be sure it has been installed.


-- Configuring incomplete, errors occurred!

The file Qt5Config.cmake is available in /usr/local/lib/qt5/cmake/Qt5/Qt5Config.cmake, probably just some search path has to be extended here.

[hebasto]

Reworked integration with depends.

bitcoin-qt can be cross compiled now (except for Android).

The build instructions in the PR description have been updated.

[furszy]

Big concept ACK.

I'm having the same problem as @theStack in macOS Monterey.

This fixes it (tested on macOS only):

if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
  list(APPEND CMAKE_PREFIX_PATH /usr/local/opt/qt5 /opt/homebrew/opt/qt5)
elseif(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
  list(APPEND CMAKE_PREFIX_PATH /usr/lib/x86_64-linux-gnu/cmake/Qt5)
  set(Qt5core_DIR "/usr/lib/x86_64-linux-gnu/cmake/Qt5/QtCore")
endif()

find_package(Qt5 5.11.3 REQUIRED COMPONENTS Widgets LinguistTools)

[hebasto]

Added support for system Qt6 on Linux.

[hebasto]

@furszy

I'm having the same problem as @theStack in macOS Monterey.

Yes. It fails with qt@5 (will be fixed).

But it builds successfully with qt@6 from Homebrew 🐅

[hebasto]

I'm having the same problem as @theStack in macOS Monterey.

Fixed build with Homebrew's Qt 5 on macOS.

[furszy]

Fixed build with Homebrew's Qt 5 on macOS.

Confirmed that is working on macOS 👍🏼

[Sjors]

I was also able to build on macOS 12.4 with qt 6 via homebrew, but only without the wallet. Otherwise it fails with:

[ 99%] Linking CXX executable bitcoin-qt
Undefined symbols for architecture x86_64:
  "interfaces::MakeWalletLoader(interfaces::Chain&, ArgsManager&)", referenced from:
      init::(anonymous namespace)::BitcoinQtInit::makeWalletLoader(interfaces::Chain&) in bitcoin-qt.cpp.o
ld: symbol(s) not found for architecture x86_64

Why -DENABLE_WALLET=OFF, which also disables SQLite? Is there a way to turn off BDB only?

What's the equivalent of our existing ./configure options? And can we get it to print a similar summary?

It even worked with distcc. When the other machine runs Linux, I had to copy the SDK over to the same path and set export CFLAGS="-target x86_64-apple-darwin21.5.0" CXXFLAGS="-target x86_64-apple-darwin21.5.0" CC=clang CXX=clang++.

[hebasto]

@Sjors

Building GUI with wallet requires bitcoin#25338.

UPDATE: ... and bitcoin-core/gui#618.

[hebasto]

@theStack

The bad news: building bitcoin-qt fails due to a missing CMake file (qt5 was installed via # pkg_add qt5 which should bring the necessary development files):

CMake Error at src/qt/CMakeLists.txt:14 (find_package):
  By not providing "FindQt5.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "Qt5", but
  CMake did not find one.

  Could not find a package configuration file provided by "Qt5" (requested
  version 5.11.3) with any of the following names:

    Qt5Config.cmake
    qt5-config.cmake

  Add the installation prefix of "Qt5" to CMAKE_PREFIX_PATH or set "Qt5_DIR"
  to a directory containing one of the above files.  If "Qt5" provides a
  separate development package or SDK, be sure it has been installed.


-- Configuring incomplete, errors occurred!

The file Qt5Config.cmake is available in /usr/local/lib/qt5/cmake/Qt5/Qt5Config.cmake, probably just some search path has to be extended here.

Additional options -DBUILD_GUI=Qt5 -DQt5_DIR=/usr/local/lib/qt5/cmake/Qt5 are required. The example for OpenBSD 7.1 has been updated in the PR description.

[hebasto]

Building the GUI with wallet (only SQLite for now).

Added support for libnatpmp and libminiupnpc optional packages.

@Sjors

What's the equivalent of our existing ./configure options?

Added "Configuration Options Comparison Table" to the PR description.

[Sjors]

GUI wallet works for me on macOS 12.4 with qt 6 now.

I get a few minor warnings (building without depends):

[ 38%] Linking CXX static library libbitcoin_util.a
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libbitcoin_util.a(sync.cpp.o) has no symbols
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib: file: libbitcoin_util.a(sync.cpp.o) has no symbols

There's also a deprecation warning warning: 'location' is deprecated: Use path() [-Wdeprecated-declarations] but I'm guessing that's a QT 6 issue, not cmake.

It also seems to run the libsecp256k ./configure during the cmake --build build step, rather than the configuration step. This creates noise when compiling with -jN, because the configure output lines are mixed with building lines.

The two issues above make it difficult to notice any other warnings, so they might be worth addressing (and rebasing) for that reason.

I was also able to build and run with depends (without cross compilation), like so:

make -C depends
 rm -rf build && cmake --toolchain depends/x86_64-apple-darwin21.5.0/share/toolchain.cmake -S . -B build

The binaries now end up in build/src/bitcoind, so that either needs to change, or we need the functional tests to use the new location. There's also no test/config.ini yet, so I guess you're still working on that.

When building with distcc, I get bunch of clang: warning: argument unused during compilation: '-iframework /usr/local/lib'. This was without using depends, and the only other machine run the same macOS and XCode version, and has the same SDK.

[hebasto]

Synced with the bitcoin#25797.

[hebasto]

Autotools -- CMake Feature Parity Table

Autotool-based build system (AT) features being listed according ./configure --help output.

AT feature	CM feature
--enable-c++20	TBD
--disable-wallet	-DENABLE_WALLET
--enable-usdt	-DWITH_USDT
--enable-upnp-default	-DENABLE_UPNP_DEFAULT
--enable-natpmp-default	-DENABLE_NATPMP_DEFAULT
--disable-tests	TBD
--disable-gui-tests	TBD
--disable-bench	TBD
--enable-extended-functional-tests	TBD
--enable-fuzz	TBD
--enable-fuzz-binary	TBD
--disable-hardening	-DCMAKE_BUILD_TYPE=RelHardened
--enable-reduce-exports	-DREDUCE_EXPORTS
--disable-ccache	-DUSE_CCACHE
--enable-suppress-external-warnings	TBD
--enable-lcov	TBD
--enable-lcov-branch-coverage	TBD
--enable-threadlocal	TBD
--disable-asm	TBD
--disable-zmq	-DWITH_ZMQ
--enable-multiprocess	TBD
--disable-man	TBD
--enable-debug	TBD
--enable-gprof	TBD
--enable-werror	TBD
--enable-external-signer	-DWITH_EXTERNAL_SIGNER
--enable-lto	TBD
--enable-util-cli	-DBUILD_CLI
--enable-util-tx	-DBUILD_TX
--enable-util-wallet	-DBUILD_WALLET_TOOL
--enable-util-util	-DBUILD_UTIL
--enable-experimental-util-chainstate	TBD
--with-seccomp	-DWITH_SECCOMP
--with-sqlite	-DWITH_SQLITE
--without-bdb	-DWITH_BDB
--with-miniupnpc	-DWITH_MINIUPNPC
--with-natpmp	-DWITH_NATPMP
--with-qrencode	-DWITH_QRENCODE
--with-libmultiprocess	TBD
--with-mpgen	TBD
--with-sanitizers	TBD
--with-utils	individual options
--with-libs	TBD
--with-experimental-kernel-lib	TBD
--with-daemon	-DBUILD_DAEMON
--with-gui	-DWITH_GUI
...

[Rspigler]

Is it true that --without-bdb is -DWITH_BDB?
Could you add some more with/without enable/disable values? For example, what is CM version of --disable-external-signer?

[hebasto]

Is it true that --without-bdb is -DWITH_BDB? Could you add some more with/without enable/disable values? For example, what is CM version of --disable-external-signer?

More detailed:

• --with-bdb=auto or nothing == -DWITH_BDB=auto or nothing
• --with-bdb or --with-bdb=yes == -DWITH_BDB=yes
• --with-bdb=no or --without-bdb == -DWITH_BDB=no

[hebasto]

what is CM version of --disable-external-signer?

-DWITH_EXTERNAL_SIGNER=auto,yes,no

[hebasto]

@Rspigler

cmake-gui can be used to see all available options in a nice way.

[Rspigler]

Thanks!

[fanquake]

Maybe close this for now, to avoid any confusion, and given we've got the parent PR open on the main repo?

[hebasto]

Maybe close this for now, to avoid any confusion, and given we've got the parent PR open on the main repo?

Yes :)