Add use_default to Core

Travis CI shows linking errors on Linux and OS X when __cxa_uncaught_exceptions
is used to implement uncaught_exceptions. There's probably some library missing,
which should be linked in implicitly by the compiler, or the library indeed
does not export the symbol. In any case, __cxa_get_globals-based implementation
should provide the same effect.

.travis.yml

@@ -240,6 +240,7 @@ matrix:
         apt:
           packages:
             - libc++-dev
+            - libc++abi-dev
 
     - os: linux
       compiler: clang++-libc++
@@ -248,23 +249,52 @@ matrix:
         apt:
           packages:
             - libc++-dev
+            - libc++abi-dev
 
     - os: osx
       compiler: clang++
       env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
+      osx_image: xcode7.3
+
+    - os: osx
+      compiler: clang++
+      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
+      osx_image: xcode8.3
+
+    - os: osx
+      compiler: clang++
+      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
+      osx_image: xcode9.4
+
+    - os: osx
+      compiler: clang++
+      env: TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,14,1z
+      osx_image: xcode10.1
+
+    - os: linux
+      compiler: g++
+      env: CMAKE_SUBDIR_TEST=1
+      script:
+      - cd libs/core/test/cmake_subdir_test && mkdir __build__ && cd __build__
+      - cmake ..
+      - cmake --build .
+      - cmake --build . --target check
 
 install:
-  - BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
+  - BOOST_BRANCH=develop
+  - if [ "$TRAVIS_BRANCH" = "master" ]; then BOOST_BRANCH=master; fi
   - cd ..
   - git clone -b $BOOST_BRANCH https://github.com/boostorg/boost.git boost-root
   - cd boost-root
+  - git submodule init libs/headers
   - git submodule init libs/assert
   - git submodule init libs/config
   - git submodule init libs/predef
   - git submodule init libs/static_assert
   - git submodule init libs/type_traits
   - git submodule init tools/build
-  - git submodule update
+  - git submodule init tools/boost_install
+  - git submodule update --jobs 4
   - cp -r $TRAVIS_BUILD_DIR/* libs/core
   - ./bootstrap.sh
   - ./b2 headers
@@ -272,7 +302,8 @@ install:
 script:
   - |-
     echo "using $TOOLSET : : $COMPILER ;" > ~/user-config.jam
-  - ./b2 -j 3 libs/core/test toolset=$TOOLSET cxxstd=$CXXSTD variant=debug,release ${UBSAN:+cxxflags=-fsanitize=undefined cxxflags=-fno-sanitize-recover=undefined linkflags=-fsanitize=undefined define=UBSAN=1 debug-symbols=on} ${LINKFLAGS:+linkflags=$LINKFLAGS}
+  - BUILD_JOBS=`(nproc || sysctl -n hw.ncpu) 2> /dev/null`
+  - ./b2 -j $BUILD_JOBS libs/core/test toolset=$TOOLSET cxxstd=$CXXSTD variant=debug,release ${UBSAN:+cxxflags=-fsanitize=undefined cxxflags=-fno-sanitize-recover=undefined linkflags=-fsanitize=undefined define=UBSAN=1 debug-symbols=on} ${LINKFLAGS:+linkflags=$LINKFLAGS}
 
 notifications:
   email:

appveyor.yml

@@ -55,13 +55,15 @@ install:
   - cd ..
   - git clone -b %BOOST_BRANCH% https://github.com/boostorg/boost.git boost-root
   - cd boost-root
+  - git submodule init libs/headers
   - git submodule init libs/assert
   - git submodule init libs/config
   - git submodule init libs/predef
   - git submodule init libs/static_assert
   - git submodule init libs/type_traits
   - git submodule init tools/build
-  - git submodule update
+  - git submodule init tools/boost_install
+  - git submodule update --jobs 4
   - xcopy /s /e /q %APPVEYOR_BUILD_FOLDER% libs\core
   - cmd /c bootstrap
   - b2 headers
@@ -71,4 +73,4 @@ build: off
 test_script:
   - PATH=%ADDPATH%%PATH%
   - if not "%CXXSTD%" == "" set CXXSTD=cxxstd=%CXXSTD%
-  - b2 -j 3 libs/core/test toolset=%TOOLSET% %CXXSTD%
+  - b2 -j %NUMBER_OF_PROCESSORS% libs/core/test toolset=%TOOLSET% %CXXSTD%

doc/core.qbk

@@ -57,3 +57,5 @@ criteria for inclusion is that the utility component be:
 [include scoped_enum.qbk]
 [include swap.qbk]
 [include typeinfo.qbk]
+[include uncaught_exceptions.qbk]
+[include use_default.qbk]

doc/lightweight_test.qbk

@@ -1,7 +1,7 @@
 [/
   Copyright 2010, 2011 Beman Dawes
   Copyright 2013 Ion Gaztanaga
-  Copyright 2014, 2017 Peter Dimov
+  Copyright 2014-2019 Peter Dimov
   Copyright 2017 Kohei Takahashi
 
   Distributed under the Boost Software License, Version 1.0.
@@ -253,6 +253,7 @@ return a boolean value.
 ``
 #define BOOST_TEST_TRAIT_TRUE((Trait)) /*unspecified*/
 #define BOOST_TEST_TRAIT_FALSE((Trait)) /*unspecified*/
+#define BOOST_TEST_TRAIT_SAME(Type1, Type2) /*unspecified*/
 ``
 
 [endsect]
@@ -280,6 +281,20 @@ message containing `Trait`. Note the double set of parentheses.
 
 [endsect]
 
+[section BOOST_TEST_TRAIT_SAME]
+
+``
+BOOST_TEST_TRAIT_SAME(Type1, Type2)
+``
+
+If the two types are not the same, increases the error count and outputs a
+message containing them. This macro requires that the compiler supports
+variadic macros and `__VA_ARGS__`. (Note that unlike `BOOST_TEST_TRAIT_TRUE`
+and `BOOST_TEST_TRAIT_FALSE`, this macro only requires a single set of
+parentheses.)
+
+[endsect]
+
 [section Example]
 
 ``
@@ -297,6 +312,8 @@ int main()
 {
     BOOST_TEST_TRAIT_TRUE(( is_same<X<int, long>::type, int> ));
 
+    BOOST_TEST_TRAIT_SAME( X<int, long>::type, int );
+
     return boost::report_errors();
 }
 ``

doc/uncaught_exceptions.qbk

@@ -0,0 +1,52 @@
+[/
+ / Copyright (c) 2018 Andrey Semashev
+ /
+ / 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)
+ /]
+
+[section:uncaught_exceptions uncaught_exceptions]
+
+[simplesect Authors]
+
+* Andrey Semashev
+
+[endsimplesect]
+
+[section Header <boost/core/uncaught_exceptions.hpp>]
+
+The header `<boost/core/uncaught_exceptions.hpp>` defines the `boost::core::uncaught_exceptions` function,
+which is a more portable implementation of the same named function introduced in C++17. The function
+returns the number of the currently pending exceptions. When that function returns a value greater than 0,
+throwing an exception from a destructor can terminate the program.
+
+Unfortunately, the function cannot be implemented on every pre-C++17 compiler, although the most commonly
+used compilers are supported. When the compiler does not provide the necessary functionality,
+`boost::core::uncaught_exceptions` returns a non-zero value if at least one exception is pending (i.e. not
+necessarily the number of pending exceptions), and `BOOST_CORE_UNCAUGHT_EXCEPTIONS_EMULATED` macro
+is defined.
+
+[section Example]
+``
+class my_class
+{
+private:
+    const unsigned int m_exception_count;
+
+public:
+    my_class() : m_exception_count(boost::core::uncaught_exceptions())
+    {
+    }
+
+    ~my_class() noexcept(false)
+    {
+        if (m_exception_count == boost::core::uncaught_exceptions())
+            do_something_potentially_throwing();
+    }
+};
+``
+[endsect]
+
+[endsect]
+
+[endsect]

doc/use_default.qbk

@@ -0,0 +1,47 @@
+[/
+Copyright 2019 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+]
+
+[section:use_default use_default]
+
+[section Overview]
+
+The header <boost/core/use_default.hpp> provides the type `boost::use_default`
+which is used by other Boost libraries as a sentinel type in a templates to
+indicate defaults.
+
+[endsect]
+
+[section Example]
+
+```
+template<class Derived, class Base,
+   class Value = boost::use_default,
+   class CategoryOrTraversal = boost::use_default,
+   class Reference = boost::use_default,
+   class Difference = boost::use_default>
+class iterator_adaptor;
+
+template<class Value>
+class node_iterator
+    : public iterator_adaptor<node_iterator<Value>, Value*,
+        boost::use_default, boost::forward_traversal_tag>;
+```
+
+[endsect]
+
+[section Reference]
+
+```
+namespace boost {
+  struct use_default { };
+}
+```
+
+[endsect]
+
+[endsect]

include/boost/core/checked_delete.hpp

@@ -7,6 +7,8 @@
 # pragma once
 #endif
 
+#include <boost/config.hpp>
+
 //
 //  boost/checked_delete.hpp
 //
@@ -26,7 +28,7 @@ namespace boost
 
 // verify that types are complete for increased safety
 
-template<class T> inline void checked_delete(T * x)
+template<class T> inline void checked_delete(T * x) BOOST_NOEXCEPT
 {
     // intentionally complex - simplification causes regressions
     typedef char type_must_be_complete[ sizeof(T)? 1: -1 ];
@@ -34,7 +36,7 @@ template<class T> inline void checked_delete(T * x)
     delete x;
 }
 
-template<class T> inline void checked_array_delete(T * x)
+template<class T> inline void checked_array_delete(T * x) BOOST_NOEXCEPT
 {
     typedef char type_must_be_complete[ sizeof(T)? 1: -1 ];
     (void) sizeof(type_must_be_complete);
@@ -46,7 +48,7 @@ template<class T> struct checked_deleter
     typedef void result_type;
     typedef T * argument_type;
 
-    void operator()(T * x) const
+    void operator()(T * x) const BOOST_NOEXCEPT
     {
         // boost:: disables ADL
         boost::checked_delete(x);
@@ -58,7 +60,7 @@ template<class T> struct checked_array_deleter
     typedef void result_type;
     typedef T * argument_type;
 
-    void operator()(T * x) const
+    void operator()(T * x) const BOOST_NOEXCEPT
     {
         boost::checked_array_delete(x);
     }

include/boost/core/lightweight_test_trait.hpp

@@ -9,7 +9,7 @@
 
 // boost/core/lightweight_test_trait.hpp
 //
-// BOOST_TEST_TRAIT_TRUE, BOOST_TEST_TRAIT_FALSE
+// BOOST_TEST_TRAIT_TRUE, BOOST_TEST_TRAIT_FALSE, BOOST_TEST_TRAIT_SAME
 //
 // Copyright 2014 Peter Dimov
 //
@@ -19,6 +19,7 @@
 
 #include <boost/core/lightweight_test.hpp>
 #include <boost/core/typeinfo.hpp>
+#include <boost/core/is_same.hpp>
 
 namespace boost
 {
@@ -46,11 +47,37 @@ template< class T > inline void test_trait_impl( char const * trait, void (*)( T
     }
 }
 
+template<class T> inline bool test_trait_same_impl_( T )
+{
+    return T::value;
+}
+
+template<class T1, class T2> inline void test_trait_same_impl( char const * types,
+  boost::core::is_same<T1, T2> same, char const * file, int line, char const * function )
+{
+    if( test_trait_same_impl_( same ) )
+    {
+        test_results();
+    }
+    else
+    {
+        BOOST_LIGHTWEIGHT_TEST_OSTREAM
+            << file << "(" << line << "): test 'is_same<" << types << ">'"
+            << " failed in function '" << function
+            << "' ('" << boost::core::demangled_name( BOOST_CORE_TYPEID(T1) )
+            << "' != '" << boost::core::demangled_name( BOOST_CORE_TYPEID(T2) ) << "')"
+            << std::endl;
+
+        ++test_results().errors();
+    }
+}
+
 } // namespace detail
 
 } // namespace boost
 
 #define BOOST_TEST_TRAIT_TRUE(type) ( ::boost::detail::test_trait_impl(#type, (void(*)type)0, true, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION) )
 #define BOOST_TEST_TRAIT_FALSE(type) ( ::boost::detail::test_trait_impl(#type, (void(*)type)0, false, __FILE__, __LINE__, BOOST_CURRENT_FUNCTION) )
+#define BOOST_TEST_TRAIT_SAME(...) ( ::boost::detail::test_trait_same_impl(#__VA_ARGS__, ::boost::core::is_same<__VA_ARGS__>(), __FILE__, __LINE__, BOOST_CURRENT_FUNCTION) )
 
 #endif // #ifndef BOOST_CORE_LIGHTWEIGHT_TEST_TRAIT_HPP

include/boost/core/uncaught_exceptions.hpp

@@ -0,0 +1,131 @@
+/*
+ *             Copyright Andrey Semashev 2018.
+ * Distributed under the Boost Software License, Version 1.0.
+ *    (See accompanying file LICENSE_1_0.txt or copy at
+ *          https://www.boost.org/LICENSE_1_0.txt)
+ */
+/*!
+ * \file   uncaught_exceptions.hpp
+ * \author Andrey Semashev
+ * \date   2018-11-10
+ *
+ * \brief  This header provides an `uncaught_exception` function implementation, which was introduced in C++17.
+ *
+ * The code in this file is based on the implementation by Evgeny Panasyuk:
+ *
+ * https://github.com/panaseleus/stack_unwinding/blob/master/boost/exception/uncaught_exception_count.hpp
+ */
+
+#ifndef BOOST_CORE_UNCAUGHT_EXCEPTIONS_HPP_INCLUDED_
+#define BOOST_CORE_UNCAUGHT_EXCEPTIONS_HPP_INCLUDED_
+
+#include <exception>
+#include <boost/config.hpp>
+
+#if defined(BOOST_HAS_PRAGMA_ONCE)
+#pragma once
+#endif
+
+// Visual Studio 14 supports N4152 std::uncaught_exceptions()
+#if (defined(__cpp_lib_uncaught_exceptions) && __cpp_lib_uncaught_exceptions >= 201411) || \
+    (defined(_MSC_VER) && _MSC_VER >= 1900)
+#define BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS
+#endif
+
+#if !defined(BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS)
+
+// cxxabi.h availability macro
+#if defined(__has_include) && (!defined(BOOST_GCC) || (__GNUC__ >= 5))
+#   if __has_include(<cxxabi.h>)
+#       define BOOST_CORE_HAS_CXXABI_H
+#   endif
+#elif defined(__GLIBCXX__) || defined(__GLIBCPP__)
+#   define BOOST_CORE_HAS_CXXABI_H
+#endif
+
+#if defined(BOOST_CORE_HAS_CXXABI_H)
+// MinGW GCC 4.4 seem to not work the same way the newer GCC versions do. As a result, __cxa_get_globals based implementation will always return 0.
+// Just disable it for now and fall back to std::uncaught_exception().
+#if !(defined(__MINGW32__) && (defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__) < 405))
+#include <cxxabi.h>
+#include <cstring>
+#define BOOST_CORE_HAS_CXA_GET_GLOBALS
+// At least on MinGW and Linux, only GCC since 4.7 declares __cxa_get_globals() in cxxabi.h. Older versions of GCC do not expose this function but it's there.
+// On OpenBSD, it seems, the declaration is also missing.
+// Note that at least on FreeBSD 11, cxxabi.h declares __cxa_get_globals with a different exception specification, so we can't declare the function unconditionally.
+// On Linux with clang and libc++ and on OS X, there is a version of cxxabi.h from libc++abi that doesn't declare __cxa_get_globals, but provides __cxa_uncaught_exceptions.
+// The function only appeared in version _LIBCPPABI_VERSION >= 1002 of the library. Unfortunately, there are linking errors about undefined reference to __cxa_uncaught_exceptions
+// on Ubuntu Trusty and OS X, so we avoid using it and forward-declare __cxa_get_globals instead.
+#if !defined(__FreeBSD__) && \
+    ( \
+        (defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__) < 407) || \
+        defined(__OpenBSD__) || \
+        defined(_LIBCPPABI_VERSION) \
+    )
+namespace __cxxabiv1 {
+struct __cxa_eh_globals;
+#if defined(__OpenBSD__)
+extern "C" __cxa_eh_globals* __cxa_get_globals();
+#else
+extern "C" __cxa_eh_globals* __cxa_get_globals() BOOST_NOEXCEPT_OR_NOTHROW __attribute__((__const__));
+#endif
+} // namespace __cxxabiv1
+#endif
+#endif // !(defined(__MINGW32__) && (defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__) < 405))
+#endif // defined(BOOST_CORE_HAS_CXXABI_H)
+
+#if defined(_MSC_VER) && _MSC_VER >= 1400
+#include <cstring>
+#define BOOST_CORE_HAS_GETPTD
+namespace boost {
+namespace core {
+namespace detail {
+extern "C" void* _getptd();
+} // namespace detail
+} // namespace core
+} // namespace boost
+#endif // defined(_MSC_VER) && _MSC_VER >= 1400
+
+#endif // !defined(BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS)
+
+#if !defined(BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS) && !defined(BOOST_CORE_HAS_CXA_GET_GLOBALS) && !defined(BOOST_CORE_HAS_GETPTD)
+//! This macro is defined when `uncaught_exceptions` is not guaranteed to return values greater than 1 if multiple exceptions are pending
+#define BOOST_CORE_UNCAUGHT_EXCEPTIONS_EMULATED
+#endif
+
+namespace boost {
+
+namespace core {
+
+//! Returns the number of currently pending exceptions
+inline unsigned int uncaught_exceptions() BOOST_NOEXCEPT
+{
+#if defined(BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS)
+    // C++17 implementation
+    return static_cast< unsigned int >(std::uncaught_exceptions());
+#elif defined(BOOST_CORE_HAS_CXA_GET_GLOBALS)
+    // Tested on {clang 3.2,GCC 3.5.6,GCC 4.1.2,GCC 4.4.6,GCC 4.4.7}x{x32,x64}
+    unsigned int count;
+    std::memcpy(&count, reinterpret_cast< const unsigned char* >(::abi::__cxa_get_globals()) + sizeof(void*), sizeof(count)); // __cxa_eh_globals::uncaughtExceptions, x32 offset - 0x4, x64 - 0x8
+    return count;
+#elif defined(BOOST_CORE_HAS_GETPTD)
+    // MSVC specific. Tested on {MSVC2005SP1,MSVC2008SP1,MSVC2010SP1,MSVC2012}x{x32,x64}.
+    unsigned int count;
+    std::memcpy(&count, static_cast< const unsigned char* >(boost::core::detail::_getptd()) + (sizeof(void*) == 8u ? 0x100 : 0x90), sizeof(count)); // _tiddata::_ProcessingThrow, x32 offset - 0x90, x64 - 0x100
+    return count;
+#else
+    // Portable C++03 implementation. Does not allow to detect multiple nested exceptions.
+    return static_cast< unsigned int >(std::uncaught_exception());
+#endif
+}
+
+} // namespace core
+
+} // namespace boost
+
+#undef BOOST_CORE_HAS_CXXABI_H
+#undef BOOST_CORE_HAS_CXA_GET_GLOBALS
+#undef BOOST_CORE_HAS_UNCAUGHT_EXCEPTIONS
+#undef BOOST_CORE_HAS_GETPTD
+
+#endif // BOOST_CORE_UNCAUGHT_EXCEPTIONS_HPP_INCLUDED_

include/boost/core/use_default.hpp

@@ -0,0 +1,17 @@
+/*
+Copyright 2019 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+*/
+#ifndef BOOST_CORE_USE_DEFAULT_HPP
+#define BOOST_CORE_USE_DEFAULT_HPP
+
+namespace boost {
+
+struct use_default { };
+
+} /* boost */
+
+#endif

test/Jamfile.v2

@@ -76,6 +76,8 @@ run lightweight_test_lt_le_test.cpp ;
 run lightweight_test_gt_ge_test.cpp ;
 run lightweight_test_eq_nullptr.cpp ;
 run lightweight_test_test3.cpp ;
+run lightweight_test_test4.cpp ;
+run lightweight_test_test5.cpp ;
 
 run-fail lightweight_test_fail.cpp ;
 run-fail lightweight_test_fail2.cpp ;
@@ -126,10 +128,13 @@ run exchange_move_test.cpp ;
 
 run empty_value_test.cpp ;
 run empty_value_size_test.cpp ;
+run empty_value_final_test.cpp ;
 
 run quick_exit_test.cpp ;
 run-fail quick_exit_fail.cpp ;
 
+compile use_default_test.cpp ;
+
 lib lib_typeid : lib_typeid.cpp : <link>shared:<define>LIB_TYPEID_DYN_LINK=1 ;
 
 run test_lib_typeid.cpp lib_typeid : : : <link>shared : test_lib_typeid_shared ;
@@ -138,5 +143,8 @@ run test_lib_typeid.cpp lib_typeid : : : <link>static : test_lib_typeid_static ;
 run test_lib_typeid.cpp lib_typeid : : : <link>shared <rtti>off : test_lib_typeid_shared_no_rtti ;
 run test_lib_typeid.cpp lib_typeid : : : <link>static <rtti>off  : test_lib_typeid_static_no_rtti ;
 
+run uncaught_exceptions.cpp : : : <exception-handling>on ;
+run uncaught_exceptions_np.cpp : : : <exception-handling>on ;
+
 use-project /boost/core/swap : ./swap ;
 build-project ./swap ;

test/cmake_subdir_test/CMakeLists.txt

@@ -0,0 +1,19 @@
+# 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)
+
+project(cmake_subdir_test LANGUAGES CXX)
+
+add_subdirectory(../.. boostorg/core)
+add_subdirectory(../../../assert boostorg/assert)
+add_subdirectory(../../../config boostorg/config)
+
+add_executable(quick ../quick.cpp)
+target_link_libraries(quick Boost::core)
+
+enable_testing()
+add_test(quick quick)
+
+add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND} --output-on-failure -C $<CONFIG>)

test/empty_value_final_test.cpp

@@ -0,0 +1,62 @@
+/*
+Copyright 2018 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+*/
+#include <boost/core/empty_value.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+#if !defined(BOOST_NO_CXX11_FINAL)
+class type final {
+public:
+    explicit type(int count)
+        : value_(count) { }
+    int value() const {
+        return value_ + 1;
+    }
+    int value() {
+        return value_ + 2;
+    }
+private:
+    int value_;
+};
+
+struct empty final {
+    int value() const {
+        return 1;
+    }
+    int value() {
+        return 2;
+    }
+};
+
+void test_type()
+{
+    const boost::empty_value<type> v1(boost::empty_init_t(), 3);
+    BOOST_TEST(v1.get().value() == 4);
+    boost::empty_value<type> v2(boost::empty_init_t(), 3);
+    BOOST_TEST(v2.get().value() == 5);
+}
+
+void test_empty()
+{
+    const boost::empty_value<empty> v1 = boost::empty_init_t();
+    BOOST_TEST(v1.get().value() == 1);
+    boost::empty_value<empty> v2;
+    BOOST_TEST(v2.get().value() == 2);
+}
+
+int main()
+{
+    test_type();
+    test_empty();
+    return boost::report_errors();
+}
+#else
+int main()
+{
+    return 0;
+}
+#endif

test/empty_value_test.cpp

@@ -9,67 +9,63 @@ Distributed under the Boost Software License, Version 1.0.
 #include <boost/core/lightweight_test.hpp>
 
 struct empty {
-    operator bool() const {
-        return false;
+    int value() const {
+        return 1;
     }
-    operator bool() {
-        return true;
+    int value() {
+        return 2;
     }
 };
 
 class type {
 public:
-    type()
-        : value_(false) { }
-    explicit type(bool value)
-        : value_(value) { }
-    operator bool() const {
-        return value_;
+    explicit type(int count)
+        : value_(count) { }
+    int value() const {
+        return value_ + 1;
+    }
+    int value() {
+        return value_ + 2;
     }
 private:
-    bool value_;
+    int value_;
 };
 
-void test_bool()
+void test_int()
 {
-    const boost::empty_value<bool> v1(boost::empty_init_t(), true);
-    BOOST_TEST(v1.get());
-    boost::empty_value<bool> v2 = boost::empty_init_t();
-    BOOST_TEST(!v2.get());
+    const boost::empty_value<int> v1(boost::empty_init_t(), 7);
+    BOOST_TEST(v1.get() == 7);
+    boost::empty_value<int> v2 = boost::empty_init_t();
+    BOOST_TEST(v2.get() == 0);
     v2 = v1;
-    BOOST_TEST(v2.get());
-    v2.get() = false;
-    BOOST_TEST(!v2.get());
+    BOOST_TEST(v2.get() == 7);
+    v2.get() = 8;
+    BOOST_TEST(v2.get() == 8);
 }
 
 void test_empty()
 {
-    empty e;
-    const boost::empty_value<empty> v1(boost::empty_init_t(), e);
-    BOOST_TEST(!v1.get());
+    const boost::empty_value<empty> v1 = boost::empty_init_t();
+    BOOST_TEST(v1.get().value() == 1);
     boost::empty_value<empty> v2;
-    BOOST_TEST(v2.get());
-    v2 = v1;
-    BOOST_TEST(v2.get());
-    v2.get() = empty();
-    BOOST_TEST(v2.get());
+    BOOST_TEST(v2.get().value() == 2);
 }
 
 void test_type()
 {
-    const boost::empty_value<type> v1(boost::empty_init_t(), true);
-    BOOST_TEST(v1.get());
-    boost::empty_value<type> v2;
-    BOOST_TEST(!v2.get());
+    const boost::empty_value<type> v1(boost::empty_init_t(), 2);
+    BOOST_TEST(v1.get().value() == 3);
+    boost::empty_value<type> v2(boost::empty_init_t(), 3);
+    BOOST_TEST(v2.get().value() == 5);
     v2 = v1;
-    BOOST_TEST(v2.get());
-    v2.get() = type();
-    BOOST_TEST(!v2.get());
+    BOOST_TEST(v2.get().value() == 4);
+    v2.get() = type(4);
+    BOOST_TEST(v2.get().value() == 6);
 }
 
 int main()
 {
-    test_bool();
+    test_int();
     test_empty();
     test_type();
     return boost::report_errors();

test/lightweight_test_test4.cpp

@@ -0,0 +1,36 @@
+//
+// Test for BOOST_TEST_TRAIT_SAME
+//
+// Copyright 2014, 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 <boost/core/lightweight_test_trait.hpp>
+
+struct X
+{
+    typedef int type;
+};
+
+template<class T1, class T2> struct Y
+{
+    typedef T1 type;
+};
+
+int main()
+{
+    BOOST_TEST_TRAIT_SAME(X, X);
+    BOOST_TEST_TRAIT_SAME(void, void);
+    BOOST_TEST_TRAIT_SAME(char[1], char[1]);
+    BOOST_TEST_TRAIT_SAME(char[], char[]);
+    BOOST_TEST_TRAIT_SAME(void(), void());
+    BOOST_TEST_TRAIT_SAME(X::type, X::type);
+    BOOST_TEST_TRAIT_SAME(X::type, Y<int, float>::type);
+    BOOST_TEST_TRAIT_SAME(Y<int, float>, Y<int, float>);
+    BOOST_TEST_TRAIT_SAME(Y<void, float>::type, void);
+
+    return boost::report_errors();
+}

test/lightweight_test_test5.cpp

@@ -0,0 +1,37 @@
+//
+// Negative test for BOOST_TEST_TRAIT_SAME
+//
+// Copyright 2014, 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 <boost/core/lightweight_test_trait.hpp>
+
+struct X
+{
+    typedef int type;
+};
+
+template<class T1, class T2> struct Y
+{
+    typedef T1 type;
+};
+
+int main()
+{
+    BOOST_TEST_TRAIT_SAME(char[1], char[2]);
+    BOOST_TEST_TRAIT_SAME(char[1], char[]);
+    BOOST_TEST_TRAIT_SAME(char[1], char*);
+    BOOST_TEST_TRAIT_SAME(void(), void(int));
+    BOOST_TEST_TRAIT_SAME(void(), void(*)());
+    BOOST_TEST_TRAIT_SAME(X, void);
+    BOOST_TEST_TRAIT_SAME(X::type, void);
+    BOOST_TEST_TRAIT_SAME(X, Y<void, void>);
+    BOOST_TEST_TRAIT_SAME(X::type, Y<float, int>::type);
+    BOOST_TEST_TRAIT_SAME(Y<int, float>, Y<int, double>);
+
+    return boost::report_errors() == 10;
+}

test/uncaught_exceptions.cpp

@@ -0,0 +1,55 @@
+/*
+ *             Copyright Andrey Semashev 2018.
+ * Distributed under the Boost Software License, Version 1.0.
+ *    (See accompanying file LICENSE_1_0.txt or copy at
+ *          https://www.boost.org/LICENSE_1_0.txt)
+ */
+/*!
+ * \file   uncaught_exceptions.cpp
+ * \author Andrey Semashev
+ * \date   2018-11-10
+ *
+ * \brief  This file contains tests for the uncaught_exceptions function.
+ *
+ * This file only contains the very basic checks of functionality that can be portably achieved
+ * through C++03 std::uncaught_exception.
+ */
+
+#include <boost/core/uncaught_exceptions.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+struct my_exception {};
+
+class exception_watcher
+{
+    unsigned int& m_count;
+
+public:
+    explicit exception_watcher(unsigned int& count) : m_count(count) {}
+    ~exception_watcher() { m_count = boost::core::uncaught_exceptions(); }
+};
+
+// Tests for uncaught_exceptions when used in a destructor while an exception propagates
+void test_in_destructor()
+{
+    const unsigned int root_count = boost::core::uncaught_exceptions();
+
+    unsigned int level1_count = root_count;
+    try
+    {
+        exception_watcher watcher(level1_count);
+        throw my_exception();
+    }
+    catch (...)
+    {
+    }
+
+    BOOST_TEST_NE(root_count, level1_count);
+}
+
+int main()
+{
+    test_in_destructor();
+
+    return boost::report_errors();
+}

test/uncaught_exceptions_np.cpp

@@ -0,0 +1,90 @@
+/*
+ *             Copyright Andrey Semashev 2018.
+ * Distributed under the Boost Software License, Version 1.0.
+ *    (See accompanying file LICENSE_1_0.txt or copy at
+ *          https://www.boost.org/LICENSE_1_0.txt)
+ */
+/*!
+ * \file   uncaught_exceptions_np.cpp
+ * \author Andrey Semashev
+ * \date   2018-11-10
+ *
+ * \brief  This file contains tests for the uncaught_exceptions function.
+ *
+ * This file contains checks that are compiler specific and not quite portable or require C++17.
+ */
+
+#include <boost/core/uncaught_exceptions.hpp>
+
+#if !defined(BOOST_CORE_UNCAUGHT_EXCEPTIONS_EMULATED)
+
+#include <boost/core/lightweight_test.hpp>
+
+struct my_exception1 {};
+struct my_exception2 {};
+
+class exception_watcher2
+{
+    unsigned int& m_count;
+
+public:
+    explicit exception_watcher2(unsigned int& count) : m_count(count) {}
+    ~exception_watcher2() { m_count = boost::core::uncaught_exceptions(); }
+};
+
+class exception_watcher1
+{
+    unsigned int& m_count1;
+    unsigned int& m_count2;
+
+public:
+    exception_watcher1(unsigned int& count1, unsigned int& count2) : m_count1(count1), m_count2(count2) {}
+    ~exception_watcher1()
+    {
+        m_count1 = boost::core::uncaught_exceptions();
+        try
+        {
+            exception_watcher2 watcher2(m_count2);
+            throw my_exception2();
+        }
+        catch (...)
+        {
+        }
+    }
+};
+
+// Tests for uncaught_exceptions when used in nested destructors while an exception propagates
+void test_in_nested_destructors()
+{
+    const unsigned int root_count = boost::core::uncaught_exceptions();
+
+    unsigned int level1_count = root_count, level2_count = root_count;
+    try
+    {
+        exception_watcher1 watcher1(level1_count, level2_count);
+        throw my_exception1();
+    }
+    catch (...)
+    {
+    }
+
+    BOOST_TEST_NE(root_count, level1_count);
+    BOOST_TEST_NE(root_count, level2_count);
+    BOOST_TEST_NE(level1_count, level2_count);
+}
+
+int main()
+{
+    test_in_nested_destructors();
+
+    return boost::report_errors();
+}
+
+#else
+
+int main()
+{
+    return 0;
+}
+
+#endif

test/use_default_test.cpp

@@ -0,0 +1,15 @@
+/*
+Copyright 2019 Glen Joseph Fernandes
+(glenjofe@gmail.com)
+
+Distributed under the Boost Software License, Version 1.0.
+(http://www.boost.org/LICENSE_1_0.txt)
+*/
+
+#include <boost/core/use_default.hpp>
+
+template<class, class = boost::use_default>
+struct type { };
+
+template class type<int>;
+template class type<void, boost::use_default>;