CMake/Modules/FindThreads.cmake

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Simplify CMake per-source license notices Per-source copyright/license notice headers that spell out copyright holder names and years are hard to maintain and often out-of-date or plain wrong. Precise contributor information is already maintained automatically by the version control tool. Ultimately it is the receiver of a file who is responsible for determining its licensing status, and per-source notices are merely a convenience. Therefore it is simpler and more accurate for each source to have a generic notice of the license name and references to more detailed information on copyright holders and full license terms. Our `Copyright.txt` file now contains a list of Contributors whose names appeared source-level copyright notices. It also references version control history for more precise information. Therefore we no longer need to spell out the list of Contributors in each source file notice. Replace CMake per-source copyright/license notice headers with a short description of the license and links to `Copyright.txt` and online information available from "https://cmake.org/licensing". The online URL also handles cases of modules being copied out of our source into other projects, so we can drop our notices about replacing links with full license text. Run the `Utilities/Scripts/filter-notices.bash` script to perform the majority of the replacements mechanically. Manually fix up shebang lines and trailing newlines in a few files. Manually update the notices in a few files that the script does not handle.
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# Distributed under the OSI-approved BSD 3-Clause License. See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.
#.rst:
# FindThreads
# -----------
#
# This module determines the thread library of the system.
#
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# The following variables are set
#
# ::
#
# CMAKE_THREAD_LIBS_INIT - the thread library
# CMAKE_USE_SPROC_INIT - are we using sproc?
# CMAKE_USE_WIN32_THREADS_INIT - using WIN32 threads?
# CMAKE_USE_PTHREADS_INIT - are we using pthreads
# CMAKE_HP_PTHREADS_INIT - are we using hp pthreads
#
# The following import target is created
#
# ::
#
# Threads::Threads
#
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# For systems with multiple thread libraries, caller can set
#
# ::
#
# CMAKE_THREAD_PREFER_PTHREAD
#
# If the use of the -pthread compiler and linker flag is preferred then the
# caller can set
#
# ::
#
# THREADS_PREFER_PTHREAD_FLAG
#
# Please note that the compiler flag can only be used with the imported
# target. Use of both the imported target as well as this switch is highly
# recommended for new code.
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include (CheckLibraryExists)
include (CheckSymbolExists)
set(Threads_FOUND FALSE)
set(CMAKE_REQUIRED_QUIET_SAVE ${CMAKE_REQUIRED_QUIET})
set(CMAKE_REQUIRED_QUIET ${Threads_FIND_QUIETLY})
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if(CMAKE_C_COMPILER_LOADED)
include (CheckIncludeFile)
elseif(CMAKE_CXX_COMPILER_LOADED)
include (CheckIncludeFileCXX)
else()
message(FATAL_ERROR "FindThreads only works if either C or CXX language is enabled")
endif()
# Do we have sproc?
if(CMAKE_SYSTEM_NAME MATCHES IRIX AND NOT CMAKE_THREAD_PREFER_PTHREAD)
include (CheckIncludeFiles)
CHECK_INCLUDE_FILES("sys/types.h;sys/prctl.h" CMAKE_HAVE_SPROC_H)
endif()
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# Internal helper macro.
# Do NOT even think about using it outside of this file!
macro(_check_threads_lib LIBNAME FUNCNAME VARNAME)
if(NOT Threads_FOUND)
CHECK_LIBRARY_EXISTS(${LIBNAME} ${FUNCNAME} "" ${VARNAME})
if(${VARNAME})
set(CMAKE_THREAD_LIBS_INIT "-l${LIBNAME}")
set(CMAKE_HAVE_THREADS_LIBRARY 1)
set(Threads_FOUND TRUE)
endif()
endif ()
endmacro()
# Internal helper macro.
# Do NOT even think about using it outside of this file!
macro(_check_pthreads_flag)
if(NOT Threads_FOUND)
# If we did not found -lpthread, -lpthread, or -lthread, look for -pthread
if(NOT DEFINED THREADS_HAVE_PTHREAD_ARG)
message(STATUS "Check if compiler accepts -pthread")
if(CMAKE_C_COMPILER_LOADED)
set(_threads_src ${CMAKE_CURRENT_LIST_DIR}/CheckForPthreads.c)
elseif(CMAKE_CXX_COMPILER_LOADED)
set(_threads_src ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/FindThreads/CheckForPthreads.cxx)
configure_file(${CMAKE_CURRENT_LIST_DIR}/CheckForPthreads.c "${_threads_src}" COPYONLY)
endif()
try_run(THREADS_PTHREAD_ARG THREADS_HAVE_PTHREAD_ARG
${CMAKE_BINARY_DIR}
${_threads_src}
CMAKE_FLAGS -DLINK_LIBRARIES:STRING=-pthread
COMPILE_OUTPUT_VARIABLE OUTPUT)
unset(_threads_src)
if(THREADS_HAVE_PTHREAD_ARG)
if(THREADS_PTHREAD_ARG STREQUAL "2")
set(Threads_FOUND TRUE)
message(STATUS "Check if compiler accepts -pthread - yes")
else()
message(STATUS "Check if compiler accepts -pthread - no")
file(APPEND
${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
"Determining if compiler accepts -pthread returned ${THREADS_PTHREAD_ARG} instead of 2. The compiler had the following output:\n${OUTPUT}\n\n")
endif()
else()
message(STATUS "Check if compiler accepts -pthread - no")
file(APPEND
${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeError.log
"Determining if compiler accepts -pthread failed with the following output:\n${OUTPUT}\n\n")
endif()
endif()
if(THREADS_HAVE_PTHREAD_ARG)
set(Threads_FOUND TRUE)
set(CMAKE_THREAD_LIBS_INIT "-pthread")
endif()
endif()
endmacro()
if(CMAKE_HAVE_SPROC_H AND NOT CMAKE_THREAD_PREFER_PTHREAD)
# We have sproc
set(CMAKE_USE_SPROC_INIT 1)
else()
# Do we have pthreads?
if(CMAKE_C_COMPILER_LOADED)
CHECK_INCLUDE_FILE("pthread.h" CMAKE_HAVE_PTHREAD_H)
else()
CHECK_INCLUDE_FILE_CXX("pthread.h" CMAKE_HAVE_PTHREAD_H)
endif()
if(CMAKE_HAVE_PTHREAD_H)
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#
# We have pthread.h
# Let's check for the library now.
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#
set(CMAKE_HAVE_THREADS_LIBRARY)
if(NOT THREADS_HAVE_PTHREAD_ARG)
# Check if pthread functions are in normal C library
CHECK_SYMBOL_EXISTS(pthread_create pthread.h CMAKE_HAVE_LIBC_CREATE)
if(CMAKE_HAVE_LIBC_CREATE)
set(CMAKE_THREAD_LIBS_INIT "")
set(CMAKE_HAVE_THREADS_LIBRARY 1)
set(Threads_FOUND TRUE)
else()
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# Check for -pthread first if enabled. This is the recommended
# way, but not backwards compatible as one must also pass -pthread
# as compiler flag then.
if (THREADS_PREFER_PTHREAD_FLAG)
_check_pthreads_flag()
endif ()
_check_threads_lib(pthreads pthread_create CMAKE_HAVE_PTHREADS_CREATE)
_check_threads_lib(pthread pthread_create CMAKE_HAVE_PTHREAD_CREATE)
if(CMAKE_SYSTEM_NAME MATCHES "SunOS")
# On sun also check for -lthread
_check_threads_lib(thread thr_create CMAKE_HAVE_THR_CREATE)
endif()
endif()
endif()
_check_pthreads_flag()
endif()
endif()
if(CMAKE_THREAD_LIBS_INIT OR CMAKE_HAVE_LIBC_CREATE)
set(CMAKE_USE_PTHREADS_INIT 1)
set(Threads_FOUND TRUE)
endif()
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if(CMAKE_SYSTEM_NAME MATCHES "Windows")
set(CMAKE_USE_WIN32_THREADS_INIT 1)
set(Threads_FOUND TRUE)
endif()
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if(CMAKE_USE_PTHREADS_INIT)
if(CMAKE_SYSTEM_NAME MATCHES "HP-UX")
# Use libcma if it exists and can be used. It provides more
# symbols than the plain pthread library. CMA threads
# have actually been deprecated:
# http://docs.hp.com/en/B3920-90091/ch12s03.html#d0e11395
# http://docs.hp.com/en/947/d8.html
# but we need to maintain compatibility here.
# The CMAKE_HP_PTHREADS setting actually indicates whether CMA threads
# are available.
CHECK_LIBRARY_EXISTS(cma pthread_attr_create "" CMAKE_HAVE_HP_CMA)
if(CMAKE_HAVE_HP_CMA)
set(CMAKE_THREAD_LIBS_INIT "-lcma")
set(CMAKE_HP_PTHREADS_INIT 1)
set(Threads_FOUND TRUE)
endif()
set(CMAKE_USE_PTHREADS_INIT 1)
endif()
if(CMAKE_SYSTEM MATCHES "OSF1-V")
set(CMAKE_USE_PTHREADS_INIT 0)
set(CMAKE_THREAD_LIBS_INIT )
endif()
if(CMAKE_SYSTEM MATCHES "CYGWIN_NT")
set(CMAKE_USE_PTHREADS_INIT 1)
set(Threads_FOUND TRUE)
set(CMAKE_THREAD_LIBS_INIT )
set(CMAKE_USE_WIN32_THREADS_INIT 0)
endif()
endif()
set(CMAKE_REQUIRED_QUIET ${CMAKE_REQUIRED_QUIET_SAVE})
include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
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FIND_PACKAGE_HANDLE_STANDARD_ARGS(Threads DEFAULT_MSG Threads_FOUND)
if(THREADS_FOUND AND NOT TARGET Threads::Threads)
add_library(Threads::Threads INTERFACE IMPORTED)
if(THREADS_HAVE_PTHREAD_ARG)
set_property(TARGET Threads::Threads PROPERTY INTERFACE_COMPILE_OPTIONS "-pthread")
endif()
if(CMAKE_THREAD_LIBS_INIT)
set_property(TARGET Threads::Threads PROPERTY INTERFACE_LINK_LIBRARIES "${CMAKE_THREAD_LIBS_INIT}")
endif()
endif()