CGAL_Core no longer needs Boost.Thread

CGAL_Core/include/CGAL/CORE/MemoryPool.h

@@ -26,14 +26,6 @@
 
 #include <CGAL/config.h>
 #include <CGAL/tss.h>
-#include <boost/config.hpp>
-#if defined(CGAL_HAS_THREADS) && defined(BOOST_GCC) && BOOST_GCC < 90100
-// Force the use of Boost.Thread with g++ and C++11, because of the PR66944
-//   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66944
-// See also CGAL PR #1888
-//   https://github.com/CGAL/cgal/pull/1888#issuecomment-278284232
-#  include <boost/thread/tss.hpp>
-#endif
 
 #include <new>           // for placement new
 #include <cassert>
@@ -85,10 +77,7 @@ public:
 
   // Access the corresponding static global allocator.
   static MemoryPool<T,nObjects>& global_allocator() {
-#if defined(CGAL_HAS_THREADS) && defined(BOOST_GCC) && BOOST_GCC < 90100
-    if(memPool_ptr.get() == nullptr) {memPool_ptr.reset(new Self());}
-    Self& memPool =  * memPool_ptr.get();
-#elif defined(CGAL_HAS_THREADS) // use the C++11 implementation
+#if defined(CGAL_HAS_THREADS) // use the C++11 implementation
     static thread_local Self memPool;
 #else // not CGAL_HAS_THREADS
     static Self memPool;
@@ -99,18 +88,8 @@ public:
 private:
    Thunk* head; // next available block in the pool
   std::vector<void*> blocks;
-
-#if defined(CGAL_HAS_THREADS) && defined(BOOST_GCC) && BOOST_GCC < 90100
-  static boost::thread_specific_ptr<Self> memPool_ptr;
-#endif // not CGAL_HAS_THREADS
 };
 
-#if defined(CGAL_HAS_THREADS) && defined(BOOST_GCC) && BOOST_GCC < 90100
-template <class T, int nObjects >
-boost::thread_specific_ptr<MemoryPool<T, nObjects> >
-MemoryPool<T, nObjects>::memPool_ptr;
-#endif
-
 template< class T, int nObjects >
 void* MemoryPool< T, nObjects >::allocate(std::size_t) {
    if ( head == 0 ) { // if no more memory in the pool

Documentation/doc/Documentation/Third_party.txt

@@ -64,10 +64,6 @@ installed as binaries.
 
 \cgal only requires the headers of the \sc{Boost} libraries, but some demos and examples
 depend on the binary library `Boost.Program_options`.
-As an exception and because of a bug in the \gcc compiler about the \cpp 11
-keyword `thread_local`, the `CGAL_Core` library always requires
-the binary library `Boost.Thread` if the \gcc compiler version 9.0 or
-earlier is used.
 
 In case the \sc{Boost} libraries are not installed on your system already, you
 can obtain them from <A HREF="https://www.boost.org">`https://www.boost.org/`</A>.

Installation/CHANGES.md

@@ -30,6 +30,10 @@ Release date: July 2020
 
     See also the associated [blog entry](https://www.cgal.org/2020/04/20/Optimal_bounding_box/).
 
+### Installation
+
+-   The CGAL\_Core library no longer requires `Boost.Thread`, even if the g++ compiler is used.
+
 ### [Tutorials](https://doc.cgal.org/5.1/Manual/tutorials.html)
 
 -   Two new, detailed tutorials have been added:

Installation/cmake/modules/CGAL_SetupCGAL_CoreDependencies.cmake

@@ -53,13 +53,6 @@ endif()
 #   keyword, or ``PUBLIC`` otherwise.
 #
 
-# See the release notes of CGAL-4.10: CGAL_Core now requires
-# Boost.Thread, with GNU G++ < 9.1.
-if (CMAKE_CXX_COMPILER_ID STREQUAL GNU AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.1)
-  include(${CMAKE_CURRENT_LIST_DIR}/CGAL_TweakFindBoost.cmake)
-  find_package( Boost 1.48 REQUIRED COMPONENTS thread system )
-endif()
-
 function(CGAL_setup_CGAL_Core_dependencies target)
   if(ARGV1 STREQUAL INTERFACE)
     set(keyword INTERFACE)
@@ -71,20 +64,4 @@ function(CGAL_setup_CGAL_Core_dependencies target)
   target_compile_definitions(${target} ${keyword} CGAL_USE_CORE=1)
   target_link_libraries( CGAL_Core ${keyword} CGAL::CGAL )
 
-  # See the release notes of CGAL-4.10: CGAL_Core now requires
-  # Boost.Thread, with GNU G++.
-  if (CMAKE_CXX_COMPILER_ID STREQUAL GNU AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.1)
-    if(TARGET Boost::thread)
-      target_link_libraries( CGAL_Core ${keyword} Boost::thread)
-    else()
-      # Note that `find_package( Boost...)` must be called in the
-      # function `CGAL_setup_CGAL_Core_dependencies()` because the
-      # calling `CMakeLists.txt` may also call `find_package(Boost)`
-      # between the inclusion of this module, and the call to this
-      # function. That resets `Boost_LIBRARIES`.
-      find_package( Boost 1.48 REQUIRED thread system )
-      target_link_libraries( CGAL_Core ${keyword} ${Boost_LIBRARIES})
-    endif()
-  endif()
-
 endfunction()