cmake: Add LibmultiprocessMacros module

Co-authored-by: Ryan Ofsky <[email protected]>

Author: hebasto

CMakeLists.txt

@@ -77,6 +77,7 @@ add_library(multiprocess STATIC
   ${MP_PUBLIC_HEADERS}
   src/mp/proxy.cpp
   $<TARGET_OBJECTS:util>)
+add_library(Libmultiprocess::multiprocess ALIAS multiprocess)
 target_include_directories(multiprocess PUBLIC
   $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/include>
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
@@ -102,6 +103,7 @@ add_custom_target(install-lib
 add_dependencies(install-lib multiprocess)
 
 add_executable(mpgen src/mp/gen.cpp $<TARGET_OBJECTS:util>)
+add_executable(Libmultiprocess::mpgen ALIAS mpgen)
 target_include_directories(mpgen PRIVATE $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}/include>)
 target_include_directories(mpgen PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include> $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>)
 target_link_libraries(mpgen PRIVATE CapnProto::capnp)

cmake/LibmultiprocessMacros.cmake

@@ -0,0 +1,94 @@
+# Copyright (c) 2024-present The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or https://opensource.org/license/mit/.
+
+#[=[
+
+target_capnp_sources
+--------------------
+
+This function adds build steps to generate C++ files from Cap'n Proto files
+and build them as part of a specified target.
+
+Arguments:
+
+  target: The name of the CMake target (e.g., a library or executable) to
+    which the generated source files will be added. This target must already
+    be defined elsewhere in the CMake scripts.
+
+  include_prefix: Absolute path indicating what portion of capnp source paths
+    should be used in relative #include statements in the generated C++
+    files. For example, if the .capnp path is /home/src/lib/schema.capnp
+    and include_prefix is /home/src, generated includes look like:
+
+      #include <lib/schema.capnp.h>
+
+    And if include_prefix is /home/src/lib, generated includes look like:
+
+      #include <schema.capnp.h>
+
+    The specified include_prefix should be ${CMAKE_SOURCE_DIR} or a
+    subdirectory of it to include files relative to the project root. It can
+    be ${CMAKE_CURRENT_SOURCE_DIR} to include files relative to the current
+    source directory.
+
+Additional Unnamed Arguments:
+
+  After `target` and `include_prefix`, all unnamed arguments are treated as
+  paths to `.capnp` schema files. These should be paths relative to
+  ${CMAKE_CURRENT_SOURCE_DIR}.
+
+Optional Keyword Arguments:
+
+  IMPORT_PATHS: Specifies additional directories to search for imported
+    `.capnp` files.
+
+Example:
+  # Assuming `my_library` is a target and `lib/` contains `.capnp` schema
+  # files with imports from `include/`.
+  target_capnp_sources(my_library "${CMAKE_SOURCE_DIR}"
+                       lib/schema1.capnp lib/schema2.capnp
+                       IMPORT_PATHS ${CMAKE_SOURCE_DIR}/include)
+
+#]=]
+
+function(target_capnp_sources target include_prefix)
+  cmake_parse_arguments(PARSE_ARGV 2
+    "TCS"           # prefix
+    ""              # options
+    ""              # one_value_keywords
+    "IMPORT_PATHS"  # multi_value_keywords
+  )
+
+  if(NOT TARGET Libmultiprocess::mpgen)
+    message(FATAL_ERROR "Target 'Libmultiprocess::mpgen' does not exist.")
+  endif()
+
+  foreach(capnp_file IN LISTS TCS_UNPARSED_ARGUMENTS)
+    add_custom_command(
+      OUTPUT ${capnp_file}.c++ ${capnp_file}.h ${capnp_file}.proxy-client.c++ ${capnp_file}.proxy-types.h ${capnp_file}.proxy-server.c++ ${capnp_file}.proxy-types.c++ ${capnp_file}.proxy.h
+      COMMAND Libmultiprocess::mpgen ${CMAKE_CURRENT_SOURCE_DIR} ${include_prefix} ${CMAKE_CURRENT_SOURCE_DIR}/${capnp_file} ${TCS_IMPORT_PATHS}
+      DEPENDS ${capnp_file}
+      VERBATIM
+    )
+    target_sources(${target} PRIVATE
+      ${CMAKE_CURRENT_BINARY_DIR}/${capnp_file}.c++
+      ${CMAKE_CURRENT_BINARY_DIR}/${capnp_file}.proxy-client.c++
+      ${CMAKE_CURRENT_BINARY_DIR}/${capnp_file}.proxy-server.c++
+      ${CMAKE_CURRENT_BINARY_DIR}/${capnp_file}.proxy-types.c++
+    )
+  endforeach()
+
+  # Translate include_prefix from a source path to a binary path and add it as a
+  # target include directory.
+  set(build_include_prefix ${CMAKE_BINARY_DIR})
+  file(RELATIVE_PATH relative_path ${CMAKE_SOURCE_DIR} ${include_prefix})
+  if(relative_path)
+    string(APPEND build_include_prefix "/" "${relative_path}")
+  endif()
+  target_include_directories(${target} PUBLIC $<BUILD_INTERFACE:${build_include_prefix}>)
+
+  if(TARGET Libmultiprocess::multiprocess)
+    target_link_libraries(${target} PRIVATE Libmultiprocess::multiprocess)
+  endif()
+endfunction()