From 29288e5d895b21f5508c15294f1303b367534a63 Mon Sep 17 00:00:00 2001
From: Davis King <davis@dlib.net>
Date: Sun, 31 Jul 2022 17:45:18 -0400
Subject: [PATCH] Make C++14 and CMake 3.8.0 the new minimum required versions

---
 CMakeLists.txt                                |   2 +-
 dlib/CMakeLists.txt                           |  26 ++--
 dlib/cmake                                    |   2 +-
 .../add_global_compiler_switch.cmake          |  35 ------
 ..._avx_instructions_executable_on_host.cmake |   2 +-
 .../cmake_utils/check_if_neon_available.cmake |   2 +-
 ...sse4_instructions_executable_on_host.cmake |   2 +-
 dlib/cmake_utils/find_libjpeg.cmake           |   2 +-
 dlib/cmake_utils/find_libpng.cmake            |   2 +-
 .../set_compiler_specific_options.cmake       |  41 +------
 ..._visual_studio_to_use_static_runtime.cmake |   5 +-
 dlib/cmake_utils/test_for_avx/CMakeLists.txt  |   2 +-
 .../cmake_utils/test_for_cpp11/CMakeLists.txt |  17 ---
 .../cmake_utils/test_for_cpp11/cpp11_test.cpp |  53 --------
 dlib/cmake_utils/test_for_cuda/CMakeLists.txt |   4 +-
 .../cmake_utils/test_for_cudnn/CMakeLists.txt |   7 +-
 .../test_for_libjpeg/CMakeLists.txt           |   2 +-
 .../test_for_libpng/CMakeLists.txt            |   2 +-
 dlib/cmake_utils/test_for_neon/CMakeLists.txt |   2 +-
 dlib/cmake_utils/test_for_sse4/CMakeLists.txt |   2 +-
 dlib/cmake_utils/use_cpp_11.cmake             | 115 ------------------
 dlib/external/cblas/CMakeLists.txt            |   2 +-
 dlib/external/pybind11/CMakeLists.txt         |  14 +--
 .../pybind11/tools/pybind11Tools.cmake        |   2 +-
 dlib/java/CMakeLists.txt                      |   2 +-
 dlib/java/cmake_swig_jni                      |   8 +-
 dlib/matlab/CMakeLists.txt                    |   2 +-
 dlib/matlab/cmake_mex_wrapper                 |   2 +-
 dlib/test/CMakeLists.txt                      |   2 +-
 dlib/test/blas_bindings/CMakeLists.txt        |   2 +-
 dlib/test/tools/CMakeLists.txt                |   2 +-
 examples/CMakeLists.txt                       |  98 ++++++---------
 tools/archive/CMakeLists.txt                  |   2 +-
 .../convert_dlib_nets_to_caffe/CMakeLists.txt |   2 +-
 tools/htmlify/CMakeLists.txt                  |   2 +-
 tools/imglab/CMakeLists.txt                   |   2 +-
 tools/python/CMakeLists.txt                   |   7 +-
 37 files changed, 81 insertions(+), 397 deletions(-)
 delete mode 100644 dlib/cmake_utils/add_global_compiler_switch.cmake
 delete mode 100644 dlib/cmake_utils/test_for_cpp11/CMakeLists.txt
 delete mode 100644 dlib/cmake_utils/test_for_cpp11/cpp11_test.cpp
 delete mode 100644 dlib/cmake_utils/use_cpp_11.cmake

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c46c3e070..da92454aa 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 project(dlib_project)
 
diff --git a/dlib/CMakeLists.txt b/dlib/CMakeLists.txt
index 14a619780..fb5d7b157 100644
--- a/dlib/CMakeLists.txt
+++ b/dlib/CMakeLists.txt
@@ -4,14 +4,11 @@
 #
 
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 set(CMAKE_DISABLE_SOURCE_CHANGES ON)
 set(CMAKE_DISABLE_IN_SOURCE_BUILD ON)
 
-if(POLICY CMP0048)
-   cmake_policy(SET CMP0048 NEW)
-endif()
 if(POLICY CMP0077)
    cmake_policy(SET CMP0077 NEW)
 endif()
@@ -36,18 +33,12 @@ include(cmake_utils/set_compiler_specific_options.cmake)
 # Adhere to GNU filesystem layout conventions
 include(GNUInstallDirs)
 
-if (POLICY CMP0063)
-   # This policy tells cmake to really honor CXX_VISIBILITY_PRESET rather than
-   # ignore it for backwards compatibility.
-   cmake_policy(SET CMP0063 NEW)
-endif()
 if (POLICY CMP0075)
    cmake_policy(SET CMP0075 NEW)
 endif()
 
 # default to a Release build (except if CMAKE_BUILD_TYPE is set)
 include(cmake_utils/release_build_by_default)
-include(cmake_utils/use_cpp_11.cmake)
 
 # Set DLIB_VERSION in the including CMake file so they can use it to do whatever they want. 
 get_directory_property(has_parent PARENT_DIRECTORY)
@@ -644,7 +635,7 @@ if (NOT TARGET dlib)
             set(CUDA_FOUND 0)
          endif()
 
-         if (CUDA_FOUND AND (NOT USING_OLD_VISUAL_STUDIO_COMPILER))
+         if (CUDA_FOUND)
 
             # There is some bug in cmake that causes it to mess up the
             # -std=c++11 option if you let it propagate it to nvcc in some
@@ -676,7 +667,7 @@ if (NOT TARGET dlib)
                LIST(APPEND CUDA_NVCC_FLAGS -DDLIB__CMAKE_GENERATED_A_CONFIG_H_FILE)
             endif()
             if (NOT MSVC)
-               list(APPEND CUDA_NVCC_FLAGS "-std=c++11")
+               list(APPEND CUDA_NVCC_FLAGS "-std=c++14")
             endif()
             if (CMAKE_POSITION_INDEPENDENT_CODE)
                # sometimes this setting isn't propagated to NVCC, which then causes the
@@ -776,7 +767,7 @@ if (NOT TARGET dlib)
             endif()
          endif()
 
-         if (CUDA_FOUND AND cudnn AND (NOT USING_OLD_VISUAL_STUDIO_COMPILER) AND cuda_test_compile_worked AND cudnn_test_compile_worked AND cudnn_include)
+         if (CUDA_FOUND AND cudnn AND cuda_test_compile_worked AND cudnn_test_compile_worked AND cudnn_include)
             set(source_files ${source_files} 
                cuda/cuda_dlib.cu 
                cuda/cudnn_dlibapi.cpp
@@ -802,9 +793,6 @@ if (NOT TARGET dlib)
          else()
             set(DLIB_USE_CUDA OFF CACHE STRING ${DLIB_USE_BLAS_STR} FORCE )
             toggle_preprocessor_switch(DLIB_USE_CUDA)
-            if (USING_OLD_VISUAL_STUDIO_COMPILER)
-               message(STATUS "*** Dlib CUDA support requires C++11 but your compiler doesn't support it. ***")
-            endif()
             if (NOT CUDA_FOUND)
                message(STATUS "DID NOT FIND CUDA")
             endif()
@@ -889,11 +877,11 @@ if (NOT TARGET dlib)
       add_library(dlib_all_source_cpp STATIC all/source.cpp) 
       target_link_libraries(dlib_all_source_cpp dlib)
       target_compile_options(dlib_all_source_cpp PUBLIC ${active_preprocessor_switches})
-      enable_cpp11_for_target(dlib_all_source_cpp)
+      target_compile_features(dlib_all_source_cpp PUBLIC cxx_std_14)
    endif()
 
-   enable_cpp11_for_target(dlib)
-   if((MSVC AND CMAKE_VERSION VERSION_LESS 3.11) OR CMAKE_VERSION VERSION_LESS 3.3)
+   target_compile_features(dlib PUBLIC cxx_std_14)
+   if((MSVC AND CMAKE_VERSION VERSION_LESS 3.11))
       target_compile_options(dlib PUBLIC ${active_compile_opts})
       target_compile_options(dlib PRIVATE ${active_compile_opts_private})
    else()
diff --git a/dlib/cmake b/dlib/cmake
index d3695b30e..224ba3a49 100644
--- a/dlib/cmake
+++ b/dlib/cmake
@@ -1,5 +1,5 @@
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 add_subdirectory(${CMAKE_CURRENT_LIST_DIR} dlib_build)
 
diff --git a/dlib/cmake_utils/add_global_compiler_switch.cmake b/dlib/cmake_utils/add_global_compiler_switch.cmake
deleted file mode 100644
index 5f3d83ce4..000000000
--- a/dlib/cmake_utils/add_global_compiler_switch.cmake
+++ /dev/null
@@ -1,35 +0,0 @@
-
-
-cmake_minimum_required(VERSION 2.8.12)
-
-message(WARNING "add_global_compiler_switch() is deprecated.  Use target_compile_options() instead")
-
-# Make macros that can add compiler switches to the entire project.  Not just
-# to the current cmake folder being built.  
-macro ( add_global_compiler_switch switch_name )
-   # If removing the switch would change the flags then it's already present
-   # and we don't need to do anything.
-   string(REPLACE "${switch_name}" "" tempstr "${CMAKE_CXX_FLAGS}")
-   if ("${CMAKE_CXX_FLAGS}" STREQUAL "${tempstr}" )
-      set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${switch_name}" 
-         CACHE STRING "Flags used by the compiler during all C++ builds." 
-         FORCE)
-   endif ()
-endmacro()
-
-macro ( remove_global_compiler_switch switch_name )
-   string(REPLACE "${switch_name}" "" tempstr "${CMAKE_CXX_FLAGS}")
-   if (NOT "${CMAKE_CXX_FLAGS}" STREQUAL "${tempstr}" )
-      set (CMAKE_CXX_FLAGS "${tempstr}" 
-         CACHE STRING "Flags used by the compiler during all C++ builds." 
-         FORCE)
-   endif ()
-endmacro()
-
-macro (add_global_define def_name)
-   add_global_compiler_switch(-D${def_name})
-endmacro()
-
-macro (remove_global_define def_name)
-   remove_global_compiler_switch(-D${def_name})
-endmacro()
diff --git a/dlib/cmake_utils/check_if_avx_instructions_executable_on_host.cmake b/dlib/cmake_utils/check_if_avx_instructions_executable_on_host.cmake
index a5d7320f4..4f2cfef93 100644
--- a/dlib/cmake_utils/check_if_avx_instructions_executable_on_host.cmake
+++ b/dlib/cmake_utils/check_if_avx_instructions_executable_on_host.cmake
@@ -1,6 +1,6 @@
 # This script checks if your compiler and host processor can generate and then run programs with AVX instructions.
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 # Don't rerun this script if its already been executed.
 if (DEFINED AVX_IS_AVAILABLE_ON_HOST)
diff --git a/dlib/cmake_utils/check_if_neon_available.cmake b/dlib/cmake_utils/check_if_neon_available.cmake
index 0510707df..895c810b7 100644
--- a/dlib/cmake_utils/check_if_neon_available.cmake
+++ b/dlib/cmake_utils/check_if_neon_available.cmake
@@ -1,6 +1,6 @@
 # This script checks if __ARM_NEON__ is defined for your compiler
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 # Don't rerun this script if its already been executed.
 if (DEFINED ARM_NEON_IS_AVAILABLE)
diff --git a/dlib/cmake_utils/check_if_sse4_instructions_executable_on_host.cmake b/dlib/cmake_utils/check_if_sse4_instructions_executable_on_host.cmake
index e2605819e..c47560997 100644
--- a/dlib/cmake_utils/check_if_sse4_instructions_executable_on_host.cmake
+++ b/dlib/cmake_utils/check_if_sse4_instructions_executable_on_host.cmake
@@ -1,6 +1,6 @@
 # This script checks if your compiler and host processor can generate and then run programs with SSE4 instructions.
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 # Don't rerun this script if its already been executed.
 if (DEFINED SSE4_IS_AVAILABLE_ON_HOST)
diff --git a/dlib/cmake_utils/find_libjpeg.cmake b/dlib/cmake_utils/find_libjpeg.cmake
index 3b9e65650..028217b07 100644
--- a/dlib/cmake_utils/find_libjpeg.cmake
+++ b/dlib/cmake_utils/find_libjpeg.cmake
@@ -1,7 +1,7 @@
 #This script just runs CMake's built in JPEG finding tool.  But it also checks that the
 #copy of libjpeg that cmake finds actually builds and links.
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 if (BUILDING_PYTHON_IN_MSVC)
    # Never use any system copy of libjpeg when building python in visual studio
diff --git a/dlib/cmake_utils/find_libpng.cmake b/dlib/cmake_utils/find_libpng.cmake
index 1b3560431..676073922 100644
--- a/dlib/cmake_utils/find_libpng.cmake
+++ b/dlib/cmake_utils/find_libpng.cmake
@@ -1,7 +1,7 @@
 #This script just runs CMake's built in PNG finding tool.  But it also checks that the
 #copy of libpng that cmake finds actually builds and links.
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 if (BUILDING_PYTHON_IN_MSVC)
    # Never use any system copy of libpng when building python in visual studio
diff --git a/dlib/cmake_utils/set_compiler_specific_options.cmake b/dlib/cmake_utils/set_compiler_specific_options.cmake
index f1f7bcfb1..8093ca6d3 100644
--- a/dlib/cmake_utils/set_compiler_specific_options.cmake
+++ b/dlib/cmake_utils/set_compiler_specific_options.cmake
@@ -1,10 +1,5 @@
 
-cmake_minimum_required(VERSION 2.8.12)
-
-if (POLICY CMP0054)
-   cmake_policy(SET CMP0054 NEW)
-endif()
-
+cmake_minimum_required(VERSION 3.8.0)
 
 
 # Check if we are being built as part of a pybind11 module. 
@@ -26,40 +21,6 @@ endif()
 
 
 
-set(USING_OLD_VISUAL_STUDIO_COMPILER 0)
-if(MSVC AND MSVC_VERSION VERSION_LESS 1900)
-   message(FATAL_ERROR "C++11 is required to use dlib, but the version of Visual Studio you are using is too old and doesn't support C++11.  You need Visual Studio 2015 or newer. ")
-elseif(MSVC AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 19.0.24210.0 AND "MSVC" MATCHES ${CMAKE_CXX_COMPILER_ID})
-   message(STATUS "NOTE: Visual Studio didn't have good enough C++11 support until Visual Studio 2015 update 3 (v19.0.24210.0)")
-   message(STATUS "So we aren't enabling things that require full C++11 support (e.g. the deep learning tools).")
-   message(STATUS "Also, be aware that Visual Studio's version naming is confusing, in particular, there are multiple versions of 'update 3'")
-   message(STATUS "So if you are getting this message you need to update to the newer version of Visual Studio to use full C++11.")
-   set(USING_OLD_VISUAL_STUDIO_COMPILER 1)
-elseif(MSVC AND (MSVC_VERSION EQUAL 1911 OR MSVC_VERSION EQUAL 1910))
-   message(STATUS "******************************************************************************************")
-   message(STATUS "Your version of Visual Studio has incomplete C++11 support and is unable to compile the ")
-   message(STATUS "DNN examples. So we are disabling the deep learning tools.  If you want to use the DNN ")
-   message(STATUS "tools in dlib then update your copy of Visual Studio.")
-   message(STATUS "******************************************************************************************")
-   set(USING_OLD_VISUAL_STUDIO_COMPILER 1)
-endif()
-
-if(CMAKE_COMPILER_IS_GNUCXX)
-   execute_process(COMMAND ${CMAKE_CXX_COMPILER} -dumpversion OUTPUT_VARIABLE GCC_VERSION)
-   if (GCC_VERSION VERSION_LESS 4.9)
-      message(FATAL_ERROR "C++11 is required to use dlib, but the version of GCC you are using is too old and doesn't support C++11.  You need GCC 4.9 or newer. ")
-   endif()
-endif()
-
-
-# push USING_OLD_VISUAL_STUDIO_COMPILER to the parent so we can use it in the
-# examples CMakeLists.txt file.
-get_directory_property(has_parent PARENT_DIRECTORY)
-if(has_parent)
-   set(USING_OLD_VISUAL_STUDIO_COMPILER ${USING_OLD_VISUAL_STUDIO_COMPILER} PARENT_SCOPE)
-endif()
-
-
 
 set(gcc_like_compilers GNU Clang  Intel)
 set(intel_archs x86_64 i386 i686 AMD64 amd64 x86)
diff --git a/dlib/cmake_utils/tell_visual_studio_to_use_static_runtime.cmake b/dlib/cmake_utils/tell_visual_studio_to_use_static_runtime.cmake
index bc84ba0d6..80122d801 100644
--- a/dlib/cmake_utils/tell_visual_studio_to_use_static_runtime.cmake
+++ b/dlib/cmake_utils/tell_visual_studio_to_use_static_runtime.cmake
@@ -2,10 +2,7 @@
 # Including this cmake script into your cmake project will cause visual studio
 # to build your project against the static C runtime.
 
-cmake_minimum_required(VERSION 2.8.12)
-if (POLICY CMP0054)
-   cmake_policy(SET CMP0054 NEW)
-endif()
+cmake_minimum_required(VERSION 3.8.0)
 
 if (MSVC OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
    option (DLIB_FORCE_MSVC_STATIC_RUNTIME "use static runtime" ON)
diff --git a/dlib/cmake_utils/test_for_avx/CMakeLists.txt b/dlib/cmake_utils/test_for_avx/CMakeLists.txt
index 7d7240233..10890153c 100644
--- a/dlib/cmake_utils/test_for_avx/CMakeLists.txt
+++ b/dlib/cmake_utils/test_for_avx/CMakeLists.txt
@@ -1,5 +1,5 @@
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 project(avx_test)
 
 set(USE_AVX_INSTRUCTIONS ON CACHE BOOL "Use AVX instructions")
diff --git a/dlib/cmake_utils/test_for_cpp11/CMakeLists.txt b/dlib/cmake_utils/test_for_cpp11/CMakeLists.txt
deleted file mode 100644
index bc6f02563..000000000
--- a/dlib/cmake_utils/test_for_cpp11/CMakeLists.txt
+++ /dev/null
@@ -1,17 +0,0 @@
-
-cmake_minimum_required(VERSION 2.8.12)
-project(cpp11_test)
-
-# Try to enable C++11
-include(CheckCXXCompilerFlag)
-CHECK_CXX_COMPILER_FLAG("-std=c++11" COMPILER_SUPPORTS_CXX11)
-CHECK_CXX_COMPILER_FLAG("-std=c++0x" COMPILER_SUPPORTS_CXX0X)
-if(COMPILER_SUPPORTS_CXX11)
-   message(STATUS "C++11 activated.")
-   ADD_DEFINITIONS("-std=c++11")
-elseif(COMPILER_SUPPORTS_CXX0X)
-   message(STATUS "C++0x activated.")
-   ADD_DEFINITIONS("-std=c++0x")
-endif()
-
-add_library(cpp11_test STATIC cpp11_test.cpp )
diff --git a/dlib/cmake_utils/test_for_cpp11/cpp11_test.cpp b/dlib/cmake_utils/test_for_cpp11/cpp11_test.cpp
deleted file mode 100644
index 59ca7e8e1..000000000
--- a/dlib/cmake_utils/test_for_cpp11/cpp11_test.cpp
+++ /dev/null
@@ -1,53 +0,0 @@
-// Copyright (C) 2015  Davis E. King (davis@dlib.net)
-// License: Boost Software License   See LICENSE.txt for the full license.
-
-#include <memory>
-#include <iostream>
-
-using namespace std;
-
-class testme
-{
-public:
-
-    testme(testme&&) = default;
-    testme(const testme&) = delete;
-
-
-    template <typename T>
-    auto auto_return(T f) -> decltype(f(4)) { return f(4); }
-
-    template <typename T>
-    auto auto_return(T f) -> decltype(f()) { return f(); }
-
-    static int returnint() { return 0; }
-
-    void dostuff()
-    {
-        thread_local int stuff1 = 999;
-        auto x = 4;
-        ++stuff1;
-
-        decltype(x) asdf = 9;
-        ++asdf;
-
-        auto f = []() { cout << "in a lambda!" << endl; };
-        f();
-
-        auto_return(returnint);
-    }
-
-    template <typename ...T>
-    void variadic_template(
-        T&& ...args
-    )
-    {
-    }
-
-
-
-    std::shared_ptr<int> asdf;
-};
-
-// ------------------------------------------------------------------------------------
-
diff --git a/dlib/cmake_utils/test_for_cuda/CMakeLists.txt b/dlib/cmake_utils/test_for_cuda/CMakeLists.txt
index 1826348c7..8b6cd7e7b 100644
--- a/dlib/cmake_utils/test_for_cuda/CMakeLists.txt
+++ b/dlib/cmake_utils/test_for_cuda/CMakeLists.txt
@@ -1,5 +1,5 @@
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 project(cuda_test)
 
 include_directories(../../cuda)
@@ -9,6 +9,6 @@ add_definitions(-DDLIB_USE_CUDA)
 option(CUDA_PROPAGATE_HOST_FLAGS "Propage C/CXX_FLAGS and friends to the host compiler via -Xcompile" OFF)
 find_package(CUDA 7.5 REQUIRED)
 set(CUDA_HOST_COMPILATION_CPP ON)
-list(APPEND CUDA_NVCC_FLAGS "-arch=sm_50;-std=c++11;-D__STRICT_ANSI__;-D_MWAITXINTRIN_H_INCLUDED;-D_FORCE_INLINES")
+list(APPEND CUDA_NVCC_FLAGS "-arch=sm_50;-std=c++14;-D__STRICT_ANSI__;-D_MWAITXINTRIN_H_INCLUDED;-D_FORCE_INLINES")
 
 cuda_add_library(cuda_test STATIC cuda_test.cu )
diff --git a/dlib/cmake_utils/test_for_cudnn/CMakeLists.txt b/dlib/cmake_utils/test_for_cudnn/CMakeLists.txt
index 0d0d66164..0ca0f6b6a 100644
--- a/dlib/cmake_utils/test_for_cudnn/CMakeLists.txt
+++ b/dlib/cmake_utils/test_for_cudnn/CMakeLists.txt
@@ -1,13 +1,12 @@
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 project(cudnn_test)
-include(../use_cpp_11.cmake)
 
 # Override the FindCUDA.cmake setting to avoid duplication of host flags if using a toolchain:
 option(CUDA_PROPAGATE_HOST_FLAGS "Propage C/CXX_FLAGS and friends to the host compiler via -Xcompile" OFF)
 find_package(CUDA 7.5 REQUIRED)
 set(CUDA_HOST_COMPILATION_CPP ON)
-list(APPEND CUDA_NVCC_FLAGS "-arch=sm_50;-std=c++11;-D__STRICT_ANSI__")
+list(APPEND CUDA_NVCC_FLAGS "-arch=sm_50;-std=c++14;-D__STRICT_ANSI__")
 add_definitions(-DDLIB_USE_CUDA)
 
 include(find_cudnn.txt)
@@ -15,5 +14,5 @@ include(find_cudnn.txt)
 if (cudnn_include AND cudnn)
    include_directories(${cudnn_include})
    cuda_add_library(cudnn_test STATIC ../../cuda/cudnn_dlibapi.cpp ${cudnn} )
-   enable_cpp11_for_target(cudnn_test)
+   target_compile_features(cudnn_test PUBLIC cxx_std_14)
 endif()
diff --git a/dlib/cmake_utils/test_for_libjpeg/CMakeLists.txt b/dlib/cmake_utils/test_for_libjpeg/CMakeLists.txt
index 1650bd099..a3c6910db 100644
--- a/dlib/cmake_utils/test_for_libjpeg/CMakeLists.txt
+++ b/dlib/cmake_utils/test_for_libjpeg/CMakeLists.txt
@@ -1,5 +1,5 @@
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 project(test_if_libjpeg_is_broken)
 
 find_package(JPEG)
diff --git a/dlib/cmake_utils/test_for_libpng/CMakeLists.txt b/dlib/cmake_utils/test_for_libpng/CMakeLists.txt
index 65cd85a4d..0be920613 100644
--- a/dlib/cmake_utils/test_for_libpng/CMakeLists.txt
+++ b/dlib/cmake_utils/test_for_libpng/CMakeLists.txt
@@ -1,5 +1,5 @@
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 project(test_if_libpng_is_broken)
 
 find_package(PNG)
diff --git a/dlib/cmake_utils/test_for_neon/CMakeLists.txt b/dlib/cmake_utils/test_for_neon/CMakeLists.txt
index 0b6eb6f28..b9c6e51e8 100644
--- a/dlib/cmake_utils/test_for_neon/CMakeLists.txt
+++ b/dlib/cmake_utils/test_for_neon/CMakeLists.txt
@@ -1,5 +1,5 @@
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 project(neon_test)
 
 add_library(neon_test STATIC neon_test.cpp )
diff --git a/dlib/cmake_utils/test_for_sse4/CMakeLists.txt b/dlib/cmake_utils/test_for_sse4/CMakeLists.txt
index 6a07d1a5d..4cd4e95ce 100644
--- a/dlib/cmake_utils/test_for_sse4/CMakeLists.txt
+++ b/dlib/cmake_utils/test_for_sse4/CMakeLists.txt
@@ -1,5 +1,5 @@
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 project(sse4_test)
 
 set(USE_SSE4_INSTRUCTIONS ON CACHE BOOL "Use SSE4 instructions")
diff --git a/dlib/cmake_utils/use_cpp_11.cmake b/dlib/cmake_utils/use_cpp_11.cmake
deleted file mode 100644
index 6b02f740e..000000000
--- a/dlib/cmake_utils/use_cpp_11.cmake
+++ /dev/null
@@ -1,115 +0,0 @@
-# This script creates a function, enable_cpp11_for_target(), which checks if your
-# compiler has C++11 support and enables it if it does.
-
-
-cmake_minimum_required(VERSION 2.8.12)
-
-if (POLICY CMP0054)
-   cmake_policy(SET CMP0054 NEW)
-endif()
-
-
-set(_where_is_cmake_utils_dir ${CMAKE_CURRENT_LIST_DIR})
-
-function(enable_cpp11_for_target target_name)
-
-
-# Set to false unless we find out otherwise in the code below.
-set(COMPILER_CAN_DO_CPP_11 0)
-
-
-
-macro(test_compiler_for_cpp11)
-   message(STATUS "Building a C++11 test project to see if your compiler supports C++11")
-   try_compile(test_for_cpp11_worked ${PROJECT_BINARY_DIR}/cpp11_test_build 
-      ${_where_is_cmake_utils_dir}/test_for_cpp11 cpp11_test
-      OUTPUT_VARIABLE cpp11_test_output)
-   if (test_for_cpp11_worked)
-      message(STATUS "C++11 activated.")
-      set(COMPILER_CAN_DO_CPP_11 1)
-   else()
-      set(COMPILER_CAN_DO_CPP_11 0)
-      message(STATUS "********** Your compiler failed to build a C++11 project.  C++11 is required to use all parts of dlib! **********")
-      message(STATUS "********** Compiler output: ${cpp11_test_output} **********")
-   endif()
-endmacro()
-
-# Now turn on the appropriate compiler switch to enable C++11 if you have a
-# C++11 compiler.  In CMake 3.1 there is a simple flag you can set, but earlier
-# verions of CMake are not so convenient.
-if (CMAKE_VERSION VERSION_LESS "3.1.2")
-   if(CMAKE_COMPILER_IS_GNUCXX)
-      execute_process(COMMAND ${CMAKE_CXX_COMPILER} -dumpversion OUTPUT_VARIABLE GCC_VERSION)
-      if (GCC_VERSION VERSION_GREATER 4.8 OR GCC_VERSION VERSION_EQUAL 4.8)
-         message(STATUS "C++11 activated.")
-         target_compile_options(${target_name} PUBLIC "-std=gnu++11")
-         set(COMPILER_CAN_DO_CPP_11 1)
-      endif()
-   elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
-      execute_process( COMMAND ${CMAKE_CXX_COMPILER} --version OUTPUT_VARIABLE clang_full_version_string )
-      string (REGEX REPLACE ".*clang version ([0-9]+\\.[0-9]+).*" "\\1" CLANG_VERSION ${clang_full_version_string})
-      if (CLANG_VERSION VERSION_GREATER 3.3)
-         message(STATUS "C++11 activated.")
-         target_compile_options(${target_name} PUBLIC "-std=c++11")
-         set(COMPILER_CAN_DO_CPP_11 1)
-      endif()
-   else()
-      # Since we don't know what compiler this is just try to build a c++11 project and see if it compiles.
-      test_compiler_for_cpp11()
-   endif()
-else()  
-
-   # Set a flag if the compiler you are using is capable of providing C++11 features.
-   get_property(cxx_features GLOBAL PROPERTY CMAKE_CXX_KNOWN_FEATURES)
-   if (";${cxx_features};" MATCHES ";cxx_rvalue_references;" AND
-         ";${cxx_features};" MATCHES ";cxx_variadic_templates;" AND
-         ";${cxx_features};" MATCHES ";cxx_lambdas;" AND
-         ";${cxx_features};" MATCHES ";cxx_defaulted_move_initializers;" AND
-         ";${cxx_features};" MATCHES ";cxx_delegating_constructors;" AND
-         ";${cxx_features};" MATCHES ";cxx_thread_local;" AND
-         ";${cxx_features};" MATCHES ";cxx_constexpr;" AND
-         ";${cxx_features};" MATCHES ";cxx_decltype_incomplete_return_types;" AND
-         ";${cxx_features};" MATCHES ";cxx_auto_type;")
-
-      set(COMPILER_CAN_DO_CPP_11 1)
-      # Tell cmake that we need C++11 for dlib
-      target_compile_features(${target_name} 
-         PUBLIC 
-            cxx_rvalue_references
-            cxx_variadic_templates
-            cxx_lambdas
-            cxx_defaulted_move_initializers
-            cxx_delegating_constructors
-            cxx_thread_local
-            cxx_constexpr
-            # cxx_decltype_incomplete_return_types  # purposfully commented out because cmake errors out on this when using visual studio and cmake 3.8.0
-            cxx_auto_type
-         )
-
-      if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
-         # Sometimes clang will lie and report that it supports C++11 when
-         # really it doesn't support thread_local.  So check for that.
-         test_compiler_for_cpp11()
-      else()
-         message(STATUS "C++11 activated.")
-      endif()
-   endif()
-endif()
-
-# Always enable whatever partial C++11 support we have, even if it isn't full
-# support, and just hope for the best.
-if (NOT COMPILER_CAN_DO_CPP_11)
-   include(CheckCXXCompilerFlag)
-   CHECK_CXX_COMPILER_FLAG("-std=c++11" COMPILER_SUPPORTS_CXX11)
-   CHECK_CXX_COMPILER_FLAG("-std=c++0x" COMPILER_SUPPORTS_CXX0X)
-   if(COMPILER_SUPPORTS_CXX11)
-      message(STATUS "C++11 activated (compiler doesn't have full C++11 support).")
-      target_compile_options(${target_name} PUBLIC "-std=c++11")
-   elseif(COMPILER_SUPPORTS_CXX0X)
-      message(STATUS "C++0x activated (compiler doesn't have full C++11 support).")
-      target_compile_options(${target_name} PUBLIC "-std=c++0x")
-   endif()
-endif()
-
-endfunction()
-
diff --git a/dlib/external/cblas/CMakeLists.txt b/dlib/external/cblas/CMakeLists.txt
index 0d800ae13..c5379dd9f 100644
--- a/dlib/external/cblas/CMakeLists.txt
+++ b/dlib/external/cblas/CMakeLists.txt
@@ -4,7 +4,7 @@
 #
 
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 project(cblas)
 
 
diff --git a/dlib/external/pybind11/CMakeLists.txt b/dlib/external/pybind11/CMakeLists.txt
index 85ecd9028..cbee64be6 100644
--- a/dlib/external/pybind11/CMakeLists.txt
+++ b/dlib/external/pybind11/CMakeLists.txt
@@ -5,19 +5,9 @@
 # All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
-if (POLICY CMP0048)
-  # cmake warns if loaded from a min-3.0-required parent dir, so silence the warning:
-  cmake_policy(SET CMP0048 NEW)
-endif()
-
-# CMake versions < 3.4.0 do not support try_compile/pthread checks without C as active language.
-if(CMAKE_VERSION VERSION_LESS 3.4.0)
-  project(pybind11)
-else()
-  project(pybind11 CXX)
-endif()
+project(pybind11 CXX)
 
 # Check if pybind11 is being used directly or via add_subdirectory
 set(PYBIND11_MASTER_PROJECT OFF)
diff --git a/dlib/external/pybind11/tools/pybind11Tools.cmake b/dlib/external/pybind11/tools/pybind11Tools.cmake
index 6293cc645..63ce75ffe 100644
--- a/dlib/external/pybind11/tools/pybind11Tools.cmake
+++ b/dlib/external/pybind11/tools/pybind11Tools.cmake
@@ -5,7 +5,7 @@
 # All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 # Add a CMake parameter for choosing a desired Python version
 if(NOT PYBIND11_PYTHON_VERSION)
diff --git a/dlib/java/CMakeLists.txt b/dlib/java/CMakeLists.txt
index 4d66a513c..b31bfad0d 100644
--- a/dlib/java/CMakeLists.txt
+++ b/dlib/java/CMakeLists.txt
@@ -1,5 +1,5 @@
 
-cmake_minimum_required (VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 project (myproject)
 set(java_package_name net.dlib)
 set(source_files
diff --git a/dlib/java/cmake_swig_jni b/dlib/java/cmake_swig_jni
index d74dd60ec..48f960f41 100644
--- a/dlib/java/cmake_swig_jni
+++ b/dlib/java/cmake_swig_jni
@@ -2,7 +2,7 @@
 # it by defining some CMake variables and then include(cmake_swig_jni).  You
 # would make a CMakeLists.txt file that looks like the following:
 #
-#   cmake_minimum_required (VERSION 2.8.12)
+#   cmake_minimum_required (VERSION 3.8.0)
 #   project (example)
 #   set(java_package_name "org.mycompany")
 #   set(source_files
@@ -40,9 +40,7 @@
 ################################################################################
 ################################################################################
 
-cmake_minimum_required (VERSION 2.8.12)
-
-include(${CMAKE_CURRENT_LIST_DIR}/../cmake_utils/use_cpp_11.cmake)
+cmake_minimum_required (VERSION 3.8.0)
 
 # This block of code tries to figure out what the JAVA_HOME environment
 # variable should be by looking at the folder that contains the java
@@ -180,7 +178,7 @@ FILE(MAKE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/${binary_dir_name}")
 
 set_source_files_properties(${CMAKE_CURRENT_BINARY_DIR}/swig.i PROPERTIES CPLUSPLUS ON)
 swig_add_module(${output_library_name} java ${CMAKE_CURRENT_BINARY_DIR}/swig.i ${source_files})
-enable_cpp11_for_target(${output_library_name})
+target_compile_features(${output_library_name} PUBLIC cxx_std_14)
 
 include_directories(${JNI_INCLUDE_DIRS})
 swig_link_libraries(${output_library_name}  ${additional_link_libraries})
diff --git a/dlib/matlab/CMakeLists.txt b/dlib/matlab/CMakeLists.txt
index b9a0beab9..2dee98c60 100644
--- a/dlib/matlab/CMakeLists.txt
+++ b/dlib/matlab/CMakeLists.txt
@@ -1,5 +1,5 @@
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 PROJECT(mex_functions)
 
diff --git a/dlib/matlab/cmake_mex_wrapper b/dlib/matlab/cmake_mex_wrapper
index 5091e4e5b..6cbc27afc 100644
--- a/dlib/matlab/cmake_mex_wrapper
+++ b/dlib/matlab/cmake_mex_wrapper
@@ -3,7 +3,7 @@
 # that additional library dependencies can be added like this: add_mex_function(name lib1 dlib libetc).
 # That is, just add more libraries after the name and they will be build into the mex file.
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 set(BUILDING_MATLAB_MEX_FILE true)
 set(CMAKE_POSITION_INDEPENDENT_CODE True)
diff --git a/dlib/test/CMakeLists.txt b/dlib/test/CMakeLists.txt
index 895a07adc..a2998f032 100644
--- a/dlib/test/CMakeLists.txt
+++ b/dlib/test/CMakeLists.txt
@@ -3,7 +3,7 @@
 # information about it at http://www.cmake.org
 #
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 # create a variable called target_name and set it to the string "dtest"
 set (target_name dtest)
diff --git a/dlib/test/blas_bindings/CMakeLists.txt b/dlib/test/blas_bindings/CMakeLists.txt
index 5deddee04..f9c0b05a1 100644
--- a/dlib/test/blas_bindings/CMakeLists.txt
+++ b/dlib/test/blas_bindings/CMakeLists.txt
@@ -3,7 +3,7 @@
 # information about it at http://www.cmake.org
 #
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 # This variable contains a list of all the tests we are building
 # into the regression test suite.
diff --git a/dlib/test/tools/CMakeLists.txt b/dlib/test/tools/CMakeLists.txt
index adbd43cb9..80371d6d8 100644
--- a/dlib/test/tools/CMakeLists.txt
+++ b/dlib/test/tools/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 add_subdirectory(../../../tools/imglab imglab_build)
 add_subdirectory(../../../tools/htmlify htmlify_build)
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
index 3a67e4fe7..ff28f1c03 100644
--- a/examples/CMakeLists.txt
+++ b/examples/CMakeLists.txt
@@ -32,7 +32,7 @@
 #
 
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 # Every project needs a name.  We call this the "examples" project.
 project(examples)
 
@@ -117,66 +117,29 @@ macro(add_gui_example name)
    endif()
 endmacro()
 
-# The deep learning toolkit requires a compiler with essentially complete C++11
-# support.  However, versions of Visual Studio prior to October 2016 didn't
-# provide enough C++11 support to compile the DNN tooling, but were good enough
-# to compile the rest of dlib.  So new versions of Visual Studio 2015 will
-# work.  However, Visual Studio 2017 had some C++11 support regressions, so it
-# wasn't until December 2017 that Visual Studio 2017 had good enough C++11
-# support to compile the DNN examples.  So if you are using Visual Studio, make
-# sure you have an updated version if you want to compile the DNN code.
-#
-# Also note that Visual Studio users should give the -T host=x64 option so that
-# CMake will instruct Visual Studio to use its 64bit toolchain.  If you don't
-# do this then by default Visual Studio uses a 32bit toolchain, WHICH RESTRICTS
-# THE COMPILER TO ONLY 2GB OF RAM, causing it to run out of RAM and crash when
-# compiling some of the DNN examples.  So generate your project with a statement
-# like this:
-#   cmake .. -G "Visual Studio 14 2015 Win64" -T host=x64 
-if (NOT USING_OLD_VISUAL_STUDIO_COMPILER)
-   add_example(dnn_metric_learning_ex)
-   add_gui_example(dnn_face_recognition_ex)
-   add_example(dnn_introduction_ex)
-   add_example(dnn_introduction2_ex)
-   add_example(dnn_introduction3_ex)
-   add_example(dnn_inception_ex)
-   add_gui_example(dnn_mmod_ex)
-   add_gui_example(dnn_mmod_face_detection_ex)
-   add_gui_example(random_cropper_ex)
-   add_gui_example(dnn_mmod_dog_hipsterizer)
-   add_gui_example(dnn_imagenet_ex)
-   add_gui_example(dnn_mmod_find_cars_ex)
-   add_gui_example(dnn_mmod_find_cars2_ex)
-   add_example(dnn_mmod_train_find_cars_ex)
-   add_gui_example(dnn_semantic_segmentation_ex)
-   add_gui_example(dnn_instance_segmentation_ex)
-   add_example(dnn_imagenet_train_ex)
-   add_example(dnn_semantic_segmentation_train_ex)
-   add_example(dnn_instance_segmentation_train_ex)
-   add_example(dnn_metric_learning_on_images_ex)
-   add_gui_example(dnn_dcgan_train_ex)
-   add_gui_example(dnn_yolo_train_ex)
-   add_gui_example(dnn_self_supervised_learning_ex)
-endif()
-
-
-if (DLIB_NO_GUI_SUPPORT)
-   message("No GUI support, so we won't build the webcam_face_pose_ex example.")
-else()
-   find_package(OpenCV QUIET)
-   if (OpenCV_FOUND)
-      include_directories(${OpenCV_INCLUDE_DIRS})
-
-      add_executable(webcam_face_pose_ex webcam_face_pose_ex.cpp)
-      target_link_libraries(webcam_face_pose_ex dlib::dlib ${OpenCV_LIBS} )
-   else()
-      message("OpenCV not found, so we won't build the webcam_face_pose_ex example.")
-   endif()
-endif()
-
-
-
-#here we apply our macros 
+add_example(dnn_metric_learning_ex)
+add_gui_example(dnn_face_recognition_ex)
+add_example(dnn_introduction_ex)
+add_example(dnn_introduction2_ex)
+add_example(dnn_introduction3_ex)
+add_example(dnn_inception_ex)
+add_gui_example(dnn_mmod_ex)
+add_gui_example(dnn_mmod_face_detection_ex)
+add_gui_example(random_cropper_ex)
+add_gui_example(dnn_mmod_dog_hipsterizer)
+add_gui_example(dnn_imagenet_ex)
+add_gui_example(dnn_mmod_find_cars_ex)
+add_gui_example(dnn_mmod_find_cars2_ex)
+add_example(dnn_mmod_train_find_cars_ex)
+add_gui_example(dnn_semantic_segmentation_ex)
+add_gui_example(dnn_instance_segmentation_ex)
+add_example(dnn_imagenet_train_ex)
+add_example(dnn_semantic_segmentation_train_ex)
+add_example(dnn_instance_segmentation_train_ex)
+add_example(dnn_metric_learning_on_images_ex)
+add_gui_example(dnn_dcgan_train_ex)
+add_gui_example(dnn_yolo_train_ex)
+add_gui_example(dnn_self_supervised_learning_ex)
 add_gui_example(3d_point_cloud_ex)
 add_example(bayes_net_ex)
 add_example(bayes_net_from_disk_ex)
@@ -264,4 +227,17 @@ if (DLIB_LINK_WITH_SQLITE3)
    add_example(sqlite_ex)
 endif()
 
+if (DLIB_NO_GUI_SUPPORT)
+   message("No GUI support, so we won't build the webcam_face_pose_ex example.")
+else()
+   find_package(OpenCV QUIET)
+   if (OpenCV_FOUND)
+      include_directories(${OpenCV_INCLUDE_DIRS})
+
+      add_executable(webcam_face_pose_ex webcam_face_pose_ex.cpp)
+      target_link_libraries(webcam_face_pose_ex dlib::dlib ${OpenCV_LIBS} )
+   else()
+      message("OpenCV not found, so we won't build the webcam_face_pose_ex example.")
+   endif()
+endif()
 
diff --git a/tools/archive/CMakeLists.txt b/tools/archive/CMakeLists.txt
index 8a3e4d7bf..796e46985 100644
--- a/tools/archive/CMakeLists.txt
+++ b/tools/archive/CMakeLists.txt
@@ -4,7 +4,7 @@
 #
 
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 PROJECT(archive)
 
 
diff --git a/tools/convert_dlib_nets_to_caffe/CMakeLists.txt b/tools/convert_dlib_nets_to_caffe/CMakeLists.txt
index f9518df21..2325366fe 100644
--- a/tools/convert_dlib_nets_to_caffe/CMakeLists.txt
+++ b/tools/convert_dlib_nets_to_caffe/CMakeLists.txt
@@ -3,7 +3,7 @@
 # information about it at http://www.cmake.org
 #
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 set (target_name dtoc)
 
diff --git a/tools/htmlify/CMakeLists.txt b/tools/htmlify/CMakeLists.txt
index 02cae2172..35f327f27 100644
--- a/tools/htmlify/CMakeLists.txt
+++ b/tools/htmlify/CMakeLists.txt
@@ -3,7 +3,7 @@
 # information about it at http://www.cmake.org
 #
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 # create a variable called target_name and set it to the string "htmlify"
 set (target_name htmlify)
diff --git a/tools/imglab/CMakeLists.txt b/tools/imglab/CMakeLists.txt
index 46c64fb3e..5fb1331d1 100644
--- a/tools/imglab/CMakeLists.txt
+++ b/tools/imglab/CMakeLists.txt
@@ -3,7 +3,7 @@
 # information about it at http://www.cmake.org
 #
 
-cmake_minimum_required(VERSION 2.8.12)
+cmake_minimum_required(VERSION 3.8.0)
 
 # create a variable called target_name and set it to the string "imglab"
 set (target_name imglab)
diff --git a/tools/python/CMakeLists.txt b/tools/python/CMakeLists.txt
index a67bba8f9..8309d5fb9 100644
--- a/tools/python/CMakeLists.txt
+++ b/tools/python/CMakeLists.txt
@@ -1,5 +1,5 @@
 
-CMAKE_MINIMUM_REQUIRED(VERSION 2.8.12)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.8.0)
 
 if (WIN32 AND NOT "${CMAKE_GENERATOR}" MATCHES "Visual Studio") 
    message(FATAL_ERROR "\n"
@@ -38,11 +38,6 @@ endif()
 add_subdirectory(../../dlib/external/pybind11 pybind11_build)
 add_subdirectory(../../dlib dlib_build)
 
-if (USING_OLD_VISUAL_STUDIO_COMPILER)
-   message(FATAL_ERROR "You have to use a version of Visual Studio that supports C++11.  As of December 2017, the only versions that have good enough C++11 support to compile the dlib Python API is a fully updated Visual Studio 2015 or a fully updated Visual Studio 2017.  Older versions of either of these compilers have bad C++11 support and will fail to compile the Python extension. ***SO UPDATE YOUR VISUAL STUDIO TO MAKE THIS ERROR GO AWAY***")
-endif()
-
-
 add_definitions(-DDLIB_VERSION=${DLIB_VERSION})
 
 # Tell cmake to compile all these cpp files into a dlib python module.