FindThreadsCMake31.cmake

#.rst:
# FindThreads
# -----------
#
# This module determines the thread library of the system.
#
# This file is a modified copy from CMake 3.1. Do not edit this
# file. Remove this file once we rely on at least CMake 3.1.
#
# 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
#
# For systems with multiple thread libraries, caller can set
#
# ::
#
#   CMAKE_THREAD_PREFER_PTHREAD
#
# If the use of the -pthread compiler and linker flag is prefered 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.
#
#=============================================================================
# CMake - Cross Platform Makefile Generator
# Copyright 2000-2015 Kitware, Inc.
# Copyright 2011-2014 Rolf Eike Beer <eike@sf-mail.de>
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# * Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
#
# * Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
#
# * Neither the names of Kitware, Inc., the Insight Software Consortium,
#   nor the names of their contributors may be used to endorse or promote
#   products derived from this software without specific prior written
#   permission.
#
#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
#  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
#  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
#  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
#  HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
#  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
#  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
#  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
#  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
#  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
#  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#
# ------------------------------------------------------------------------------
#
# The above copyright and license notice applies to distributions of
# CMake in source and binary form.  Some source files contain additional
# notices of original copyright by their contributors; see each source
# for details.  Third-party software packages supplied with CMake under
# compatible licenses provide their own copyright notices documented in
# corresponding subdirectories.
#
# ------------------------------------------------------------------------------
#
# CMake was initially developed by Kitware with the following sponsorship:
#
#  * National Library of Medicine at the National Institutes of Health
#    as part of the Insight Segmentation and Registration Toolkit (ITK).
#
#  * US National Labs (Los Alamos, Livermore, Sandia) ASC Parallel
#    Visualization Initiative.
#
#  * National Alliance for Medical Image Computing (NAMIC) is funded by the
#    National Institutes of Health through the NIH Roadmap for Medical Research,
#    Grant U54 EB005149.
#
#  * Kitware, Inc.

include (CheckIncludeFiles)
include (CheckLibraryExists)
include (CheckSymbolExists)
set(Threads_FOUND FALSE)
set(CMAKE_REQUIRED_QUIET_SAVE ${CMAKE_REQUIRED_QUIET})
set(CMAKE_REQUIRED_QUIET ${Threads_FIND_QUIETLY})

# Do we have sproc?
if(CMAKE_SYSTEM_NAME MATCHES IRIX AND NOT CMAKE_THREAD_PREFER_PTHREAD)
  CHECK_INCLUDE_FILES("sys/types.h;sys/prctl.h"  CMAKE_HAVE_SPROC_H)
endif()

# 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")
      try_run(THREADS_PTHREAD_ARG THREADS_HAVE_PTHREAD_ARG
        ${CMAKE_BINARY_DIR}
        ${CMAKE_CURRENT_LIST_DIR}/CheckForPthreads.c
        CMAKE_FLAGS -DLINK_LIBRARIES:STRING=-pthread
        COMPILE_OUTPUT_VARIABLE OUTPUT)

      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?
  CHECK_INCLUDE_FILES("pthread.h" CMAKE_HAVE_PTHREAD_H)
  if(CMAKE_HAVE_PTHREAD_H)

    #
    # We have pthread.h
    # Let's check for the library now.
    #
    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()

        # 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()

if(CMAKE_SYSTEM_NAME MATCHES "Windows")
  set(CMAKE_USE_WIN32_THREADS_INIT 1)
  set(Threads_FOUND TRUE)
endif()

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(FindPackageHandleStandardArgs)
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()