1 # Copyright (c) 2024-present The Bitcoin Core developers
2 # Distributed under the MIT software license, see the accompanying
3 # file COPYING or https://opensource.org/license/mit/.
4 5 #[=[
6 7 target_capnp_sources
8 --------------------
9 10 This function adds build steps to generate C++ files from Cap'n Proto files
11 and build them as part of a specified target.
12 13 Arguments:
14 15 target: The name of the CMake target (e.g., a library or executable) to
16 which the generated source files will be added. This target must already
17 be defined elsewhere in the CMake scripts.
18 19 include_prefix: Absolute path indicating what portion of capnp source paths
20 should be used in relative #include statements in the generated C++
21 files. For example, if the .capnp path is /home/src/lib/schema.capnp
22 and include_prefix is /home/src, generated includes look like:
23 24 #include <lib/schema.capnp.h>
25 26 And if include_prefix is /home/src/lib, generated includes look like:
27 28 #include <schema.capnp.h>
29 30 Pass ${CMAKE_CURRENT_SOURCE_DIR} or a subdirectory of it to include files
31 relative to the current source directory (the typical usage).
32 33 Additional Unnamed Arguments:
34 35 After `target` and `include_prefix`, all unnamed arguments are treated as
36 paths to `.capnp` schema files. These should be paths relative to
37 ${CMAKE_CURRENT_SOURCE_DIR}.
38 39 Optional Keyword Arguments:
40 41 IMPORT_PATHS: Specifies additional directories to search for imported
42 `.capnp` files.
43 44 ONLY_CAPNP: If specified, only the Cap'n Proto serialization files
45 (`.capnp.h`, `.capnp.c++`) are generated and compiled. The mpgen proxy
46 files (`.capnp.proxy-client.c++`, `.capnp.proxy-server.c++`,
47 `.capnp.proxy-types.c++`, etc.) are skipped. Useful when you need
48 Cap'n Proto serialization without the multiprocess RPC proxy
49 infrastructure.
50 51 Example:
52 # Assuming `my_library` is a target and `lib/` contains `.capnp` schema
53 # files with imports from `include/`.
54 target_capnp_sources(my_library "${CMAKE_CURRENT_SOURCE_DIR}"
55 lib/schema1.capnp lib/schema2.capnp
56 IMPORT_PATHS ${CMAKE_CURRENT_SOURCE_DIR}/include)
57 58 #]=]
59 60 function(target_capnp_sources target include_prefix)
61 cmake_parse_arguments(PARSE_ARGV 2
62 "TCS" # prefix
63 "ONLY_CAPNP" # options
64 "" # one_value_keywords
65 "IMPORT_PATHS" # multi_value_keywords
66 )
67 68 set(MPGEN_BINARY "")
69 if(MPGEN_EXECUTABLE)
70 set(MPGEN_BINARY "${MPGEN_EXECUTABLE}")
71 if(NOT EXISTS "${MPGEN_BINARY}")
72 message(FATAL_ERROR "MPGEN_EXECUTABLE: \"${MPGEN_BINARY}\" does not exist.")
73 endif()
74 elseif(TARGET Libmultiprocess::multiprocess)
75 set(MPGEN_BINARY Libmultiprocess::mpgen)
76 else()
77 message(FATAL_ERROR "No usable mpgen. Set MPGEN_EXECUTABLE or enable the internal target.")
78 endif()
79 80 get_property(mp_include_dir GLOBAL PROPERTY MP_INCLUDE_DIR)
81 set(generated_headers "")
82 foreach(capnp_file IN LISTS TCS_UNPARSED_ARGUMENTS)
83 add_custom_command(
84 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
85 COMMAND ${MPGEN_BINARY} ${CMAKE_CURRENT_SOURCE_DIR} ${include_prefix} ${CMAKE_CURRENT_SOURCE_DIR}/${capnp_file} ${TCS_IMPORT_PATHS} ${mp_include_dir}
86 DEPENDS ${capnp_file}
87 VERBATIM
88 )
89 # Skip linting for capnp-generated files but keep it for mpgen-generated ones
90 set_source_files_properties(${capnp_file}.c++ PROPERTIES SKIP_LINTING TRUE) # Ignored before cmake 3.27
91 target_sources(${target} PRIVATE
92 ${CMAKE_CURRENT_BINARY_DIR}/${capnp_file}.c++
93 )
94 if(NOT TCS_ONLY_CAPNP)
95 target_sources(${target} PRIVATE
96 ${CMAKE_CURRENT_BINARY_DIR}/${capnp_file}.proxy-client.c++
97 ${CMAKE_CURRENT_BINARY_DIR}/${capnp_file}.proxy-server.c++
98 ${CMAKE_CURRENT_BINARY_DIR}/${capnp_file}.proxy-types.c++
99 )
100 endif()
101 list(APPEND generated_headers ${capnp_file}.h)
102 endforeach()
103 104 # Translate include_prefix from a source path to a binary path and add it as a
105 # target include directory.
106 set(build_include_prefix ${CMAKE_CURRENT_BINARY_DIR})
107 file(RELATIVE_PATH relative_path ${CMAKE_CURRENT_SOURCE_DIR} ${include_prefix})
108 if(relative_path)
109 string(APPEND build_include_prefix "/" "${relative_path}")
110 endif()
111 target_include_directories(${target} PUBLIC $<BUILD_INTERFACE:${build_include_prefix}> ${mp_include_dir})
112 113 if(TARGET Libmultiprocess::multiprocess)
114 target_link_libraries(${target} PRIVATE Libmultiprocess::multiprocess)
115 endif()
116 117 # Add a custom target that can be specified as a dependency of c++ targets
118 # that include generated headers. It can be necessary to specify these
119 # dependencies explicitly because while cmake detect dependencies of non
120 # generated files on generated headers, it does not reliably detect
121 # dependencies of generated headers on other generated headers.
122 if(NOT TARGET "${target}_headers")
123 add_custom_target("${target}_headers" DEPENDS ${generated_headers})
124 endif()
125 endfunction()
126