cmake/FindSharedPtr.cmake

# Ceres Solver - A fast non-linear least squares minimizer
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# Author: sergey.vfx@gmail.com (Sergey Sharybin)
#

# FindSharedPtr.cmake - Find shared pointer header and namespace.
#
# This module defines the following variables:
#
# SHARED_PTR_FOUND: TRUE if shared_ptr found.
# SHARED_PTR_TR1_MEMORY_HEADER: True if <tr1/memory> header is to be used
# for the shared_ptr object, otherwise use <memory>.
# SHARED_PTR_TR1_NAMESPACE: TRUE if shared_ptr is defined in std::tr1 namespace,
# otherwise it's assumed to be defined in std namespace.

macro(FIND_SHARED_PTR)
  # To support CXX11 option, clear the results of all check_xxx() functions
  # s/t we always perform the checks each time, otherwise CMake fails to
  # detect that the tests should be performed again after CXX11 is toggled.
  unset(HAVE_STD_MEMORY_HEADER CACHE)
  unset(HAVE_SHARED_PTR_IN_STD_NAMESPACE CACHE)
  unset(HAVE_SHARED_PTR_IN_TR1_NAMESPACE CACHE)
  unset(HAVE_TR1_MEMORY_HEADER CACHE)
  unset(HAVE_SHARED_PTR_IN_TR1_NAMESPACE_FROM_TR1_MEMORY_HEADER CACHE)

  set(SHARED_PTR_FOUND FALSE)
  check_include_file_cxx(memory HAVE_STD_MEMORY_HEADER)
  if (HAVE_STD_MEMORY_HEADER)
    # Finding the memory header doesn't mean that shared_ptr is in std
    # namespace.
    #
    # In particular, MSVC 2008 has shared_ptr declared in std::tr1.  In
    # order to support this, we do an extra check to see which namespace
    # should be used.
    include(CheckCXXSourceCompiles)
    check_cxx_source_compiles("#include <memory>
                               int main() {
                                 std::shared_ptr<int> int_ptr;
                                 return 0;
                               }"
                              HAVE_SHARED_PTR_IN_STD_NAMESPACE)

    if (HAVE_SHARED_PTR_IN_STD_NAMESPACE)
      message("-- Found shared_ptr in std namespace using <memory> header.")
      set(SHARED_PTR_FOUND TRUE)
    else (HAVE_SHARED_PTR_IN_STD_NAMESPACE)
      check_cxx_source_compiles("#include <memory>
                                 int main() {
                                   std::tr1::shared_ptr<int> int_ptr;
                                   return 0;
                                 }"
                                HAVE_SHARED_PTR_IN_TR1_NAMESPACE)
      if (HAVE_SHARED_PTR_IN_TR1_NAMESPACE)
        message("-- Found shared_ptr in std::tr1 namespace using <memory> header.")
        set(SHARED_PTR_TR1_NAMESPACE TRUE)
        set(SHARED_PTR_FOUND TRUE)
      endif (HAVE_SHARED_PTR_IN_TR1_NAMESPACE)
    endif (HAVE_SHARED_PTR_IN_STD_NAMESPACE)
  endif (HAVE_STD_MEMORY_HEADER)

  if (NOT SHARED_PTR_FOUND)
    # Further, gcc defines shared_ptr in std::tr1 namespace and
    # <tr1/memory> is to be included for this. And what makes things
    # even more tricky is that gcc does have <memory> header, so
    # all the checks above wouldn't find shared_ptr.
    check_include_file_cxx("tr1/memory" HAVE_TR1_MEMORY_HEADER)
    if (HAVE_TR1_MEMORY_HEADER)
      check_cxx_source_compiles("#include <tr1/memory>
                                 int main() {
                                   std::tr1::shared_ptr<int> int_ptr;
                                   return 0;
                                 }"
                                HAVE_SHARED_PTR_IN_TR1_NAMESPACE_FROM_TR1_MEMORY_HEADER)
      if (HAVE_SHARED_PTR_IN_TR1_NAMESPACE_FROM_TR1_MEMORY_HEADER)
        message("-- Found shared_ptr in std::tr1 namespace using <tr1/memory> header.")
          set(SHARED_PTR_TR1_MEMORY_HEADER TRUE)
          set(SHARED_PTR_TR1_NAMESPACE TRUE)
        set(SHARED_PTR_FOUND TRUE)
      endif (HAVE_SHARED_PTR_IN_TR1_NAMESPACE_FROM_TR1_MEMORY_HEADER)
    endif (HAVE_TR1_MEMORY_HEADER)
  endif (NOT SHARED_PTR_FOUND)
endmacro(FIND_SHARED_PTR)