Merge branch 'develop'

Latest Borland with clang can support variadic macros. Updated iso test to be more correct choosing compiler level.
2025-06-29 05:51:02 +02:00 · 2020-03-01 00:18:20 -05:00 · 2020-02-18 02:44:51 -05:00 · 2020-02-01 23:12:13 -05:00 · 2020-01-06 02:34:42 -05:00 · 2020-01-05 20:20:29 -05:00
85 changed files with 2611 additions and 413 deletions
--- a/.travis.yml
+++ b/.travis.yml
@ -1,38 +1,322 @@
-# Copyright 2016 Edward Diener
+# Copyright 2016-2019 Peter Dimov
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt or copy at http://boost.org/LICENSE_1_0.txt)

 language: cpp

-sudo: false
-
-python: "2.7"
-
-os:
-  - linux
-  - osx
+dist: xenial

 branches:
  only:
    - master
    - develop
+    - /feature\/.*/
+
+env:
+  matrix:
+    - BOGUS_JOB=true
+
+matrix:
+
+  exclude:
+    - env: BOGUS_JOB=true
+
+  include:
+    - os: linux
+      compiler: g++
+      env: TOOLSET=gcc COMPILER=g++ CXXSTD=03,11
+
+    - os: linux
+      compiler: g++-4.4
+      env: TOOLSET=gcc COMPILER=g++-4.4 CXXSTD=98
+      addons:
+        apt:
+          packages:
+            - g++-4.4
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: g++-4.6
+      env: TOOLSET=gcc COMPILER=g++-4.6 CXXSTD=03,0x
+      addons:
+        apt:
+          packages:
+            - g++-4.6
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: g++-4.7
+      env: TOOLSET=gcc COMPILER=g++-4.7 CXXSTD=03,11
+      addons:
+        apt:
+          packages:
+            - g++-4.7
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: g++-4.8
+      env: TOOLSET=gcc COMPILER=g++-4.8 CXXSTD=03,11
+      addons:
+        apt:
+          packages:
+            - g++-4.8
+          sources:
+            - ubuntu-toolchain-r-test
+    - os: linux
+      compiler: g++-4.9
+      env: TOOLSET=gcc COMPILER=g++-4.9 CXXSTD=03,11
+      addons:
+        apt:
+          packages:
+            - g++-4.9
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: g++-5
+      env: TOOLSET=gcc COMPILER=g++-5 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - g++-5
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: g++-6
+      env: TOOLSET=gcc COMPILER=g++-6 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - g++-6
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      dist: trusty
+      compiler: g++-7
+      env: TOOLSET=gcc COMPILER=g++-7 CXXSTD=03,11,14,17
+      addons:
+        apt:
+          packages:
+            - g++-7
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: g++-8
+      env: TOOLSET=gcc COMPILER=g++-8 CXXSTD=03,11,14,17,2a
+      addons:
+        apt:
+          packages:
+            - g++-8
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: g++-9
+      env: TOOLSET=gcc COMPILER=g++-9 CXXSTD=03,11,14,17,2a
+      addons:
+        apt:
+          packages:
+            - g++-9
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: clang++
+      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11
+
+    - os: linux
+      dist: trusty
+      compiler: /usr/bin/clang++
+      env: TOOLSET=clang COMPILER=/usr/bin/clang++ CXXSTD=03,11
+      addons:
+        apt:
+          packages:
+            - clang-3.3
+
+    - os: linux
+      dist: trusty
+      compiler: /usr/bin/clang++
+      env: TOOLSET=clang COMPILER=/usr/bin/clang++ CXXSTD=03,11
+      addons:
+        apt:
+          packages:
+            - clang-3.4
+
+    - os: linux
+      compiler: clang++-3.5
+      env: TOOLSET=clang COMPILER=clang++-3.5 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - clang-3.5
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: clang++-3.6
+      env: TOOLSET=clang COMPILER=clang++-3.6 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - clang-3.6
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: clang++-3.7
+      env: TOOLSET=clang COMPILER=clang++-3.7 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - clang-3.7
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: clang++-3.8
+      env: TOOLSET=clang COMPILER=clang++-3.8 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - clang-3.8
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: clang++-3.9
+      env: TOOLSET=clang COMPILER=clang++-3.9 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - clang-3.9
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: clang++-4.0
+      env: TOOLSET=clang COMPILER=clang++-4.0 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - clang-4.0
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: clang++-5.0
+      env: TOOLSET=clang COMPILER=clang++-5.0 CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - clang-5.0
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: clang++-6.0
+      env: TOOLSET=clang COMPILER=clang++-6.0 CXXSTD=03,11,14,17,2a
+      addons:
+        apt:
+          packages:
+            - clang-6.0
+          sources:
+            - ubuntu-toolchain-r-test
+
+    - os: linux
+      compiler: clang++-7
+      env: TOOLSET=clang COMPILER=clang++-7 CXXSTD=03,11,14,17,2a
+      addons:
+        apt:
+          packages:
+            - clang-7
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-xenial-7
+
+    - os: linux
+      compiler: clang++-8
+      env: TOOLSET=clang COMPILER=clang++-8 CXXSTD=03,11,14,17,2a
+      addons:
+        apt:
+          packages:
+            - clang-8
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-xenial-8
+
+    - os: linux
+      compiler: clang++-9
+      env: TOOLSET=clang COMPILER=clang++-9 CXXSTD=03,11,14,17,2a
+      addons:
+        apt:
+          packages:
+            - clang-9
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main'
+              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
+
+    - os: linux
+      dist: trusty
+      compiler: clang++-libc++
+      env: TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=03,11,14,1z
+      addons:
+        apt:
+          packages:
+            - libc++-dev
+
+    - os: osx
+      compiler: clang++
+      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
+
+    - os: linux
+      env: CMAKE_TEST=1
+      script:
+        - mkdir __build__ && cd __build__
+        - cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=1 -DBOOST_INCLUDE_LIBRARIES=preprocessor ..
+        - ctest --output-on-failure -R boost_preprocessor
+
+    - os: linux
+      env: CMAKE_SUBDIR_TEST=1
+      install: true
+      script:
+      - cd test/cmake_subdir_test && mkdir __build__ && cd __build__
+      - cmake ..
+      - cmake --build .
+      - cmake --build . --target check
+
+    - os: linux
+      env: CMAKE_INSTALL_TEST=1
+      script:
+        - mkdir __build__ && cd __build__
+        - cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=1 -DBOOST_INCLUDE_LIBRARIES=preprocessor -DCMAKE_INSTALL_PREFIX=~/.local ..
+        - cmake --build . --target install
+        - cd ../libs/preprocessor/test/cmake_install_test && mkdir __build__ && cd __build__
+        - cmake -DCMAKE_INSTALL_PREFIX=~/.local ..
+        - cmake --build .
+        - cmake --build . --target check

 install:
+  - BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
  - cd ..
-  - git clone -b $TRAVIS_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
+  - git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
  - cd boost-root
-  - git submodule update --init --depth 1 tools/build
-  - git submodule update --init --depth 1 libs/config
-  - git submodule update --init --depth 1 tools/boostdep
+  - git submodule update --init tools/boostdep
  - cp -r $TRAVIS_BUILD_DIR/* libs/preprocessor
  - python tools/boostdep/depinst/depinst.py preprocessor
  - ./bootstrap.sh
  - ./b2 headers

 script:
-  - TOOLSET=gcc,clang
-  - if [ $TRAVIS_OS_NAME == osx ]; then TOOLSET=clang; fi
-  - ./b2 libs/preprocessor/test toolset=$TOOLSET
+  - |-
+    echo "using $TOOLSET : : $COMPILER ;" > ~/user-config.jam
+  - ./b2 -j 3 libs/preprocessor/test toolset=$TOOLSET cxxstd=$CXXSTD

 notifications:
  email:
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@ -0,0 +1,25 @@
+# Copyright 2019 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
+
+cmake_minimum_required(VERSION 3.5...3.16)
+
+project(boost_preprocessor VERSION "${BOOST_SUPERPROJECT_VERSION}" LANGUAGES CXX)
+
+add_library(boost_preprocessor INTERFACE)
+add_library(Boost::preprocessor ALIAS boost_preprocessor)
+
+target_include_directories(boost_preprocessor INTERFACE include)
+
+if(BOOST_SUPERPROJECT_VERSION)
+
+  include(BoostInstall)
+  boost_install(TARGETS boost_preprocessor HEADER_DIRECTORY include/)
+
+endif()
+
+if(BUILD_TESTING)
+
+  add_subdirectory(test)
+
+endif()
--- a/appveyor.yml
+++ b/appveyor.yml
@ -0,0 +1,95 @@
+# Copyright 2017 Edward Diener
+# Copyright 2018 Mike Dev
+# Copyright 2019 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# (See accompanying file LICENSE_1_0.txt or copy at http://boost.org/LICENSE_1_0.txt)
+
+version: 1.0.{build}-{branch}
+
+shallow_clone: true
+
+configuration:
+  - boost_build_test
+  - cmake_test
+  - cmake_subdir_test
+  - cmake_install_test
+
+branches:
+  only:
+    - master
+    - develop
+    - /feature\/.*/
+
+environment:
+  matrix:
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      TOOLSET: msvc-9.0,msvc-10.0,msvc-11.0,msvc-12.0,msvc-14.0
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      TOOLSET: msvc-14.1
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
+      TOOLSET: msvc-14.2
+
+matrix:
+  exclude:
+    - configuration: cmake_test
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+    - configuration: cmake_test
+      APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+
+build: off
+
+install:
+  - set BOOST_BRANCH=develop
+  - if "%APPVEYOR_REPO_BRANCH%" == "master" set BOOST_BRANCH=master
+  - cd ..
+  - git clone -b %BOOST_BRANCH% --depth 1 https://github.com/boostorg/boost.git boost-root
+  - cd boost-root
+  - git submodule update --init tools/boostdep
+  - xcopy /s /e /q %APPVEYOR_BUILD_FOLDER% libs\preprocessor\
+  - python tools/boostdep/depinst/depinst.py preprocessor
+
+for:
+-
+  matrix:
+    only:
+      - configuration: boost_build_test
+
+  test_script:
+    - bootstrap
+    - b2 -d0 headers
+    - b2 -j3 libs/preprocessor/test toolset=%TOOLSET%
+
+-
+  matrix:
+    only:
+      - configuration: cmake_test
+
+  test_script:
+    - mkdir __build__ && cd __build__
+    - cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=1 -DBOOST_INCLUDE_LIBRARIES=preprocessor ..
+    - ctest --output-on-failure -R boost_preprocessor -C Debug
+
+-
+  matrix:
+    only:
+      - configuration: cmake_subdir_test
+
+  test_script:
+    - cd libs/preprocessor/test/cmake_subdir_test && mkdir __build__ && cd __build__
+    - cmake ..
+    - cmake --build .
+    - cmake --build . --target check
+
+-
+  matrix:
+    only:
+      - configuration: cmake_install_test
+
+  test_script:
+    - mkdir __build__ && cd __build__
+    - cmake -DBOOST_ENABLE_CMAKE=1 -DBoost_VERBOSE=1 -DBOOST_INCLUDE_LIBRARIES=preprocessor -DCMAKE_INSTALL_PREFIX=C:/cmake-prefix ..
+    - cmake --build . --target install
+    - cd ../libs/preprocessor/test/cmake_install_test && mkdir __build__ && cd __build__
+    - cmake -DCMAKE_INSTALL_PREFIX=C:/cmake-prefix ..
+    - cmake --build .
+    - cmake --build . --target check
--- a/doc/headers.html
+++ b/doc/headers.html
@ -80,12 +80,16 @@
      <li><a href="headers/facilities.html">facilities.hpp</a></li>
      <li>facilities/</li>
      <li class="ps"><a href="headers/facilities/apply.html">apply.hpp</a></li>
+      <li class="ps"><a href="headers/facilities/check_empty.html">check_empty.hpp</a>
+        <a href="topics/variadic_macros.html#VNotation">(v)</a></li>
      <li class="ps"><a href="headers/facilities/empty.html">empty.hpp</a></li>
      <li class="ps"><a href="headers/facilities/expand.html">expand.hpp</a></li>
      <li class="ps"><a href="headers/facilities/identity.html">identity.hpp</a></li>
      <li class="ps"><a href="headers/facilities/intercept.html">intercept.hpp</a></li>
      <li class="ps"><a href="headers/facilities/overload.html">overload.hpp</a>
        <a href="topics/variadic_macros.html#VNotation">(v)</a></li>
+      <li class="ps"><a href="headers/facilities/va_opt.html">va_opt.hpp</a>
+        <a href="topics/variadic_macros.html#VNotation">(v)</a></li>
      <li><a href="headers/for.html">for.hpp*</a></li>
      <li><a href="headers/identity.html">identity.hpp*</a></li>
      <li><a href="headers/if.html">if.hpp*</a></li>
@ -230,6 +234,7 @@
      <li><a href="headers/variadic.html">variadic.hpp</a></li>
      <li>variadic/</li>
      <li class="ps"><a href="headers/variadic/elem.html">elem.hpp</a> <a href="topics/variadic_macros.html#VNotation">(v)</a></li>
+      <li class="ps"><a href="headers/variadic/has_opt.html">has_opt.hpp</a> </li>
      <li class="ps"><a href="headers/variadic/size.html">size.hpp</a> <a href="topics/variadic_macros.html#VNotation">(v)</a></li>
      <li class="ps"><a href="headers/variadic/to_array.html">to_array.hpp</a> <a
          href="topics/variadic_macros.html#VNotation">(v)</a></li>
--- a/doc/headers/facilities.html
+++ b/doc/headers/facilities.html
@ -15,6 +15,7 @@
 		<ul>
 			<li><a href="facilities/apply.html">&lt;boost/preprocessor/facilities/apply.hpp&gt;</a></li>
 			<li><a href="facilities/empty.html">&lt;boost/preprocessor/facilities/empty.hpp&gt;</a></li>
+			<li><a href="facilities/check_empty.html">&lt;boost/preprocessor/facilities/check_empty.hpp&gt;</a> <a href="../topics/variadic_macros.html#VNotation" target="_self">(v)</a></li>
 			<li><a href="facilities/expand.html">&lt;boost/preprocessor/facilities/expand.hpp&gt;</a></li>
 			<li><a href="facilities/identity.html">&lt;boost/preprocessor/facilities/identity.hpp&gt;</a></li>
 			<li><a href="facilities/intercept.html">&lt;boost/preprocessor/facilities/intercept.hpp&gt;</a></li>
--- a/doc/headers/facilities/check_empty.html
+++ b/doc/headers/facilities/check_empty.html
@ -0,0 +1,29 @@
+<html>
+<head>
+	<title>facilities/check_empty.hpp</title>
+	<link rel="stylesheet" type="text/css" href="../../styles.css">
+</head>
+<body>
+	<div style="margin-left:  0px;">
+		The <b>facilities/check_empty.hpp</b> header defines a variadic macro for the C++20 level that checks if its data is empty or not.
+	</div>
+	<h4>Usage</h4>
+		<div class="code">
+			#include <b>&lt;boost/preprocessor/facilities/check_empty.hpp&gt;</b>
+		</div>
+	<h4>Contents</h4>
+		<ul>
+			<li><a href="../../ref/check_empty.html">BOOST_PP_CHECK_EMPTY</a> <a href="../../topics/variadic_macros.html#VNotation" target="_self">(v)</a></li>
+		</ul>
+	<hr size="1">
+	<div style="margin-left: 0px;">
+		<i></i><i><EFBFBD> Copyright Edward Diener 2019</i>
+	</div>
+	<div style="margin-left: 0px;">
+		<p><small>Distributed under the Boost Software License, Version 1.0. (See
+		accompanying file <a href="../../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
+		copy at <a href=
+		"http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
+	</div>
+</body>
+</html>
--- a/doc/headers/facilities/va_opt.html
+++ b/doc/headers/facilities/va_opt.html
@ -0,0 +1,32 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
+<html>
+  <head>
+    <meta http-equiv="content-type" content="text/html;
+      charset=windows-1252">
+    <title>facilities/va_opt.hpp</title>
+    <link rel="stylesheet" type="text/css" href="../../styles.css">
+  </head>
+  <body>
+    <div style="margin-left: 0px;"> The <b>facilities/va_opt.hpp</b>
+      header defines a variadic macro for the C++20 level that offers a
+      more flexible alternative to the __VA_OPT__ construct. </div>
+    <h4>Usage</h4>
+    <div class="code"> #include <b>&lt;boost/preprocessor/facilities/va_opt.hpp&gt;</b>
+    </div>
+    <h4>Contents</h4>
+    <ul>
+      <li><a href="../../ref/va_opt.html">BOOST_PP_VA_OPT</a> <a
+          href="../../topics/variadic_macros.html#VNotation"
+          target="_self">(v)</a></li>
+    </ul>
+    <hr size="1">
+    <div style="margin-left: 0px;"> <i><EFBFBD> Copyright Edward Diener 2019</i>
+    </div>
+    <div style="margin-left: 0px;">
+      <p><small>Distributed under the Boost Software License, Version
+          1.0. (See accompanying file <a
+            href="../../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
+          copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
+    </div>
+  </body>
+</html>
--- a/doc/headers/variadic.html
+++ b/doc/headers/variadic.html
@ -14,6 +14,7 @@
 	<h4>Includes</h4>
 		<ul>
 			<li><a href="variadic/elem.html">&lt;boost/preprocessor/variadic/elem.hpp&gt;</a> <a href="../topics/variadic_macros.html#VNotation" target="_self">(v)</a></li>
+			<li><a href="variadic/has_opt.html">&lt;boost/preprocessor/variadic/has_opt.hpp&gt;</a> </li>
 			<li><a href="variadic/size.html">&lt;boost/preprocessor/variadic/size.hpp&gt;</a> <a href="../topics/variadic_macros.html#VNotation" target="_self">(v)</a></li>
 			<li><a href="variadic/to_array.html">&lt;boost/preprocessor/variadic/to_array.hpp&gt;</a> <a href="../topics/variadic_macros.html#VNotation" target="_self">(v)</a></li>
 			<li><a href="variadic/to_list.html">&lt;boost/preprocessor/variadic/to_list.hpp&gt;</a> <a href="../topics/variadic_macros.html#VNotation" target="_self">(v)</a></li>
@ -22,7 +23,7 @@
 		</ul>
 	<hr size="1">
 	<div style="margin-left: 0px;">
-		<i></i><i><EFBFBD> Copyright Edward Diener 2011,2013</i>
+		<i></i><i><EFBFBD> Copyright Edward Diener 2011,2013,2019</i>
 	</div>
 	<div style="margin-left: 0px;">
 		<p><small>Distributed under the Boost Software License, Version 1.0. (See
--- a/doc/headers/variadic/has_opt.html
+++ b/doc/headers/variadic/has_opt.html
@ -0,0 +1,25 @@
+<html><head>
+  <title>variadic/has_opt.hpp</title>
+  <link rel="stylesheet" type="text/css" href="../../styles.css"></head><body>
+   <div style="margin-left: 0px;">
+   The <b>variadic/has_opt.hpp</b> header defines a macro that determines whether or not the __VA_OPT__ construct is supported.
+   </div>
+   <h4>Usage</h4>
+   <div class="code">
+   #include <b>&lt;boost/preprocessor/variadic/has_opt.hpp&gt;</b>
+   </div>
+   <h4>Contents</h4>
+   <ul>
+   <li><a href="../../ref/variadic_has_opt.html">BOOST_PP_VARIADIC_HAS_OPT</a> <br>
+   </li>
+   </ul>
+   <hr size="1">
+   <div style="margin-left: 0px;">
+   <i></i><i><EFBFBD> Copyright Edward Diener 2019</i>
+   </div>
+   <div style="margin-left: 0px;">
+   <p><small>Distributed under the Boost Software License, Version 1.0. (See
+   accompanying file <a href="../../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
+   copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
+   </div>
+   </body></html>
--- a/doc/ref.html
+++ b/doc/ref.html
@ -45,6 +45,7 @@
      <li><a href="ref/bool.html">BOOL</a></li>
      <!-- C -->
      <li><a href="ref/cat.html">CAT</a></li>
+      <li><a href="ref/check_empty.html">CHECK_EMPTY</a> <a href="topics/variadic_macros.html#VNotation">(v)</a></li>
      <li><a href="ref/comma.html">COMMA</a></li>
      <li><a href="ref/comma_if.html">COMMA_IF</a></li>
      <li><a href="ref/compl.html">COMPL</a></li>
@ -295,9 +296,11 @@
      <!-- U -->
      <li><a href="ref/update_counter.html">UPDATE_COUNTER</a></li>
      <!-- V -->
+      <li><a href="ref/va_opt.html">VA_OPT</a> <a href="topics/variadic_macros.html#VNotation">(v)</a></li>
      <li><a href="ref/value.html">VALUE</a></li>
      <li><a href="ref/variadics.html">VARIADICS</a></li>
      <li><a href="ref/variadic_elem.html">VARIADIC_ELEM</a> <a href="topics/variadic_macros.html#VNotation">(v)</a></li>
+      <li><a href="ref/variadic_has_opt.html">VARIADIC_HAS_OPT</a></li>
      <li><a href="ref/variadic_seq_to_seq.html">VARIADIC_SEQ_TO_SEQ</a> <a href="topics/variadic_macros.html#VNotation">(v)</a></li>
      <li><a href="ref/variadic_size.html">VARIADIC_SIZE</a> <a href="topics/variadic_macros.html#VNotation">(v)</a></li>
      <li><a href="ref/variadic_to_array.html">VARIADIC_TO_ARRAY</a> <a href="topics/variadic_macros.html#VNotation">(v)</a></li>
--- a/doc/ref/check_empty.html
+++ b/doc/ref/check_empty.html
@ -0,0 +1,68 @@
+<html>
+<head>
+  <title>BOOST_PP_CHECK_EMPTY</title>
+  <link rel="stylesheet" type="text/css" href="../styles.css">
+</head>
+<body>
+<div style="margin-left: 0px;"> The <b>BOOST_PP_CHECK_EMPTY</b> variadic macro
+checks to see if its variadic input is empty or not. It expands to 1 if its input
+is empty and expands to 0 if its input is not empty. The macro only exists when
+the compilation is at the C++20 level and the __VA_OPT__ construct is supported.</div>
+<h4>Usage</h4>
+<div class="code"> <b>BOOST_PP_CHECK_EMPTY</b>(<i>...</i>) <a href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a><br>
+ </div>
+<h4>Arguments</h4>
+<dl>
+  <dt>...<br>
+</dt>
+  <dd> The <i>variadic data</i> to be checked for emptiness. </dd>
+</dl>
+<h4>Remarks</h4>
+<div>
+When the macro invocation BOOST_PP_VARIADIC_HAS_OPT() expands to 1, then this
+macro exists and can be invoked, otherwise this macro does not exist
+and attempting to invoke it will lead to a preprocessor error that the macro
+can not be found. Because of this condition the header file for including
+this macro includes the header file for the BOOST_PP_VARIADIC_HAS_OPT macro.<br>
+It is possible to pass data to this macro which expands to nothing, in which
+case this macro will expand to 1 just as if nothing has been passed.
+</div>
+<h4>See Also</h4>
+<ul>
+  <li><a href="variadic_has_opt.html">BOOST_PP_VARIADIC_HAS_OPT</a></li>
+</ul>
+<h4>Requirements</h4>
+<div> <b>Header:</b> &nbsp;<a href="../headers/facilities/check_empty.html">&lt;boost/preprocessor/facilities/check_empty.hpp&gt;</a>
+</div>
+<h4>Sample Code</h4>
+<div>
+<pre>
+#include &lt;<a href="../headers/facilities/check_empty.html">boost/preprocessor/facilities/check_empty.hpp</a>&gt;
+
+# if <a href="variadic_has_opt.html">BOOST_PP_VARIADIC_HAS_OPT</a>()
+
+#define DATA
+#define OBJECT OBJECT2
+#define OBJECT2
+#define FUNC(x) FUNC2(x)
+#define FUNC2(x)
+#define FUNC_GEN(x,y) (1,2,3)
+
+<a href="check_empty.html">BOOST_PP_CHECK_EMPTY</a>(DATA)     // expands to 1
+<a href="check_empty.html">BOOST_PP_CHECK_EMPTY</a>(OBJECT)   // expands to 1
+<a href="check_empty.html">BOOST_PP_CHECK_EMPTY</a>(FUNC(1))  // expands to 1
+<a href="check_empty.html">BOOST_PP_CHECK_EMPTY</a>(FUNC)     // expands to 0
+<a href="check_empty.html">BOOST_PP_CHECK_EMPTY</a>(FUNC_GEN) // expands to 0
+
+#endif
+</pre>
+</div>
+<hr size="1">
+<div style="margin-left: 0px;"> <i></i><i><EFBFBD> Copyright Edward Diener 2019</i> </div>
+<div style="margin-left: 0px;">
+<p><small>Distributed under the Boost Software License, Version 1.0.
+(See accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a>
+or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
+</div>
+</body>
+</html>
--- a/doc/ref/expand.html
+++ b/doc/ref/expand.html
@ -22,7 +22,7 @@
 		<div>
 			This macro is useful when a delay is necessary to produce the correct semantics of a macro invocation.&nbsp;
 			For example, when a macro expands to an argument list to another macro.&nbsp;
-			This macro will expand the the argument list on the first pass, and then rescan to expand any more macros.
+			This macro will expand the argument list on the first pass, and then rescan to expand any more macros.
 		</div>
 	<h4>Requirements</h4>
 		<div>
--- a/doc/ref/identity_n.html
+++ b/doc/ref/identity_n.html
@ -33,7 +33,7 @@
 		</ul>
 	<h4>Requirements</h4>
 		<div>
-			<b>Header:</b> &nbsp;<a href="../headers/facilities/identity_n.html">&lt;boost/preprocessor/facilities/identity.hpp&gt;</a>
+			<b>Header:</b> &nbsp;<a href="../headers/facilities/identity.html">&lt;boost/preprocessor/facilities/identity.hpp&gt;</a>
 		</div>
 	<h4>Sample Code</h4>
 <div><pre>
--- a/doc/ref/list_to_array_d.html
+++ b/doc/ref/list_to_array_d.html
@ -30,5 +30,13 @@
    <h4> Requirements </h4>
    <div> <b>Header:</b> &nbsp;<a href="../headers/list/to_array.html">&lt;boost/preprocessor/list/to_array.hpp&gt;</a>
    </div>
+    <hr size="1">
+    <div style="margin-left: 0px;"> <i></i><i>© Copyright Edward Diener 2011</i>
+    </div>
+    <div style="margin-left: 0px;">
+      <p><small>Distributed under the Boost Software License, Version 1.0. (See
+          accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a>
+          or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
+    </div>
  </body>
 </html>
--- a/doc/ref/list_to_seq_r.html
+++ b/doc/ref/list_to_seq_r.html
@ -28,5 +28,12 @@
    <h4> Requirements </h4>
    <div> <b>Header:</b> &nbsp;<a href="../headers/list/to_seq.html">&lt;boost/preprocessor/list/to_seq.hpp&gt;</a>
    </div>
+    <hr size="1">
+    <div style="margin-left: 0px;"> <i>© Copyright Edward Diener 2011</i> </div>
+    <div style="margin-left: 0px;">
+      <p><small>Distributed under the Boost Software License, Version 1.0. (See
+          accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a>
+          or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
+    </div>
  </body>
 </html>
--- a/doc/ref/tuple_eat.html
+++ b/doc/ref/tuple_eat.html
@ -42,7 +42,7 @@ not occur.<br>
 			<b>Header:</b> &nbsp;<a href="../headers/tuple/eat.html">&lt;boost/preprocessor/tuple/eat.hpp&gt;</a>
 		</div>
 	<h4>Sample Code</h4>
-<div><pre>#include &lt;<a href="../headers/control/if.html">boost/preprocessor/control/if.hpp</a>&gt;<br>#include &lt;<a href="../headers/tuple/eat.html">boost/preprocessor/tuple/eat.hpp</a>&gt;<br><br>#define OP(a, b) (a b)<br><br>#define MACRO(n) <a href="if.html">BOOST_PP_IF</a>(n, OP, <a href="tuple_eat.html">BOOST_PP_TUPLE_EAT</a>(2))(1, 2)<br><br>// or for the variadic version <a href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a><br><br>#define MACRO(n) <a href="if.html">BOOST_PP_IF</a>(n, OP, <a href="file:///C:/Programming/VersionControl/sandbox/variadics/libs/preprocessor/doc/ref/tuple_eat.html">BOOST_PP_TUPLE_EAT</a>())(1, 2)<br><br>MACRO(0) // expands to nothing<br>MACRO(1) // expands to (1, 2)<br></pre></div>
+<div><pre>#include &lt;<a href="../headers/control/if.html">boost/preprocessor/control/if.hpp</a>&gt;<br>#include &lt;<a href="../headers/tuple/eat.html">boost/preprocessor/tuple/eat.hpp</a>&gt;<br><br>#define OP(a, b) (a b)<br><br>#define MACRO(n) <a href="if.html">BOOST_PP_IF</a>(n, OP, <a href="tuple_eat.html">BOOST_PP_TUPLE_EAT</a>(2))(1, 2)<br><br>// or for the variadic version <a href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a><br><br>#define MACRO(n) <a href="if.html">BOOST_PP_IF</a>(n, OP, <a href="tuple_eat.html">BOOST_PP_TUPLE_EAT</a>())(1, 2)<br><br>MACRO(0) // expands to nothing<br>MACRO(1) // expands to (1, 2)<br></pre></div>
 	<hr size="1">
 	<div style="margin-left: 0px;">
 		<i><EFBFBD> Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i>
--- a/doc/ref/tuple_elem.html
+++ b/doc/ref/tuple_elem.html
@ -49,7 +49,7 @@ or<br>
 			<b>Header:</b> &nbsp;<a href="../headers/tuple/elem.html">&lt;boost/preprocessor/tuple/elem.hpp&gt;</a>
 		</div>
 	<h4>Sample Code</h4>
-<div><pre>#include &lt;<a href="../headers/tuple/elem.html">boost/preprocessor/tuple/elem.hpp</a>&gt;<br><br>#define TUPLE (a, b, c, d)<br><br><a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 0, TUPLE) // expands to a<br><a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 3, TUPLE) // expands to d<br><br>// or for the variadic version <a href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a><br><br><a href="file:///C:/Programming/VersionControl/sandbox/variadics/libs/preprocessor/doc/ref/tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(0, TUPLE) // expands to a in the variadic version<br><a href="file:///C:/Programming/VersionControl/sandbox/variadics/libs/preprocessor/doc/ref/tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(3, TUPLE) // expands to d in the variadic version<br></pre></div>
+<div><pre>#include &lt;<a href="../headers/tuple/elem.html">boost/preprocessor/tuple/elem.hpp</a>&gt;<br><br>#define TUPLE (a, b, c, d)<br><br><a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 0, TUPLE) // expands to a<br><a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(4, 3, TUPLE) // expands to d<br><br>// or for the variadic version <a href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a><br><br><a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(0, TUPLE) // expands to a in the variadic version<br><a href="tuple_elem.html">BOOST_PP_TUPLE_ELEM</a>(3, TUPLE) // expands to d in the variadic version<br></pre></div>
 	<hr size="1">
 	<div style="margin-left: 0px;">
 		<i><EFBFBD> Copyright <a href="http://www.housemarque.com" target="_top">Housemarque Oy</a> 2002</i>
--- a/doc/ref/va_opt.html
+++ b/doc/ref/va_opt.html
@ -0,0 +1,124 @@
+<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
+<html>
+  <head>
+    <meta http-equiv="content-type" content="text/html;
+      charset=windows-1252">
+    <title>BOOST_PP_VA_OPT</title>
+    <link rel="stylesheet" type="text/css" href="../styles.css">
+  </head>
+  <body>
+    <div style="margin-left: 0px;"> The <b>BOOST_PP_VA_OPT</b> variadic
+      macro is a more flexible alternative to the C++20 __VA_OPT__
+      construct. It expands to either one of two inputs depending on
+      whether the variadic data is empty or not, whereas the C++20
+      __VA_OPT__ constructs expands to either its input or nothing
+      depending on whether the variadic data is empty or not. This macro
+      only exists when the compilation is at the C++20 level and the
+      __VA_OPT__ construct is supported.</div>
+    <h4>Usage</h4>
+    <div class="code"> <b>BOOST_PP_VA_OPT</b>(x,y,<i>...</i>) <a
+        href="../topics/variadic_macros.html#VNotation" target="_self"><sup>(v)</sup></a><br>
+    </div>
+    <h4>Arguments</h4>
+    <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; x<br>
+      &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; A tuple
+      whose data is the macro expansion if the <i>variadic data</i> is
+      <b>not</b> empty<br>
+      &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; y<br>
+      &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; A tuple
+      whose data is the macro expansion if the <i>variadic data</i> is
+      empty<br>
+      &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ,,,<br>
+      &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; The <i>variadic
+        data</i> to be checked for emptiness<br>
+    </p>
+    <dl>
+    </dl>
+    <h4>Remarks</h4>
+    <div> When the macro invocation BOOST_PP_VARIADIC_HAS_OPT() expands
+      to 1, then this macro exists and can be invoked, otherwise this
+      macro does not exist and attempting to invoke it will lead to a
+      preprocessor error that the macro can not be found. Because of
+      this condition the header file for including this macro includes
+      the header file for the BOOST_PP_VARIADIC_HAS_OPT macro.<br>
+      <br>
+      The difference between this macro and the __VA_OPT__ construct
+      illustrates a limitation of the latter construct with a trade off
+      of simpler syntax. The differences between the __VA_OPT__
+      construct and this macro are:<br>
+      <ul>
+        <li>The __VA_OPT__ construct offers a choice as its expansion
+          only between its input preprocessing tokens or nothing (
+          called a "single placemarker token" ) depending on whether the
+          implicit variadic data is empty or not. There is no way using
+          the __VA_OPT__ construct to specify any alternative but the
+          "single placemarker token" when the variadic data is empty
+          whereas any preprocessing tokens can be specified when the
+          variadic data is not empty. With the BOOST_PP_VA_OPT macro the
+          user can specify as its expansion preprocessing tokens both
+          when the variadic data is empty and when the variadic data is
+          not empty.</li>
+        <li>The __VA_OPT__ construct offers a simple syntax whereas this
+          macro is more verbose. The BOOST_PP_VA_OPT macro's first and
+          second parameters must be Boost PP tuples of data, in order to
+          expand to normal or variadic data, and the third parameter
+          must be the variadic data to check for emptiness, whereas the
+          __VA_OPT__ construct has an implied variadic data as
+          __VA_ARGS__ to check for emptiness and can specify its
+          expansion directly in terms of its input.</li>
+        <li>The __VA_OPT__ construct can only be specified in the
+          replacement list of some macro, whereas the BOOST_PP_VA_OPT
+          macro can be used both as an alternative to the __VA_OPT__
+          construct in the replacement list of some macro and anywhere
+          else a macro can be used.</li>
+        <li>It is impossible to have a left parenthesis '(' or a right
+          parenthesis ')' as preprocessing token data within the
+          __VA_OPT__ construct whereas both are possible as part of the
+          expanded data for the BOOST_PP_VA_OPT macro.<br>
+        </li>
+      </ul>
+      <br>
+      The exact BOOST_PP_VA_OPT equivalent to the construct of&nbsp;
+      '__VA_OPT__ ( pp-tokens )' in the replacement list of a macro is
+      'BOOST_PP_VA_OPT (( pp-tokens ),(),__VA_ARGS__)'.</div>
+    <h4>See Also</h4>
+    <ul>
+      <li><a href="variadic_has_opt.html">BOOST_PP_VARIADIC_HAS_OPT</a></li>
+    </ul>
+    <h4>Requirements</h4>
+    <div> <b>Header:</b> &nbsp;<a
+        href="../headers/facilities/va_opt.html">&lt;boost/preprocessor/facilities/va_opt.hpp&gt;</a>
+    </div>
+    <h4>Sample Code</h4>
+    <div>
+      <pre>#include &lt;<a href="../headers/facilities/va_opt.html">boost/preprocessor/facilities/va_opt.hpp</a>&gt;
+
+# if <a href="variadic_has_opt.html">BOOST_PP_VARIADIC_HAS_OPT</a>()
+
+#define DATA
+#define OBJECT OBJECT2
+#define OBJECT2
+#define FUNC(x) FUNC2(x)
+#define FUNC2(x)
+#define FUNC_GEN(x,y) (1,2,3)
+
+<a href="va_opt.html">BOOST_PP_VA_OPT</a>((1),(2),DATA)                      // expands to 2
+<a href="va_opt.html">BOOST_PP_VA_OPT</a>((3),(4),OBJECT)                    // expands to 4
+<a href="va_opt.html">BOOST_PP_VA_OPT</a>((5),(6),FUNC(1))                   // expands to 6
+<a href="va_opt.html">BOOST_PP_VA_OPT</a>((7,8),(9,10),FUNC)                 // expands to 7,8
+<a href="va_opt.html">BOOST_PP_VA_OPT</a>((1,2,3,4,5),(6,7,8,9,10),FUNC_GEN) // expands to 1,2,3,4,5
+
+#endif
+</pre>
+    </div>
+    <hr size="1">
+    <div style="margin-left: 0px;"> <i><EFBFBD> Copyright Edward Diener 2019</i>
+    </div>
+    <div style="margin-left: 0px;">
+      <p><small>Distributed under the Boost Software License, Version
+          1.0. (See accompanying file <a
+            href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
+          copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
+    </div>
+  </body>
+</html>
--- a/doc/ref/variadic_has_opt.html
+++ b/doc/ref/variadic_has_opt.html
@ -0,0 +1,63 @@
+<html>
+<head>
+  <title>BOOST_PP_VARIADIC_HAS_OPT</title>
+  <link rel="stylesheet" type="text/css" href="../styles.css">
+</head>
+<body>
+<div style="margin-left: 0px;"> The <b>BOOST_PP_VARIADIC_HAS_OPT</b> macro
+determines whether or not the C++20 __VA_OPT__ construct is supported for the compiler's preprocessor being used. 
+Expands to 1 if the __VA_OPT__ construct is supported, otherwise expands to 0.
+</div>
+<h4>Usage</h4>
+<div class="code"> <b>BOOST_PP_VARIADIC_HAS_OPT</b>() <br>
+  </div>
+<h4>Arguments</h4>
+<dl>
+  <dt>None<br>
+</dt>
+</dl>
+	<h4>Remarks</h4>
+		<div>
+			This macro only returns 1 if the compiler is compiling at its own C++20 level and
+			__VA_OPT__ is supported. It is possible for a compiler to support the __VA_OPT__
+			construct when not compiling at its own C++20 level, but this macro will return
+			0 in that case even if __VA_OPT__ is normally supported for that level. The reason
+			for this is that such a compiler may have a compiler switch, enforcing a strict
+			adherence to a particular C++ standard level, which	gives a warning or an error
+			if __VA_OPT__ is specified below the C++20 level, and the preprocessor library
+			wants to avoid that happening. Therefore the macro will only test to see whether
+			or not __VA_OPT__ is supported at the C++20 level, while otherwise always returning
+			0 for all lesser C++ standard levels.
+		</div>
+<h4>Requirements</h4>
+<div> <b>Header:</b> &nbsp;<a href="../headers/variadic/has_opt.html">&lt;boost/preprocessor/variadic/has_opt.hpp&gt;</a>
+</div>
+<h4>Sample Code</h4>
+<div>
+<pre>
+#include &lt;<a href="../headers/variadic/has_opt.html">boost/preprocessor/variadic/has_opt.hpp</a>&gt;<br>
+#if <a href="variadic_has_opt.html">BOOST_PP_VARIADIC_HAS_OPT</a>()
+// Preprocessor code which uses __VA_OPT__
+#else
+// Preprocessor code which does not use __VA_OPT__
+#endif
+</pre>
+<br>
+or within a macro definition<br><br>
+<pre>
+#include &lt;boost/preprocessor/control/iif.hpp&gt;
+#include &lt;<a href="../headers/variadic/has_opt.html">boost/preprocessor/variadic/has_opt.hpp</a>&gt;<br>
+#define USE_OPT(...) BOOST_PP_IIF(<a href="variadic_has_opt.html">BOOST_PP_VARIADIC_HAS_OPT</a>(),MACRO_USING_OPT,MACRO_NOT_USING_OPT)(__VA_ARGS__)
+#define MACRO_USING_OPT(...) __VA_OPT__( preprocessor tokens ) anything
+#define MACRO_NOT_USING_OPT(...) anything
+</pre>
+</div>
+<hr size="1">
+<div style="margin-left: 0px;"> <i></i><i><EFBFBD> Copyright Edward Diener 2019</i> </div>
+<div style="margin-left: 0px;">
+<p><small>Distributed under the Boost Software License, Version 1.0.
+(See accompanying file <a href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a>
+or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
+</div>
+</body>
+</html>
--- a/doc/ref/while_d_macros.html
+++ b/doc/ref/while_d_macros.html
@ -12,12 +12,12 @@
    <ul>
      <li><a href="add_d.html"><span style="color: gray;">BOOST_PP_ADD_D</span></a></li>
      <li><a href="div_d.html"><span style="    color: gray;">BOOST_PP_DIV_D</span></a></li>
-      <li><a href="file:///C:/Programming/VersionControl/modular-boost/libs/preprocessor/doc/ref/div_d.html"><span
+      <li><a href="div_d.html"><span
            style="    color: gray;"></span></a><a href="mod_d.html"><span style="                      color: gray;">BOOST_PP_MOD_D</span></a></li>
-      <li><a href="file:///C:/Programming/VersionControl/modular-boost/libs/preprocessor/doc/ref/mod_d.html"><span
+      <li><a href="mod_d.html"><span
            style="                      color: gray;"></span></a><a href="mul_d.html"><span
            style="                       color: gray;">BOOST_PP_MUL_D</span></a></li>
-      <li><a href="file:///C:/Programming/VersionControl/modular-boost/libs/preprocessor/doc/ref/mul_d.html"><span
+      <li><a href="mul_d.html"><span
            style="                       color: gray;"></span></a><a href="sub_d.html"><span
            style="                          color: gray;">BOOST_PP_SUB_D</span></a></li>
    </ul>
--- a/doc/syntax.html
+++ b/doc/syntax.html
@ -284,6 +284,7 @@
 	<!-- V -->
 	<br>BOOST_PP_VALUE
    <br>BOOST_PP_VARIADIC_ELEM
+    <br>BOOST_PP_VARIADIC_HAS_OPT
    <br>BOOST_PP_VARIADIC_SIZE
    <br>BOOST_PP_VARIADIC_TO_ARRAY
    <br>BOOST_PP_VARIADIC_TO_LIST
--- a/doc/topics.html
+++ b/doc/topics.html
@ -15,6 +15,7 @@
 	<li><a href="topics/file_iteration.html">file iteration</a></li>
 	<li><a href="topics/evaluated_slots.html">evaluated slots</a></li>
    <li><a href="topics/variadic_macros.html">variadic macros</a></li>
+    <li><a href="topics/emptiness.html">emptiness</a></li>
 </ul>
 <!--
 <EFBFBD> Copyright Housemarque Oy 2002
--- a/doc/topics/emptiness.html
+++ b/doc/topics/emptiness.html
@ -0,0 +1,211 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
+<html>
+  <head>
+    <meta content="text/html; charset=windows-1252"
+      http-equiv="content-type">
+    <title>emptiness.html</title>
+    <link rel="stylesheet" type="text/css" href="../styles.css">
+    <style>
+    u { font-weight: normal; text-decoration: none; }
+    </style>
+  </head>
+  <body>
+    <h4>Passing nothing</h4>
+    <div> Although rarely desirable it has always been legal in C++ to
+      pass nothing, aka no preprocessor tokens, as an argument when
+      invoking a macro, whether the equivalent parameter be a regular
+      parameter or a variadic one. </div>
+    <div class="code">
+      <pre>      #define SOME_MACRO(Parameter1,Parameter2) macro expansion using Parameter1 and Parameter2
+      #define SOME_VARIADIC_MACRO(Parameter1,...) macro expansion using Parameter1 and __VA_ARGS__
+      
+      SOME_MACRO(a,b) // Normal
+      SOME_MACRO(a,)  // Legal, second argument is empty
+      SOME_MACRO(,b)  // Legal, first argument is empty
+      SOME_MACRO(a)   // Preprocessor error, passing the wrong number of arguments
+      
+      SOME_VARIADIC_MACRO(a,b,c,d) // Normal
+      SOME_VARIADIC_MACRO(a,)      // Legal, variadic argument is empty
+      SOME_VARIADIC_MACRO(,b,c,d)  // Legal, first argument is empty
+      SOME_VARIADIC_MACRO(a)       /* Preprocessor error in standard below C++20 level,
+                                      but in C++20 exactly equivalent to SOME_VARIADIC_MACRO(a,) */</pre>
+    </div>
+    <h4>Expanding to nothing</h4>
+    <div> Given certain arguments a macro might expand to nothing, aka
+      no preprocessor tokens. This may happen more than in the previous
+      case of an argument to a macro being nothing because the expansion
+      of a macro is often used to initialize some C++ construct, and C++
+      has some places where a part of a compile-time construct can be
+      empty. However a macro which expands to nothing rarely occurs when
+      that macro's expansion is used as an argument to another macro
+      because we would again have a macro where we are passing nothing
+      as an argument. </div>
+    <div class="code">
+      <pre>      #define ANOTHER_MACRO(Parameter1,Parameter2) /* expands to nothing when Parameter1 and Parameter2
+                                                      are numbers, otherwise expands to some preprocessing
+                                                      token, such as '1' */
+      
+      int another_int = { ANOTHER_MACRO(x,y) }; // ANOTHER_MACRO Expands to 1
+      int some_int = { ANOTHER_MACRO(1,2) };    // ANOTHER_MACRO Expands to nothing
+      SOME_MACRO(ANOTHER_MACRO(x,y),z)          // Normal, ANOTHER_MACRO Expands to 1
+      SOME_MACRO(ANOTHER_MACRO(1,2),z)          // Legal, first argument is empty as ANOTHER_MACRO Expands to nothing</pre>
+    </div>
+    <h4>Emptiness defined</h4>
+    <div> Passing nothing as a macro argument or a macro expanding to
+      nothing I term as 'emptiness', as 'nothing' is too amorphous a
+      term which can be used in too many other contexts for my liking.
+      In the vast majority of cases when designing a macro for use
+      emptiness is not a part of such a design, and passing emptiness as
+      an argument or expanding to emptiness is not anything that someone
+      writing a macro takes into account when he explains to other
+      programmers how a macro should be used.<br>
+      <br>
+      Other than the fact that macros are generally created so that some
+      actual preprocessor data of a particular kind needs to be passed
+      as arguments or gets generated as part of macro expansion when a
+      macro is invoked, there is another very good reason why working
+      with emptiness is not part of a macro's design: there has been no
+      perfectly fail-safe way to test for emptiness during macro
+      expansion, whether it be in creating macros using just the
+      facilities of the C++ standard or using a 3rd party library, such
+      as this Boost preprocessor library. When I say 'fail-safe' I mean
+      that there has always been some argument input, no matter how
+      small the number of potential cases, where a macro designed to
+      test whether or not the preprocessor data passed to it as an
+      argument when the macro is invoked is actually empty fails in some
+      way, with the failure normally occurring as a preprocessor error.<br>
+      <br>
+      Of course this does not mean that the best macro designed to test
+      for emptiness will not work correctly the vast majority of the
+      time. It only means that there has been no guarantee that such a
+      macro will work correctly all 100% of the time. Nonetheless there
+      have been uses of testing for emptiness, when a macro documents
+      what a particular argument should generally consist of, even if
+      the test is not guaranteed to work 100% of the time if particular
+      unexpected argument data does get passed. </div>
+    <h4>A C++20 solution for testing for emptiness</h4>
+    <div> The C++ standard committee recognized, in the upcoming
+      specification for the C++20 standard, that a way of testing
+      whether variadic data is empty or not in the expansion of a
+      variadic macro would be very useful when designing certain types
+      of macros. Because of this the C++20 standard added a preprocessor
+      construct which could do this in a certain way for variadic data
+      in the expansion of a variadic macro. The construct is called
+      __VA_OPT__, as in '__VA_OPT__ ( prepocessing tokens )' specified
+      in the replacement list of a variadic macro. <br>
+      <br>
+      The way that the __VA_OPT__ constructs works is that if the
+      variadic arguments to the variadic macro are empty or expand to
+      emptiness then the __VA_OPT__ construct and its enclosed
+      preprocessing token data expands to nothing, or in C++ terms "a
+      single placemarker preprocessing token". Otherwise the __VA_OPT__
+      construct expands to its enclosed preprocessing tokens. A further,
+      possibly unintended, upshot of adding the __VA_OPT__ construct to
+      C++20 is that it is now possible to create a variadic macro which
+      is 100% reliable in testing for emptiness whenever a compiler
+      supports the __VA_OPT__ construct in its compilation of
+      preprocessor code.<br>
+      <br>
+      For such a macro to always work which tests for emptiness the code
+      must know when the __VA_OPT__ construct is available. It is not
+      enough to know that a compiler is working at the C++20 level,
+      since as all C++ programmers know an adherence to a C++ standard
+      level never guarantees that a particular compiler supports every
+      aspect of that level. Happily there is a way to test whether a
+      compiler supports the __VA_OPT__ construct as long as the compiler
+      supports variadic macros, and that way has been openly published
+      on the Internet, although the actual macro code would not have
+      been hard to create even if it had not publicly appeared. This
+      library uses that code to test for __VA_OPT__ as a necessary
+      prelude for creating a variadic macro which is 100% reliable in
+      testing for emptiness.<br>
+      <br>
+      The Boost Preprocessor macro for testing whether the __VA_OPT__
+      construct is supported during compilation is called
+      BOOST_PP_VARIADIC_HAS_OPT, which is a function-like macro taking
+      no parameters and returning 1 if the __VA_OPT__ construct is
+      supported and 0 if it is not. The macro only returns 1 when
+      variadic macros are supported, when the compiler is at the C++20
+      level, and when the __VA_OPT__ construct can be used according to
+      the C++20 standard. In particular the macro needs the compiler to
+      be working at the C++20 level despite the fact that at least one
+      major compiler supports the __VA_OPT__ construct in some of its
+      latest releases even when the compiler is being used at a C++
+      standard level below that of C++20. The reason this Boost
+      preprocessor library requires the C++20 level is because that same
+      major compiler can produce a warning, or even an error, when it
+      even sees a macro using the __VA_OPT__ construct at a level below
+      C++20, even though it supports it, if other compiler options
+      requiring strict adherence to the level of the C++ standard being
+      used are passed on the command line. So taking a conservative
+      approach the BOOST_PP_VARIADIC_HAS_OPT macros requires compilation
+      at the C++20 level, along with variadic macro support, along with
+      the testing code expanding to 1, in order to specify that
+      __VA_OPT__ is supported.<br>
+      <br>
+      The actual Boost Preprocessor library for testing for emptiness in
+      C++20 mode is called BOOST_PP_CHECK_EMPTY. The macro is a variadic
+      macro with a single variadic parameter. The macro only exists if
+      our previous macro for testing for __VA_OPT__, called
+      BOOST_PP_VARIADIC_HAS_OPT, expands to 1 when invoked as
+      BOOST_PP_VARIADIC_HAS_OPT(). If BOOST_PP_VARIADIC_HAS_OPT()
+      expands to 0 the BOOST_PP_CHECK_EMPTY macro does not exist at all
+      in this library. The input to the BOOST_PP_CHECK_EMPTY macro can
+      be any variadic data. If the data passed to the macro is empty, or
+      if the data passed to the macro is not empty but when the data
+      itself is expanded it is empty, the macro returns 1, otherwise it
+      returns 0. The macro works 100% of the time and is completely
+      reliable no matter what preprocessor data is passed to it. But of
+      course it only works when compiling at the C++20 level with the
+      __VA_OPT__ construct supported by the compiler. It solves an old
+      problem that it has never been possible, prior to C++20, to
+      provide a 100% reliable implementation of a macro which tests for
+      emptiness in C++.<br>
+      <br>
+      Along with the valuable BOOST_PP_CHECK_EMPTY macro the Boost
+      Preprocessor library has also added a more flexible, if slightly
+      verbose, alternative to the __VA_OPT__ construct, which works by
+      using the ability of BOOST_PP_CHECK_EMPTY to reliably test for
+      emptiness. This macro is called BOOST_PP_VA_OPT and allows the
+      programmer to specify preprocessing tokens for expansion both when
+      the variadic data is <b>not</b> empty and when the variadic data
+      is empty. This improves on the __VA_OPT__ construct's ability to
+      specify preprocessing tokens for expansion only when the variadic
+      data is not empty. Like BOOST_PP_CHECK_EMPTY, which it uses, the
+      BOOST_PP_VA_OPT macro only exists when BOOST_PP_VARIADIC_HAS_OPT()
+      expands to 1. You can read further about how this macro works as
+      an alternative to the C++20 __VA_OPT__ construct in the
+      documentation for the macro itself.<br>
+      <br>
+      Eventually more C++ compilers will support C++20 and the
+      __VA_OPT__ construct and more programmers will use compilers at
+      the C++20 level. At that point the macro BOOST_PP_CHECK_EMPTY can
+      be used reliably for testing emptiness in preprocessor data in
+      macro code by all those programmers. The BOOST_PP_VA_OPT macro
+      serves as a useful example of such use. This does not mean that
+      designing macros with emptiness in mind needs to be done, much
+      less considered, but that the possibility of doing so with
+      complete reliability will be there if needed by the macro
+      programmer. Along with the __VA_OPT__ construct as mandated by the
+      C++20 standard the BOOST_PP_CHECK_EMPTY and BOOST_PP_VA_OPT macros
+      add three more tools in the arsenal of macro programming, which is
+      a good thing, while programmers who wanted to ignore any dealing
+      with emptiness in macro code can continue to do so. </div>
+    <b>See</b> <b>Also</b><br>
+    <ul>
+      <li><a href="../ref/variadic_has_opt.html">BOOST_PP_VARIADIC_HAS_OPT</a></li>
+      <li><a href="../ref/check_empty.html">BOOST_PP_CHECK_EMPTY</a></li>
+      <li><a href="../ref/va_opt.html">BOOST_PP_VA_OPT</a><br>
+      </li>
+    </ul>
+    <hr size="1">
+    <div style="margin-left: 0px;"> <i><EFBFBD> Copyright Edward Diener 2019</i>
+    </div>
+    <div style="margin-left: 0px;">
+      <p><small>Distributed under the Boost Software License, Version
+          1.0. (See accompanying file <a
+            href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a> or
+          copy at <a href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
+    </div>
+  </body>
+</html>
--- a/doc/topics/variadic_macros.html
+++ b/doc/topics/variadic_macros.html
@ -136,6 +136,27 @@
      use this variadic data reliably as arguments to other macros, one needs
      variadic macro support.<br>
    </div>
+    <h4>C++20 Support For Variadic Macros</h4>
+    <div>
+      In the C++20 specification there is a new construct which can be
+      used in the expansion of a variadic macro, called __VA_OPT__. This
+      construct when used in the expansion of a variadic macro is followed
+      by an opening paranthesis ('('), preprocessor data, and a closing
+      parenthesis ('}'). When the variadic data passed by the invocation
+      of a variadic macro is empty, this new construct expands to nothing.
+      When the variadic data passed by the invocation of a variadic macro
+      is not empty, this new construct expands to the preprocessor data
+      between its opening and closing parentheses.
+      <br><br>
+      This library offers support for this new C++20 construct by automatically
+      detecting whether this new construct is supported by the compiler's
+      preprocessor when using the library. The library macro which detects
+      support for the __VA_OPT__ construct is called BOOST_PP_VARIADIC_HAS_OPT.
+      This is a function-like macro which takes no parameters and returns
+      1 if the compiler is working in C++20 mode and supports the __VA_OPT__
+      construct, while otherwise it returns 0.
+      <br>
+    </div>
    <u  style="font-weight: bold;"> Using a Tuple Instead of an Array<br>
    </u>
    <div>An array as a preprocessor data type is a two-element tuple where the
@ -257,6 +278,5 @@
          (See accompanying file <a  href="../../../../LICENSE_1_0.txt">LICENSE_1_0.txt</a>
          or copy at <a  href="http://www.boost.org/LICENSE_1_0.txt">www.boost.org/LICENSE_1_0.txt</a>)</small></p>
    </div>
-  
-
-</body></html>
+  </body>
+</html>
--- a/include/boost/preprocessor/array/detail/get_data.hpp
+++ b/include/boost/preprocessor/array/detail/get_data.hpp
@ -23,33 +23,33 @@
 # define BOOST_PP_ARRAY_DETAIL_GET_DATA_NONE(size, data)

 # if BOOST_PP_VARIADICS && !(BOOST_PP_VARIADICS_MSVC && _MSC_VER <= 1400)
-# 	 if BOOST_PP_VARIADICS_MSVC
-# 		define BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY_VC_DEFAULT(size, data) BOOST_PP_TUPLE_REM(size) data
-# 		define BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY_VC_CAT(size, data) BOOST_PP_TUPLE_REM_CAT(size) data
-# 		define BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY(size, data) \
-			BOOST_PP_IIF \
-				( \
-				BOOST_PP_IS_1(size), \
-				BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY_VC_CAT, \
-				BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY_VC_DEFAULT \
-				) \
-			(size,data) \
+#    if BOOST_PP_VARIADICS_MSVC
+#       define BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY_VC_DEFAULT(size, data) BOOST_PP_TUPLE_REM(size) data
+#       define BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY_VC_CAT(size, data) BOOST_PP_TUPLE_REM_CAT(size) data
+#       define BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY(size, data) \
+            BOOST_PP_IIF \
+                ( \
+                BOOST_PP_IS_1(size), \
+                BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY_VC_CAT, \
+                BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY_VC_DEFAULT \
+                ) \
+            (size,data) \
 /**/
 #    else
-# 		define BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY(size, data) BOOST_PP_TUPLE_REM(size) data
+#       define BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY(size, data) BOOST_PP_TUPLE_REM(size) data
 #    endif
 # else
-# 	 define BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY(size, data) BOOST_PP_TUPLE_REM(size) data
+#    define BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY(size, data) BOOST_PP_TUPLE_REM(size) data
 # endif

 # define BOOST_PP_ARRAY_DETAIL_GET_DATA(size, data) \
-	BOOST_PP_IF \
-		( \
-		size, \
-		BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY, \
-		BOOST_PP_ARRAY_DETAIL_GET_DATA_NONE \
-		) \
-	(size,data) \
+    BOOST_PP_IF \
+        ( \
+        size, \
+        BOOST_PP_ARRAY_DETAIL_GET_DATA_ANY, \
+        BOOST_PP_ARRAY_DETAIL_GET_DATA_NONE \
+        ) \
+    (size,data) \
 /**/
 #
 # endif /* BOOST_PREPROCESSOR_ARRAY_DETAIL_GET_DATA_HPP */
--- a/include/boost/preprocessor/array/to_list.hpp
+++ b/include/boost/preprocessor/array/to_list.hpp
@ -22,13 +22,13 @@
 # /* BOOST_PP_ARRAY_TO_LIST */
 #
 #    define BOOST_PP_ARRAY_TO_LIST(array) \
-		BOOST_PP_IF \
-			( \
-			BOOST_PP_ARRAY_SIZE(array), \
-			BOOST_PP_ARRAY_TO_LIST_DO, \
-			BOOST_PP_ARRAY_TO_LIST_EMPTY \
-			) \
-		(array) \
+        BOOST_PP_IF \
+            ( \
+            BOOST_PP_ARRAY_SIZE(array), \
+            BOOST_PP_ARRAY_TO_LIST_DO, \
+            BOOST_PP_ARRAY_TO_LIST_EMPTY \
+            ) \
+        (array) \
 /**/
 #
 #    define BOOST_PP_ARRAY_TO_LIST_EMPTY(array) BOOST_PP_NIL
--- a/include/boost/preprocessor/array/to_seq.hpp
+++ b/include/boost/preprocessor/array/to_seq.hpp
@ -22,13 +22,13 @@
 # /* BOOST_PP_ARRAY_TO_SEQ */
 #
 #    define BOOST_PP_ARRAY_TO_SEQ(array) \
-		BOOST_PP_IF \
-			( \
-			BOOST_PP_ARRAY_SIZE(array), \
-			BOOST_PP_ARRAY_TO_SEQ_DO, \
-			BOOST_PP_ARRAY_TO_SEQ_EMPTY \
-			) \
-		(array) \
+        BOOST_PP_IF \
+            ( \
+            BOOST_PP_ARRAY_SIZE(array), \
+            BOOST_PP_ARRAY_TO_SEQ_DO, \
+            BOOST_PP_ARRAY_TO_SEQ_EMPTY \
+            ) \
+        (array) \
 /**/
 #    define BOOST_PP_ARRAY_TO_SEQ_EMPTY(array)
 #
--- a/include/boost/preprocessor/array/to_tuple.hpp
+++ b/include/boost/preprocessor/array/to_tuple.hpp
@ -20,13 +20,13 @@
 # /* BOOST_PP_ARRAY_TO_TUPLE */
 #
 #    define BOOST_PP_ARRAY_TO_TUPLE(array) \
-		BOOST_PP_IF \
-			( \
-			BOOST_PP_ARRAY_SIZE(array), \
-			BOOST_PP_ARRAY_DATA, \
-			BOOST_PP_ARRAY_TO_TUPLE_EMPTY \
-			) \
-		(array) \
+        BOOST_PP_IF \
+            ( \
+            BOOST_PP_ARRAY_SIZE(array), \
+            BOOST_PP_ARRAY_DATA, \
+            BOOST_PP_ARRAY_TO_TUPLE_EMPTY \
+            ) \
+        (array) \
 /**/
 #    define BOOST_PP_ARRAY_TO_TUPLE_EMPTY(array)
 #
--- a/include/boost/preprocessor/config/config.hpp
+++ b/include/boost/preprocessor/config/config.hpp
@ -29,7 +29,11 @@
 #        define BOOST_PP_CONFIG_FLAGS() (BOOST_PP_CONFIG_STRICT())
 #    elif defined(__EDG__) || defined(__EDG_VERSION__)
 #        if defined(_MSC_VER) && !defined(__clang__) && (defined(__INTELLISENSE__) || __EDG_VERSION__ >= 308)
-#            define BOOST_PP_CONFIG_FLAGS() (BOOST_PP_CONFIG_MSVC())
+#           if !defined(_MSVC_TRADITIONAL) || _MSVC_TRADITIONAL
+#               define BOOST_PP_CONFIG_FLAGS() (BOOST_PP_CONFIG_MSVC())
+#           else
+#               define BOOST_PP_CONFIG_FLAGS() (BOOST_PP_CONFIG_STRICT())
+#           endif
 #        else
 #            define BOOST_PP_CONFIG_FLAGS() (BOOST_PP_CONFIG_EDG() | BOOST_PP_CONFIG_STRICT())
 #        endif
@ -44,7 +48,11 @@
 #    elif defined(__BORLANDC__) || defined(__IBMC__) || defined(__IBMCPP__) || defined(__SUNPRO_CC)
 #        define BOOST_PP_CONFIG_FLAGS() (BOOST_PP_CONFIG_BCC())
 #    elif defined(_MSC_VER)
-#        define BOOST_PP_CONFIG_FLAGS() (BOOST_PP_CONFIG_MSVC())
+#        if !defined(_MSVC_TRADITIONAL) || _MSVC_TRADITIONAL
+#           define BOOST_PP_CONFIG_FLAGS() (BOOST_PP_CONFIG_MSVC())
+#        else
+#           define BOOST_PP_CONFIG_FLAGS() (BOOST_PP_CONFIG_STRICT())
+#        endif
 #    else
 #        define BOOST_PP_CONFIG_FLAGS() (BOOST_PP_CONFIG_STRICT())
 #    endif
@ -71,15 +79,18 @@
 # define BOOST_PP_VARIADICS_MSVC 0
 # if !defined BOOST_PP_VARIADICS
 #    /* variadic support explicitly disabled for all untested compilers */
-#    if defined __GCCXML__ || defined __CUDACC__ || defined __PATHSCALE__ || defined __DMC__ || defined __CODEGEARC__ || defined __BORLANDC__ || defined __MWERKS__ || ( defined __SUNPRO_CC && __SUNPRO_CC < 0x5120 ) || defined __HP_aCC && !defined __EDG__ || defined __MRC__ || defined __SC__ || defined __IBMCPP__ || defined __PGI
+
+#    if defined __GCCXML__ || (defined __NVCC__ && defined __CUDACC__) || defined __PATHSCALE__ || defined __DMC__ || (defined __CODEGEARC__ && !defined(__clang__)) || (defined __BORLANDC__ && !defined(__clang__)) || defined __MWERKS__ || ( defined __SUNPRO_CC && __SUNPRO_CC < 0x5120 ) || (defined __HP_aCC && !defined __EDG__) || defined __MRC__ || defined __SC__ || (defined(__PGI) && !defined(__EDG__))
 #        define BOOST_PP_VARIADICS 0
 #    elif defined(_MSC_VER) && defined(__clang__)
 #        define BOOST_PP_VARIADICS 1
 #    /* VC++ (C/C++) and Intel C++ Compiler >= 17.0 with MSVC */
 #    elif defined _MSC_VER && _MSC_VER >= 1400 && (!defined __EDG__ || defined(__INTELLISENSE__) || defined(__INTEL_COMPILER) && __INTEL_COMPILER >= 1700)
 #        define BOOST_PP_VARIADICS 1
-#        undef BOOST_PP_VARIADICS_MSVC
-#        define BOOST_PP_VARIADICS_MSVC 1
+#        if !defined(_MSVC_TRADITIONAL) || _MSVC_TRADITIONAL
+#           undef BOOST_PP_VARIADICS_MSVC
+#           define BOOST_PP_VARIADICS_MSVC 1
+#        endif
 #    /* Wave (C/C++), GCC (C++) */
 #    elif defined __WAVE__ && __WAVE_HAS_VARIADICS__ || defined __GNUC__ && defined __GXX_EXPERIMENTAL_CXX0X__ && __GXX_EXPERIMENTAL_CXX0X__
 #        define BOOST_PP_VARIADICS 1
@ -92,7 +103,7 @@
 # elif !BOOST_PP_VARIADICS + 1 < 2
 #    undef BOOST_PP_VARIADICS
 #    define BOOST_PP_VARIADICS 1
-#    if defined _MSC_VER && _MSC_VER >= 1400 && !defined(__clang__) && (defined(__INTELLISENSE__) || (defined(__INTEL_COMPILER) && __INTEL_COMPILER >= 1700) || !(defined __EDG__ || defined __GCCXML__ || defined __CUDACC__ || defined __PATHSCALE__ || defined __DMC__ || defined __CODEGEARC__ || defined __BORLANDC__ || defined __MWERKS__ || defined __SUNPRO_CC || defined __HP_aCC || defined __MRC__ || defined __SC__ || defined __IBMCPP__ || defined __PGI))
+#    if defined _MSC_VER && _MSC_VER >= 1400 && !defined(__clang__) && (defined(__INTELLISENSE__) || (defined(__INTEL_COMPILER) && __INTEL_COMPILER >= 1700) || !(defined __EDG__ || defined __GCCXML__ || (defined __NVCC__ && defined __CUDACC__) || defined __PATHSCALE__ || defined __DMC__ || defined __CODEGEARC__ || defined __BORLANDC__ || defined __MWERKS__ || defined __SUNPRO_CC || defined __HP_aCC || defined __MRC__ || defined __SC__ || defined __IBMCPP__ || defined __PGI)) && (!defined(_MSVC_TRADITIONAL) || _MSVC_TRADITIONAL)
 #        undef BOOST_PP_VARIADICS_MSVC
 #        define BOOST_PP_VARIADICS_MSVC 1
 #    endif
--- a/include/boost/preprocessor/facilities.hpp
+++ b/include/boost/preprocessor/facilities.hpp
@ -14,10 +14,12 @@
 # define BOOST_PREPROCESSOR_FACILITIES_HPP
 #
 # include <boost/preprocessor/facilities/apply.hpp>
+# include <boost/preprocessor/facilities/check_empty.hpp>
 # include <boost/preprocessor/facilities/empty.hpp>
 # include <boost/preprocessor/facilities/expand.hpp>
 # include <boost/preprocessor/facilities/identity.hpp>
 # include <boost/preprocessor/facilities/intercept.hpp>
 # include <boost/preprocessor/facilities/overload.hpp>
+# include <boost/preprocessor/facilities/va_opt.hpp>
 #
 # endif
--- a/include/boost/preprocessor/facilities/check_empty.hpp
+++ b/include/boost/preprocessor/facilities/check_empty.hpp
@ -0,0 +1,19 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2019.
+#  *     Distributed under the Boost Software License, Version 1.0. (See
+#  *     accompanying file LICENSE_1_0.txt or copy at
+#  *     http://www.boost.org/LICENSE_1_0.txt)
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# ifndef BOOST_PREPROCESSOR_FACILITIES_CHECK_EMPTY_HPP
+# define BOOST_PREPROCESSOR_FACILITIES_CHECK_EMPTY_HPP
+# include <boost/preprocessor/variadic/has_opt.hpp>
+# if BOOST_PP_VARIADIC_HAS_OPT()
+# include <boost/preprocessor/facilities/is_empty_variadic.hpp>
+# define BOOST_PP_CHECK_EMPTY(...) BOOST_PP_IS_EMPTY_OPT(__VA_ARGS__)
+# endif /* BOOST_PP_VARIADIC_HAS_OPT() */
+# endif /* BOOST_PREPROCESSOR_FACILITIES_CHECK_EMPTY_HPP */
--- a/include/boost/preprocessor/facilities/detail/is_empty.hpp
+++ b/include/boost/preprocessor/facilities/detail/is_empty.hpp
@ -31,8 +31,8 @@
 #if BOOST_PP_VARIADICS_MSVC && _MSC_VER <= 1400

 #define BOOST_PP_DETAIL_IS_EMPTY_PROCESS(param) \
-	BOOST_PP_IS_BEGIN_PARENS \
-    	( \
+    BOOST_PP_IS_BEGIN_PARENS \
+        ( \
        BOOST_PP_DETAIL_IS_EMPTY_NON_FUNCTION_C param () \
        ) \
 /**/
@ -40,7 +40,7 @@
 #else

 #define BOOST_PP_DETAIL_IS_EMPTY_PROCESS(...) \
-	BOOST_PP_IS_BEGIN_PARENS \
+    BOOST_PP_IS_BEGIN_PARENS \
        ( \
        BOOST_PP_DETAIL_IS_EMPTY_NON_FUNCTION_C __VA_ARGS__ () \
        ) \
--- a/include/boost/preprocessor/facilities/is_empty_variadic.hpp
+++ b/include/boost/preprocessor/facilities/is_empty_variadic.hpp
@ -1,6 +1,6 @@
 # /* **************************************************************************
 #  *                                                                          *
-#  *     (C) Copyright Edward Diener 2014.
+#  *     (C) Copyright Edward Diener 2014,2019.
 #  *     Distributed under the Boost Software License, Version 1.0. (See
 #  *     accompanying file LICENSE_1_0.txt or copy at
 #  *     http://www.boost.org/LICENSE_1_0.txt)
@ -37,7 +37,34 @@
 /**/
 #define BOOST_PP_IS_EMPTY_ZERO(param) 0
 # else
+# if defined(__cplusplus) && __cplusplus > 201703L
+# include <boost/preprocessor/variadic/has_opt.hpp>
 #define BOOST_PP_IS_EMPTY(...) \
+    BOOST_PP_DETAIL_IS_EMPTY_IIF \
+      ( \
+      BOOST_PP_VARIADIC_HAS_OPT() \
+      ) \
+      ( \
+      BOOST_PP_IS_EMPTY_OPT, \
+      BOOST_PP_IS_EMPTY_NO_OPT \
+      ) \
+    (__VA_ARGS__) \
+/**/
+#define BOOST_PP_IS_EMPTY_FUNCTION2(...) \
+    __VA_OPT__(0,) 1 \
+/**/
+#define BOOST_PP_IS_EMPTY_FUNCTION(...) \
+    BOOST_PP_IS_EMPTY_FUNCTION2(__VA_ARGS__) \
+/**/
+#define BOOST_PP_IS_EMPTY_OPT(...) \
+    BOOST_PP_VARIADIC_HAS_OPT_ELEM0(BOOST_PP_IS_EMPTY_FUNCTION(__VA_ARGS__),) \
+/**/
+# else
+#define BOOST_PP_IS_EMPTY(...) \
+    BOOST_PP_IS_EMPTY_NO_OPT(__VA_ARGS__) \
+/**/
+# endif /* defined(__cplusplus) && __cplusplus > 201703L */
+#define BOOST_PP_IS_EMPTY_NO_OPT(...) \
    BOOST_PP_DETAIL_IS_EMPTY_IIF \
      ( \
      BOOST_PP_IS_BEGIN_PARENS \
--- a/include/boost/preprocessor/facilities/va_opt.hpp
+++ b/include/boost/preprocessor/facilities/va_opt.hpp
@ -0,0 +1,34 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2019.
+#  *     Distributed under the Boost Software License, Version 1.0. (See
+#  *     accompanying file LICENSE_1_0.txt or copy at
+#  *     http://www.boost.org/LICENSE_1_0.txt)
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# ifndef BOOST_PREPROCESSOR_FACILITIES_VA_OPT_HPP
+# define BOOST_PREPROCESSOR_FACILITIES_VA_OPT_HPP
+# include <boost/preprocessor/variadic/has_opt.hpp>
+# if BOOST_PP_VARIADIC_HAS_OPT()
+# include <boost/preprocessor/control/iif.hpp>
+# include <boost/preprocessor/facilities/check_empty.hpp>
+# include <boost/preprocessor/tuple/rem.hpp>
+# define BOOST_PP_VA_OPT_IMPL(atuple) \
+    BOOST_PP_TUPLE_REM() atuple       \
+/**/
+# define BOOST_PP_VA_OPT(rdata,rempty,...)     \
+    BOOST_PP_VA_OPT_IMPL                       \
+        (                                      \
+        BOOST_PP_IIF                           \
+            (                                  \
+            BOOST_PP_CHECK_EMPTY(__VA_ARGS__), \
+            rempty,                            \
+            rdata                              \
+            )                                  \
+        )                                      \
+/**/
+# endif /* BOOST_PP_VARIADIC_HAS_OPT() */
+# endif /* BOOST_PREPROCESSOR_FACILITIES_VA_OPT_HPP */
--- a/include/boost/preprocessor/list/to_array.hpp
+++ b/include/boost/preprocessor/list/to_array.hpp
@ -28,13 +28,13 @@
 #
 # if BOOST_PP_VARIADICS && BOOST_PP_VARIADICS_MSVC && (_MSC_VER <= 1400)
 # define BOOST_PP_LIST_TO_ARRAY(list) \
-	BOOST_PP_IIF \
-		( \
-		BOOST_PP_LIST_IS_NIL(list), \
-		BOOST_PP_LIST_TO_ARRAY_VC8ORLESS_EMPTY, \
-		BOOST_PP_LIST_TO_ARRAY_VC8ORLESS_DO \
-		) \
-	(list) \
+    BOOST_PP_IIF \
+        ( \
+        BOOST_PP_LIST_IS_NIL(list), \
+        BOOST_PP_LIST_TO_ARRAY_VC8ORLESS_EMPTY, \
+        BOOST_PP_LIST_TO_ARRAY_VC8ORLESS_DO \
+        ) \
+    (list) \
 /**/
 # define BOOST_PP_LIST_TO_ARRAY_VC8ORLESS_EMPTY(list) (0,())
 # define BOOST_PP_LIST_TO_ARRAY_VC8ORLESS_DO(list) BOOST_PP_LIST_TO_ARRAY_I(BOOST_PP_WHILE, list)
@ -46,7 +46,7 @@
 #    define BOOST_PP_LIST_TO_ARRAY_I(w, list) \
        BOOST_PP_LIST_TO_ARRAY_II(((BOOST_PP_TUPLE_REM_CTOR( \
            3, \
-	        w(BOOST_PP_LIST_TO_ARRAY_P, BOOST_PP_LIST_TO_ARRAY_O, (list, 1, (~))) \
+            w(BOOST_PP_LIST_TO_ARRAY_P, BOOST_PP_LIST_TO_ARRAY_O, (list, 1, (~))) \
        )))) \
        /**/
 #    define BOOST_PP_LIST_TO_ARRAY_II(p) BOOST_PP_LIST_TO_ARRAY_II_B(p)
@ -56,7 +56,7 @@
 #    define BOOST_PP_LIST_TO_ARRAY_I(w, list) \
        BOOST_PP_LIST_TO_ARRAY_II(BOOST_PP_TUPLE_REM_CTOR( \
            3, \
-	        w(BOOST_PP_LIST_TO_ARRAY_P, BOOST_PP_LIST_TO_ARRAY_O, (list, 1, (~))) \
+            w(BOOST_PP_LIST_TO_ARRAY_P, BOOST_PP_LIST_TO_ARRAY_O, (list, 1, (~))) \
        )) \
        /**/
 #    define BOOST_PP_LIST_TO_ARRAY_II(im) BOOST_PP_LIST_TO_ARRAY_III(im)
@ -138,13 +138,13 @@
 #
 # if BOOST_PP_VARIADICS && BOOST_PP_VARIADICS_MSVC && (_MSC_VER <= 1400)
 # define BOOST_PP_LIST_TO_ARRAY_D(d, list) \
-	BOOST_PP_IIF \
-		( \
-		BOOST_PP_LIST_IS_NIL(list), \
-		BOOST_PP_LIST_TO_ARRAY_D_VC8ORLESS_EMPTY, \
-		BOOST_PP_LIST_TO_ARRAY_D_VC8ORLESS_DO \
-		) \
-	(d, list) \
+    BOOST_PP_IIF \
+        ( \
+        BOOST_PP_LIST_IS_NIL(list), \
+        BOOST_PP_LIST_TO_ARRAY_D_VC8ORLESS_EMPTY, \
+        BOOST_PP_LIST_TO_ARRAY_D_VC8ORLESS_DO \
+        ) \
+    (d, list) \
 /**/
 # define BOOST_PP_LIST_TO_ARRAY_D_VC8ORLESS_EMPTY(d, list) (0,())
 # define BOOST_PP_LIST_TO_ARRAY_D_VC8ORLESS_DO(d, list) BOOST_PP_LIST_TO_ARRAY_I(BOOST_PP_WHILE_ ## d, list)
--- a/include/boost/preprocessor/list/to_tuple.hpp
+++ b/include/boost/preprocessor/list/to_tuple.hpp
@ -21,13 +21,13 @@
 # /* BOOST_PP_LIST_TO_TUPLE */
 #
 # define BOOST_PP_LIST_TO_TUPLE(list) \
-	BOOST_PP_IIF \
-		( \
-		BOOST_PP_LIST_IS_NIL(list), \
-		BOOST_PP_LIST_TO_TUPLE_EMPTY, \
-		BOOST_PP_LIST_TO_TUPLE_DO \
-		) \
-	(list) \
+    BOOST_PP_IIF \
+        ( \
+        BOOST_PP_LIST_IS_NIL(list), \
+        BOOST_PP_LIST_TO_TUPLE_EMPTY, \
+        BOOST_PP_LIST_TO_TUPLE_DO \
+        ) \
+    (list) \
 /**/
 # define BOOST_PP_LIST_TO_TUPLE_EMPTY(list)
 #
@ -41,13 +41,13 @@
 # /* BOOST_PP_LIST_TO_TUPLE_R */
 #
 # define BOOST_PP_LIST_TO_TUPLE_R(r, list) \
-	BOOST_PP_IIF \
-		( \
-		BOOST_PP_LIST_IS_NIL(list), \
-		BOOST_PP_LIST_TO_TUPLE_R_EMPTY, \
-		BOOST_PP_LIST_TO_TUPLE_R_DO \
-		) \
-	(r, list) \
+    BOOST_PP_IIF \
+        ( \
+        BOOST_PP_LIST_IS_NIL(list), \
+        BOOST_PP_LIST_TO_TUPLE_R_EMPTY, \
+        BOOST_PP_LIST_TO_TUPLE_R_DO \
+        ) \
+    (r, list) \
 /**/
 # define BOOST_PP_LIST_TO_TUPLE_R_EMPTY(r,list)
 #
--- a/include/boost/preprocessor/repetition/for.hpp
+++ b/include/boost/preprocessor/repetition/for.hpp
@ -52,13 +52,13 @@

 # define BOOST_PP_FOR_257_ERROR() BOOST_PP_ERROR(0x0002)
 # define BOOST_PP_FOR_257(s, p, o, m) \
-	BOOST_PP_IIF \
-		( \
-		BOOST_PP_FOR_257_PR(s,p), \
-		BOOST_PP_FOR_257_ERROR, \
-		BOOST_PP_EMPTY \
-		) \
-	() \
+    BOOST_PP_IIF \
+        ( \
+        BOOST_PP_FOR_257_PR(s,p), \
+        BOOST_PP_FOR_257_ERROR, \
+        BOOST_PP_EMPTY \
+        ) \
+    () \
 /**/
 // # define BOOST_PP_FOR_257(s, p, o, m) BOOST_PP_ERROR(0x0002)
 #
--- a/include/boost/preprocessor/seq/detail/binary_transform.hpp
+++ b/include/boost/preprocessor/seq/detail/binary_transform.hpp
@ -30,13 +30,13 @@
 # endif
 # if BOOST_PP_VARIADICS
 #    if BOOST_PP_VARIADICS_MSVC
-#		define BOOST_PP_SEQ_BINARY_TRANSFORM_REM(data) data
+#       define BOOST_PP_SEQ_BINARY_TRANSFORM_REM(data) data
 #       define BOOST_PP_SEQ_BINARY_TRANSFORM_A(...) (BOOST_PP_SEQ_BINARY_TRANSFORM_REM, __VA_ARGS__)() BOOST_PP_SEQ_BINARY_TRANSFORM_B
 #       define BOOST_PP_SEQ_BINARY_TRANSFORM_B(...) (BOOST_PP_SEQ_BINARY_TRANSFORM_REM, __VA_ARGS__)() BOOST_PP_SEQ_BINARY_TRANSFORM_A
-#	 else
+#    else
 #       define BOOST_PP_SEQ_BINARY_TRANSFORM_A(...) (BOOST_PP_REM, __VA_ARGS__)() BOOST_PP_SEQ_BINARY_TRANSFORM_B
 #       define BOOST_PP_SEQ_BINARY_TRANSFORM_B(...) (BOOST_PP_REM, __VA_ARGS__)() BOOST_PP_SEQ_BINARY_TRANSFORM_A
-#	 endif
+#    endif
 # else
 #    define BOOST_PP_SEQ_BINARY_TRANSFORM_A(e) (BOOST_PP_REM, e)() BOOST_PP_SEQ_BINARY_TRANSFORM_B
 #    define BOOST_PP_SEQ_BINARY_TRANSFORM_B(e) (BOOST_PP_REM, e)() BOOST_PP_SEQ_BINARY_TRANSFORM_A
--- a/include/boost/preprocessor/seq/detail/is_empty.hpp
+++ b/include/boost/preprocessor/seq/detail/is_empty.hpp
@ -21,29 +21,29 @@
 /* An empty seq is one that is just BOOST_PP_SEQ_NIL */
 #
 # define BOOST_PP_SEQ_DETAIL_IS_EMPTY(seq) \
-	BOOST_PP_COMPL \
-		( \
-		BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq) \
-		) \
+    BOOST_PP_COMPL \
+        ( \
+        BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq) \
+        ) \
 /**/
 #
 # define BOOST_PP_SEQ_DETAIL_IS_EMPTY_SIZE(size) \
-	BOOST_PP_COMPL \
-		( \
-		BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY_SIZE(size) \
-		) \
+    BOOST_PP_COMPL \
+        ( \
+        BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY_SIZE(size) \
+        ) \
 /**/
 #
 # define BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq) \
-	BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY_SIZE(BOOST_PP_SEQ_DETAIL_EMPTY_SIZE(seq)) \
+    BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY_SIZE(BOOST_PP_SEQ_DETAIL_EMPTY_SIZE(seq)) \
 /**/
 #
 # define BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY_SIZE(size) \
-	BOOST_PP_BOOL(size) \
+    BOOST_PP_BOOL(size) \
 /**/
 #
 # define BOOST_PP_SEQ_DETAIL_EMPTY_SIZE(seq) \
-	BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(seq (nil))) \
+    BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(seq (nil))) \
 /**/
 #
 # endif
--- a/include/boost/preprocessor/seq/for_each.hpp
+++ b/include/boost/preprocessor/seq/for_each.hpp
@ -36,13 +36,13 @@
 #    define BOOST_PP_SEQ_FOR_EACH_DETAIL_CHECK_EMPTY(macro, data, seq)
 #
 #    define BOOST_PP_SEQ_FOR_EACH_DETAIL_CHECK(macro, data, seq) \
-		BOOST_PP_IIF \
-			( \
-			BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq), \
-			BOOST_PP_SEQ_FOR_EACH_DETAIL_CHECK_EXEC, \
-			BOOST_PP_SEQ_FOR_EACH_DETAIL_CHECK_EMPTY \
-			) \
-		(macro, data, seq) \
+        BOOST_PP_IIF \
+            ( \
+            BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq), \
+            BOOST_PP_SEQ_FOR_EACH_DETAIL_CHECK_EXEC, \
+            BOOST_PP_SEQ_FOR_EACH_DETAIL_CHECK_EMPTY \
+            ) \
+        (macro, data, seq) \
 /**/
 #
 # define BOOST_PP_SEQ_FOR_EACH_P(r, x) BOOST_PP_TUPLE_ELEM(4, 3, x)
@ -54,21 +54,21 @@
 # endif
 #
 # define BOOST_PP_SEQ_FOR_EACH_O_I(macro, data, seq, sz) \
-	BOOST_PP_SEQ_FOR_EACH_O_I_DEC(macro, data, seq, BOOST_PP_DEC(sz)) \
+    BOOST_PP_SEQ_FOR_EACH_O_I_DEC(macro, data, seq, BOOST_PP_DEC(sz)) \
 /**/
 # define BOOST_PP_SEQ_FOR_EACH_O_I_DEC(macro, data, seq, sz) \
-	( \
-	macro, \
-	data, \
-	BOOST_PP_IF \
-		( \
-		sz, \
-		BOOST_PP_SEQ_FOR_EACH_O_I_TAIL, \
-		BOOST_PP_SEQ_FOR_EACH_O_I_NIL \
-		) \
-	(seq), \
-	sz \
-	) \
+    ( \
+    macro, \
+    data, \
+    BOOST_PP_IF \
+        ( \
+        sz, \
+        BOOST_PP_SEQ_FOR_EACH_O_I_TAIL, \
+        BOOST_PP_SEQ_FOR_EACH_O_I_NIL \
+        ) \
+    (seq), \
+    sz \
+    ) \
 /**/
 # define BOOST_PP_SEQ_FOR_EACH_O_I_TAIL(seq) BOOST_PP_SEQ_TAIL(seq)
 # define BOOST_PP_SEQ_FOR_EACH_O_I_NIL(seq) BOOST_PP_NIL
@ -95,13 +95,13 @@
 #    define BOOST_PP_SEQ_FOR_EACH_DETAIL_CHECK_EMPTY_R(r, macro, data, seq)
 #
 #    define BOOST_PP_SEQ_FOR_EACH_DETAIL_CHECK_R(r, macro, data, seq) \
-		BOOST_PP_IIF \
-			( \
-			BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq), \
-			BOOST_PP_SEQ_FOR_EACH_DETAIL_CHECK_EXEC_R, \
-			BOOST_PP_SEQ_FOR_EACH_DETAIL_CHECK_EMPTY_R \
-			) \
-		(r, macro, data, seq) \
+        BOOST_PP_IIF \
+            ( \
+            BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq), \
+            BOOST_PP_SEQ_FOR_EACH_DETAIL_CHECK_EXEC_R, \
+            BOOST_PP_SEQ_FOR_EACH_DETAIL_CHECK_EMPTY_R \
+            ) \
+        (r, macro, data, seq) \
 /**/
 #
 # endif
--- a/include/boost/preprocessor/seq/for_each_i.hpp
+++ b/include/boost/preprocessor/seq/for_each_i.hpp
@ -37,13 +37,13 @@
 #    define BOOST_PP_SEQ_FOR_EACH_I_DETAIL_CHECK_EMPTY(macro, data, seq)
 #
 #    define BOOST_PP_SEQ_FOR_EACH_I_DETAIL_CHECK(macro, data, seq) \
-		BOOST_PP_IIF \
-			( \
-			BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq), \
-			BOOST_PP_SEQ_FOR_EACH_I_DETAIL_CHECK_EXEC, \
-			BOOST_PP_SEQ_FOR_EACH_I_DETAIL_CHECK_EMPTY \
-			) \
-		(macro, data, seq) \
+        BOOST_PP_IIF \
+            ( \
+            BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq), \
+            BOOST_PP_SEQ_FOR_EACH_I_DETAIL_CHECK_EXEC, \
+            BOOST_PP_SEQ_FOR_EACH_I_DETAIL_CHECK_EMPTY \
+            ) \
+        (macro, data, seq) \
 /**/
 #
 # define BOOST_PP_SEQ_FOR_EACH_I_P(r, x) BOOST_PP_TUPLE_ELEM(5, 4, x)
@ -55,22 +55,22 @@
 # endif
 #
 # define BOOST_PP_SEQ_FOR_EACH_I_O_I(macro, data, seq, i, sz) \
-	BOOST_PP_SEQ_FOR_EACH_I_O_I_DEC(macro, data, seq, i, BOOST_PP_DEC(sz)) \
+    BOOST_PP_SEQ_FOR_EACH_I_O_I_DEC(macro, data, seq, i, BOOST_PP_DEC(sz)) \
 /**/
 # define BOOST_PP_SEQ_FOR_EACH_I_O_I_DEC(macro, data, seq, i, sz) \
-	( \
-	macro, \
-	data, \
-	BOOST_PP_IF \
-		( \
-		sz, \
-		BOOST_PP_SEQ_FOR_EACH_I_O_I_TAIL, \
-		BOOST_PP_SEQ_FOR_EACH_I_O_I_NIL \
-		) \
-	(seq), \
-	BOOST_PP_INC(i), \
-	sz \
-	) \
+    ( \
+    macro, \
+    data, \
+    BOOST_PP_IF \
+        ( \
+        sz, \
+        BOOST_PP_SEQ_FOR_EACH_I_O_I_TAIL, \
+        BOOST_PP_SEQ_FOR_EACH_I_O_I_NIL \
+        ) \
+    (seq), \
+    BOOST_PP_INC(i), \
+    sz \
+    ) \
 /**/
 # define BOOST_PP_SEQ_FOR_EACH_I_O_I_TAIL(seq) BOOST_PP_SEQ_TAIL(seq)
 # define BOOST_PP_SEQ_FOR_EACH_I_O_I_NIL(seq) BOOST_PP_NIL
@ -97,13 +97,13 @@
 #    define BOOST_PP_SEQ_FOR_EACH_I_R_DETAIL_CHECK_EMPTY(r, macro, data, seq)
 #
 #    define BOOST_PP_SEQ_FOR_EACH_I_R_DETAIL_CHECK(r, macro, data, seq) \
-		BOOST_PP_IIF \
-			( \
-			BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq), \
-			BOOST_PP_SEQ_FOR_EACH_I_R_DETAIL_CHECK_EXEC, \
-			BOOST_PP_SEQ_FOR_EACH_I_R_DETAIL_CHECK_EMPTY \
-			) \
-		(r, macro, data, seq) \
+        BOOST_PP_IIF \
+            ( \
+            BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY(seq), \
+            BOOST_PP_SEQ_FOR_EACH_I_R_DETAIL_CHECK_EXEC, \
+            BOOST_PP_SEQ_FOR_EACH_I_R_DETAIL_CHECK_EMPTY \
+            ) \
+        (r, macro, data, seq) \
 /**/
 #
 # endif
--- a/include/boost/preprocessor/seq/replace.hpp
+++ b/include/boost/preprocessor/seq/replace.hpp
@ -33,13 +33,13 @@
 #    define BOOST_PP_SEQ_REPLACE_DETAIL_REST_EMPTY(seq, i)
 #    define BOOST_PP_SEQ_REPLACE_DETAIL_REST_VALID(seq, i) BOOST_PP_SEQ_REST_N(BOOST_PP_INC(i), seq)
 #    define BOOST_PP_SEQ_REPLACE_DETAIL_REST(seq, i) \
-		BOOST_PP_IIF \
-			( \
-			BOOST_PP_EQUAL(i,BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(seq))), \
-			BOOST_PP_SEQ_REPLACE_DETAIL_REST_EMPTY, \
-			BOOST_PP_SEQ_REPLACE_DETAIL_REST_VALID \
-			) \
-		(seq, i) \
+        BOOST_PP_IIF \
+            ( \
+            BOOST_PP_EQUAL(i,BOOST_PP_DEC(BOOST_PP_SEQ_SIZE(seq))), \
+            BOOST_PP_SEQ_REPLACE_DETAIL_REST_EMPTY, \
+            BOOST_PP_SEQ_REPLACE_DETAIL_REST_VALID \
+            ) \
+        (seq, i) \
 /**/
 #
 # endif
--- a/include/boost/preprocessor/seq/rest_n.hpp
+++ b/include/boost/preprocessor/seq/rest_n.hpp
@ -32,15 +32,15 @@
 # endif
 #
 #    define BOOST_PP_SEQ_REST_N_DETAIL_EXEC(n, seq, size) \
-		BOOST_PP_EXPR_IIF \
-			( \
-			BOOST_PP_BITAND \
-				( \
-				BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY_SIZE(size), \
-				BOOST_PP_NOT_EQUAL(n,size) \
-				), \
-			BOOST_PP_TUPLE_ELEM(2, 1, BOOST_PP_SEQ_SPLIT(BOOST_PP_INC(n), BOOST_PP_IDENTITY( (nil) seq )))() \
-			) \
+        BOOST_PP_EXPR_IIF \
+            ( \
+            BOOST_PP_BITAND \
+                ( \
+                BOOST_PP_SEQ_DETAIL_IS_NOT_EMPTY_SIZE(size), \
+                BOOST_PP_NOT_EQUAL(n,size) \
+                ), \
+            BOOST_PP_TUPLE_ELEM(2, 1, BOOST_PP_SEQ_SPLIT(BOOST_PP_INC(n), BOOST_PP_IDENTITY( (nil) seq )))() \
+            ) \
 /**/
 #
 # endif
--- a/include/boost/preprocessor/stringize.hpp
+++ b/include/boost/preprocessor/stringize.hpp
@ -28,6 +28,10 @@
 #    define BOOST_PP_STRINGIZE(text) BOOST_PP_STRINGIZE_I(text)
 # endif
 #
+#if BOOST_PP_VARIADICS
+# define BOOST_PP_STRINGIZE_I(...) #__VA_ARGS__
+#else
 # define BOOST_PP_STRINGIZE_I(text) #text
+#endif
 #
 # endif
--- a/include/boost/preprocessor/tuple/detail/is_single_return.hpp
+++ b/include/boost/preprocessor/tuple/detail/is_single_return.hpp
@ -20,9 +20,9 @@
 # include <boost/preprocessor/control/iif.hpp>
 # include <boost/preprocessor/facilities/is_1.hpp>
 # include <boost/preprocessor/tuple/size.hpp>
-# define BOOST_PP_TUPLE_IS_SINGLE_RETURN(sr,nsr,tuple)	\
-	BOOST_PP_IIF(BOOST_PP_IS_1(BOOST_PP_TUPLE_SIZE(tuple)),sr,nsr) \
-	/**/
+# define BOOST_PP_TUPLE_IS_SINGLE_RETURN(sr,nsr,tuple)  \
+    BOOST_PP_IIF(BOOST_PP_IS_1(BOOST_PP_TUPLE_SIZE(tuple)),sr,nsr) \
+    /**/
 # endif /* BOOST_PP_VARIADICS && BOOST_PP_VARIADICS_MSVC */
 #
 # endif /* BOOST_PREPROCESSOR_TUPLE_DETAIL_IS_SINGLE_RETURN_HPP */
--- a/include/boost/preprocessor/tuple/elem.hpp
+++ b/include/boost/preprocessor/tuple/elem.hpp
@ -33,12 +33,12 @@
  else use BOOST_PP_REM. This fixes a VC++ problem with an empty tuple and BOOST_PP_TUPLE_ELEM
  functionality. See tuple_elem_bug_test.cxx.
 */
-#    	 define BOOST_PP_TUPLE_ELEM_O_2(n, tuple) \
-			BOOST_PP_VARIADIC_ELEM(n, BOOST_PP_EXPAND(BOOST_PP_TUPLE_IS_SINGLE_RETURN(BOOST_PP_REM_CAT,BOOST_PP_REM,tuple) tuple)) \
-			/**/
+#        define BOOST_PP_TUPLE_ELEM_O_2(n, tuple) \
+            BOOST_PP_VARIADIC_ELEM(n, BOOST_PP_EXPAND(BOOST_PP_TUPLE_IS_SINGLE_RETURN(BOOST_PP_REM_CAT,BOOST_PP_REM,tuple) tuple)) \
+            /**/
 #    else
 #        define BOOST_PP_TUPLE_ELEM(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_ELEM_O_, __VA_ARGS__)(__VA_ARGS__)
-#    	 define BOOST_PP_TUPLE_ELEM_O_2(n, tuple) BOOST_PP_VARIADIC_ELEM(n, BOOST_PP_REM tuple)
+#        define BOOST_PP_TUPLE_ELEM_O_2(n, tuple) BOOST_PP_VARIADIC_ELEM(n, BOOST_PP_REM tuple)
 #    endif
 #    define BOOST_PP_TUPLE_ELEM_O_3(size, n, tuple) BOOST_PP_TUPLE_ELEM_O_2(n, tuple)
 # else
--- a/include/boost/preprocessor/tuple/insert.hpp
+++ b/include/boost/preprocessor/tuple/insert.hpp
@ -23,13 +23,13 @@
 # /* BOOST_PP_TUPLE_INSERT */
 #
 # define BOOST_PP_TUPLE_INSERT(tuple, i, elem) \
-	BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_INSERT(BOOST_PP_TUPLE_TO_ARRAY(tuple), i, elem)) \
+    BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_INSERT(BOOST_PP_TUPLE_TO_ARRAY(tuple), i, elem)) \
 /**/
 #
 # /* BOOST_PP_TUPLE_INSERT_D */
 #
 # define BOOST_PP_TUPLE_INSERT_D(d, tuple, i, elem) \
-	BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_INSERT_D(d, BOOST_PP_TUPLE_TO_ARRAY(tuple), i, elem)) \
+    BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_INSERT_D(d, BOOST_PP_TUPLE_TO_ARRAY(tuple), i, elem)) \
 /**/
 #
 # endif // BOOST_PP_VARIADICS
--- a/include/boost/preprocessor/tuple/pop_back.hpp
+++ b/include/boost/preprocessor/tuple/pop_back.hpp
@ -26,17 +26,17 @@
 # /* BOOST_PP_TUPLE_POP_BACK */
 #
 # define BOOST_PP_TUPLE_POP_BACK(tuple) \
-	BOOST_PP_IIF \
-		( \
-		BOOST_PP_GREATER(BOOST_PP_TUPLE_SIZE(tuple),1), \
-		BOOST_PP_TUPLE_POP_BACK_EXEC, \
-		BOOST_PP_TUPLE_POP_BACK_RETURN \
-		) \
-	(tuple) \
+    BOOST_PP_IIF \
+        ( \
+        BOOST_PP_GREATER(BOOST_PP_TUPLE_SIZE(tuple),1), \
+        BOOST_PP_TUPLE_POP_BACK_EXEC, \
+        BOOST_PP_TUPLE_POP_BACK_RETURN \
+        ) \
+    (tuple) \
 /**/
 #
 # define BOOST_PP_TUPLE_POP_BACK_EXEC(tuple) \
-	BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_POP_BACK(BOOST_PP_TUPLE_TO_ARRAY(tuple))) \
+    BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_POP_BACK(BOOST_PP_TUPLE_TO_ARRAY(tuple))) \
 /**/
 #
 # define BOOST_PP_TUPLE_POP_BACK_RETURN(tuple) tuple
@ -44,17 +44,17 @@
 # /* BOOST_PP_TUPLE_POP_BACK_Z */
 #
 # define BOOST_PP_TUPLE_POP_BACK_Z(z, tuple) \
-	BOOST_PP_IIF \
-		( \
-		BOOST_PP_GREATER(BOOST_PP_TUPLE_SIZE(tuple),1), \
-		BOOST_PP_TUPLE_POP_BACK_Z_EXEC, \
-		BOOST_PP_TUPLE_POP_BACK_Z_RETURN \
-		) \
-	(z, tuple) \
+    BOOST_PP_IIF \
+        ( \
+        BOOST_PP_GREATER(BOOST_PP_TUPLE_SIZE(tuple),1), \
+        BOOST_PP_TUPLE_POP_BACK_Z_EXEC, \
+        BOOST_PP_TUPLE_POP_BACK_Z_RETURN \
+        ) \
+    (z, tuple) \
 /**/
 #
 # define BOOST_PP_TUPLE_POP_BACK_Z_EXEC(z, tuple) \
-	BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_POP_BACK_Z(z, BOOST_PP_TUPLE_TO_ARRAY(tuple))) \
+    BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_POP_BACK_Z(z, BOOST_PP_TUPLE_TO_ARRAY(tuple))) \
 /**/
 #
 # define BOOST_PP_TUPLE_POP_BACK_Z_RETURN(z, tuple) tuple
--- a/include/boost/preprocessor/tuple/pop_front.hpp
+++ b/include/boost/preprocessor/tuple/pop_front.hpp
@ -27,17 +27,17 @@
 # /* BOOST_PP_TUPLE_POP_FRONT */
 #
 # define BOOST_PP_TUPLE_POP_FRONT(tuple) \
-	BOOST_PP_IIF \
-		( \
-		BOOST_PP_GREATER(BOOST_PP_TUPLE_SIZE(tuple),1), \
-		BOOST_PP_TUPLE_POP_FRONT_EXEC, \
-		BOOST_PP_TUPLE_POP_FRONT_RETURN \
-		) \
-	(tuple) \
+    BOOST_PP_IIF \
+        ( \
+        BOOST_PP_GREATER(BOOST_PP_TUPLE_SIZE(tuple),1), \
+        BOOST_PP_TUPLE_POP_FRONT_EXEC, \
+        BOOST_PP_TUPLE_POP_FRONT_RETURN \
+        ) \
+    (tuple) \
 /**/
 #
 # define BOOST_PP_TUPLE_POP_FRONT_EXEC(tuple) \
-	BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_POP_FRONT(BOOST_PP_TUPLE_TO_ARRAY(tuple))) \
+    BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_POP_FRONT(BOOST_PP_TUPLE_TO_ARRAY(tuple))) \
 /**/
 #
 # define BOOST_PP_TUPLE_POP_FRONT_RETURN(tuple) tuple
@ -45,17 +45,17 @@
 # /* BOOST_PP_TUPLE_POP_FRONT_Z */
 #
 # define BOOST_PP_TUPLE_POP_FRONT_Z(z, tuple) \
-	BOOST_PP_IIF \
-		( \
-		BOOST_PP_GREATER(BOOST_PP_TUPLE_SIZE(tuple),1), \
-		BOOST_PP_TUPLE_POP_FRONT_Z_EXEC, \
-		BOOST_PP_TUPLE_POP_FRONT_Z_RETURN \
-		) \
-	(z, tuple) \
+    BOOST_PP_IIF \
+        ( \
+        BOOST_PP_GREATER(BOOST_PP_TUPLE_SIZE(tuple),1), \
+        BOOST_PP_TUPLE_POP_FRONT_Z_EXEC, \
+        BOOST_PP_TUPLE_POP_FRONT_Z_RETURN \
+        ) \
+    (z, tuple) \
 /**/
 #
 # define BOOST_PP_TUPLE_POP_FRONT_Z_EXEC(z, tuple) \
-	BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_POP_FRONT_Z(z, BOOST_PP_TUPLE_TO_ARRAY(tuple))) \
+    BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_POP_FRONT_Z(z, BOOST_PP_TUPLE_TO_ARRAY(tuple))) \
 /**/
 #
 # define BOOST_PP_TUPLE_POP_FRONT_Z_RETURN(z, tuple) tuple
--- a/include/boost/preprocessor/tuple/push_back.hpp
+++ b/include/boost/preprocessor/tuple/push_back.hpp
@ -23,7 +23,7 @@
 # /* BOOST_PP_TUPLE_PUSH_BACK */
 #
 # define BOOST_PP_TUPLE_PUSH_BACK(tuple, elem) \
-	BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_PUSH_BACK(BOOST_PP_TUPLE_TO_ARRAY(tuple), elem)) \
+    BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_PUSH_BACK(BOOST_PP_TUPLE_TO_ARRAY(tuple), elem)) \
 /**/
 #
 # endif // BOOST_PP_VARIADICS
--- a/include/boost/preprocessor/tuple/push_front.hpp
+++ b/include/boost/preprocessor/tuple/push_front.hpp
@ -24,7 +24,7 @@
 # /* BOOST_PP_TUPLE_PUSH_FRONT */
 #
 # define BOOST_PP_TUPLE_PUSH_FRONT(tuple, elem) \
-	BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_PUSH_FRONT(BOOST_PP_TUPLE_TO_ARRAY(tuple), elem)) \
+    BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_PUSH_FRONT(BOOST_PP_TUPLE_TO_ARRAY(tuple), elem)) \
 /**/
 #
 # endif // BOOST_PP_VARIADICS
--- a/include/boost/preprocessor/tuple/rem.hpp
+++ b/include/boost/preprocessor/tuple/rem.hpp
@ -22,10 +22,10 @@
 # /* BOOST_PP_REM */
 #
 # if BOOST_PP_VARIADICS
-# 	 if BOOST_PP_VARIADICS_MSVC
-		/* To be used internally when __VA_ARGS__ could be empty ( or is a single element ) */
-#    	define BOOST_PP_REM_CAT(...) BOOST_PP_CAT(__VA_ARGS__,)
-# 	 endif
+#    if BOOST_PP_VARIADICS_MSVC
+        /* To be used internally when __VA_ARGS__ could be empty ( or is a single element ) */
+#       define BOOST_PP_REM_CAT(...) BOOST_PP_CAT(__VA_ARGS__,)
+#    endif
 #    define BOOST_PP_REM(...) __VA_ARGS__
 # else
 #    define BOOST_PP_REM(x) x
@ -37,10 +37,10 @@
  VC++8.0 cannot handle the variadic version of BOOST_PP_TUPLE_REM(size)
 */
 # if BOOST_PP_VARIADICS && !(BOOST_PP_VARIADICS_MSVC && _MSC_VER <= 1400)
-# 	 if BOOST_PP_VARIADICS_MSVC
-		/* To be used internally when the size could be 0 ( or 1 ) */
-#    	define BOOST_PP_TUPLE_REM_CAT(size) BOOST_PP_REM_CAT
-# 	 endif
+#    if BOOST_PP_VARIADICS_MSVC
+        /* To be used internally when the size could be 0 ( or 1 ) */
+#       define BOOST_PP_TUPLE_REM_CAT(size) BOOST_PP_REM_CAT
+#    endif
 #    define BOOST_PP_TUPLE_REM(size) BOOST_PP_REM
 # else
 #    if ~BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MWCC()
@ -124,10 +124,10 @@
 #        define BOOST_PP_TUPLE_REM_CTOR(...) BOOST_PP_TUPLE_REM_CTOR_I(BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_REM_CTOR_O_, __VA_ARGS__), (__VA_ARGS__))
 #        define BOOST_PP_TUPLE_REM_CTOR_I(m, args) BOOST_PP_TUPLE_REM_CTOR_II(m, args)
 #        define BOOST_PP_TUPLE_REM_CTOR_II(m, args) BOOST_PP_CAT(m ## args,)
-#    	 define BOOST_PP_TUPLE_REM_CTOR_O_1(tuple) BOOST_PP_EXPAND(BOOST_PP_TUPLE_IS_SINGLE_RETURN(BOOST_PP_REM_CAT,BOOST_PP_REM,tuple) tuple)
+#        define BOOST_PP_TUPLE_REM_CTOR_O_1(tuple) BOOST_PP_EXPAND(BOOST_PP_TUPLE_IS_SINGLE_RETURN(BOOST_PP_REM_CAT,BOOST_PP_REM,tuple) tuple)
 #    else
 #        define BOOST_PP_TUPLE_REM_CTOR(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_REM_CTOR_O_, __VA_ARGS__)(__VA_ARGS__)
-#    	 define BOOST_PP_TUPLE_REM_CTOR_O_1(tuple) BOOST_PP_REM tuple
+#        define BOOST_PP_TUPLE_REM_CTOR_O_1(tuple) BOOST_PP_REM tuple
 #    endif
 #    define BOOST_PP_TUPLE_REM_CTOR_O_2(size, tuple) BOOST_PP_TUPLE_REM_CTOR_O_1(tuple)
 # else
--- a/include/boost/preprocessor/tuple/remove.hpp
+++ b/include/boost/preprocessor/tuple/remove.hpp
@ -26,17 +26,17 @@
 # /* BOOST_PP_TUPLE_REMOVE */
 #
 # define BOOST_PP_TUPLE_REMOVE(tuple, i) \
-	BOOST_PP_IIF \
-		( \
-		BOOST_PP_GREATER(BOOST_PP_TUPLE_SIZE(tuple),1), \
-		BOOST_PP_TUPLE_REMOVE_EXEC, \
-		BOOST_PP_TUPLE_REMOVE_RETURN \
-		) \
-	(tuple, i) \
+    BOOST_PP_IIF \
+        ( \
+        BOOST_PP_GREATER(BOOST_PP_TUPLE_SIZE(tuple),1), \
+        BOOST_PP_TUPLE_REMOVE_EXEC, \
+        BOOST_PP_TUPLE_REMOVE_RETURN \
+        ) \
+    (tuple, i) \
 /**/
 #
 # define BOOST_PP_TUPLE_REMOVE_EXEC(tuple, i) \
-	BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_REMOVE(BOOST_PP_TUPLE_TO_ARRAY(tuple), i)) \
+    BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_REMOVE(BOOST_PP_TUPLE_TO_ARRAY(tuple), i)) \
 /**/
 #
 # define BOOST_PP_TUPLE_REMOVE_RETURN(tuple, i) tuple
@ -44,17 +44,17 @@
 # /* BOOST_PP_TUPLE_REMOVE_D */
 #
 # define BOOST_PP_TUPLE_REMOVE_D(d, tuple, i) \
-	BOOST_PP_IIF \
-		( \
-		BOOST_PP_GREATER_D(d, BOOST_PP_TUPLE_SIZE(tuple), 1), \
-		BOOST_PP_TUPLE_REMOVE_D_EXEC, \
-		BOOST_PP_TUPLE_REMOVE_D_RETURN \
-		) \
-	(d, tuple, i) \
+    BOOST_PP_IIF \
+        ( \
+        BOOST_PP_GREATER_D(d, BOOST_PP_TUPLE_SIZE(tuple), 1), \
+        BOOST_PP_TUPLE_REMOVE_D_EXEC, \
+        BOOST_PP_TUPLE_REMOVE_D_RETURN \
+        ) \
+    (d, tuple, i) \
 /**/
 #
 # define BOOST_PP_TUPLE_REMOVE_D_EXEC(d, tuple, i) \
-	BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_REMOVE_D(d, BOOST_PP_TUPLE_TO_ARRAY(tuple), i)) \
+    BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_REMOVE_D(d, BOOST_PP_TUPLE_TO_ARRAY(tuple), i)) \
 /**/
 #
 # define BOOST_PP_TUPLE_REMOVE_D_RETURN(d, tuple, i) tuple
--- a/include/boost/preprocessor/tuple/replace.hpp
+++ b/include/boost/preprocessor/tuple/replace.hpp
@ -23,13 +23,13 @@
 # /* BOOST_PP_TUPLE_REPLACE */
 #
 # define BOOST_PP_TUPLE_REPLACE(tuple, i, elem) \
-	BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_REPLACE(BOOST_PP_TUPLE_TO_ARRAY(tuple), i, elem)) \
+    BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_REPLACE(BOOST_PP_TUPLE_TO_ARRAY(tuple), i, elem)) \
 /**/
 #
 # /* BOOST_PP_TUPLE_REPLACE_D */
 #
 # define BOOST_PP_TUPLE_REPLACE_D(d, tuple, i, elem) \
-	BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_REPLACE_D(d, BOOST_PP_TUPLE_TO_ARRAY(tuple), i, elem)) \
+    BOOST_PP_ARRAY_TO_TUPLE(BOOST_PP_ARRAY_REPLACE_D(d, BOOST_PP_TUPLE_TO_ARRAY(tuple), i, elem)) \
 /**/
 #
 # endif // BOOST_PP_VARIADICS
--- a/include/boost/preprocessor/tuple/reverse.hpp
+++ b/include/boost/preprocessor/tuple/reverse.hpp
@ -28,10 +28,10 @@
 #        define BOOST_PP_TUPLE_REVERSE(...) BOOST_PP_TUPLE_REVERSE_I(BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_REVERSE_O_, __VA_ARGS__), (__VA_ARGS__))
 #        define BOOST_PP_TUPLE_REVERSE_I(m, args) BOOST_PP_TUPLE_REVERSE_II(m, args)
 #        define BOOST_PP_TUPLE_REVERSE_II(m, args) BOOST_PP_CAT(m ## args,)
-#    	 define BOOST_PP_TUPLE_REVERSE_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_REVERSE_, BOOST_PP_TUPLE_SIZE(tuple)) tuple
+#        define BOOST_PP_TUPLE_REVERSE_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_REVERSE_, BOOST_PP_TUPLE_SIZE(tuple)) tuple
 #    else
 #        define BOOST_PP_TUPLE_REVERSE(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_REVERSE_O_, __VA_ARGS__)(__VA_ARGS__)
-#    	 define BOOST_PP_TUPLE_REVERSE_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_REVERSE_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        define BOOST_PP_TUPLE_REVERSE_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_REVERSE_, BOOST_PP_VARIADIC_SIZE tuple) tuple
 #    endif
 #    define BOOST_PP_TUPLE_REVERSE_O_2(size, tuple) BOOST_PP_TUPLE_REVERSE_O_1(tuple)
 # else
--- a/include/boost/preprocessor/tuple/to_list.hpp
+++ b/include/boost/preprocessor/tuple/to_list.hpp
@ -28,10 +28,10 @@
 #        define BOOST_PP_TUPLE_TO_LIST(...) BOOST_PP_TUPLE_TO_LIST_I(BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_TO_LIST_O_, __VA_ARGS__), (__VA_ARGS__))
 #        define BOOST_PP_TUPLE_TO_LIST_I(m, args) BOOST_PP_TUPLE_TO_LIST_II(m, args)
 #        define BOOST_PP_TUPLE_TO_LIST_II(m, args) BOOST_PP_CAT(m ## args,)
-#    	 define BOOST_PP_TUPLE_TO_LIST_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_LIST_, BOOST_PP_TUPLE_SIZE(tuple)) tuple
+#        define BOOST_PP_TUPLE_TO_LIST_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_LIST_, BOOST_PP_TUPLE_SIZE(tuple)) tuple
 #    else
 #        define BOOST_PP_TUPLE_TO_LIST(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_TO_LIST_O_, __VA_ARGS__)(__VA_ARGS__)
-#    	 define BOOST_PP_TUPLE_TO_LIST_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_LIST_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        define BOOST_PP_TUPLE_TO_LIST_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_LIST_, BOOST_PP_VARIADIC_SIZE tuple) tuple
 #    endif
 #    define BOOST_PP_TUPLE_TO_LIST_O_2(size, tuple) BOOST_PP_TUPLE_TO_LIST_O_1(tuple)
 # else
--- a/include/boost/preprocessor/tuple/to_seq.hpp
+++ b/include/boost/preprocessor/tuple/to_seq.hpp
@ -26,10 +26,10 @@
 #        define BOOST_PP_TUPLE_TO_SEQ(...) BOOST_PP_TUPLE_TO_SEQ_I(BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_TO_SEQ_O_, __VA_ARGS__), (__VA_ARGS__))
 #        define BOOST_PP_TUPLE_TO_SEQ_I(m, args) BOOST_PP_TUPLE_TO_SEQ_II(m, args)
 #        define BOOST_PP_TUPLE_TO_SEQ_II(m, args) BOOST_PP_CAT(m ## args,)
-#    	 define BOOST_PP_TUPLE_TO_SEQ_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_SEQ_, BOOST_PP_TUPLE_SIZE(tuple)) tuple
+#        define BOOST_PP_TUPLE_TO_SEQ_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_SEQ_, BOOST_PP_TUPLE_SIZE(tuple)) tuple
 #    else
 #        define BOOST_PP_TUPLE_TO_SEQ(...) BOOST_PP_OVERLOAD(BOOST_PP_TUPLE_TO_SEQ_O_, __VA_ARGS__)(__VA_ARGS__)
-#    	 define BOOST_PP_TUPLE_TO_SEQ_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_SEQ_, BOOST_PP_VARIADIC_SIZE tuple) tuple
+#        define BOOST_PP_TUPLE_TO_SEQ_O_1(tuple) BOOST_PP_CAT(BOOST_PP_TUPLE_TO_SEQ_, BOOST_PP_VARIADIC_SIZE tuple) tuple
 #    endif
 #    define BOOST_PP_TUPLE_TO_SEQ_O_2(size, tuple) BOOST_PP_TUPLE_TO_SEQ_O_1(tuple)
 # else
--- a/include/boost/preprocessor/variadic.hpp
+++ b/include/boost/preprocessor/variadic.hpp
@ -14,6 +14,7 @@
 # define BOOST_PREPROCESSOR_VARIADIC_HPP
 #
 # include <boost/preprocessor/variadic/elem.hpp>
+# include <boost/preprocessor/variadic/has_opt.hpp>
 # include <boost/preprocessor/variadic/size.hpp>
 # include <boost/preprocessor/variadic/to_array.hpp>
 # include <boost/preprocessor/variadic/to_list.hpp>
--- a/include/boost/preprocessor/variadic/detail/has_opt.hpp
+++ b/include/boost/preprocessor/variadic/detail/has_opt.hpp
@ -0,0 +1,39 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2019.                                    *
+#  *     Distributed under the Boost Software License, Version 1.0. (See      *
+#  *     accompanying file LICENSE_1_0.txt or copy at                         *
+#  *     http://www.boost.org/LICENSE_1_0.txt)                                *
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# ifndef BOOST_PREPROCESSOR_VARIADIC_DETAIL_HAS_OPT_HPP
+# define BOOST_PREPROCESSOR_VARIADIC_DETAIL_HAS_OPT_HPP
+#
+# include <boost/preprocessor/config/config.hpp>
+#
+# if BOOST_PP_VARIADICS && defined(__cplusplus) && __cplusplus > 201703L
+#
+# if BOOST_PP_VARIADICS_MSVC
+# include <boost/preprocessor/cat.hpp>
+# endif
+#
+# define BOOST_PP_VARIADIC_HAS_OPT_FUNCTION(...) \
+    __VA_OPT__(,) , 1, 0 \
+/**/
+#
+# if BOOST_PP_VARIADICS_MSVC
+# define BOOST_PP_VARIADIC_HAS_OPT_ELEM0(e0, ...) BOOST_PP_CAT(BOOST_PP_VARIADIC_HAS_OPT_ELEM_0(e0,__VA_ARGS__),)
+# define BOOST_PP_VARIADIC_HAS_OPT_ELEM2(e0, ...) BOOST_PP_CAT(BOOST_PP_VARIADIC_HAS_OPT_ELEM_2(e0,__VA_ARGS__),)
+# else
+# define BOOST_PP_VARIADIC_HAS_OPT_ELEM0(e0, ...) BOOST_PP_VARIADIC_HAS_OPT_ELEM_0(e0,__VA_ARGS__)
+# define BOOST_PP_VARIADIC_HAS_OPT_ELEM2(e0, ...) BOOST_PP_VARIADIC_HAS_OPT_ELEM_2(e0,__VA_ARGS__)
+# endif
+# define BOOST_PP_VARIADIC_HAS_OPT_ELEM_0(e0, ...) e0
+# define BOOST_PP_VARIADIC_HAS_OPT_ELEM_2(e0, e1, e2, ...) e2
+#
+# endif
+#
+# endif
--- a/include/boost/preprocessor/variadic/detail/is_single_return.hpp
+++ b/include/boost/preprocessor/variadic/detail/is_single_return.hpp
@ -20,9 +20,9 @@
 # include <boost/preprocessor/control/iif.hpp>
 # include <boost/preprocessor/facilities/is_1.hpp>
 # include <boost/preprocessor/variadic/size.hpp>
-# define BOOST_PP_VARIADIC_IS_SINGLE_RETURN(sr,nsr,...)	\
-	BOOST_PP_IIF(BOOST_PP_IS_1(BOOST_PP_VARIADIC_SIZE(__VA_ARGS__)),sr,nsr) \
-	/**/
+# define BOOST_PP_VARIADIC_IS_SINGLE_RETURN(sr,nsr,...) \
+    BOOST_PP_IIF(BOOST_PP_IS_1(BOOST_PP_VARIADIC_SIZE(__VA_ARGS__)),sr,nsr) \
+    /**/
 # endif /* BOOST_PP_VARIADICS && BOOST_PP_VARIADICS_MSVC */
 #
 # endif /* BOOST_PREPROCESSOR_VARIADIC_DETAIL_IS_SINGLE_RETURN_HPP */
--- a/include/boost/preprocessor/variadic/has_opt.hpp
+++ b/include/boost/preprocessor/variadic/has_opt.hpp
@ -0,0 +1,28 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2019.                                    *
+#  *     Distributed under the Boost Software License, Version 1.0. (See      *
+#  *     accompanying file LICENSE_1_0.txt or copy at                         *
+#  *     http://www.boost.org/LICENSE_1_0.txt)                                *
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# ifndef BOOST_PREPROCESSOR_VARIADIC_HAS_OPT_HPP
+# define BOOST_PREPROCESSOR_VARIADIC_HAS_OPT_HPP
+#
+# include <boost/preprocessor/config/config.hpp>
+#
+# /* BOOST_PP_VARIADIC_HAS_OPT */
+#
+# if BOOST_PP_VARIADICS && defined(__cplusplus) && __cplusplus > 201703L
+# include <boost/preprocessor/variadic/detail/has_opt.hpp>
+# define BOOST_PP_VARIADIC_HAS_OPT() \
+  BOOST_PP_VARIADIC_HAS_OPT_ELEM2(BOOST_PP_VARIADIC_HAS_OPT_FUNCTION(?),) \
+/**/
+# else
+# define BOOST_PP_VARIADIC_HAS_OPT() 0
+# endif
+#
+# endif
--- a/include/boost/preprocessor/wstringize.hpp
+++ b/include/boost/preprocessor/wstringize.hpp
@ -23,7 +23,11 @@
 #    define BOOST_PP_WSTRINGIZE_OO(par) BOOST_PP_WSTRINGIZE_I ## par
 # endif
 #
+#if BOOST_PP_VARIADICS
+# define BOOST_PP_WSTRINGIZE_I(...) BOOST_PP_WSTRINGIZE_II(#__VA_ARGS__)
+#else
 # define BOOST_PP_WSTRINGIZE_I(text) BOOST_PP_WSTRINGIZE_II(#text)
+#endif
 # define BOOST_PP_WSTRINGIZE_II(str) L ## str
 #
 # endif
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@ -0,0 +1,33 @@
+# Copyright 2018, 2019 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
+
+include(BoostTest OPTIONAL RESULT_VARIABLE HAVE_BOOST_TEST)
+
+if(NOT HAVE_BOOST_TEST)
+  return()
+endif()
+
+enable_language(C)
+
+set(tests_common arithmetic array comparison control debug facilities list logical punctuation selection seq slot stringize tuple variadic isempty)
+set(tests_c ${tests_common})
+set(tests_cpp ${tests_common} iteration repetition quick)
+
+set(BOOST_TEST_LINK_LIBRARIES Boost::preprocessor)
+
+include_directories(../../..) # for `include <libs/preprocessor/...>` to work
+
+foreach(test IN LISTS tests_c)
+
+  boost_test(TYPE compile SOURCES ${test}.c)
+  boost_test(TYPE compile NAME ${test}_c_nvm SOURCES ${test}.c COMPILE_DEFINITIONS BOOST_PP_VARIADICS=0)
+
+endforeach()
+
+foreach(test IN LISTS tests_cpp)
+
+  boost_test(TYPE compile SOURCES ${test}.cpp)
+  boost_test(TYPE compile NAME ${test}_cpp_nvm SOURCES ${test}.cpp COMPILE_DEFINITIONS BOOST_PP_VARIADICS=0)
+
+endforeach()
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@ -3,6 +3,7 @@
 #~ (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

 import testing ;
+import cast ;

 project preprocessor_tests : requirements <warnings>on
                                          <toolset>gcc-4.3.0:<warnings>all
@ -21,35 +22,36 @@ alias preprocessor : :
        <toolset>gcc
        <toolset-gcc:version>3.4
    ;
-    
+
 alias preprocessor : : 
        <toolset>gcc
        <toolset-gcc:version>4.1
    ;
-    
+
 alias preprocessor : : 
        <toolset>gcc
        <toolset-gcc:version>4.2
    ;
-    
+
 alias preprocessor
   :   
-        [ compile arithmetic.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile array.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile comparison.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile control.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile debug.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile facilities.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile iteration.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile list.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile logical.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile punctuation.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile repetition.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile selection.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile seq.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile slot.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile tuple.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-        [ compile variadic.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
+        [ compile arithmetic.cpp ]
+        [ compile array.cpp ]
+        [ compile comparison.cpp ]
+        [ compile control.cpp ]
+        [ compile debug.cpp ]
+        [ compile facilities.cpp ]
+        [ compile iteration.cpp ]
+        [ compile list.cpp ]
+        [ compile logical.cpp ]
+        [ compile punctuation.cpp ]
+        [ compile repetition.cpp ]
+        [ compile selection.cpp ]
+        [ compile seq.cpp ]
+        [ compile slot.cpp ]
+        [ compile stringize.cpp ]
+        [ compile tuple.cpp ]
+        [ compile variadic.cpp ]
  ;

 alias preprocessor_nvm
@ -67,65 +69,70 @@ alias preprocessor_nvm
        [ compile selection.cpp : <define>BOOST_PP_VARIADICS=0 : selection_nvm ]
        [ compile seq.cpp : <define>BOOST_PP_VARIADICS=0 : seq_nvm ]
        [ compile slot.cpp : <define>BOOST_PP_VARIADICS=0 : slot_nvm ]
+        [ compile stringize.cpp : <define>BOOST_PP_VARIADICS=0 : stringize_nvm ]
        [ compile tuple.cpp : <define>BOOST_PP_VARIADICS=0 : tuple_nvm ]
  ;

 alias preprocessor_c
   :   
        [ compile arithmetic.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : arithmetic_c 
        ]
        [ compile array.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : array_c 
        ]
        [ compile comparison.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : comparison_c 
        ]
        [ compile control.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : control_c 
        ]
        [ compile debug.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : debug_c 
        ]
        [ compile facilities.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : facilities_c 
        ]
        [ compile list.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : list_c 
        ]
        [ compile logical.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : logical_c 
        ]
        [ compile punctuation.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : punctuation_c 
        ]
        [ compile selection.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : selection_c 
        ]
        [ compile seq.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : seq_c 
        ]
        [ compile slot.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : slot_c 
        ]
+        [ compile stringize.c 
+          : 
+          : stringize_c 
+        ]
        [ compile tuple.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : tuple_c 
        ]
        [ compile variadic.c 
-          : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : 
          : variadic_c 
        ]
  ;
@ -133,115 +140,108 @@ alias preprocessor_c
 alias preprocessor_c_nvm
   :   
        [ compile arithmetic.c 
-          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : <define>BOOST_PP_VARIADICS=0            
          : arithmetic_c_nvm 
        ]
        [ compile array.c 
-          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+          : <define>BOOST_PP_VARIADICS=0            
          : array_c_nvm 
        ]
        [ compile comparison.c 
          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
          : comparison_c_nvm 
        ]
        [ compile control.c 
          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
          : control_c_nvm 
        ]
        [ compile debug.c 
          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
          : debug_c_nvm 
        ]
        [ compile facilities.c 
          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
          : facilities_c_nvm 
        ]
        [ compile list.c 
          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
          : list_c_nvm 
        ]
        [ compile logical.c 
          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
          : logical_c_nvm 
        ]
        [ compile selection.c 
          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
          : selection_c_nvm 
        ]
        [ compile seq.c 
          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
          : seq_c_nvm 
        ]
        [ compile slot.c 
          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
          : slot_c_nvm 
        ]
+        [ compile stringize.c 
+          : <define>BOOST_PP_VARIADICS=0
+          : stringize_c_nvm 
+        ]
        [ compile tuple.c 
          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
          : tuple_c_nvm 
        ]
  ;
-  
+
 alias preprocessor_isempty : : 
        <toolset>gcc
        <toolset-gcc:version>3.4
    ;
-    
+
 alias preprocessor_isempty : : 
        <toolset>gcc
        <toolset-gcc:version>4.1
    ;
-    
+
 alias preprocessor_isempty : : 
        <toolset>gcc
        <toolset-gcc:version>4.2
    ;
-    
+
 alias preprocessor_isempty
  :   
-       [ compile isempty.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-       [ compile-fail isempty_variadic_standard_failure.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
-       [ compile-fail isempty_variadic_standard_failure2.cpp : <toolset>gcc:<cxxflags>-std=c++0x <toolset>clang-linux:<cxxflags>-std=c++0x ]
+       [ compile isempty.cpp ]
+       [ compile checkempty.cpp ]
+       [ compile-fail isempty_variadic_standard_failure.cpp : <define>BOOST_PP_VARIADICS=1 ]
+       [ compile-fail isempty_variadic_standard_failure2.cpp : <define>BOOST_PP_VARIADICS=1 ]
+       [ compile vaopt.cpp ]
 ; 
-  
+
 alias preprocessor_isempty_nvm
   :   
-        [ compile isempty.cpp : <define>BOOST_PP_VARIADICS=0 : isempty_nvm ]
+       [ compile isempty.cpp : <define>BOOST_PP_VARIADICS=0 : isempty_nvm ]
  ;
-  
+
 alias preprocessor_isempty_c
  :   
       [ compile isempty.c 
-         : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+         : 
         : isempty_c 
       ]
       [ compile-fail isempty_variadic_standard_failure.c 
-         : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+         : <define>BOOST_PP_VARIADICS=1
         : isempty_variadic_standard_failure_c 
       ]
       [ compile-fail isempty_variadic_standard_failure2.c 
-         : <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
+         : <define>BOOST_PP_VARIADICS=1
         : isempty_variadic_standard_failure2_c 
       ]
 ;
-  
+
 alias preprocessor_isempty_c_nvm
   :   
        [ compile isempty.c 
          : <define>BOOST_PP_VARIADICS=0
-            <toolset>gcc:<cflags>-std=c99 <toolset>clang-linux:<cflags>-std=c99
          : isempty_c_nvm 
        ]
  ;
@ -250,3 +250,24 @@ alias preprocessor_config
   :   
        [ run config_info.cpp ]
  ;
+
+alias test_clang_cuda
+   :   
+        [ compile [ cast _ cpp : clang_cuda.cu ]
+          : <cxxflags>-nocudalib
+            <cxxflags>-nocudainc
+            <cxxflags>"-x cuda"
+          : clang_cuda_cu
+        ]
+  ;
+
+explicit test_clang_cuda ;
+
+alias test_iso
+   :   
+        [ run cpp_standard.cpp ]
+  ;
+
+explicit test_iso ;
+
+explicit compile quick.cpp ; # "Quick" test (for CI)
--- a/test/checkempty.cpp
+++ b/test/checkempty.cpp
@ -0,0 +1,12 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2019.
+#  *     Distributed under the Boost Software License, Version 1.0. (See
+#  *     accompanying file LICENSE_1_0.txt or copy at
+#  *     http://www.boost.org/LICENSE_1_0.txt)
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# include <libs/preprocessor/test/checkempty.cxx>
--- a/test/checkempty.cxx
+++ b/test/checkempty.cxx
@ -0,0 +1,61 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2019.
+#  *     Distributed under the Boost Software License, Version 1.0. (See
+#  *     accompanying file LICENSE_1_0.txt or copy at
+#  *     http://www.boost.org/LICENSE_1_0.txt)
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# include <libs/preprocessor/test/test.h>
+# include <boost/preprocessor/facilities/check_empty.hpp>
+
+# if BOOST_PP_VARIADIC_HAS_OPT()
+
+# include <boost/preprocessor/facilities/empty.hpp>
+
+#define DATA
+#define OBJECT OBJECT2
+#define OBJECT2
+#define FUNC(x) FUNC2(x)
+#define FUNC2(x)
+#define FUNC_GEN() ()
+#define FUNC_GEN2(x) ()
+#define FUNC_GEN3() (&)
+#define FUNC_GEN4(x) (y)
+#define FUNC_GEN5() (y,z)
+#define FUNC_GEN6() anything
+#define FUNC_GEN7(x) anything
+#define FUNC_GEN8(x,y) (1,2,3)
+#define FUNC_GEN9(x,y,z) anything
+#define FUNC_GEN10(x) (y) data
+#define NAME &name
+#define ATUPLE (atuple)
+#define ATUPLE_PLUS (atuple) data
+
+BEGIN BOOST_PP_CHECK_EMPTY(FUNC_GEN) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(FUNC_GEN2) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(FUNC_GEN3) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(FUNC_GEN4) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(FUNC_GEN5) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(FUNC_GEN8) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(FUNC_GEN9) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(FUNC_GEN10) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(BOOST_PP_EMPTY()) == 1 END
+BEGIN BOOST_PP_CHECK_EMPTY(DATA BOOST_PP_EMPTY()) == 1 END
+BEGIN BOOST_PP_CHECK_EMPTY(x BOOST_PP_EMPTY()) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(OBJECT BOOST_PP_EMPTY()) == 1 END
+BEGIN BOOST_PP_CHECK_EMPTY(FUNC(z) BOOST_PP_EMPTY()) == 1 END
+BEGIN BOOST_PP_CHECK_EMPTY(FUNC_GEN6) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(FUNC_GEN7) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(NAME) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(ATUPLE) == 0 END
+BEGIN BOOST_PP_CHECK_EMPTY(ATUPLE_PLUS) == 0 END
+
+# else
+
+BEGIN 1 == 1 END
+
+# endif
--- a/test/clang_cuda.cu
+++ b/test/clang_cuda.cu
@ -0,0 +1,26 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2019.
+#  *     Distributed under the Boost Software License, Version 1.0. (See
+#  *     accompanying file LICENSE_1_0.txt or copy at
+#  *     http://www.boost.org/LICENSE_1_0.txt)
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# include <libs/preprocessor/test/test_macro.h>
+
+#if defined(__clang__) && defined(__CUDACC__) && defined(__CUDA__)
+
+BEGIN BOOST_PP_VARIADICS == 1 END
+
+#else
+
+BEGIN 0 == 1 END
+
+#endif
+
+int main(void) {
+    return 0;
+}
--- a/test/cmake_install_test/CMakeLists.txt
+++ b/test/cmake_install_test/CMakeLists.txt
@ -0,0 +1,17 @@
+# Copyright 2018, 2019 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
+
+cmake_minimum_required(VERSION 3.5...3.16)
+
+project(cmake_install_test LANGUAGES CXX)
+
+find_package(boost_preprocessor REQUIRED)
+
+add_executable(quick ../quick.cpp)
+target_link_libraries(quick Boost::preprocessor)
+
+enable_testing()
+add_test(quick quick)
+
+add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND} --output-on-failure -C $<CONFIG>)
--- a/test/cmake_subdir_test/CMakeLists.txt
+++ b/test/cmake_subdir_test/CMakeLists.txt
@ -0,0 +1,17 @@
+# Copyright 2018, 2019 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
+
+cmake_minimum_required(VERSION 3.5...3.16)
+
+project(cmake_subdir_test LANGUAGES CXX)
+
+add_subdirectory(../.. boostorg/preprocessor)
+
+add_executable(quick ../quick.cpp)
+target_link_libraries(quick Boost::preprocessor)
+
+enable_testing()
+add_test(quick quick)
+
+add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND} --output-on-failure -C $<CONFIG>)
--- a/test/config_info.cpp
+++ b/test/config_info.cpp
@ -1,7 +1,19 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2014,2019.
+#  *     Distributed under the Boost Software License, Version 1.0. (See
+#  *     accompanying file LICENSE_1_0.txt or copy at
+#  *     http://www.boost.org/LICENSE_1_0.txt)
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
 #include <iostream>
 #include <iomanip>
 #include <string.h>
 #include <boost/preprocessor/stringize.hpp>
+#include <boost/preprocessor/variadic/has_opt.hpp>

 static unsigned int indent = 4;
 static unsigned int width = 40;
@ -82,6 +94,7 @@ void print_macros()
  PRINT_MACRO(BOOST_PP_CONFIG_FLAGS());
  PRINT_MACRO(BOOST_PP_VARIADICS);
  PRINT_MACRO(BOOST_PP_VARIADICS_MSVC);
+  PRINT_MACRO(BOOST_PP_VARIADIC_HAS_OPT());
 }

 int main()
--- a/test/cpp_standard.cpp
+++ b/test/cpp_standard.cpp
@ -0,0 +1,551 @@
+#include <iostream>
+#include <iomanip>
+#include <string>
+#include <boost/preprocessor/config/config.hpp>
+
+static unsigned int indent = 4;
+static unsigned int width = 90;
+
+using std::cout;
+using std::istream;
+
+void print_separator()
+{
+   std::cout <<
+"\n\n*********************************************************************\n\n";
+}
+
+std::string remove_spaces(const std::string ss)
+    {
+    
+    bool inquotes(false);
+    bool escape(false);
+    char qchar;
+    int len(static_cast<int>(ss.length()));
+    
+    std::string ret;
+    
+    for (int i = 0; i < len; ++i)
+        {
+        
+        char ch(ss[i]);
+        
+        if (inquotes)
+            {
+            if (escape)
+                {
+                escape = false;
+                }
+            else if (ch == '\\')
+                {
+                escape = true;
+                }
+            else if (ch == qchar)
+                {
+                inquotes = false;
+                }
+            ret.push_back(ch);
+            }
+        else
+            {
+            if (ch == '\'' || ch == '"')
+                {
+                inquotes = true;
+                qchar = ch;
+                ret.push_back(ch);
+                }
+            else if (ch != ' ')
+                {
+                ret.push_back(ch);
+                }
+            }
+        }
+    
+    return ret;
+    }
+
+int print_macro(const std::string name,const std::string expected, const std::string expansion)
+{
+   int bret(0);
+   const std::string sg("Success: ");
+   const std::string sb("Failure: ");
+   for(unsigned i = 0; i < indent; ++i) std::cout.put(' ');
+   if (name == expansion)
+    {
+    if (expected == expansion)
+        {
+        std::cout << sg;
+        std::cout << std::setw(width);
+        cout.setf(istream::left, istream::adjustfield);
+        std::cout << name;
+        std::cout << " [no value]\n";
+        }
+    else
+        {
+        std::cout << sb;
+        std::cout << std::setw(width);
+        cout.setf(istream::left, istream::adjustfield);
+        std::cout << name;
+        std::cout << " [no value]: ";
+        std::cout << " [expected]: ";
+        std::cout << expected << "\n";
+        bret = 1;
+        }
+    }
+   else
+    {
+    
+    std::string sexpected(remove_spaces(expected));
+    std::string sexpansion(remove_spaces(expansion));
+    
+    if (sexpected == sexpansion)
+        {
+        std::cout << sg;
+        std::cout << std::setw(width);
+        cout.setf(istream::left, istream::adjustfield);
+        std::cout << name;
+        std::cout << expansion << "\n";
+        }
+    else
+        {
+        std::cout << sb;
+        std::cout << std::setw(width);
+        cout.setf(istream::left, istream::adjustfield);
+        std::cout << name;
+        std::cout << expansion;
+        std::cout << " [expected]: ";
+        std::cout << expected << "\n";
+        bret = 1;
+        }
+    }
+ return bret;
+}
+
+#if !BOOST_PP_VARIADICS
+
+#define STRINGIZE(arg) # arg
+
+#define PRINT_MACRO_RESULTS(X,exp) print_macro(std::string(# X), std::string(# exp), std::string(STRINGIZE(X)))
+#define PRINT_MACRO(x) std::string(# x)
+#define PRINT_EXPECTED(x) std::string(# x)
+#define PRINT_EXPANSION(x) std::string(STRINGIZE(x))
+
+#else
+
+#define STRINGIZE(...) # __VA_ARGS__
+
+#define PRINT_MACRO_RESULTS(X,...) print_macro(std::string(# X), std::string(# __VA_ARGS__), std::string(STRINGIZE(X)))
+#define PRINT_MACRO(...) std::string(# __VA_ARGS__)
+#define PRINT_EXPECTED(...) std::string(# __VA_ARGS__)
+#define PRINT_EXPANSION(...) std::string(STRINGIZE(__VA_ARGS__))
+
+#endif
+
+#if __cplusplus > 201703L
+
+int print_macros_common_c20()
+{
+
+  int bret = 0;
+  
+#define LPAREN() (
+#define G(Q) 42
+#define F(R, X, ...) __VA_OPT__(G R X) )
+
+// int x = F(LPAREN(), 0, <:-);
+
+// replaced by 
+
+// int x = 42;
+
+bret += PRINT_MACRO_RESULTS(int x = F(LPAREN(), 0, <:-);,int x = 42;);
+
+#undef LPAREN
+#undef G
+#undef F
+
+#define F(...) f(0 __VA_OPT__(,) __VA_ARGS__)
+#define G(X, ...) f(0, X __VA_OPT__(,) __VA_ARGS__)
+#define SDEF(sname, ...) S sname __VA_OPT__(= { __VA_ARGS__ })
+#define EMP
+
+// F(a, b, c) 
+// F() 
+// F(EMP) 
+
+// replaced by 
+
+// f(0, a, b, c)
+// f(0)
+// f(0)
+
+// G(a, b, c) 
+// G(a, ) 
+// G(a) 
+
+// replaced by 
+
+// f(0, a, b, c)
+// f(0, a)
+// f(0, a)
+
+// SDEF(foo); 
+// SDEF(bar, 1, 2); 
+
+// replaced by 
+
+// S foo;
+// S bar = { 1, 2 };
+
+bret += PRINT_MACRO_RESULTS(F(a, b, c),f(0, a, b, c));
+bret += PRINT_MACRO_RESULTS(F(),f(0));
+bret += PRINT_MACRO_RESULTS(F(EMP),f(0));
+bret += PRINT_MACRO_RESULTS(G(a, b, c),f(0, a, b, c));
+bret += PRINT_MACRO_RESULTS(G(a, ),f(0, a));
+bret += PRINT_MACRO_RESULTS(G(a),f(0, a));
+bret += PRINT_MACRO_RESULTS(SDEF(foo);,S foo;);
+bret += PRINT_MACRO_RESULTS(SDEF(bar, 1, 2);,S bar = { 1, 2 };);
+
+#undef F
+#undef G
+#undef SDEF
+#undef EMP
+
+#define H2(X, Y, ...) __VA_OPT__(X ## Y,) __VA_ARGS__
+#define H3(X, ...) #__VA_OPT__(X##X X##X)
+#define H4(X, ...) __VA_OPT__(a X ## X) ## b
+#define H5A(...) __VA_OPT__()/**/__VA_OPT__()
+#define H5B(X) a ## X ## b
+#define H5C(X) H5B(X)
+
+// H2(a, b, c, d) 
+
+// replaced by 
+
+// ab, c, d
+
+// H3(, 0) 
+
+// replaced by 
+
+// ""
+
+// H4(, 1) 
+
+// replaced by 
+
+// a b
+
+// H5C(H5A()) 
+
+// replaced by 
+
+// ab
+
+bret += PRINT_MACRO_RESULTS(H2(a, b, c, d),ab, c, d);
+bret += PRINT_MACRO_RESULTS(H3(, 0),"");
+bret += PRINT_MACRO_RESULTS(H4(, 1),a b);
+bret += PRINT_MACRO_RESULTS(H5C(H5A()),ab);
+
+#undef H2
+#undef H3
+#undef H4
+#undef H5A
+#undef H5B
+#undef H5C
+
+  return bret;
+
+}
+
+#endif
+
+int print_macros_common_1()
+{
+
+  int bret = 0;
+
+#define x 3
+#define f(a) f(x * (a))
+#undef x
+
+#define x 2
+#define g f
+#define z z[0]
+#define h g(~
+#define m(a) a(w)
+#define w 0,1
+#define t(a) a
+
+// f(y+1) + f(f(z)) % t(t(g)(0) + t)(1);
+// g(x+(3,4)-w) | h 5) & m(f)^m(m);
+
+// results in
+
+// f(2 * (y+1)) + f(2 * (f(2 * (z[0])))) % f(2 * (0)) + t(1);
+// f(2 * (2+(3,4)-0,1)) | f(2 * ( ~ 5)) & f(2 * (0,1))^m(0,1);
+
+bret += PRINT_MACRO_RESULTS(f(y+1) + f(f(z)) % t(t(g)(0) + t)(1);,f(2 * (y+1)) + f(2 * (f(2 * (z[0])))) % f(2 * (0)) + t(1););
+
+#define PRINT_INPUT g(x+(3,4)-w) | h 5) & m(f)^m(m);
+
+bret += print_macro
+    (
+    std::string("g(x+(3,4)-w) | h 5) & m(f)^m(m);"),
+    PRINT_EXPECTED(f(2 * (2+(3,4)-0,1)) | f(2 * ( ~ 5)) & f(2 * (0,1))^m(0,1);),
+    PRINT_EXPANSION(PRINT_INPUT)
+    );
+    
+#undef PRINT_INPUT
+
+#undef f
+#undef x
+#undef g
+#undef z
+#undef h
+#undef m
+#undef w
+#undef t
+
+  return bret;
+
+}
+
+int print_macros_common_4()
+{
+
+  int bret = 0;
+  
+#define str(s) # s
+#define xstr(s) str(s)
+#define debug(s, t) printf("x" # s "= %d, x" # t "= %s", x ## s, x ## t)
+#define INCFILE(n) vers ## n
+#define glue(a, b) a ## b
+#define xglue(a, b) glue(a, b)
+#define HIGHLOW "hello"
+#define LOW LOW ", world"
+
+// debug(1, 2);
+// fputs(str(strncmp("abc\0d", "abc", <20>\4<>) // this goes away
+// == 0) str(: @\n), s);
+// #include xstr(INCFILE(2).h)
+// glue(HIGH, LOW);
+// xglue(HIGH, LOW)
+
+// results in
+
+// printf("x" "1" "= %d, x" "2" "= %s", x1, x2);
+// fputs("strncmp(\"abc\\0d\", \"abc\", <20>\\4<>) == 0" ": @\n", s);
+// #include "vers2.h" (after macro replacement, before file access)
+// "hello";
+// "hello" ", world"
+
+bret += PRINT_MACRO_RESULTS(debug(1, 2);,printf("x" "1" "= %d, x" "2" "= %s", x1, x2););
+bret += print_macro
+    (
+    std::string("fputs(str(strncmp(\"abc\\0d\", \"abc\", '\\4') /* this goes away */== 0) str(: @\\n), s);"),
+    PRINT_EXPECTED(fputs("strncmp(\"abc\\0d\", \"abc\", '\\4') == 0" ": @\n", s);),
+    PRINT_EXPANSION(fputs(str(strncmp("abc\0d", "abc", '\4') /* this goes away */== 0) str(: @\n), s);)
+    );
+bret += PRINT_MACRO_RESULTS(xstr(INCFILE(2).h),"vers2.h");
+bret += PRINT_MACRO_RESULTS(glue(HIGH, LOW);,"hello";);
+
+#if __cplusplus <= 199711L
+
+bret += print_macro
+    (
+    PRINT_MACRO(xglue(HIGH, LOW)),
+    std::string("\"hello\" \", world\""),
+    PRINT_EXPANSION(xglue(HIGH, LOW))
+    );
+
+#else
+
+bret += PRINT_MACRO_RESULTS(xglue(HIGH, LOW),"hello" ", world");
+    
+#endif
+
+#undef str
+#undef xstr
+#undef debug
+#undef INCFILE
+#undef glue
+#undef xglue
+#undef HIGHLOW
+#undef LOW
+
+  return bret;
+  
+}
+
+int print_macros_common_2()
+{
+
+  int bret = 0;
+
+#define hash_hash # ## #
+#define mkstr(a) # a
+#define in_between(a) mkstr(a)
+#define join(c, d) in_between(c hash_hash d)
+
+// char p[] = join(x, y);
+
+// equivalent to
+
+// char p[] = "x ## y";
+
+bret += PRINT_MACRO_RESULTS(char p[] = join(x, y);,char p[] = "x ## y";);
+
+#undef hash_hash
+#undef mkstr
+#undef in_between
+#undef join
+
+  return bret;
+  
+}
+
+#if BOOST_PP_VARIADICS && __cplusplus > 199711L
+
+int print_macros_common_3()
+{
+
+  int bret = 0;
+
+#define p() int
+#define q(x) x
+#define r(x,y) x ## y
+#define str(x) # x
+
+// p() i[q()] = { q(1), r(2,3), r(4,), r(,5), r(,) };
+// char c[2][6] = { str(hello), str() };
+
+// results in
+
+// int i[] = { 1, 23, 4, 5, };
+// char c[2][6] = { "hello", "" };
+
+bret += print_macro
+    (
+    PRINT_MACRO(p() i[q()] = { q(1), r(2,3), r(4,), r(,5), r(,) };),
+    PRINT_EXPECTED(int i[] = { 1, 23, 4, 5, };),
+    PRINT_EXPANSION(p() i[q()] = { q(1), r(2,3), r(4,), r(,5), r(,) };)
+    );
+bret += print_macro
+    (
+    PRINT_MACRO(char c[2][6] = { str(hello), str() };),
+    PRINT_EXPECTED(char c[2][6] = { "hello", "" };),
+    PRINT_EXPANSION(char c[2][6] = { str(hello), str() };)
+    );
+    
+#undef p
+#undef q
+#undef r
+#undef str
+
+bret += print_macros_common_4();
+
+#define t(x,y,z) x ## y ## z
+
+// int j[] = { t(1,2,3), t(,4,5), t(6,,7), t(8,9,), t(10,,), t(,11,), t(,,12), t(,,) };
+
+// results in
+
+// int j[] = { 123, 45, 67, 89, 10, 11, 12, };
+
+bret += print_macro
+    (
+    PRINT_MACRO(int j[] = { t(1,2,3), t(,4,5), t(6,,7), t(8,9,), t(10,,), t(,11,), t(,,12), t(,,) };),
+    PRINT_EXPECTED(int j[] = { 123, 45, 67, 89, 10, 11, 12, };),
+    PRINT_EXPANSION(int j[] = { t(1,2,3), t(,4,5), t(6,,7), t(8,9,), t(10,,), t(,11,), t(,,12), t(,,) };)
+    );
+    
+#undef t
+
+#define debug(...) fprintf(stderr, __VA_ARGS__)
+#define showlist(...) puts(#__VA_ARGS__)
+#define report(test, ...) ((test) ? puts(#test) : printf(__VA_ARGS__))
+
+// debug("Flag");
+// debug("X = %d\n", x);
+// showlist(The first, second, and third items.);
+// report(x>y, "x is %d but y is %d", x, y);
+
+// results in
+
+// fprintf(stderr, "Flag");
+// fprintf(stderr, "X = %d\n", x);
+// puts("The first, second, and third items.");
+// ((x>y) ? puts("x>y") : printf("x is %d but y is %d", x, y));
+
+#define save_stderr stderr
+#undef stderr
+
+bret += PRINT_MACRO_RESULTS(debug("Flag");,fprintf(stderr, "Flag"););
+bret += PRINT_MACRO_RESULTS(debug("X = %d\n", x);,fprintf(stderr, "X = %d\n", x););
+
+#define stderr save_stderr
+
+bret += PRINT_MACRO_RESULTS(showlist(The first, second, and third items.);,puts("The first, second, and third items."););
+bret += PRINT_MACRO_RESULTS(report(x>y, "x is %d but y is %d", x, y);,((x>y) ? puts("x>y") : printf("x is %d but y is %d", x, y)););
+
+#undef debug
+#undef showlist
+#undef report
+
+  return bret;
+  
+}
+
+#endif
+
+int print_macros()
+{
+  int bret = 0;
+  
+  print_separator();
+  
+  std::cout << "__cplusplus = " << __cplusplus;
+  
+  print_separator();
+  
+#define OBJ_LIKE (1-1)
+#define OBJ_LIKE /* white space */ (1-1) /* other */
+#define FTN_LIKE(a) ( a )
+#define FTN_LIKE( a )( /* note the white space */ a /* other stuff on this line */ )
+
+#if !BOOST_PP_VARIADICS
+
+bret += print_macros_common_1();
+bret += print_macros_common_4();
+
+#elif __cplusplus <= 199711L
+
+bret += print_macros_common_2();
+bret += print_macros_common_1();
+bret += print_macros_common_4();
+
+#elif __cplusplus <= 201703L
+
+bret += print_macros_common_2();
+bret += print_macros_common_1();
+bret += print_macros_common_3();
+
+#else
+
+bret += print_macros_common_c20();
+bret += print_macros_common_2();
+bret += print_macros_common_1();
+bret += print_macros_common_3();
+
+#endif
+
+  print_separator();
+  
+  return bret;
+}
+
+int main()
+{
+  return (print_macros());
+}
--- a/test/isempty.cxx
+++ b/test/isempty.cxx
@ -38,7 +38,20 @@

 #if BOOST_PP_VARIADICS

-#if BOOST_PP_VARIADICS_MSVC /* Testing the VC++ variadic version */
+# include <boost/preprocessor/variadic/has_opt.hpp>
+
+#if defined(__cplusplus) && __cplusplus > 201703L && BOOST_PP_VARIADIC_HAS_OPT()
+
+BEGIN BOOST_PP_IS_EMPTY(FUNC_GEN) == 0 END
+BEGIN BOOST_PP_IS_EMPTY(FUNC_GEN2) == 0 END
+BEGIN BOOST_PP_IS_EMPTY(FUNC_GEN3) == 0 END
+BEGIN BOOST_PP_IS_EMPTY(FUNC_GEN4) == 0 END
+BEGIN BOOST_PP_IS_EMPTY(FUNC_GEN5) == 0 END
+BEGIN BOOST_PP_IS_EMPTY(FUNC_GEN8) == 0 END
+BEGIN BOOST_PP_IS_EMPTY(FUNC_GEN9) == 0 END
+BEGIN BOOST_PP_IS_EMPTY(FUNC_GEN10) == 0 END
+
+#elif BOOST_PP_VARIADICS_MSVC /* Testing the VC++ variadic version */

 /* INCORRECT */

--- a/test/isempty_variadic_standard_failure.cxx
+++ b/test/isempty_variadic_standard_failure.cxx
@ -15,9 +15,19 @@
 #if BOOST_PP_VARIADICS && (BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_STRICT()) && !BOOST_PP_VARIADICS_MSVC

 #define FUNC_GEN8(x,y) (1,2,3)
+
+#if defined(__cplusplus) && __cplusplus > 201703L
  
+# include <boost/preprocessor/variadic/has_opt.hpp>
+
+BEGIN BOOST_PP_IS_EMPTY(FUNC_GEN8) == BOOST_PP_VARIADIC_HAS_OPT() END
+
+#else
+
 BEGIN BOOST_PP_IS_EMPTY(FUNC_GEN8) == 0 END

+#endif
+
 #else
  
 BEGIN 1 == 0 END
--- a/test/isempty_variadic_standard_failure2.cxx
+++ b/test/isempty_variadic_standard_failure2.cxx
@ -16,8 +16,18 @@

 #define FUNC_GEN9(x,y,z) anything
  
+#if defined(__cplusplus) && __cplusplus > 201703L
+  
+# include <boost/preprocessor/variadic/has_opt.hpp>
+
+BEGIN BOOST_PP_IS_EMPTY(FUNC_GEN9) == BOOST_PP_VARIADIC_HAS_OPT() END
+
+#else
+
 BEGIN BOOST_PP_IS_EMPTY(FUNC_GEN9) == 0 END

+#endif
+
 #else
  
 BEGIN 1 == 0 END
--- a/test/quick.cpp
+++ b/test/quick.cpp
@ -0,0 +1,43 @@
+// Copyright 2002 Paul Mensonides
+// Copyright 2019 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/preprocessor/comparison.hpp>
+#include "test_macro.h"
+
+/* equality */
+
+BEGIN BOOST_PP_EQUAL(2, 0) == 0 END
+BEGIN BOOST_PP_EQUAL(2, 2) == 1 END
+
+/* inequality */
+
+BEGIN BOOST_PP_NOT_EQUAL(2, 0) == 1 END
+BEGIN BOOST_PP_NOT_EQUAL(2, 2) == 0 END
+
+/* less */
+
+BEGIN BOOST_PP_LESS(2, 1) == 0 END
+BEGIN BOOST_PP_LESS(1, 2) == 1 END
+
+/* less_equal */
+
+BEGIN BOOST_PP_LESS_EQUAL(2, 1) == 0 END
+BEGIN BOOST_PP_LESS_EQUAL(1, 2) == 1 END
+BEGIN BOOST_PP_LESS_EQUAL(2, 2) == 1 END
+
+/* greater */
+
+BEGIN BOOST_PP_GREATER(2, 1) == 1 END
+BEGIN BOOST_PP_GREATER(1, 2) == 0 END
+
+/* greater_equal */
+
+BEGIN BOOST_PP_GREATER_EQUAL(2, 1) == 1 END
+BEGIN BOOST_PP_GREATER_EQUAL(1, 2) == 0 END
+BEGIN BOOST_PP_GREATER_EQUAL(2, 2) == 1 END
+
+int main()
+{
+}
--- a/test/seq.cxx
+++ b/test/seq.cxx
@ -35,46 +35,46 @@
 # define SEQ (4)(1)(5)(2)

 # define SEQ_100 \
-	(1)(2)(3)(4)(5)(6)(7)(8)(9) \
-	(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) \
-	(20)(21)(22)(23)(24)(25)(26)(27)(28)(29) \
-	(30)(31)(32)(33)(34)(35)(36)(37)(38)(39) \
-	(40)(41)(42)(43)(44)(45)(46)(47)(48)(49) \
-	(50)(51)(52)(53)(54)(55)(56)(57)(58)(59) \
-	(60)(61)(62)(63)(64)(65)(66)(67)(68)(69) \
-	(70)(71)(72)(73)(74)(75)(76)(77)(78)(79) \
-	(80)(81)(82)(83)(84)(85)(86)(87)(88)(89) \
-	(90)(91)(92)(93)(94)(95)(96)(97)(98)(99) \
-	(100)
-	
+    (1)(2)(3)(4)(5)(6)(7)(8)(9) \
+    (10)(11)(12)(13)(14)(15)(16)(17)(18)(19) \
+    (20)(21)(22)(23)(24)(25)(26)(27)(28)(29) \
+    (30)(31)(32)(33)(34)(35)(36)(37)(38)(39) \
+    (40)(41)(42)(43)(44)(45)(46)(47)(48)(49) \
+    (50)(51)(52)(53)(54)(55)(56)(57)(58)(59) \
+    (60)(61)(62)(63)(64)(65)(66)(67)(68)(69) \
+    (70)(71)(72)(73)(74)(75)(76)(77)(78)(79) \
+    (80)(81)(82)(83)(84)(85)(86)(87)(88)(89) \
+    (90)(91)(92)(93)(94)(95)(96)(97)(98)(99) \
+    (100)
+    
 # define SEQ_255 \
-	(1)(2)(3)(4)(5)(6)(7)(8)(9) \
-	(10)(11)(12)(13)(14)(15)(16)(17)(18)(19) \
-	(20)(21)(22)(23)(24)(25)(26)(27)(28)(29) \
-	(30)(31)(32)(33)(34)(35)(36)(37)(38)(39) \
-	(40)(41)(42)(43)(44)(45)(46)(47)(48)(49) \
-	(50)(51)(52)(53)(54)(55)(56)(57)(58)(59) \
-	(60)(61)(62)(63)(64)(65)(66)(67)(68)(69) \
-	(70)(71)(72)(73)(74)(75)(76)(77)(78)(79) \
-	(80)(81)(82)(83)(84)(85)(86)(87)(88)(89) \
-	(90)(91)(92)(93)(94)(95)(96)(97)(98)(99) \
-	(100)(101)(102)(103)(104)(105)(106)(107)(108)(109) \
-	(110)(111)(112)(113)(114)(115)(116)(117)(118)(119) \
-	(120)(121)(122)(123)(124)(125)(126)(127)(128)(129) \
-	(130)(131)(132)(133)(134)(135)(136)(137)(138)(139) \
-	(140)(141)(142)(143)(144)(145)(146)(147)(148)(149) \
-	(150)(151)(152)(153)(154)(155)(156)(157)(158)(159) \
-	(160)(161)(162)(163)(164)(165)(166)(167)(168)(169) \
-	(170)(171)(172)(173)(174)(175)(176)(177)(178)(179) \
-	(180)(181)(182)(183)(184)(185)(186)(187)(188)(189) \
-	(190)(191)(192)(193)(194)(195)(196)(197)(198)(199) \
-	(200)(201)(202)(203)(204)(205)(206)(207)(208)(209) \
-	(210)(211)(212)(213)(214)(215)(216)(217)(218)(219) \
-	(220)(221)(222)(223)(224)(225)(226)(227)(228)(229) \
-	(230)(231)(232)(233)(234)(235)(236)(237)(238)(239) \
-	(240)(241)(242)(243)(244)(245)(246)(247)(248)(249) \
-	(250)(251)(252)(253)(254)(255)
-	
+    (1)(2)(3)(4)(5)(6)(7)(8)(9) \
+    (10)(11)(12)(13)(14)(15)(16)(17)(18)(19) \
+    (20)(21)(22)(23)(24)(25)(26)(27)(28)(29) \
+    (30)(31)(32)(33)(34)(35)(36)(37)(38)(39) \
+    (40)(41)(42)(43)(44)(45)(46)(47)(48)(49) \
+    (50)(51)(52)(53)(54)(55)(56)(57)(58)(59) \
+    (60)(61)(62)(63)(64)(65)(66)(67)(68)(69) \
+    (70)(71)(72)(73)(74)(75)(76)(77)(78)(79) \
+    (80)(81)(82)(83)(84)(85)(86)(87)(88)(89) \
+    (90)(91)(92)(93)(94)(95)(96)(97)(98)(99) \
+    (100)(101)(102)(103)(104)(105)(106)(107)(108)(109) \
+    (110)(111)(112)(113)(114)(115)(116)(117)(118)(119) \
+    (120)(121)(122)(123)(124)(125)(126)(127)(128)(129) \
+    (130)(131)(132)(133)(134)(135)(136)(137)(138)(139) \
+    (140)(141)(142)(143)(144)(145)(146)(147)(148)(149) \
+    (150)(151)(152)(153)(154)(155)(156)(157)(158)(159) \
+    (160)(161)(162)(163)(164)(165)(166)(167)(168)(169) \
+    (170)(171)(172)(173)(174)(175)(176)(177)(178)(179) \
+    (180)(181)(182)(183)(184)(185)(186)(187)(188)(189) \
+    (190)(191)(192)(193)(194)(195)(196)(197)(198)(199) \
+    (200)(201)(202)(203)(204)(205)(206)(207)(208)(209) \
+    (210)(211)(212)(213)(214)(215)(216)(217)(218)(219) \
+    (220)(221)(222)(223)(224)(225)(226)(227)(228)(229) \
+    (230)(231)(232)(233)(234)(235)(236)(237)(238)(239) \
+    (240)(241)(242)(243)(244)(245)(246)(247)(248)(249) \
+    (250)(251)(252)(253)(254)(255)
+    
 # define SEQ_256 SEQ_255(256)

 # define SEQVAR (4,5,8,3,61)(1,0)(5,22,43)(2)(17,45,33)
--- a/test/stringize.c
+++ b/test/stringize.c
@ -0,0 +1,12 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2018.
+#  *     Distributed under the Boost Software License, Version 1.0. (See
+#  *     accompanying file LICENSE_1_0.txt or copy at
+#  *     http://www.boost.org/LICENSE_1_0.txt)
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# include <libs/preprocessor/test/stringize.cxx>
--- a/test/stringize.cpp
+++ b/test/stringize.cpp
@ -0,0 +1,12 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2018.
+#  *     Distributed under the Boost Software License, Version 1.0. (See
+#  *     accompanying file LICENSE_1_0.txt or copy at
+#  *     http://www.boost.org/LICENSE_1_0.txt)
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# include <libs/preprocessor/test/stringize.cxx>
--- a/test/stringize.cxx
+++ b/test/stringize.cxx
@ -0,0 +1,38 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2018.
+#  *     Distributed under the Boost Software License, Version 1.0. (See
+#  *     accompanying file LICENSE_1_0.txt or copy at
+#  *     http://www.boost.org/LICENSE_1_0.txt)
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# include <boost/preprocessor/stringize.hpp>
+# include <boost/preprocessor/wstringize.hpp>
+# include <boost/preprocessor/arithmetic/inc.hpp>
+# if !defined __cplusplus
+#include <wchar.h>
+#endif
+# include <libs/preprocessor/test/test.h>
+
+#define VDATA 1,2,3,4
+#define NDATA
+#define DATA data
+#define FDATA(x) BOOST_PP_INC(x)
+
+# if ~BOOST_PP_CONFIG_FLAGS() & BOOST_PP_CONFIG_MSVC()
+BEGIN sizeof(BOOST_PP_STRINGIZE(NDATA)) / sizeof(char) == 1 END
+BEGIN sizeof(BOOST_PP_WSTRINGIZE(NDATA)) / sizeof(wchar_t) == 1 END
+#endif
+BEGIN sizeof(BOOST_PP_STRINGIZE(DATA)) / sizeof(char) == 5 END
+BEGIN sizeof(BOOST_PP_STRINGIZE(FDATA(1))) / sizeof(char) == 2 END
+BEGIN sizeof(BOOST_PP_STRINGIZE(FDATA(9))) / sizeof(char) == 3 END
+BEGIN sizeof(BOOST_PP_WSTRINGIZE(DATA)) / sizeof(wchar_t) == 5 END
+BEGIN sizeof(BOOST_PP_WSTRINGIZE(FDATA(1))) / sizeof(wchar_t) == 2 END
+BEGIN sizeof(BOOST_PP_WSTRINGIZE(FDATA(9))) / sizeof(wchar_t) == 3 END
+#if BOOST_PP_VARIADICS
+BEGIN sizeof(BOOST_PP_STRINGIZE(VDATA)) / sizeof(char) == 8 END
+BEGIN sizeof(BOOST_PP_WSTRINGIZE(VDATA)) / sizeof(wchar_t) == 8 END
+#endif
--- a/test/test.h
+++ b/test/test.h
@ -14,24 +14,7 @@
 # ifndef BOOST_LIBS_PREPROCESSOR_REGRESSION_TEST_H
 # define BOOST_LIBS_PREPROCESSOR_REGRESSION_TEST_H
 #
-# include <boost/preprocessor/cat.hpp>
+# include <libs/preprocessor/test/test_macro.h>
+# include <libs/preprocessor/test/test_main.h>
 #
-# define BEGIN typedef int BOOST_PP_CAT(test_, __LINE__)[((
-# define END )==1) ? 1 : -1];
-
-#if defined(__cplusplus)
-#include <cstdio>
-#if !defined(_STLP_MSVC) || _STLP_MSVC >= 1300
-namespace std { }
-using namespace std;
-#endif
-#else
-#include <stdio.h>
-#endif
-
-int main(void) {
-    printf("pass " __TIME__);
-    return 0;
-}
-
 # endif
--- a/test/test_macro.h
+++ b/test/test_macro.h
@ -0,0 +1,22 @@
+# /* Copyright (C) 2001
+#  * Housemarque Oy
+#  * http://www.housemarque.com
+#  *
+#  * Distributed under the Boost Software License, Version 1.0. (See
+#  * accompanying file LICENSE_1_0.txt or copy at
+#  * http://www.boost.org/LICENSE_1_0.txt)
+#  */
+#
+# /* Revised by Paul Mensonides (2002) */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# ifndef BOOST_LIBS_PREPROCESSOR_REGRESSION_TEST_MACRO_H
+# define BOOST_LIBS_PREPROCESSOR_REGRESSION_TEST_MACRO_H
+#
+# include <boost/preprocessor/cat.hpp>
+#
+# define BEGIN typedef int BOOST_PP_CAT(test_, __LINE__)[((
+# define END )==1) ? 1 : -1];
+#
+# endif
--- a/test/test_main.h
+++ b/test/test_main.h
@ -0,0 +1,32 @@
+# /* Copyright (C) 2001
+#  * Housemarque Oy
+#  * http://www.housemarque.com
+#  *
+#  * Distributed under the Boost Software License, Version 1.0. (See
+#  * accompanying file LICENSE_1_0.txt or copy at
+#  * http://www.boost.org/LICENSE_1_0.txt)
+#  */
+#
+# /* Revised by Paul Mensonides (2002) */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# ifndef BOOST_LIBS_PREPROCESSOR_REGRESSION_TEST_MAIN_H
+# define BOOST_LIBS_PREPROCESSOR_REGRESSION_TEST_MAIN_H
+#
+#if defined(__cplusplus)
+#include <cstdio>
+#if !defined(_STLP_MSVC) || _STLP_MSVC >= 1300
+namespace std { }
+using namespace std;
+#endif
+#else
+#include <stdio.h>
+#endif
+
+int main(void) {
+    printf("pass " __TIME__);
+    return 0;
+}
+
+# endif
--- a/test/tuple_elem_bug_test.cxx
+++ b/test/tuple_elem_bug_test.cxx
@ -17,21 +17,21 @@
 #define TN_GEN_ONE(p) (1)
 #define TN_GEN_ZERO(p) (0)
 #define TN_TEST_ONE_MORE(parameter,ens) \
-		BOOST_PP_IF \
-			( \
-			BOOST_PP_CAT(BOOST_PP_TUPLE_ELEM(1,0,ens),0), \
-			TN_GEN_ONE, \
-			TN_GEN_ZERO \
-			) \
-		(parameter) \
+        BOOST_PP_IF \
+            ( \
+            BOOST_PP_CAT(BOOST_PP_TUPLE_ELEM(1,0,ens),0), \
+            TN_GEN_ONE, \
+            TN_GEN_ZERO \
+            ) \
+        (parameter) \
 /**/
 #define TN_TEST_ONE(parameter,ens) \
-	BOOST_PP_TUPLE_ELEM \
-		( \
-		1, \
-		0, \
-		TN_TEST_ONE_MORE(parameter,ens) \
-		) \
+    BOOST_PP_TUPLE_ELEM \
+        ( \
+        1, \
+        0, \
+        TN_TEST_ONE_MORE(parameter,ens) \
+        ) \
 /**/

 BEGIN TN_TEST_ONE(A,(1)) == 1 END
--- a/test/vaopt.cpp
+++ b/test/vaopt.cpp
@ -0,0 +1,12 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2019.
+#  *     Distributed under the Boost Software License, Version 1.0. (See
+#  *     accompanying file LICENSE_1_0.txt or copy at
+#  *     http://www.boost.org/LICENSE_1_0.txt)
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# include <libs/preprocessor/test/vaopt.cxx>
--- a/test/vaopt.cxx
+++ b/test/vaopt.cxx
@ -0,0 +1,88 @@
+# /* **************************************************************************
+#  *                                                                          *
+#  *     (C) Copyright Edward Diener 2019.
+#  *     Distributed under the Boost Software License, Version 1.0. (See
+#  *     accompanying file LICENSE_1_0.txt or copy at
+#  *     http://www.boost.org/LICENSE_1_0.txt)
+#  *                                                                          *
+#  ************************************************************************** */
+#
+# /* See http://www.boost.org for most recent version. */
+#
+# include <libs/preprocessor/test/test.h>
+# include <boost/preprocessor/variadic/has_opt.hpp>
+
+# if BOOST_PP_VARIADIC_HAS_OPT()
+
+# include <boost/preprocessor/facilities/empty.hpp>
+# include <boost/preprocessor/facilities/va_opt.hpp>
+# include <boost/preprocessor/variadic/elem.hpp>
+
+#define DATA
+#define OBJECT OBJECT2
+#define OBJECT2
+#define FUNC(x) FUNC2(x)
+#define FUNC2(x)
+#define FUNC_GEN() ()
+#define FUNC_GEN2(x) ()
+#define FUNC_GEN3() (&)
+#define FUNC_GEN4(x) (y)
+#define FUNC_GEN5() (y,z)
+#define FUNC_GEN6() anything
+#define FUNC_GEN7(x) anything
+#define FUNC_GEN8(x,y) (1,2,3)
+#define FUNC_GEN9(x,y,z) anything
+#define FUNC_GEN10(x) (y) data
+#define NAME &name
+#define ATUPLE (atuple)
+#define ATUPLE_PLUS (atuple) data
+
+#define TRY_PASS_EMPTY_STD(...) BOOST_PP_VARIADIC_ELEM(0, __VA_OPT__ (0,) 1)
+#define TRY_PASS_EMPTY_BOOST(...) BOOST_PP_VARIADIC_ELEM(0,BOOST_PP_VA_OPT((0),(1),__VA_ARGS__))
+
+BEGIN TRY_PASS_EMPTY_STD(FUNC_GEN) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(FUNC_GEN) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(FUNC_GEN2) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(FUNC_GEN2) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(FUNC_GEN3) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(FUNC_GEN3) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(FUNC_GEN4) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(FUNC_GEN4) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(FUNC_GEN5) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(FUNC_GEN5) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(FUNC_GEN8) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(FUNC_GEN8) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(FUNC_GEN9) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(FUNC_GEN9) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(FUNC_GEN10) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(FUNC_GEN10) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(BOOST_PP_EMPTY()) == 1 END
+BEGIN TRY_PASS_EMPTY_BOOST(BOOST_PP_EMPTY()) == 1 END
+BEGIN TRY_PASS_EMPTY_STD(DATA BOOST_PP_EMPTY()) == 1 END
+BEGIN TRY_PASS_EMPTY_BOOST(DATA BOOST_PP_EMPTY()) == 1 END
+BEGIN TRY_PASS_EMPTY_STD() == 1 END
+BEGIN TRY_PASS_EMPTY_BOOST() == 1 END
+BEGIN TRY_PASS_EMPTY_STD(DATA) == 1 END
+BEGIN TRY_PASS_EMPTY_BOOST(DATA) == 1 END
+BEGIN TRY_PASS_EMPTY_STD(x BOOST_PP_EMPTY()) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(x BOOST_PP_EMPTY()) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(OBJECT BOOST_PP_EMPTY()) == 1 END
+BEGIN TRY_PASS_EMPTY_BOOST(OBJECT BOOST_PP_EMPTY()) == 1 END
+BEGIN TRY_PASS_EMPTY_STD(FUNC(z) BOOST_PP_EMPTY()) == 1 END
+BEGIN TRY_PASS_EMPTY_BOOST(FUNC(z) BOOST_PP_EMPTY()) == 1 END
+BEGIN TRY_PASS_EMPTY_STD(FUNC_GEN6) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(FUNC_GEN6) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(FUNC_GEN7) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(FUNC_GEN7) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(NAME) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(NAME) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(ATUPLE) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(ATUPLE) == 0 END
+BEGIN TRY_PASS_EMPTY_STD(ATUPLE_PLUS) == 0 END
+BEGIN TRY_PASS_EMPTY_BOOST(ATUPLE_PLUS) == 0 END
+
+# else
+
+BEGIN 1 == 1 END
+
+# endif
Author	SHA1	Message	Date
Edward Diener	e4fb5f4866	Merge branch 'develop'	2020-03-01 00:18:20 -05:00
Edward Diener	9cf66925d4	Latest Borland with clang can support variadic macros. Updated iso test to be more correct choosing compiler level.	2020-02-18 02:44:51 -05:00
Edward Diener	e4ce0f06f5	Merge branch 'develop'	2020-02-01 23:12:13 -05:00
Edward Diener	98f6c75e1e	Make the quick.cpp test 'explicit'.	2020-01-06 02:34:42 -05:00
Edward Diener	f99ed9921a	Merge pull request #28 from boostorg/feature/add-cmake-tests Add CMake install support, tests	2020-01-05 20:20:29 -05:00
Peter Dimov	a378d239da	Disable the Appveyor cmake_test configuration on 2015/2017 as it's too slow; only bootstrap b2 in the boost_build_test configuration	2020-01-05 07:19:59 +02:00
Peter Dimov	0332a793f5	Fix Appveyor branch handling	2020-01-05 06:48:21 +02:00
Peter Dimov	6c350c6fc3	Update appveyor.yml	2020-01-05 06:46:08 +02:00
Peter Dimov	728c71ba75	Enable C in test/CMakeLists.txt; add `int main() {}` to quick.cpp	2020-01-05 05:07:08 +02:00
Peter Dimov	1ab9385a91	Add CMake install support, tests	2020-01-05 04:32:16 +02:00
Edward Diener	688c3f2ee6	Turn off variadic macro support by default for nvcc only when compiling CUDA files.	2019-12-14 13:20:45 -05:00
Edward Diener	bd0db5ce8b	Changed __CUDACC__ to __NVCC__ as other compilers do define __CUDACC__ when compiling CUDA files.	2019-12-14 12:45:02 -05:00
Edward Diener	da60e76913	Added 'explicit' for test_iso.	2019-11-13 20:45:02 -05:00
Edward Diener	661dd91603	Added explicit test with the alias 'test_iso' to run tests for macro expansion for the various C++ standards.	2019-11-13 20:38:10 -05:00
Edward Diener	ffb27a1d56	Merge branch 'develop'	2019-11-12 15:01:45 -05:00
Edward Diener	a6404a8fb2	Fixed __VA_OPT__ functionality for vc++ in c20 mode.	2019-11-12 14:57:09 -05:00
Edward Diener	732d00341f	For the default VC++ preprocessor turn off __VA_OPT__ support in true c20 mode ( /Zc:__cplusplus ) as it can not handle it.	2019-11-12 10:31:24 -05:00
Edward Diener	e7256313c4	Merge branch 'develop'	2019-11-03 23:32:49 -05:00
Edward Diener	b3036f1a63	Expanded emptiness explanation with the addition of the BOOST_PP_VA_OPT macro.	2019-11-02 23:58:29 -04:00
Edward Diener	de49676452	Added docs for the BOOST_PP_VA_OPT macro.	2019-11-02 18:59:55 -04:00
Edward Diener	4f4f04c56b	Added va_opt.hpp to facilities header file.	2019-11-01 15:51:34 -04:00
Edward Diener	c5e90f23b7	Updated check_empty variadic macro notation.	2019-11-01 15:34:08 -04:00
Edward Diener	776037ae56	Corrected implementation and testing for BOOST_PP_VA_OPT	2019-10-31 06:07:10 -04:00
Edward Diener	a9827c8fc8	Updated docs __VA_OPT__ support.	2019-10-30 14:32:45 -04:00
Edward Diener	6db241a78d	Merge remote-tracking branch 'remotes/origin/develop'	2019-10-20 17:03:23 -04:00
Edward Diener	4fe7807f79	Add BOOST_PP_VA_OPT implementation	2019-10-20 17:00:51 -04:00
Edward Diener	80107ea60a	Changed opt to has_opt in header file and HTML	2019-10-19 10:51:40 -04:00
Edward Diener	1473215dc7	Changed name of macro from BOOST_PP_VARIADIC_OPT to BOOST_PP_VARIADIC_HAS_OPT	2019-10-19 05:49:13 -04:00
Edward Diener	291f92696d	Merge branch 'develop'	2019-10-09 12:48:38 -04:00
Edward Diener	771edacbff	Completed the emptiness topic.	2019-10-08 15:50:08 -04:00
Edward Diener	ac99242b71	Add a topic on "emptiness"	2019-10-08 09:43:18 -04:00
Edward Diener	bda6ad9148	Updated docs	2019-10-06 22:20:19 -04:00
Edward Diener	88a0365f4d	Added the BOOST_PP_CHECK_EMPTY macro and documentation.	2019-10-06 22:06:38 -04:00
Edward Diener	6af29d8b77	Merge branch 'develop'	2019-10-04 22:51:14 -04:00
Edward Diener	af70b2872e	Updated for compiling a CUDA file with clang.	2019-10-02 18:52:09 -04:00
Edward Diener	b7b1425c7f	Remove duplicate printing of a macro in this test.	2019-09-28 11:25:09 -04:00
Edward Diener	54669af127	Fixed macro testing for __VA_OPT__ support.	2019-09-27 22:15:18 -04:00
Edward Diener	e439b2555e	Updated name and parameters for clang cuda test.	2019-09-27 13:44:19 -04:00
Edward Diener	4cce94a84e	Segregate C20 macros code from other macros for BOOST_PP_IS_EMPTY	2019-09-27 09:44:15 -04:00
Edward Diener	2f9be1086a	Less wasteful inclusion.	2019-09-26 16:07:03 -04:00
Edward Diener	684e9991ec	Only include macro if allowable.	2019-09-26 15:05:17 -04:00
Edward Diener	a42f374b97	Updated example for using the BOOST_PP_VARIADIC_OPT macro.	2019-09-26 01:19:31 -04:00
Edward Diener	0cdd09e6e1	Change to a less wasteful use of BOOST_PP_VARIADIC_OPT in BOOST_PP_IS_EMPTY code.	2019-09-26 00:43:46 -04:00
Edward Diener	22deb165b6	Documentation for variadic opt functionality.	2019-09-25 15:43:07 -04:00
Edward Diener	e476f10f52	Added OPT macro to determine whether C++20's __VA_OPT__ is supported or not. Updated the undocumented variadic IS_EMPTY to use the functionality of __VA_OPT__ if it exists to provide perfect functionality for testing for emptiness.	2019-09-25 06:29:04 -04:00
Edward Diener	c436de6142	Adjusted the configuration so that compiling a cuda source file ( .cu ) using clang does not set BOOST_PP_VARIADICS to 0. An 'explicit' test was also added for this situation.	2019-09-14 10:27:14 -04:00
Edward Diener	5756fb08ad	Fixed inspect report problems: tabs and lack of copyright notices, and a few other small html file errors.	2019-08-27 01:29:21 -04:00
Edward Diener	9b3e6a2cd6	Updated for b2 cmake support.	2018-12-19 22:09:23 -05:00
Edward Diener	d135cad759	Merge branch 'develop'	2018-10-25 19:41:15 -04:00
Edward Diener	8d26689387	Merge branch 'develop' of https://github.com/boostorg/preprocessor into develop	2018-10-25 16:58:28 -04:00
Edward Diener	f78f0a1d25	Removing any forcing of C++ levels.	2018-10-25 16:57:55 -04:00
Edward Diener	87fd89a7db	Merge pull request #20 from Mike-Devel/min_cmake [CMake] Generate cmake target that other libraries can use	2018-10-23 09:49:20 -04:00
Edward Diener	adf2746626	Add support for vc++ /experimental:preprocessor mode.	2018-10-20 14:02:20 -04:00
Edward Diener	fe70754559	Include wchar.h in order to test wide character stringize under C.	2018-10-19 16:57:17 -04:00
Edward Diener	45588469f3	Only test wide character stringize in c++.	2018-10-19 16:41:43 -04:00
Mike Dev	344ce6abf9	[CMake/CI] Use config_info.cpp for cmake self test	2018-10-17 12:13:45 +02:00
Mike Dev	31653b34c9	[CMake/CI] Some cleanup	2018-10-17 12:12:57 +02:00
Mike Dev	a4e304ca87	[CMake/CI] Add cmake self test to appveyor	2018-10-17 11:33:21 +02:00
Edward Diener	0e335df79e	Test for stringize macro and use of variadic in stringize macro.	2018-10-16 16:37:10 -04:00
Mike Dev	ee5ed2510d	[CMake] Add self-test for cmake file to travis	2018-10-16 19:58:45 +02:00
Mike Dev	dd44e1eea5	[CMake] Add minimal cmake file Generate cmake target that can be used by other libraries to express their dependency on this library and retrieve any configuration information such as the include directory.	2018-10-09 14:52:17 +02:00
Edward Diener	b5c081bf7a	Variadic macro support for the PGI compiler when EDG is being used with it.	2018-09-23 09:12:59 -04:00
Edward Diener	347f48afae	Back out previous CUDA change to turn on variadic macro support for all situations when compiling a CUDA file.	2018-09-10 17:42:32 -04:00
Edward Diener	49a72ac4f2	Corrected sentence by removing extra "the".	2018-08-23 19:20:04 -04:00
Edward Diener	56090c56b5	Merge branch 'develop'	2018-02-20 09:13:57 -05:00
Edward Diener	00b2f44624	Allow the IBM compiler to default to the level of C++/C compliance to determine default variadic macro support	2018-02-18 09:47:44 -05:00
Edward Diener	a329a67b47	NVidia compiler supports variadic macros.	2018-02-14 22:01:04 -05:00
Edward Diener	34af3a925c	Merge pull request #11 from danieljames/feature/fix-links Fix some links	2018-01-11 13:02:34 -05:00
Daniel James	ad22f9686e	Fix some links	2018-01-11 14:20:16 +00:00
eldiener	39175c471f	Merge branch 'develop'	2017-10-30 11:32:10 -04:00
eldiener	aa9ee3ae3f	Removed --depth 1	2017-10-29 21:31:25 -04:00
eldiener	50ffeeee8b	Merge branch 'develop'	2017-10-27 22:31:37 -04:00
Edward Diener	f54e270433	Better appveyor designation for tests.	2017-10-09 11:58:08 -04:00
Edward Diener	08ec2abb2e	Updated appveyor file for correct toolsets.	2017-10-09 11:39:03 -04:00
Edward Diener	c4b1ce10bd	Add VS2017 worker image.	2017-10-09 11:23:30 -04:00
Edward Diener	1ecc2e2ec9	Added Appveyor file.	2017-10-09 08:09:05 -04:00