build: depends makes libmultiprocess by default

This causes IPC binaries (bitcoin-node, bitcoin-gui) to be included
in releases.

The effect on CI is that this causes more depends builds to build IPC
binaries, but still the only build running functional tests with them
is the i686_multiprocess one.

Except for Windows and OpenBSD.

ci/test/00_setup_env_i686_multiprocess.sh

@@ -11,7 +11,7 @@ export CONTAINER_NAME=ci_i686_multiprocess
 export CI_IMAGE_NAME_TAG="mirror.gcr.io/ubuntu:24.04"
 export CI_IMAGE_PLATFORM="linux/amd64"
 export PACKAGES="llvm clang g++-multilib"
-export DEP_OPTS="DEBUG=1 MULTIPROCESS=1"
+export DEP_OPTS="DEBUG=1"
 export GOAL="install"
 export TEST_RUNNER_EXTRA="--v2transport"
 export BITCOIN_CONFIG="\

depends/Makefile

@@ -40,7 +40,10 @@ NO_BDB ?=
 NO_WALLET ?=
 NO_ZMQ ?=
 NO_USDT ?=
-MULTIPROCESS ?=
+# Default NO_IPC value is 1 on unsupported host platforms:
+# - Windows
+# - OpenBSD: https://github.com/capnproto/capnproto/pull/1907
+NO_IPC ?= $(if $(findstring mingw32,$(HOST))$(findstring openbsd,$(HOST)),1,)
 LTO ?=
 FALLBACK_DOWNLOAD_PATH ?= https://bitcoincore.org/depends-sources
 
@@ -163,7 +166,7 @@ bdb_packages_$(NO_BDB) = $(bdb_packages)
 wallet_packages_$(NO_WALLET) = $(bdb_packages_) $(sqlite_packages)
 
 zmq_packages_$(NO_ZMQ) = $(zmq_packages)
-multiprocess_packages_$(MULTIPROCESS) = $(multiprocess_packages)
+multiprocess_packages_$(NO_IPC) = $(multiprocess_packages)
 usdt_packages_$(NO_USDT) = $(usdt_$(host_os)_packages)
 
 packages += $($(host_arch)_$(host_os)_packages) $($(host_os)_packages) $(boost_packages_) $(libevent_packages_) $(qt_packages_) $(wallet_packages_) $(usdt_packages_)
@@ -173,7 +176,7 @@ ifneq ($(zmq_packages_),)
 packages += $(zmq_packages)
 endif
 
-ifeq ($(multiprocess_packages_),)
+ifneq ($(multiprocess_packages_),)
 packages += $(multiprocess_packages)
 native_packages += $(multiprocess_native_packages)
 endif
@@ -234,7 +237,7 @@ $(host_prefix)/toolchain.cmake : toolchain.cmake.in $(host_prefix)/.stamp_$(fina
             -e 's|@wallet_packages@|$(wallet_packages_)|' \
             -e 's|@bdb_packages@|$(bdb_packages_)|' \
             -e 's|@usdt_packages@|$(usdt_packages_)|' \
-            -e 's|@multiprocess@|$(MULTIPROCESS)|' \
+            -e 's|@multiprocess_packages@|$(multiprocess_packages_)|' \
             $< > $@
 	touch $@
 

depends/README.md

@@ -118,7 +118,7 @@ The following can be set when running make: `make FOO=bar`
 - `NO_WALLET`: Don't download/build/cache libs needed to enable the wallet (SQLite)
 - `NO_BDB`: Don't download/build/cache BerkeleyDB
 - `NO_USDT`: Don't download/build/cache packages needed for enabling USDT tracepoints
-- `MULTIPROCESS`: Build libmultiprocess (experimental)
+- `NO_IPC`: Don't build Cap’n Proto and libmultiprocess packages, and disable building IPC binaries (bitcoin-node, bitcoin-gui). Default on Windows and OpenBSD.
 - `DEBUG`: Disable some optimizations and enable more runtime checking
 - `HOST_ID_SALT`: Optional salt to use when generating host package ids
 - `BUILD_ID_SALT`: Optional salt to use when generating build package ids

depends/toolchain.cmake.in

@@ -158,11 +158,12 @@ else()
   set(WITH_USDT ON CACHE BOOL "")
 endif()
 
-if("@multiprocess@" STREQUAL "1")
+set(multiprocess_packages @multiprocess_packages@)
+if("${multiprocess_packages}" STREQUAL "")
+  set(ENABLE_IPC OFF CACHE BOOL "")
+else()
   set(ENABLE_IPC ON CACHE BOOL "")
   set(MPGEN_EXECUTABLE "${CMAKE_CURRENT_LIST_DIR}/native/bin/mpgen" CACHE FILEPATH "")
   set(CAPNP_EXECUTABLE "${CMAKE_CURRENT_LIST_DIR}/native/bin/capnp" CACHE FILEPATH "")
   set(CAPNPC_CXX_EXECUTABLE "${CMAKE_CURRENT_LIST_DIR}/native/bin/capnpc-c++" CACHE FILEPATH "")
-else()
-  set(ENABLE_IPC OFF CACHE BOOL "")
 endif()

doc/multiprocess.md

@@ -16,11 +16,11 @@ Specifying `-DENABLE_IPC=ON` requires [Cap'n Proto](https://capnproto.org/) to b
 
 ### Depends installation
 
-Alternately the [depends system](../depends) can be used to avoid need to install local dependencies. A simple way to get started is to pass the `MULTIPROCESS=1` [dependency option](../depends#dependency-options) to make:
+Alternatively the [depends system](../depends) can be used to avoid needing to install local dependencies:
 
 ```
 cd <BITCOIN_SOURCE_DIRECTORY>
-make -C depends NO_QT=1 MULTIPROCESS=1
+make -C depends NO_QT=1
 # Set host platform to output of gcc -dumpmachine or clang -dumpmachine or check the depends/ directory for the generated subdirectory name
 HOST_PLATFORM="x86_64-pc-linux-gnu"
 cmake -B build --toolchain=depends/$HOST_PLATFORM/toolchain.cmake
@@ -29,7 +29,7 @@ build/bin/bitcoin-node -regtest -printtoconsole -debug=ipc
 BITCOIND=$(pwd)/build/bin/bitcoin-node build/test/functional/test_runner.py
 ```
 
-The `cmake` build will pick up settings and library locations from the depends directory, so there is no need to pass `-DENABLE_IPC=ON` as a separate flag when using the depends system (it's controlled by the `MULTIPROCESS=1` option).
+The `cmake` build will pick up settings and library locations from the depends directory, so there is no need to pass `-DENABLE_IPC=ON` as a separate flag when using the depends system (it's controlled by the `NO_IPC=1` option).
 
 ### Cross-compiling