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capnproto/c++/cmake/CapnProtoTargets.cmake

222 lines
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CMake

# This CMake script adds imported targets for each shared library and executable distributed by
# Cap'n Proto's autotools build.
#
# This file IS NOT USED by the CMake build! The CMake build generates its own version of this script
# from its set of exported targets. I used such a generated script as a reference when writing this
# one.
#
# The set of library targets provided by this script is automatically generated from the list of .pc
# files maintained in configure.ac. The set of executable targets is hard-coded in this file.
#
# You can request that this script print debugging information by invoking cmake with:
#
# -DCapnProto_DEBUG=ON
#
# TODO(someday): Distinguish between debug and release builds. I.e., set IMPORTED_LOCATION_RELEASE
# rather than IMPORTED_LOCATION, etc., if this installation was configured as a release build. But
# how do we tell? grep for -g in CXXFLAGS?
if(CMAKE_VERSION VERSION_LESS 3.1)
message(FATAL_ERROR "CMake >= 3.1 required")
endif()
set(forwarded_config_flags)
if(CapnProto_FIND_QUIETLY)
list(APPEND forwarded_config_flags QUIET)
endif()
if(CapnProto_FIND_REQUIRED)
list(APPEND forwarded_config_flags REQUIRED)
endif()
# If the consuming project called find_package(CapnProto) with the QUIET or REQUIRED flags, forward
# them to calls to find_package(PkgConfig) and pkg_check_modules(). Note that find_dependency()
# would do this for us in the former case, but there is no such forwarding wrapper for
# pkg_check_modules().
find_package(PkgConfig ${forwarded_config_flags})
if(NOT ${PkgConfig_FOUND})
# If we're here, the REQUIRED flag must not have been passed, else we would have had a fatal
# error. Nevertheless, a diagnostic for this case is probably nice.
if(NOT CapnProto_FIND_QUIETLY)
message(WARNING "pkg-config cannot be found")
endif()
set(CapnProto_FOUND OFF)
return()
endif()
function(_capnp_import_pkg_config_target target)
# Add an imported library target named CapnProto::${target}, using the output of various
# invocations of `pkg-config ${target}`. The generated imported library target tries to mimic the
# behavior of a real CMake-generated imported target as closely as possible.
#
# Usage: _capnp_import_pkg_config_target(target <all Cap'n Proto targets>)
set(all_targets ${ARGN})
pkg_check_modules(${target} ${forwarded_config_flags} ${target})
if(NOT ${${target}_FOUND})
if(NOT CapnProto_FIND_QUIETLY)
message(WARNING "CapnProtoConfig.cmake was configured to search for ${target}.pc, but pkg-config cannot find it. Ignoring this target.")
endif()
return()
endif()
if(CapnProto_DEBUG)
# Dump the information pkg-config discovered.
foreach(var VERSION LIBRARY_DIRS LIBRARIES LDFLAGS_OTHER INCLUDE_DIRS CFLAGS_OTHER)
message(STATUS "${target}_${var} = ${${target}_${var}}")
endforeach()
endif()
if(NOT ${${target}_VERSION} VERSION_EQUAL ${CapnProto_VERSION})
if(NOT CapnProto_FIND_QUIETLY)
message(WARNING "CapnProtoConfig.cmake was configured to search for version ${CapnProto_VERSION}, but ${target} version ${${target}_VERSION} was found. Ignoring this target.")
endif()
return()
endif()
# Make an educated guess as to what the target's .so and .a filenames must be.
set(target_name_shared
${CMAKE_SHARED_LIBRARY_PREFIX}${target}-${CapnProto_VERSION}${CMAKE_SHARED_LIBRARY_SUFFIX})
set(target_name_static
${CMAKE_STATIC_LIBRARY_PREFIX}${target}${CMAKE_STATIC_LIBRARY_SUFFIX})
# Find the actual target's file. find_library() sets a cache variable, so I made the variable name
# unique-ish.
find_library(CapnProto_${target}_IMPORTED_LOCATION
NAMES ${target_name_shared} ${target_name_static} # prefer libfoo-version.so over libfoo.a
PATHS ${${target}_LIBRARY_DIRS}
NO_DEFAULT_PATH
)
# If the installed version of Cap'n Proto is in a system location, pkg-config will not have filled
# in ${target}_LIBRARY_DIRS. To account for this, fall back to a regular search.
find_library(CapnProto_${target}_IMPORTED_LOCATION
NAMES ${target_name_shared} ${target_name_static} # prefer libfoo-version.so over libfoo.a
)
if(NOT CapnProto_${target}_IMPORTED_LOCATION)
# Not an error if the library doesn't exist -- we may have found a lite mode installation.
if(CapnProto_DEBUG)
message(STATUS "${target} library does not exist")
endif()
return()
endif()
# Record some information about this target -- shared versus static, location and soname -- which
# we'll use to build our imported target later.
set(target_location ${CapnProto_${target}_IMPORTED_LOCATION})
get_filename_component(target_name "${target_location}" NAME)
set(target_type STATIC)
set(imported_soname_property)
if(target_name STREQUAL ${target_name_shared})
set(target_type SHARED)
set(imported_soname_property IMPORTED_SONAME ${target_name})
endif()
# Each library dependency of the target is either the target itself, a sibling Cap'n Proto
# library, or a system library. We ignore the first case by removing this target from the
# dependencies. The remaining dependencies are either passed through or, if they are a sibling
# Cap'n Proto library, prefixed with `CapnProto::`.
set(dependencies ${${target}_LIBRARIES})
list(REMOVE_ITEM dependencies ${target})
set(target_interface_libs)
foreach(dependency ${dependencies})
list(FIND all_targets ${dependency} target_index)
# TODO(cleanup): CMake >= 3.3 lets us write: `if(NOT ${dependency} IN_LIST all_targets)`
if(target_index EQUAL -1)
list(APPEND target_interface_libs ${dependency})
else()
list(APPEND target_interface_libs CapnProto::${dependency})
endif()
endforeach()
add_library(CapnProto::${target} ${target_type} IMPORTED)
set_target_properties(CapnProto::${target} PROPERTIES
${imported_soname_property}
IMPORTED_LOCATION "${target_location}"
# TODO(cleanup): Use cxx_std_14 once it's safe to require cmake 3.8.
INTERFACE_COMPILE_FEATURES "cxx_generic_lambdas"
INTERFACE_COMPILE_OPTIONS "${${target}_CFLAGS_OTHER}"
INTERFACE_INCLUDE_DIRECTORIES "${${target}_INCLUDE_DIRS}"
# I'm dumping LDFLAGS_OTHER in with the libraries because there exists no
# INTERFACE_LINK_OPTIONS. See https://gitlab.kitware.com/cmake/cmake/issues/16543.
INTERFACE_LINK_LIBRARIES "${target_interface_libs};${${target}_LDFLAGS_OTHER}"
)
if(CapnProto_DEBUG)
# Dump all the properties we generated for the imported target.
foreach(prop
IMPORTED_LOCATION
IMPORTED_SONAME
INTERFACE_COMPILE_FEATURES
INTERFACE_COMPILE_OPTIONS
INTERFACE_INCLUDE_DIRECTORIES
INTERFACE_LINK_LIBRARIES)
get_target_property(value CapnProto::${target} ${prop})
message(STATUS "CapnProto::${target} ${prop} = ${value}")
endforeach()
endif()
endfunction()
# ========================================================================================
# Imported library targets
# Build a list of targets to search for from the list of .pc files.
# I.e. [somewhere/foo.pc, somewhere/bar.pc] -> [foo, bar]
set(library_targets)
foreach(filename ${CAPNP_PKG_CONFIG_FILES})
get_filename_component(target ${filename} NAME_WE)
list(APPEND library_targets ${target})
endforeach()
# Try to add an imported library target CapnProto::foo for each foo.pc distributed with Cap'n Proto.
foreach(target ${library_targets})
_capnp_import_pkg_config_target(${target} ${library_targets})
endforeach()
# Handle lite-mode and no libraries found cases. It is tempting to set a CapnProto_LITE variable
# here, but the real CMake-generated implementation does no such thing -- we'd need to set it in
# CapnProtoConfig.cmake.in itself.
if(TARGET CapnProto::capnp AND TARGET CapnProto::kj)
if(NOT TARGET CapnProto::capnp-rpc)
if(NOT CapnProto_FIND_QUIETLY)
message(STATUS "Found an installation of Cap'n Proto lite. Executable and library targets beyond libkj and libcapnp will be unavailable.")
endif()
# Lite mode doesn't include the executables, so return here.
return()
endif()
else()
# If we didn't even find capnp or kj, then we didn't find anything usable.
set(CapnProto_FOUND OFF)
return()
endif()
# ========================================================================================
# Imported executable targets
get_filename_component(_IMPORT_PREFIX "${CMAKE_CURRENT_LIST_FILE}" PATH)
get_filename_component(_IMPORT_PREFIX "${_IMPORT_PREFIX}" PATH)
get_filename_component(_IMPORT_PREFIX "${_IMPORT_PREFIX}" PATH)
get_filename_component(_IMPORT_PREFIX "${_IMPORT_PREFIX}" PATH)
# Add executable targets for the capnp compiler and plugins. This list must be kept manually in sync
# with the rest of the project.
add_executable(CapnProto::capnp_tool IMPORTED)
set_target_properties(CapnProto::capnp_tool PROPERTIES
IMPORTED_LOCATION "${_IMPORT_PREFIX}/bin/capnp${CMAKE_EXECUTABLE_SUFFIX}"
)
add_executable(CapnProto::capnpc_cpp IMPORTED)
set_target_properties(CapnProto::capnpc_cpp PROPERTIES
IMPORTED_LOCATION "${_IMPORT_PREFIX}/bin/capnpc-c++${CMAKE_EXECUTABLE_SUFFIX}"
)
add_executable(CapnProto::capnpc_capnp IMPORTED)
set_target_properties(CapnProto::capnpc_capnp PROPERTIES
IMPORTED_LOCATION "${_IMPORT_PREFIX}/bin/capnpc-capnp${CMAKE_EXECUTABLE_SUFFIX}"
)