Remove Boost metaproject

16 files changed, 0 insertions, 2564 deletions

diff --git a/contrib/restricted/boost/context/README.md b/contrib/restricted/boost/context/README.md
deleted file mode 100644
index 44aeff04f3c..00000000000
--- a/contrib/restricted/boost/context/README.md
+++ /dev/null
@@ -1,21 +0,0 @@
-boost.context
-=============
-
-boost.context is a foundational library that provides a sort of cooperative multitasking on a single thread.
-By providing an abstraction of the current execution state in the current thread, including the stack (with 
-local variables) and stack pointer, all registers and CPU flags, and the instruction pointer, a execution_context 
-instance represents a specific point in the application's execution path. This is useful for building 
-higher-level abstractions, like coroutines, cooperative threads (userland threads) or an equivalent to 
-C# keyword yield in C++.
-
-A fiber provides the means to suspend the current execution path and to transfer execution control, 
-thereby permitting another fiber to run on the current thread. This state full transfer mechanism 
-enables a fiber to suspend execution from within nested functions and, later, to resume from where it 
-was suspended. While the execution path represented by a fiber only runs on a single thread, it can be 
-migrated to another thread at any given time.
-
-A context switch between threads requires system calls (involving the OS kernel), which can cost more than 
-thousand CPU cycles on x86 CPUs. By contrast, transferring control among fibers requires only fewer than 
-hundred CPU cycles because it does not involve system calls as it is done within a single thread.
-
-boost.context requires C++11! 
diff --git a/contrib/restricted/boost/context/include/boost/context/continuation_ucontext.hpp b/contrib/restricted/boost/context/include/boost/context/continuation_ucontext.hpp
deleted file mode 100644
index 951e542983a..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/continuation_ucontext.hpp
+++ /dev/null
@@ -1,538 +0,0 @@
-
-//          Copyright Oliver Kowalke 2017.
-// 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)
-
-#ifndef BOOST_CONTEXT_CONTINUATION_H
-#define BOOST_CONTEXT_CONTINUATION_H
-
-#include <boost/predef.h>
-#if BOOST_OS_MACOS
-#define _XOPEN_SOURCE 600
-#endif
-
-extern "C" {
-#include <ucontext.h>
-}
-
-#include <boost/context/detail/config.hpp>
-
-#include <algorithm>
-#include <cstddef>
-#include <cstdint>
-#include <cstdlib>
-#include <cstring>
-#include <functional>
-#include <memory>
-#include <ostream>
-#include <system_error>
-#include <tuple>
-#include <utility>
-
-#include <boost/assert.hpp>
-#include <boost/config.hpp>
-
-#include <boost/context/detail/disable_overload.hpp>
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-#include <boost/context/detail/exchange.hpp>
-#endif
-#include <boost/context/detail/externc.hpp>
-#if defined(BOOST_NO_CXX17_STD_INVOKE)
-#include <boost/context/detail/invoke.hpp>
-#endif
-#include <boost/context/fixedsize_stack.hpp>
-#include <boost/context/flags.hpp>
-#include <boost/context/preallocated.hpp>
-#if defined(BOOST_USE_SEGMENTED_STACKS)
-#include <boost/context/segmented_stack.hpp>
-#endif
-#include <boost/context/stack_context.hpp>
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_PREFIX
-#endif
-
-namespace boost {
-namespace context {
-namespace detail {
-
-// tampoline function
-// entered if the execution context
-// is resumed for the first time
-template< typename Record >
-static void entry_func( void * data) noexcept {
-    Record * record = static_cast< Record * >( data);
-    BOOST_ASSERT( nullptr != record);
-    // start execution of toplevel context-function
-    record->run();
-}
-
-struct BOOST_CONTEXT_DECL activation_record {
-    ucontext_t                                                  uctx{};
-    stack_context                                               sctx{};
-    bool                                                        main_ctx{ true };
-	activation_record                                       *	from{ nullptr };
-    std::function< activation_record*(activation_record*&) >    ontop{};
-    bool                                                        terminated{ false };
-    bool                                                        force_unwind{ false };
-#if defined(BOOST_USE_ASAN)
-    void                                                    *   fake_stack{ nullptr };
-    void                                                    *   stack_bottom{ nullptr };
-    std::size_t                                                 stack_size{ 0 };
-#endif
-
-    static activation_record *& current() noexcept;
-
-    // used for toplevel-context
-    // (e.g. main context, thread-entry context)
-    activation_record() {
-        if ( BOOST_UNLIKELY( 0 != ::getcontext( & uctx) ) ) {
-            throw std::system_error(
-                    std::error_code( errno, std::system_category() ),
-                    "getcontext() failed");
-        }
-    }
-
-    activation_record( stack_context sctx_) noexcept :
-        sctx( sctx_ ),
-        main_ctx( false ) {
-    } 
-
-    virtual ~activation_record() {
-	}
-
-    activation_record( activation_record const&) = delete;
-    activation_record & operator=( activation_record const&) = delete;
-
-    bool is_main_context() const noexcept {
-        return main_ctx;
-    }
-
-    activation_record * resume() {
-		from = current();
-        // store `this` in static, thread local pointer
-        // `this` will become the active (running) context
-        current() = this;
-#if defined(BOOST_USE_SEGMENTED_STACKS)
-        // adjust segmented stack properties
-        __splitstack_getcontext( from->sctx.segments_ctx);
-        __splitstack_setcontext( sctx.segments_ctx);
-#endif
-#if defined(BOOST_USE_ASAN)
-        if ( terminated) {
-            __sanitizer_start_switch_fiber( nullptr, stack_bottom, stack_size);
-        } else {
-            __sanitizer_start_switch_fiber( & from->fake_stack, stack_bottom, stack_size);
-        }
-#endif
-        // context switch from parent context to `this`-context
-        ::swapcontext( & from->uctx, & uctx);
-#if defined(BOOST_USE_ASAN)
-        __sanitizer_finish_switch_fiber( current()->fake_stack,
-                                         (const void **) & current()->from->stack_bottom,
-                                         & current()->from->stack_size);
-#endif
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        return exchange( current()->from, nullptr);
-#else
-        return std::exchange( current()->from, nullptr);
-#endif
-    }
-
-    template< typename Ctx, typename Fn >
-    activation_record * resume_with( Fn && fn) {
-		from = current();
-        // store `this` in static, thread local pointer
-        // `this` will become the active (running) context
-        // returned by continuation::current()
-        current() = this;
-#if defined(BOOST_NO_CXX14_GENERIC_LAMBDAS)
-        current()->ontop = std::bind(
-                [](typename std::decay< Fn >::type & fn, activation_record *& ptr){
-                    Ctx c{ ptr };
-                    c = fn( std::move( c) );
-                    if ( ! c) {
-                        ptr = nullptr;
-                    }
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-                    return exchange( c.ptr_, nullptr);
-#else
-                    return std::exchange( c.ptr_, nullptr);
-#endif
-                },
-                std::forward< Fn >( fn),
-                std::placeholders::_1);
-#else
-        current()->ontop = [fn=std::forward<Fn>(fn)](activation_record *& ptr){
-            Ctx c{ ptr };
-            c = fn( std::move( c) );
-            if ( ! c) {
-                ptr = nullptr;
-            }
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-            return exchange( c.ptr_, nullptr);
-#else
-            return std::exchange( c.ptr_, nullptr);
-#endif
-        };
-#endif
-#if defined(BOOST_USE_SEGMENTED_STACKS)
-        // adjust segmented stack properties
-        __splitstack_getcontext( from->sctx.segments_ctx);
-        __splitstack_setcontext( sctx.segments_ctx);
-#endif
-#if defined(BOOST_USE_ASAN)
-        __sanitizer_start_switch_fiber( & from->fake_stack, stack_bottom, stack_size);
-#endif
-        // context switch from parent context to `this`-context
-        ::swapcontext( & from->uctx, & uctx);
-#if defined(BOOST_USE_ASAN)
-        __sanitizer_finish_switch_fiber( current()->fake_stack,
-                                         (const void **) & current()->from->stack_bottom,
-                                         & current()->from->stack_size);
-#endif
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        return exchange( current()->from, nullptr);
-#else
-        return std::exchange( current()->from, nullptr);
-#endif
-    }
-
-    virtual void deallocate() noexcept {
-    }
-};
-
-struct BOOST_CONTEXT_DECL activation_record_initializer {
-    activation_record_initializer() noexcept;
-    ~activation_record_initializer();
-};
-
-struct forced_unwind {
-    activation_record   *   from{ nullptr };
-
-    forced_unwind( activation_record * from_) noexcept :
-        from{ from_ } {
-    }
-};
-
-template< typename Ctx, typename StackAlloc, typename Fn >
-class capture_record : public activation_record {
-private:
-    typename std::decay< StackAlloc >::type             salloc_;
-    typename std::decay< Fn >::type                     fn_;
-
-    static void destroy( capture_record * p) noexcept {
-        typename std::decay< StackAlloc >::type salloc = std::move( p->salloc_);
-        stack_context sctx = p->sctx;
-        // deallocate activation record
-        p->~capture_record();
-        // destroy stack with stack allocator
-        salloc.deallocate( sctx);
-    }
-
-public:
-    capture_record( stack_context sctx, StackAlloc && salloc, Fn && fn) noexcept :
-        activation_record{ sctx },
-        salloc_{ std::forward< StackAlloc >( salloc) },
-        fn_( std::forward< Fn >( fn) ) {
-    }
-
-    void deallocate() noexcept override final {
-        BOOST_ASSERT( main_ctx || ( ! main_ctx && terminated) );
-        destroy( this);
-    }
-
-    void run() {
-#if defined(BOOST_USE_ASAN)
-        __sanitizer_finish_switch_fiber( fake_stack,
-                                         (const void **) & from->stack_bottom,
-                                         & from->stack_size);
-#endif
-        Ctx c{ from };
-        try {
-            // invoke context-function
-#if defined(BOOST_NO_CXX17_STD_INVOKE)
-            c = boost::context::detail::invoke( fn_, std::move( c) );
-#else
-            c = std::invoke( fn_, std::move( c) );
-#endif  
-        } catch ( forced_unwind const& ex) {
-            c = Ctx{ ex.from };
-        }
-        // this context has finished its task
-		from = nullptr;
-        ontop = nullptr;
-        terminated = true;
-        force_unwind = false;
-        c.resume();
-        BOOST_ASSERT_MSG( false, "continuation already terminated");
-    }
-};
-
-template< typename Ctx, typename StackAlloc, typename Fn >
-static activation_record * create_context1( StackAlloc && salloc, Fn && fn) {
-    typedef capture_record< Ctx, StackAlloc, Fn >  capture_t;
-
-    auto sctx = salloc.allocate();
-    // reserve space for control structure
-    void * storage = reinterpret_cast< void * >(
-            ( reinterpret_cast< uintptr_t >( sctx.sp) - static_cast< uintptr_t >( sizeof( capture_t) ) )
-            & ~ static_cast< uintptr_t >( 0xff) );
-    // placment new for control structure on context stack
-    capture_t * record = new ( storage) capture_t{
-            sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) };
-    // stack bottom
-    void * stack_bottom = reinterpret_cast< void * >(
-            reinterpret_cast< uintptr_t >( sctx.sp) - static_cast< uintptr_t >( sctx.size) );
-    // create user-context
-    if ( BOOST_UNLIKELY( 0 != ::getcontext( & record->uctx) ) ) {
-        record->~capture_t();
-        salloc.deallocate( sctx);
-        throw std::system_error(
-                std::error_code( errno, std::system_category() ),
-                "getcontext() failed");
-    }
-    record->uctx.uc_stack.ss_sp = stack_bottom;
-    // 64byte gap between control structure and stack top
-    record->uctx.uc_stack.ss_size = reinterpret_cast< uintptr_t >( storage) -
-            reinterpret_cast< uintptr_t >( stack_bottom) - static_cast< uintptr_t >( 64);
-    record->uctx.uc_link = nullptr;
-    ::makecontext( & record->uctx, ( void (*)() ) & entry_func< capture_t >, 1, record);
-#if defined(BOOST_USE_ASAN)
-    record->stack_bottom = record->uctx.uc_stack.ss_sp;
-    record->stack_size = record->uctx.uc_stack.ss_size;
-#endif
-    return record;
-}
-
-template< typename Ctx, typename StackAlloc, typename Fn >
-static activation_record * create_context2( preallocated palloc, StackAlloc && salloc, Fn && fn) {
-    typedef capture_record< Ctx, StackAlloc, Fn >  capture_t; 
-
-    // reserve space for control structure
-    void * storage = reinterpret_cast< void * >(
-            ( reinterpret_cast< uintptr_t >( palloc.sp) - static_cast< uintptr_t >( sizeof( capture_t) ) )
-            & ~ static_cast< uintptr_t >( 0xff) );
-    // placment new for control structure on context stack
-    capture_t * record = new ( storage) capture_t{
-            palloc.sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) };
-    // stack bottom
-    void * stack_bottom = reinterpret_cast< void * >(
-            reinterpret_cast< uintptr_t >( palloc.sctx.sp) - static_cast< uintptr_t >( palloc.sctx.size) );
-    // create user-context
-    if ( BOOST_UNLIKELY( 0 != ::getcontext( & record->uctx) ) ) {
-        record->~capture_t();
-        salloc.deallocate( palloc.sctx);
-        throw std::system_error(
-                std::error_code( errno, std::system_category() ),
-                "getcontext() failed");
-    }
-    record->uctx.uc_stack.ss_sp = stack_bottom;
-    // 64byte gap between control structure and stack top
-    record->uctx.uc_stack.ss_size = reinterpret_cast< uintptr_t >( storage) -
-            reinterpret_cast< uintptr_t >( stack_bottom) - static_cast< uintptr_t >( 64);
-    record->uctx.uc_link = nullptr;
-    ::makecontext( & record->uctx,  ( void (*)() ) & entry_func< capture_t >, 1, record);
-#if defined(BOOST_USE_ASAN)
-    record->stack_bottom = record->uctx.uc_stack.ss_sp;
-    record->stack_size = record->uctx.uc_stack.ss_size;
-#endif
-    return record;
-}
-
-}
-
-class BOOST_CONTEXT_DECL continuation {
-private:
-    friend struct detail::activation_record;
-
-    template< typename Ctx, typename StackAlloc, typename Fn >
-    friend class detail::capture_record;
-
-	template< typename Ctx, typename StackAlloc, typename Fn >
-	friend detail::activation_record * detail::create_context1( StackAlloc &&, Fn &&);
-
-	template< typename Ctx, typename StackAlloc, typename Fn >
-	friend detail::activation_record * detail::create_context2( preallocated, StackAlloc &&, Fn &&);
-
-    template< typename StackAlloc, typename Fn >
-    friend continuation
-    callcc( std::allocator_arg_t, StackAlloc &&, Fn &&);
-
-    template< typename StackAlloc, typename Fn >
-    friend continuation
-    callcc( std::allocator_arg_t, preallocated, StackAlloc &&, Fn &&);
-
-    detail::activation_record   *   ptr_{ nullptr };
-
-    continuation( detail::activation_record * ptr) noexcept :
-        ptr_{ ptr } {
-    }
-
-public:
-    continuation() = default;
-
-    ~continuation() {
-        if ( BOOST_UNLIKELY( nullptr != ptr_) && ! ptr_->main_ctx) {
-            if ( BOOST_LIKELY( ! ptr_->terminated) ) {
-                ptr_->force_unwind = true;
-                ptr_->resume();
-                BOOST_ASSERT( ptr_->terminated);
-            }
-            ptr_->deallocate();
-        }
-    }
-
-    continuation( continuation const&) = delete;
-    continuation & operator=( continuation const&) = delete;
-
-    continuation( continuation && other) noexcept {
-        swap( other);
-    }
-
-    continuation & operator=( continuation && other) noexcept {
-        if ( BOOST_LIKELY( this != & other) ) {
-            continuation tmp = std::move( other);
-            swap( tmp);
-        }
-        return * this;
-    }
-
-    continuation resume() & {
-        return std::move( * this).resume();
-    }
-
-    continuation resume() && {
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        detail::activation_record * ptr = detail::exchange( ptr_, nullptr)->resume();
-#else
-        detail::activation_record * ptr = std::exchange( ptr_, nullptr)->resume();
-#endif
-        if ( BOOST_UNLIKELY( detail::activation_record::current()->force_unwind) ) {
-            throw detail::forced_unwind{ ptr};
-        } else if ( BOOST_UNLIKELY( nullptr != detail::activation_record::current()->ontop) ) {
-            ptr = detail::activation_record::current()->ontop( ptr);
-            detail::activation_record::current()->ontop = nullptr;
-        }
-        return { ptr };
-    }
-
-    template< typename Fn >
-    continuation resume_with( Fn && fn) & {
-        return std::move( * this).resume_with( std::forward< Fn >( fn) );
-    }
-
-    template< typename Fn >
-    continuation resume_with( Fn && fn) && {
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        detail::activation_record * ptr =
-            detail::exchange( ptr_, nullptr)->resume_with< continuation >( std::forward< Fn >( fn) );
-#else
-        detail::activation_record * ptr =
-            std::exchange( ptr_, nullptr)->resume_with< continuation >( std::forward< Fn >( fn) );
-#endif
-        if ( BOOST_UNLIKELY( detail::activation_record::current()->force_unwind) ) {
-            throw detail::forced_unwind{ ptr};
-        } else if ( BOOST_UNLIKELY( nullptr != detail::activation_record::current()->ontop) ) {
-            ptr = detail::activation_record::current()->ontop( ptr);
-            detail::activation_record::current()->ontop = nullptr;
-        }
-        return { ptr };
-    }
-
-    explicit operator bool() const noexcept {
-        return nullptr != ptr_ && ! ptr_->terminated;
-    }
-
-    bool operator!() const noexcept {
-        return nullptr == ptr_ || ptr_->terminated;
-    }
-
-    bool operator<( continuation const& other) const noexcept {
-        return ptr_ < other.ptr_;
-    }
-
-    #if !defined(BOOST_EMBTC)
-    
-    template< typename charT, class traitsT >
-    friend std::basic_ostream< charT, traitsT > &
-    operator<<( std::basic_ostream< charT, traitsT > & os, continuation const& other) {
-        if ( nullptr != other.ptr_) {
-            return os << other.ptr_;
-        } else {
-            return os << "{not-a-context}";
-        }
-    }
-
-    #else
-    
-    template< typename charT, class traitsT >
-    friend std::basic_ostream< charT, traitsT > &
-    operator<<( std::basic_ostream< charT, traitsT > & os, continuation const& other);
-
-    #endif
-
-    void swap( continuation & other) noexcept {
-        std::swap( ptr_, other.ptr_);
-    }
-};
-
-#if defined(BOOST_EMBTC)
-
-    template< typename charT, class traitsT >
-    inline std::basic_ostream< charT, traitsT > &
-    operator<<( std::basic_ostream< charT, traitsT > & os, continuation const& other) {
-        if ( nullptr != other.ptr_) {
-            return os << other.ptr_;
-        } else {
-            return os << "{not-a-context}";
-        }
-    }
-
-#endif
-    
-template<
-    typename Fn,
-    typename = detail::disable_overload< continuation, Fn >
->
-continuation
-callcc( Fn && fn) {
-	return callcc(
-			std::allocator_arg,
-#if defined(BOOST_USE_SEGMENTED_STACKS)
-			segmented_stack(),
-#else
-			fixedsize_stack(),
-#endif
-			std::forward< Fn >( fn) );
-}
-
-template< typename StackAlloc, typename Fn >
-continuation
-callcc( std::allocator_arg_t, StackAlloc && salloc, Fn && fn) {
-	return continuation{
-		detail::create_context1< continuation >(
-				std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) ) }.resume();
-}
-
-template< typename StackAlloc, typename Fn >
-continuation
-callcc( std::allocator_arg_t, preallocated palloc, StackAlloc && salloc, Fn && fn) {
-	return continuation{
-		detail::create_context2< continuation >(
-				palloc, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) ) }.resume();
-}
-
-inline
-void swap( continuation & l, continuation & r) noexcept {
-    l.swap( r);
-}
-
-}}
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_SUFFIX
-#endif
-
-#endif // BOOST_CONTEXT_CONTINUATION_H
diff --git a/contrib/restricted/boost/context/include/boost/context/continuation_winfib.hpp b/contrib/restricted/boost/context/include/boost/context/continuation_winfib.hpp
deleted file mode 100644
index 856c8684697..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/continuation_winfib.hpp
+++ /dev/null
@@ -1,473 +0,0 @@
-
-//          Copyright Oliver Kowalke 2017.
-// 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)
-
-#ifndef BOOST_CONTEXT_CONTINUATION_H
-#define BOOST_CONTEXT_CONTINUATION_H
-
-#include <windows.h>
-
-#include <boost/context/detail/config.hpp>
-
-#include <algorithm>
-#include <cstddef>
-#include <cstdint>
-#include <cstdlib>
-#include <cstring>
-#include <functional>
-#include <memory>
-#include <ostream>
-#include <system_error>
-#include <tuple>
-#include <utility>
-
-#include <boost/assert.hpp>
-#include <boost/config.hpp>
-
-#include <boost/context/detail/disable_overload.hpp>
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-#include <boost/context/detail/exchange.hpp>
-#endif
-#if defined(BOOST_NO_CXX17_STD_INVOKE)
-#include <boost/context/detail/invoke.hpp>
-#endif
-#include <boost/context/fixedsize_stack.hpp>
-#include <boost/context/flags.hpp>
-#include <boost/context/preallocated.hpp>
-#include <boost/context/stack_context.hpp>
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_PREFIX
-#endif
-
-#if defined(BOOST_MSVC)
-# pragma warning(push)
-# pragma warning(disable: 4702)
-#endif
-
-namespace boost {
-namespace context {
-namespace detail {
-
-// tampoline function
-// entered if the execution context
-// is resumed for the first time
-template< typename Record >
-static VOID WINAPI entry_func( LPVOID data) noexcept {
-    Record * record = static_cast< Record * >( data);
-    BOOST_ASSERT( nullptr != record);
-    // start execution of toplevel context-function
-    record->run();
-}
-
-struct BOOST_CONTEXT_DECL activation_record {
-    LPVOID                                                      fiber{ nullptr };
-    stack_context                                               sctx{};
-    bool                                                        main_ctx{ true };
-    activation_record                                       *   from{ nullptr };
-    std::function< activation_record*(activation_record*&) >    ontop{};
-    bool                                                        terminated{ false };
-    bool                                                        force_unwind{ false };
-
-    static activation_record *& current() noexcept;
-
-    // used for toplevel-context
-    // (e.g. main context, thread-entry context)
-    activation_record() noexcept {
-#if ( _WIN32_WINNT > 0x0600)
-        if ( ::IsThreadAFiber() ) {
-            fiber = ::GetCurrentFiber();
-        } else {
-            fiber = ::ConvertThreadToFiber( nullptr);
-        }
-#else
-        fiber = ::ConvertThreadToFiber( nullptr);
-        if ( BOOST_UNLIKELY( nullptr == fiber) ) {
-            DWORD err = ::GetLastError();
-            BOOST_ASSERT( ERROR_ALREADY_FIBER == err);
-            fiber = ::GetCurrentFiber(); 
-            BOOST_ASSERT( nullptr != fiber);
-            BOOST_ASSERT( reinterpret_cast< LPVOID >( 0x1E00) != fiber);
-        }
-#endif
-    }
-
-    activation_record( stack_context sctx_) noexcept :
-        sctx{ sctx_ },
-        main_ctx{ false } {
-    } 
-
-    virtual ~activation_record() {
-        if ( BOOST_UNLIKELY( main_ctx) ) {
-            ::ConvertFiberToThread();
-        } else {
-            ::DeleteFiber( fiber);
-        }
-    }
-
-    activation_record( activation_record const&) = delete;
-    activation_record & operator=( activation_record const&) = delete;
-
-    bool is_main_context() const noexcept {
-        return main_ctx;
-    }
-
-    activation_record * resume() {
-        from = current();
-        // store `this` in static, thread local pointer
-        // `this` will become the active (running) context
-        current() = this;
-        // context switch from parent context to `this`-context
-        // context switch
-        ::SwitchToFiber( fiber);
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        return detail::exchange( current()->from, nullptr);
-#else
-        return std::exchange( current()->from, nullptr);
-#endif
-    }
-
-    template< typename Ctx, typename Fn >
-    activation_record * resume_with( Fn && fn) {
-        from = current();
-        // store `this` in static, thread local pointer
-        // `this` will become the active (running) context
-        // returned by continuation::current()
-        current() = this;
-#if defined(BOOST_NO_CXX14_GENERIC_LAMBDAS)
-        current()->ontop = std::bind(
-                [](typename std::decay< Fn >::type & fn, activation_record *& ptr){
-                    Ctx c{ ptr };
-                    c = fn( std::move( c) );
-                    if ( ! c) {
-                        ptr = nullptr;
-                    }
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-                    return exchange( c.ptr_, nullptr);
-#else
-                    return std::exchange( c.ptr_, nullptr);
-#endif
-                },
-                std::forward< Fn >( fn),
-                std::placeholders::_1);
-#else
-        current()->ontop = [fn=std::forward<Fn>(fn)](activation_record *& ptr){
-            Ctx c{ ptr };
-            c = fn( std::move( c) );
-            if ( ! c) {
-                ptr = nullptr;
-            }
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-            return exchange( c.ptr_, nullptr);
-#else
-            return std::exchange( c.ptr_, nullptr);
-#endif
-        };
-#endif
-        // context switch
-        ::SwitchToFiber( fiber);
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        return detail::exchange( current()->from, nullptr);
-#else
-        return std::exchange( current()->from, nullptr);
-#endif
-    }
-
-    virtual void deallocate() noexcept {
-    }
-};
-
-struct BOOST_CONTEXT_DECL activation_record_initializer {
-    activation_record_initializer() noexcept;
-    ~activation_record_initializer();
-};
-
-struct forced_unwind {
-    activation_record   *   from{ nullptr };
-
-    explicit forced_unwind( activation_record * from_) :
-        from{ from_ } {
-    }
-};
-
-template< typename Ctx, typename StackAlloc, typename Fn >
-class capture_record : public activation_record {
-private:
-    typename std::decay< StackAlloc >::type             salloc_;
-    typename std::decay< Fn >::type                     fn_;
-
-    static void destroy( capture_record * p) noexcept {
-        typename std::decay< StackAlloc >::type salloc = std::move( p->salloc_);
-        stack_context sctx = p->sctx;
-        // deallocate activation record
-        p->~capture_record();
-        // destroy stack with stack allocator
-        salloc.deallocate( sctx);
-    }
-
-public:
-    capture_record( stack_context sctx, StackAlloc && salloc, Fn && fn) noexcept :
-        activation_record( sctx),
-        salloc_( std::forward< StackAlloc >( salloc)),
-        fn_( std::forward< Fn >( fn) ) {
-    }
-
-    void deallocate() noexcept override final {
-        BOOST_ASSERT( main_ctx || ( ! main_ctx && terminated) );
-        destroy( this);
-    }
-
-    void run() {
-        Ctx c{ from };
-        try {
-            // invoke context-function
-#if defined(BOOST_NO_CXX17_STD_INVOKE)
-            c = boost::context::detail::invoke( fn_, std::move( c) );
-#else
-            c = std::invoke( fn_, std::move( c) );
-#endif  
-        } catch ( forced_unwind const& ex) {
-            c = Ctx{ ex.from };
-        }
-        // this context has finished its task
-        from = nullptr;
-        ontop = nullptr;
-        terminated = true;
-        force_unwind = false;
-        c.resume();
-        BOOST_ASSERT_MSG( false, "continuation already terminated");
-    }
-};
-
-template< typename Ctx, typename StackAlloc, typename Fn >
-static activation_record * create_context1( StackAlloc && salloc, Fn && fn) {
-    typedef capture_record< Ctx, StackAlloc, Fn >  capture_t;
-
-    auto sctx = salloc.allocate();
-    BOOST_ASSERT( ( sizeof( capture_t) ) < sctx.size);
-    // reserve space for control structure
-    void * storage = reinterpret_cast< void * >(
-            ( reinterpret_cast< uintptr_t >( sctx.sp) - static_cast< uintptr_t >( sizeof( capture_t) ) )
-            & ~ static_cast< uintptr_t >( 0xff) );
-    // placment new for control structure on context stack
-    capture_t * record = new ( storage) capture_t{
-            sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) };
-    // create user-context
-    record->fiber = ::CreateFiber( sctx.size, & detail::entry_func< capture_t >, record);
-    return record;
-}
-
-template< typename Ctx, typename StackAlloc, typename Fn >
-static activation_record * create_context2( preallocated palloc, StackAlloc && salloc, Fn && fn) {
-    typedef capture_record< Ctx, StackAlloc, Fn >  capture_t; 
-
-    BOOST_ASSERT( ( sizeof( capture_t) ) < palloc.size);
-    // reserve space for control structure
-    void * storage = reinterpret_cast< void * >(
-            ( reinterpret_cast< uintptr_t >( palloc.sp) - static_cast< uintptr_t >( sizeof( capture_t) ) )
-            & ~ static_cast< uintptr_t >( 0xff) );
-    // placment new for control structure on context stack
-    capture_t * record = new ( storage) capture_t{
-            palloc.sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) };
-    // create user-context
-    record->fiber = ::CreateFiber( palloc.sctx.size, & detail::entry_func< capture_t >, record);
-    return record;
-}
-
-}
-
-class BOOST_CONTEXT_DECL continuation {
-private:
-    friend struct detail::activation_record;
-
-    template< typename Ctx, typename StackAlloc, typename Fn >
-    friend class detail::capture_record;
-
-    template< typename Ctx, typename StackAlloc, typename Fn >
-    friend detail::activation_record * detail::create_context1( StackAlloc &&, Fn &&);
-
-    template< typename Ctx, typename StackAlloc, typename Fn >
-    friend detail::activation_record * detail::create_context2( preallocated, StackAlloc &&, Fn &&);
-
-    template< typename StackAlloc, typename Fn >
-    friend continuation
-    callcc( std::allocator_arg_t, StackAlloc &&, Fn &&);
-
-    template< typename StackAlloc, typename Fn >
-    friend continuation
-    callcc( std::allocator_arg_t, preallocated, StackAlloc &&, Fn &&);
-
-    detail::activation_record   *   ptr_{ nullptr };
-
-    continuation( detail::activation_record * ptr) noexcept :
-        ptr_{ ptr } {
-    }
-
-public:
-    continuation() = default;
-
-    ~continuation() {
-        if ( BOOST_UNLIKELY( nullptr != ptr_) && ! ptr_->main_ctx) {
-            if ( BOOST_LIKELY( ! ptr_->terminated) ) {
-                ptr_->force_unwind = true;
-                ptr_->resume();
-                BOOST_ASSERT( ptr_->terminated);
-            }
-            ptr_->deallocate();
-        }
-    }
-
-    continuation( continuation const&) = delete;
-    continuation & operator=( continuation const&) = delete;
-
-    continuation( continuation && other) noexcept {
-        swap( other);
-    }
-
-    continuation & operator=( continuation && other) noexcept {
-        if ( BOOST_LIKELY( this != & other) ) {
-            continuation tmp = std::move( other);
-            swap( tmp);
-        }
-        return * this;
-    }
-
-    continuation resume() & {
-        return std::move( * this).resume();
-    }
-
-    continuation resume() && {
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        detail::activation_record * ptr = detail::exchange( ptr_, nullptr)->resume();
-#else
-        detail::activation_record * ptr = std::exchange( ptr_, nullptr)->resume();
-#endif
-        if ( BOOST_UNLIKELY( detail::activation_record::current()->force_unwind) ) {
-            throw detail::forced_unwind{ ptr};
-        } else if ( BOOST_UNLIKELY( nullptr != detail::activation_record::current()->ontop) ) {
-            ptr = detail::activation_record::current()->ontop( ptr);
-            detail::activation_record::current()->ontop = nullptr;
-        }
-        return { ptr };
-    }
-
-    template< typename Fn >
-    continuation resume_with( Fn && fn) & {
-        return std::move( * this).resume_with( std::forward< Fn >( fn) );
-    }
-
-    template< typename Fn >
-    continuation resume_with( Fn && fn) && {
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        detail::activation_record * ptr =
-            detail::exchange( ptr_, nullptr)->resume_with< continuation >( std::forward< Fn >( fn) );
-#else
-        detail::activation_record * ptr =
-            std::exchange( ptr_, nullptr)->resume_with< continuation >( std::forward< Fn >( fn) );
-#endif
-        if ( BOOST_UNLIKELY( detail::activation_record::current()->force_unwind) ) {
-            throw detail::forced_unwind{ ptr};
-        } else if ( BOOST_UNLIKELY( nullptr != detail::activation_record::current()->ontop) ) {
-            ptr = detail::activation_record::current()->ontop( ptr);
-            detail::activation_record::current()->ontop = nullptr;
-        }
-        return { ptr };
-    }
-
-    explicit operator bool() const noexcept {
-        return nullptr != ptr_ && ! ptr_->terminated;
-    }
-
-    bool operator!() const noexcept {
-        return nullptr == ptr_ || ptr_->terminated;
-    }
-
-    bool operator<( continuation const& other) const noexcept {
-        return ptr_ < other.ptr_;
-    }
-    
-    #if !defined(BOOST_EMBTC)
-    
-    template< typename charT, class traitsT >
-    friend std::basic_ostream< charT, traitsT > &
-    operator<<( std::basic_ostream< charT, traitsT > & os, continuation const& other) {
-        if ( nullptr != other.ptr_) {
-            return os << other.ptr_;
-        } else {
-            return os << "{not-a-context}";
-        }
-    }
-
-    #else
-    
-    template< typename charT, class traitsT >
-    friend std::basic_ostream< charT, traitsT > &
-    operator<<( std::basic_ostream< charT, traitsT > & os, continuation const& other);
-
-    #endif
-
-    void swap( continuation & other) noexcept {
-        std::swap( ptr_, other.ptr_);
-    }
-};
-
-#if defined(BOOST_EMBTC)
-
-    template< typename charT, class traitsT >
-    inline std::basic_ostream< charT, traitsT > &
-    operator<<( std::basic_ostream< charT, traitsT > & os, continuation const& other) {
-        if ( nullptr != other.ptr_) {
-            return os << other.ptr_;
-        } else {
-            return os << "{not-a-context}";
-        }
-    }
-
-#endif
-    
-template<
-    typename Fn,
-    typename = detail::disable_overload< continuation, Fn >
->
-continuation
-callcc( Fn && fn) {
-    return callcc(
-            std::allocator_arg,
-            fixedsize_stack(),
-            std::forward< Fn >( fn) );
-}
-
-template< typename StackAlloc, typename Fn >
-continuation
-callcc( std::allocator_arg_t, StackAlloc && salloc, Fn && fn) {
-    return continuation{
-        detail::create_context1< continuation >(
-                std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) ) }.resume();
-}
-
-template< typename StackAlloc, typename Fn >
-continuation
-callcc( std::allocator_arg_t, preallocated palloc, StackAlloc && salloc, Fn && fn) {
-    return continuation{
-        detail::create_context2< continuation >(
-                palloc, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) ) }.resume();
-}
-
-inline
-void swap( continuation & l, continuation & r) noexcept {
-    l.swap( r);
-}
-
-}}
-
-#if defined(BOOST_MSVC)
-# pragma warning(pop)
-#endif
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_SUFFIX
-#endif
-
-#endif // BOOST_CONTEXT_CONTINUATION_H
diff --git a/contrib/restricted/boost/context/include/boost/context/detail/disable_overload.hpp b/contrib/restricted/boost/context/include/boost/context/detail/disable_overload.hpp
deleted file mode 100644
index c88f916e399..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/detail/disable_overload.hpp
+++ /dev/null
@@ -1,40 +0,0 @@
-
-//          Copyright Oliver Kowalke 2014.
-// 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)
-
-#ifndef BOOST_CONTEXT_DETAIL_DISABLE_OVERLOAD_H
-#define BOOST_CONTEXT_DETAIL_DISABLE_OVERLOAD_H
-
-#include <type_traits>
-
-#include <boost/config.hpp>
-
-#include <boost/context/detail/config.hpp>
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_PREFIX
-#endif
-
-namespace boost {
-namespace context {
-namespace detail {
-
-// http://ericniebler.com/2013/08/07/universal-references-and-the-copy-constructo/
-template< typename X, typename Y >
-using disable_overload =
-    typename std::enable_if<
-        ! std::is_base_of<
-            X,
-            typename std::decay< Y >::type
-        >::value
-    >::type;
-
-}}}
-
-#ifdef BOOST_HAS_ABI_HEADERS
-#include BOOST_ABI_SUFFIX
-#endif
-
-#endif // BOOST_CONTEXT_DETAIL_DISABLE_OVERLOAD_H
diff --git a/contrib/restricted/boost/context/include/boost/context/detail/exchange.hpp b/contrib/restricted/boost/context/include/boost/context/detail/exchange.hpp
deleted file mode 100644
index c5ee91284e8..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/detail/exchange.hpp
+++ /dev/null
@@ -1,36 +0,0 @@
-
-//          Copyright Oliver Kowalke 2014.
-// 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)
-
-#ifndef BOOST_CONTEXT_DETAIL_EXCHANGE_H
-#define BOOST_CONTEXT_DETAIL_EXCHANGE_H
-
-#include <algorithm>
-#include <utility>
-
-#include <boost/config.hpp>
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_PREFIX
-#endif
-
-namespace boost {
-namespace context {
-namespace detail {
-
-template< typename T, typename U = T >
-T exchange( T & t, U && nv) {
-    T ov = std::move( t);
-    t = std::forward< U >( nv);
-    return ov;
-}
-
-}}}
-
-#ifdef BOOST_HAS_ABI_HEADERS
-#include BOOST_ABI_SUFFIX
-#endif
-
-#endif // BOOST_CONTEXT_DETAIL_EXCHANGE_H
diff --git a/contrib/restricted/boost/context/include/boost/context/detail/externc.hpp b/contrib/restricted/boost/context/include/boost/context/detail/externc.hpp
deleted file mode 100644
index 850bc1a3d7d..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/detail/externc.hpp
+++ /dev/null
@@ -1,23 +0,0 @@
-
-//          Copyright Oliver Kowalke 2014.
-// 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/config.hpp>
-#include <boost/context/detail/config.hpp>
-
-#if defined(BOOST_USE_ASAN)
-extern "C" {
-void __sanitizer_start_switch_fiber( void **, const void *, size_t);
-void __sanitizer_finish_switch_fiber( void *, const void **, size_t *);
-}
-#endif
-
-#if defined(BOOST_USE_SEGMENTED_STACKS)
-extern "C" {
-void __splitstack_getcontext( void * [BOOST_CONTEXT_SEGMENTS]);
-void __splitstack_setcontext( void * [BOOST_CONTEXT_SEGMENTS]);
-}
-#endif
diff --git a/contrib/restricted/boost/context/include/boost/context/detail/invoke.hpp b/contrib/restricted/boost/context/include/boost/context/detail/invoke.hpp
deleted file mode 100644
index 9173cbc7938..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/detail/invoke.hpp
+++ /dev/null
@@ -1,50 +0,0 @@
-
-//          Copyright Oliver Kowalke 2014.
-// 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)
-
-#ifndef BOOST_CONTEXT_DETAIL_INVOKE_H
-#define BOOST_CONTEXT_DETAIL_INVOKE_H
-
-#include <functional>
-#include <type_traits>
-#include <utility>
-
-#include <boost/config.hpp>
-
-#include <boost/context/detail/config.hpp>
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_PREFIX
-#endif
-
-namespace boost {
-namespace context {
-namespace detail {
-
-template< typename Fn, typename ... Args >
-typename std::enable_if<
-    std::is_member_pointer< typename std::decay< Fn >::type >::value,
-    typename std::result_of< Fn &&( Args && ... ) >::type
->::type
-invoke( Fn && fn, Args && ... args) {
-    return std::mem_fn( fn)( std::forward< Args >( args) ... );   
-}
-
-template< typename Fn, typename ... Args >
-typename std::enable_if<
-    ! std::is_member_pointer< typename std::decay< Fn >::type >::value,
-    typename std::result_of< Fn &&( Args && ... ) >::type
->::type
-invoke( Fn && fn, Args && ... args) {
-    return std::forward< Fn >( fn)( std::forward< Args >( args) ... );
-}
-
-}}}
-
-#ifdef BOOST_HAS_ABI_HEADERS
-#include BOOST_ABI_SUFFIX
-#endif
-
-#endif // BOOST_CONTEXT_DETAIL_INVOKE_H
diff --git a/contrib/restricted/boost/context/include/boost/context/fiber_ucontext.hpp b/contrib/restricted/boost/context/include/boost/context/fiber_ucontext.hpp
deleted file mode 100644
index 696ce580840..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/fiber_ucontext.hpp
+++ /dev/null
@@ -1,558 +0,0 @@
-
-//          Copyright Oliver Kowalke 2017.
-// 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)
-
-#ifndef BOOST_CONTEXT_FIBER_H
-#define BOOST_CONTEXT_FIBER_H
-
-#include <boost/predef.h>
-#if BOOST_OS_MACOS
-#define _XOPEN_SOURCE 600
-#endif
-
-extern "C" {
-#include <ucontext.h>
-}
-
-#include <boost/context/detail/config.hpp>
-
-#include <algorithm>
-#include <cstddef>
-#include <cstdint>
-#include <cstdlib>
-#include <cstring>
-#include <functional>
-#include <memory>
-#include <ostream>
-#include <system_error>
-#include <tuple>
-#include <utility>
-
-#include <boost/assert.hpp>
-#include <boost/config.hpp>
-#include <boost/predef.h>
-
-#include <boost/context/detail/disable_overload.hpp>
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-#include <boost/context/detail/exchange.hpp>
-#endif
-#include <boost/context/detail/externc.hpp>
-#if defined(BOOST_NO_CXX17_STD_INVOKE)
-#include <boost/context/detail/invoke.hpp>
-#endif
-#include <boost/context/fixedsize_stack.hpp>
-#include <boost/context/flags.hpp>
-#include <boost/context/preallocated.hpp>
-#if defined(BOOST_USE_SEGMENTED_STACKS)
-#include <boost/context/segmented_stack.hpp>
-#endif
-#include <boost/context/stack_context.hpp>
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_PREFIX
-#endif
-
-#ifdef BOOST_USE_TSAN
-#include <sanitizer/tsan_interface.h>
-#endif
-
-namespace boost {
-namespace context {
-namespace detail {
-
-// tampoline function
-// entered if the execution context
-// is resumed for the first time
-template< typename Record >
-static void fiber_entry_func( void * data) noexcept {
-    Record * record = static_cast< Record * >( data);
-    BOOST_ASSERT( nullptr != record);
-    // start execution of toplevel context-function
-    record->run();
-}
-
-struct BOOST_CONTEXT_DECL fiber_activation_record {
-    ucontext_t                                                  uctx{};
-    stack_context                                               sctx{};
-    bool                                                        main_ctx{ true };
-	fiber_activation_record                                       *	from{ nullptr };
-    std::function< fiber_activation_record*(fiber_activation_record*&) >    ontop{};
-    bool                                                        terminated{ false };
-    bool                                                        force_unwind{ false };
-#if defined(BOOST_USE_ASAN)
-    void                                                    *   fake_stack{ nullptr };
-    void                                                    *   stack_bottom{ nullptr };
-    std::size_t                                                 stack_size{ 0 };
-#endif
-
-#if defined(BOOST_USE_TSAN)
-    void * tsan_fiber{ nullptr };
-    bool destroy_tsan_fiber{ true };
-#endif
-
-    static fiber_activation_record *& current() noexcept;
-
-    // used for toplevel-context
-    // (e.g. main context, thread-entry context)
-    fiber_activation_record() {
-        if ( BOOST_UNLIKELY( 0 != ::getcontext( & uctx) ) ) {
-            throw std::system_error(
-                    std::error_code( errno, std::system_category() ),
-                    "getcontext() failed");
-        }
-
-#if defined(BOOST_USE_TSAN)
-        tsan_fiber = __tsan_get_current_fiber();
-        destroy_tsan_fiber = false;
-#endif
-    }
-
-    fiber_activation_record( stack_context sctx_) noexcept :
-        sctx( sctx_ ),
-        main_ctx( false ) {
-    } 
-
-    virtual ~fiber_activation_record() {
-#if defined(BOOST_USE_TSAN)
-        if (destroy_tsan_fiber)
-            __tsan_destroy_fiber(tsan_fiber);
-#endif
-	}
-
-    fiber_activation_record( fiber_activation_record const&) = delete;
-    fiber_activation_record & operator=( fiber_activation_record const&) = delete;
-
-    bool is_main_context() const noexcept {
-        return main_ctx;
-    }
-
-    fiber_activation_record * resume() {
-		from = current();
-        // store `this` in static, thread local pointer
-        // `this` will become the active (running) context
-        current() = this;
-#if defined(BOOST_USE_SEGMENTED_STACKS)
-        // adjust segmented stack properties
-        __splitstack_getcontext( from->sctx.segments_ctx);
-        __splitstack_setcontext( sctx.segments_ctx);
-#endif
-#if defined(BOOST_USE_ASAN)
-        if ( terminated) {
-            __sanitizer_start_switch_fiber( nullptr, stack_bottom, stack_size);
-        } else {
-            __sanitizer_start_switch_fiber( & from->fake_stack, stack_bottom, stack_size);
-        }
-#endif
-#if defined (BOOST_USE_TSAN)
-        __tsan_switch_to_fiber(tsan_fiber, 0);
-#endif
-        // context switch from parent context to `this`-context
-        ::swapcontext( & from->uctx, & uctx);
-#if defined(BOOST_USE_ASAN)
-        __sanitizer_finish_switch_fiber( current()->fake_stack,
-                                         (const void **) & current()->from->stack_bottom,
-                                         & current()->from->stack_size);
-#endif
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        return exchange( current()->from, nullptr);
-#else
-        return std::exchange( current()->from, nullptr);
-#endif
-    }
-
-    template< typename Ctx, typename Fn >
-    fiber_activation_record * resume_with( Fn && fn) {
-		from = current();
-        // store `this` in static, thread local pointer
-        // `this` will become the active (running) context
-        // returned by fiber::current()
-        current() = this;
-#if defined(BOOST_NO_CXX14_GENERIC_LAMBDAS)
-        current()->ontop = std::bind(
-                [](typename std::decay< Fn >::type & fn, fiber_activation_record *& ptr){
-                    Ctx c{ ptr };
-                    c = fn( std::move( c) );
-                    if ( ! c) {
-                        ptr = nullptr;
-                    }
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-                    return exchange( c.ptr_, nullptr);
-#else
-                    return std::exchange( c.ptr_, nullptr);
-#endif
-                },
-                std::forward< Fn >( fn),
-                std::placeholders::_1);
-#else
-        current()->ontop = [fn=std::forward<Fn>(fn)](fiber_activation_record *& ptr){
-            Ctx c{ ptr };
-            c = fn( std::move( c) );
-            if ( ! c) {
-                ptr = nullptr;
-            }
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-            return exchange( c.ptr_, nullptr);
-#else
-            return std::exchange( c.ptr_, nullptr);
-#endif
-        };
-#endif
-#if defined(BOOST_USE_SEGMENTED_STACKS)
-        // adjust segmented stack properties
-        __splitstack_getcontext( from->sctx.segments_ctx);
-        __splitstack_setcontext( sctx.segments_ctx);
-#endif
-#if defined(BOOST_USE_ASAN)
-        __sanitizer_start_switch_fiber( & from->fake_stack, stack_bottom, stack_size);
-#endif
-#if defined (BOOST_USE_TSAN)
-        __tsan_switch_to_fiber(tsan_fiber, 0);
-#endif
-        // context switch from parent context to `this`-context
-        ::swapcontext( & from->uctx, & uctx);
-#if defined(BOOST_USE_ASAN)
-        __sanitizer_finish_switch_fiber( current()->fake_stack,
-                                         (const void **) & current()->from->stack_bottom,
-                                         & current()->from->stack_size);
-#endif
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        return exchange( current()->from, nullptr);
-#else
-        return std::exchange( current()->from, nullptr);
-#endif
-    }
-
-    virtual void deallocate() noexcept {
-    }
-};
-
-struct BOOST_CONTEXT_DECL fiber_activation_record_initializer {
-    fiber_activation_record_initializer() noexcept;
-    ~fiber_activation_record_initializer();
-};
-
-struct forced_unwind {
-    fiber_activation_record  *  from{ nullptr };
-
-    forced_unwind( fiber_activation_record * from_) noexcept :
-        from{ from_ } {
-    }
-};
-
-template< typename Ctx, typename StackAlloc, typename Fn >
-class fiber_capture_record : public fiber_activation_record {
-private:
-    typename std::decay< StackAlloc >::type             salloc_;
-    typename std::decay< Fn >::type                     fn_;
-
-    static void destroy( fiber_capture_record * p) noexcept {
-        typename std::decay< StackAlloc >::type salloc = std::move( p->salloc_);
-        stack_context sctx = p->sctx;
-        // deallocate activation record
-        p->~fiber_capture_record();
-        // destroy stack with stack allocator
-        salloc.deallocate( sctx);
-    }
-
-public:
-    fiber_capture_record( stack_context sctx, StackAlloc && salloc, Fn && fn) noexcept :
-        fiber_activation_record{ sctx },
-        salloc_{ std::forward< StackAlloc >( salloc) },
-        fn_( std::forward< Fn >( fn) ) {
-    }
-
-    void deallocate() noexcept override final {
-        BOOST_ASSERT( main_ctx || ( ! main_ctx && terminated) );
-        destroy( this);
-    }
-
-    void run() {
-#if defined(BOOST_USE_ASAN)
-        __sanitizer_finish_switch_fiber( fake_stack,
-                                         (const void **) & from->stack_bottom,
-                                         & from->stack_size);
-#endif
-        Ctx c{ from };
-        try {
-            // invoke context-function
-#if defined(BOOST_NO_CXX17_STD_INVOKE)
-            c = boost::context::detail::invoke( fn_, std::move( c) );
-#else
-            c = std::invoke( fn_, std::move( c) );
-#endif  
-        } catch ( forced_unwind const& ex) {
-            c = Ctx{ ex.from };
-        }
-        // this context has finished its task
-		from = nullptr;
-        ontop = nullptr;
-        terminated = true;
-        force_unwind = false;
-        std::move( c).resume();
-        BOOST_ASSERT_MSG( false, "fiber already terminated");
-    }
-};
-
-template< typename Ctx, typename StackAlloc, typename Fn >
-static fiber_activation_record * create_fiber1( StackAlloc && salloc, Fn && fn) {
-    typedef fiber_capture_record< Ctx, StackAlloc, Fn >  capture_t;
-
-    auto sctx = salloc.allocate();
-    // reserve space for control structure
-    void * storage = reinterpret_cast< void * >(
-            ( reinterpret_cast< uintptr_t >( sctx.sp) - static_cast< uintptr_t >( sizeof( capture_t) ) )
-            & ~ static_cast< uintptr_t >( 0xff) );
-    // placment new for control structure on context stack
-    capture_t * record = new ( storage) capture_t{
-            sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) };
-    // stack bottom
-    void * stack_bottom = reinterpret_cast< void * >(
-            reinterpret_cast< uintptr_t >( sctx.sp) - static_cast< uintptr_t >( sctx.size) );
-    // create user-context
-    if ( BOOST_UNLIKELY( 0 != ::getcontext( & record->uctx) ) ) {
-        record->~capture_t();
-        salloc.deallocate( sctx);
-        throw std::system_error(
-                std::error_code( errno, std::system_category() ),
-                "getcontext() failed");
-    }
-#if BOOST_OS_BSD_FREE
-    // because FreeBSD defines stack_t::ss_sp as char *
-    record->uctx.uc_stack.ss_sp = static_cast< char * >( stack_bottom);
-#else
-    record->uctx.uc_stack.ss_sp = stack_bottom;
-#endif
-    // 64byte gap between control structure and stack top
-    record->uctx.uc_stack.ss_size = reinterpret_cast< uintptr_t >( storage) -
-            reinterpret_cast< uintptr_t >( stack_bottom) - static_cast< uintptr_t >( 64);
-    record->uctx.uc_link = nullptr;
-    ::makecontext( & record->uctx, ( void (*)() ) & fiber_entry_func< capture_t >, 1, record);
-#if defined(BOOST_USE_ASAN)
-    record->stack_bottom = record->uctx.uc_stack.ss_sp;
-    record->stack_size = record->uctx.uc_stack.ss_size;
-#endif
-#if defined (BOOST_USE_TSAN)
-    record->tsan_fiber = __tsan_create_fiber(0);
-#endif
-    return record;
-}
-
-template< typename Ctx, typename StackAlloc, typename Fn >
-static fiber_activation_record * create_fiber2( preallocated palloc, StackAlloc && salloc, Fn && fn) {
-    typedef fiber_capture_record< Ctx, StackAlloc, Fn >  capture_t; 
-
-    // reserve space for control structure
-    void * storage = reinterpret_cast< void * >(
-            ( reinterpret_cast< uintptr_t >( palloc.sp) - static_cast< uintptr_t >( sizeof( capture_t) ) )
-            & ~ static_cast< uintptr_t >( 0xff) );
-    // placment new for control structure on context stack
-    capture_t * record = new ( storage) capture_t{
-            palloc.sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) };
-    // stack bottom
-    void * stack_bottom = reinterpret_cast< void * >(
-            reinterpret_cast< uintptr_t >( palloc.sctx.sp) - static_cast< uintptr_t >( palloc.sctx.size) );
-    // create user-context
-    if ( BOOST_UNLIKELY( 0 != ::getcontext( & record->uctx) ) ) {
-        record->~capture_t();
-        salloc.deallocate( palloc.sctx);
-        throw std::system_error(
-                std::error_code( errno, std::system_category() ),
-                "getcontext() failed");
-    }
-#if BOOST_OS_BSD_FREE
-    // because FreeBSD defines stack_t::ss_sp as char *
-    record->uctx.uc_stack.ss_sp = static_cast< char * >( stack_bottom);
-#else
-    record->uctx.uc_stack.ss_sp = stack_bottom;
-#endif
-    // 64byte gap between control structure and stack top
-    record->uctx.uc_stack.ss_size = reinterpret_cast< uintptr_t >( storage) -
-            reinterpret_cast< uintptr_t >( stack_bottom) - static_cast< uintptr_t >( 64);
-    record->uctx.uc_link = nullptr;
-    ::makecontext( & record->uctx,  ( void (*)() ) & fiber_entry_func< capture_t >, 1, record);
-#if defined(BOOST_USE_ASAN)
-    record->stack_bottom = record->uctx.uc_stack.ss_sp;
-    record->stack_size = record->uctx.uc_stack.ss_size;
-#endif
-#if defined (BOOST_USE_TSAN)
-    record->tsan_fiber = __tsan_create_fiber(0);
-#endif
-    return record;
-}
-
-}
-
-class BOOST_CONTEXT_DECL fiber {
-private:
-    friend struct detail::fiber_activation_record;
-
-    template< typename Ctx, typename StackAlloc, typename Fn >
-    friend class detail::fiber_capture_record;
-
-	template< typename Ctx, typename StackAlloc, typename Fn >
-	friend detail::fiber_activation_record * detail::create_fiber1( StackAlloc &&, Fn &&);
-
-	template< typename Ctx, typename StackAlloc, typename Fn >
-	friend detail::fiber_activation_record * detail::create_fiber2( preallocated, StackAlloc &&, Fn &&);
-
-    detail::fiber_activation_record   *   ptr_{ nullptr };
-
-    fiber( detail::fiber_activation_record * ptr) noexcept :
-        ptr_{ ptr } {
-    }
-
-public:
-    fiber() = default;
-
-    template< typename Fn, typename = detail::disable_overload< fiber, Fn > >
-    fiber( Fn && fn) :
-        fiber{
-                std::allocator_arg,
-#if defined(BOOST_USE_SEGMENTED_STACKS)
-                segmented_stack(),
-#else
-                fixedsize_stack(),
-#endif
-                std::forward< Fn >( fn) } {
-    }
-
-    template< typename StackAlloc, typename Fn >
-    fiber( std::allocator_arg_t, StackAlloc && salloc, Fn && fn) :
-        ptr_{ detail::create_fiber1< fiber >(
-                std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) ) } {
-    }
-
-    template< typename StackAlloc, typename Fn >
-    fiber( std::allocator_arg_t, preallocated palloc, StackAlloc && salloc, Fn && fn) :
-        ptr_{ detail::create_fiber2< fiber >(
-                palloc, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) ) } {
-    }
-
-    ~fiber() {
-        if ( BOOST_UNLIKELY( nullptr != ptr_) && ! ptr_->main_ctx) {
-            if ( BOOST_LIKELY( ! ptr_->terminated) ) {
-                ptr_->force_unwind = true;
-                ptr_->resume();
-                BOOST_ASSERT( ptr_->terminated);
-            }
-            ptr_->deallocate();
-        }
-    }
-
-    fiber( fiber const&) = delete;
-    fiber & operator=( fiber const&) = delete;
-
-    fiber( fiber && other) noexcept {
-        swap( other);
-    }
-
-    fiber & operator=( fiber && other) noexcept {
-        if ( BOOST_LIKELY( this != & other) ) {
-            fiber tmp = std::move( other);
-            swap( tmp);
-        }
-        return * this;
-    }
-
-    fiber resume() && {
-        BOOST_ASSERT( nullptr != ptr_);
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        detail::fiber_activation_record * ptr = detail::exchange( ptr_, nullptr)->resume();
-#else
-        detail::fiber_activation_record * ptr = std::exchange( ptr_, nullptr)->resume();
-#endif
-        if ( BOOST_UNLIKELY( detail::fiber_activation_record::current()->force_unwind) ) {
-            throw detail::forced_unwind{ ptr};
-        } else if ( BOOST_UNLIKELY( nullptr != detail::fiber_activation_record::current()->ontop) ) {
-            ptr = detail::fiber_activation_record::current()->ontop( ptr);
-            detail::fiber_activation_record::current()->ontop = nullptr;
-        }
-        return { ptr };
-    }
-
-    template< typename Fn >
-    fiber resume_with( Fn && fn) && {
-        BOOST_ASSERT( nullptr != ptr_);
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        detail::fiber_activation_record * ptr =
-            detail::exchange( ptr_, nullptr)->resume_with< fiber >( std::forward< Fn >( fn) );
-#else
-        detail::fiber_activation_record * ptr =
-            std::exchange( ptr_, nullptr)->resume_with< fiber >( std::forward< Fn >( fn) );
-#endif
-        if ( BOOST_UNLIKELY( detail::fiber_activation_record::current()->force_unwind) ) {
-            throw detail::forced_unwind{ ptr};
-        } else if ( BOOST_UNLIKELY( nullptr != detail::fiber_activation_record::current()->ontop) ) {
-            ptr = detail::fiber_activation_record::current()->ontop( ptr);
-            detail::fiber_activation_record::current()->ontop = nullptr;
-        }
-        return { ptr };
-    }
-
-    explicit operator bool() const noexcept {
-        return nullptr != ptr_ && ! ptr_->terminated;
-    }
-
-    bool operator!() const noexcept {
-        return nullptr == ptr_ || ptr_->terminated;
-    }
-
-    bool operator<( fiber const& other) const noexcept {
-        return ptr_ < other.ptr_;
-    }
-
-    #if !defined(BOOST_EMBTC)
-
-    template< typename charT, class traitsT >
-    friend std::basic_ostream< charT, traitsT > &
-    operator<<( std::basic_ostream< charT, traitsT > & os, fiber const& other) {
-        if ( nullptr != other.ptr_) {
-            return os << other.ptr_;
-        } else {
-            return os << "{not-a-context}";
-        }
-    }
-
-    #else
-
-    template< typename charT, class traitsT >
-    friend std::basic_ostream< charT, traitsT > &
-    operator<<( std::basic_ostream< charT, traitsT > & os, fiber const& other);
-
-    #endif
-
-    void swap( fiber & other) noexcept {
-        std::swap( ptr_, other.ptr_);
-    }
-};
-
-#if defined(BOOST_EMBTC)
-
-    template< typename charT, class traitsT >
-    inline std::basic_ostream< charT, traitsT > &
-    operator<<( std::basic_ostream< charT, traitsT > & os, fiber const& other) {
-        if ( nullptr != other.ptr_) {
-            return os << other.ptr_;
-        } else {
-            return os << "{not-a-context}";
-        }
-    }
-
-#endif
-
-inline
-void swap( fiber & l, fiber & r) noexcept {
-    l.swap( r);
-}
-
-typedef fiber fiber_context;
-
-}}
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_SUFFIX
-#endif
-
-#endif // BOOST_CONTEXT_FIBER_H
diff --git a/contrib/restricted/boost/context/include/boost/context/fiber_winfib.hpp b/contrib/restricted/boost/context/include/boost/context/fiber_winfib.hpp
deleted file mode 100644
index cd496d1be15..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/fiber_winfib.hpp
+++ /dev/null
@@ -1,450 +0,0 @@
-
-//          Copyright Oliver Kowalke 2017.
-// 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)
-
-#ifndef BOOST_CONTEXT_FIBER_H
-#define BOOST_CONTEXT_FIBER_H
-
-#include <windows.h>
-
-#include <boost/context/detail/config.hpp>
-
-#include <algorithm>
-#include <cstddef>
-#include <cstdint>
-#include <cstdlib>
-#include <cstring>
-#include <functional>
-#include <memory>
-#include <ostream>
-#include <system_error>
-#include <tuple>
-#include <utility>
-
-#include <boost/assert.hpp>
-#include <boost/config.hpp>
-
-#include <boost/context/detail/disable_overload.hpp>
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-#include <boost/context/detail/exchange.hpp>
-#endif
-#if defined(BOOST_NO_CXX17_STD_INVOKE)
-#include <boost/context/detail/invoke.hpp>
-#endif
-#include <boost/context/fixedsize_stack.hpp>
-#include <boost/context/flags.hpp>
-#include <boost/context/preallocated.hpp>
-#include <boost/context/stack_context.hpp>
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_PREFIX
-#endif
-
-#if defined(BOOST_MSVC)
-# pragma warning(push)
-# pragma warning(disable: 4702)
-#endif
-
-namespace boost {
-namespace context {
-namespace detail {
-
-// tampoline function
-// entered if the execution context
-// is resumed for the first time
-template< typename Record >
-static VOID WINAPI fiber_entry_func( LPVOID data) noexcept {
-    Record * record = static_cast< Record * >( data);
-    BOOST_ASSERT( nullptr != record);
-    // start execution of toplevel context-function
-    record->run();
-}
-
-struct BOOST_CONTEXT_DECL fiber_activation_record {
-    LPVOID                                                      fiber{ nullptr };
-    stack_context                                               sctx{};
-    bool                                                        main_ctx{ true };
-    fiber_activation_record                                       *   from{ nullptr };
-    std::function< fiber_activation_record*(fiber_activation_record*&) >    ontop{};
-    bool                                                        terminated{ false };
-    bool                                                        force_unwind{ false };
-
-    static fiber_activation_record *& current() noexcept;
-
-    // used for toplevel-context
-    // (e.g. main context, thread-entry context)
-    fiber_activation_record() noexcept {
-#if ( _WIN32_WINNT > 0x0600)
-        if ( ::IsThreadAFiber() ) {
-            fiber = ::GetCurrentFiber();
-        } else {
-            fiber = ::ConvertThreadToFiber( nullptr);
-        }
-#else
-        fiber = ::ConvertThreadToFiber( nullptr);
-        if ( BOOST_UNLIKELY( nullptr == fiber) ) {
-            BOOST_ASSERT( ERROR_ALREADY_FIBER == ::GetLastError());
-            fiber = ::GetCurrentFiber(); 
-            BOOST_ASSERT( nullptr != fiber);
-            BOOST_ASSERT( reinterpret_cast< LPVOID >( 0x1E00) != fiber);
-        }
-#endif
-    }
-
-    fiber_activation_record( stack_context sctx_) noexcept :
-        sctx{ sctx_ },
-        main_ctx{ false } {
-    } 
-
-    virtual ~fiber_activation_record() {
-        if ( BOOST_UNLIKELY( main_ctx) ) {
-            ::ConvertFiberToThread();
-        } else {
-            ::DeleteFiber( fiber);
-        }
-    }
-
-    fiber_activation_record( fiber_activation_record const&) = delete;
-    fiber_activation_record & operator=( fiber_activation_record const&) = delete;
-
-    bool is_main_context() const noexcept {
-        return main_ctx;
-    }
-
-    fiber_activation_record * resume() {
-        from = current();
-        // store `this` in static, thread local pointer
-        // `this` will become the active (running) context
-        current() = this;
-        // context switch from parent context to `this`-context
-        // context switch
-        ::SwitchToFiber( fiber);
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        return detail::exchange( current()->from, nullptr);
-#else
-        return std::exchange( current()->from, nullptr);
-#endif
-    }
-
-    template< typename Ctx, typename Fn >
-    fiber_activation_record * resume_with( Fn && fn) {
-        from = current();
-        // store `this` in static, thread local pointer
-        // `this` will become the active (running) context
-        // returned by fiber::current()
-        current() = this;
-#if defined(BOOST_NO_CXX14_GENERIC_LAMBDAS)
-        current()->ontop = std::bind(
-                [](typename std::decay< Fn >::type & fn, fiber_activation_record *& ptr){
-                    Ctx c{ ptr };
-                    c = fn( std::move( c) );
-                    if ( ! c) {
-                        ptr = nullptr;
-                    }
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-                    return exchange( c.ptr_, nullptr);
-#else
-                    return std::exchange( c.ptr_, nullptr);
-#endif
-                },
-                std::forward< Fn >( fn),
-                std::placeholders::_1);
-#else
-        current()->ontop = [fn=std::forward<Fn>(fn)](fiber_activation_record *& ptr){
-            Ctx c{ ptr };
-            c = fn( std::move( c) );
-            if ( ! c) {
-                ptr = nullptr;
-            }
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-            return exchange( c.ptr_, nullptr);
-#else
-            return std::exchange( c.ptr_, nullptr);
-#endif
-        };
-#endif
-        // context switch
-        ::SwitchToFiber( fiber);
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        return detail::exchange( current()->from, nullptr);
-#else
-        return std::exchange( current()->from, nullptr);
-#endif
-    }
-
-    virtual void deallocate() noexcept {
-    }
-};
-
-struct BOOST_CONTEXT_DECL fiber_activation_record_initializer {
-    fiber_activation_record_initializer() noexcept;
-    ~fiber_activation_record_initializer();
-};
-
-struct forced_unwind {
-    fiber_activation_record  *  from{ nullptr };
-
-    explicit forced_unwind( fiber_activation_record * from_) :
-        from{ from_ } {
-    }
-};
-
-template< typename Ctx, typename StackAlloc, typename Fn >
-class fiber_capture_record : public fiber_activation_record {
-private:
-    typename std::decay< StackAlloc >::type             salloc_;
-    typename std::decay< Fn >::type                     fn_;
-
-    static void destroy( fiber_capture_record * p) noexcept {
-        typename std::decay< StackAlloc >::type salloc = std::move( p->salloc_);
-        stack_context sctx = p->sctx;
-        // deallocate activation record
-        p->~fiber_capture_record();
-        // destroy stack with stack allocator
-        salloc.deallocate( sctx);
-    }
-
-public:
-    fiber_capture_record( stack_context sctx, StackAlloc && salloc, Fn && fn) noexcept :
-        fiber_activation_record( sctx),
-        salloc_( std::forward< StackAlloc >( salloc)),
-        fn_( std::forward< Fn >( fn) ) {
-    }
-
-    void deallocate() noexcept override final {
-        BOOST_ASSERT( main_ctx || ( ! main_ctx && terminated) );
-        destroy( this);
-    }
-
-    void run() {
-        Ctx c{ from };
-        try {
-            // invoke context-function
-#if defined(BOOST_NO_CXX17_STD_INVOKE)
-            c = boost::context::detail::invoke( fn_, std::move( c) );
-#else
-            c = std::invoke( fn_, std::move( c) );
-#endif  
-        } catch ( forced_unwind const& ex) {
-            c = Ctx{ ex.from };
-        }
-        // this context has finished its task
-        from = nullptr;
-        ontop = nullptr;
-        terminated = true;
-        force_unwind = false;
-        std::move( c).resume();
-        BOOST_ASSERT_MSG( false, "fiber already terminated");
-    }
-};
-
-template< typename Ctx, typename StackAlloc, typename Fn >
-static fiber_activation_record * create_fiber1( StackAlloc && salloc, Fn && fn) {
-    typedef fiber_capture_record< Ctx, StackAlloc, Fn >  capture_t;
-
-    auto sctx = salloc.allocate();
-    BOOST_ASSERT( ( sizeof( capture_t) ) < sctx.size);
-    // reserve space for control structure
-    void * storage = reinterpret_cast< void * >(
-            ( reinterpret_cast< uintptr_t >( sctx.sp) - static_cast< uintptr_t >( sizeof( capture_t) ) )
-            & ~ static_cast< uintptr_t >( 0xff) );
-    // placment new for control structure on context stack
-    capture_t * record = new ( storage) capture_t{
-            sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) };
-    // create user-context
-    record->fiber = ::CreateFiber( sctx.size, & detail::fiber_entry_func< capture_t >, record);
-    return record;
-}
-
-template< typename Ctx, typename StackAlloc, typename Fn >
-static fiber_activation_record * create_fiber2( preallocated palloc, StackAlloc && salloc, Fn && fn) {
-    typedef fiber_capture_record< Ctx, StackAlloc, Fn >  capture_t; 
-
-    BOOST_ASSERT( ( sizeof( capture_t) ) < palloc.size);
-    // reserve space for control structure
-    void * storage = reinterpret_cast< void * >(
-            ( reinterpret_cast< uintptr_t >( palloc.sp) - static_cast< uintptr_t >( sizeof( capture_t) ) )
-            & ~ static_cast< uintptr_t >( 0xff) );
-    // placment new for control structure on context stack
-    capture_t * record = new ( storage) capture_t{
-            palloc.sctx, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) };
-    // create user-context
-    record->fiber = ::CreateFiber( palloc.sctx.size, & detail::fiber_entry_func< capture_t >, record);
-    return record;
-}
-
-}
-
-class BOOST_CONTEXT_DECL fiber {
-private:
-    friend struct detail::fiber_activation_record;
-
-    template< typename Ctx, typename StackAlloc, typename Fn >
-    friend class detail::fiber_capture_record;
-
-    template< typename Ctx, typename StackAlloc, typename Fn >
-    friend detail::fiber_activation_record * detail::create_fiber1( StackAlloc &&, Fn &&);
-
-    template< typename Ctx, typename StackAlloc, typename Fn >
-    friend detail::fiber_activation_record * detail::create_fiber2( preallocated, StackAlloc &&, Fn &&);
-
-    detail::fiber_activation_record   *   ptr_{ nullptr };
-
-    fiber( detail::fiber_activation_record * ptr) noexcept :
-        ptr_{ ptr } {
-    }
-
-public:
-    fiber() = default;
-
-    template< typename Fn, typename = detail::disable_overload< fiber, Fn > >
-    fiber( Fn && fn) :
-        fiber{ std::allocator_arg,
-               fixedsize_stack(),
-               std::forward< Fn >( fn) } {
-    }
-
-    template< typename StackAlloc, typename Fn >
-    fiber( std::allocator_arg_t, StackAlloc && salloc, Fn && fn) :
-        ptr_{ detail::create_fiber1< fiber >(
-                std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) ) } {;
-    }
-
-    template< typename StackAlloc, typename Fn >
-    fiber( std::allocator_arg_t, preallocated palloc, StackAlloc && salloc, Fn && fn) :
-        ptr_{ detail::create_fiber2< fiber >(
-                palloc, std::forward< StackAlloc >( salloc), std::forward< Fn >( fn) ) } {
-    }
-
-    ~fiber() {
-        if ( BOOST_UNLIKELY( nullptr != ptr_) && ! ptr_->main_ctx) {
-            if ( BOOST_LIKELY( ! ptr_->terminated) ) {
-                ptr_->force_unwind = true;
-                ptr_->resume();
-                BOOST_ASSERT( ptr_->terminated);
-            }
-            ptr_->deallocate();
-        }
-    }
-
-    fiber( fiber const&) = delete;
-    fiber & operator=( fiber const&) = delete;
-
-    fiber( fiber && other) noexcept {
-        swap( other);
-    }
-
-    fiber & operator=( fiber && other) noexcept {
-        if ( BOOST_LIKELY( this != & other) ) {
-            fiber tmp = std::move( other);
-            swap( tmp);
-        }
-        return * this;
-    }
-
-    fiber resume() && {
-        BOOST_ASSERT( nullptr != ptr_);
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        detail::fiber_activation_record * ptr = detail::exchange( ptr_, nullptr)->resume();
-#else
-        detail::fiber_activation_record * ptr = std::exchange( ptr_, nullptr)->resume();
-#endif
-        if ( BOOST_UNLIKELY( detail::fiber_activation_record::current()->force_unwind) ) {
-            throw detail::forced_unwind{ ptr};
-        } else if ( BOOST_UNLIKELY( nullptr != detail::fiber_activation_record::current()->ontop) ) {
-            ptr = detail::fiber_activation_record::current()->ontop( ptr);
-            detail::fiber_activation_record::current()->ontop = nullptr;
-        }
-        return { ptr };
-    }
-
-    template< typename Fn >
-    fiber resume_with( Fn && fn) && {
-        BOOST_ASSERT( nullptr != ptr_);
-#if defined(BOOST_NO_CXX14_STD_EXCHANGE)
-        detail::fiber_activation_record * ptr =
-            detail::exchange( ptr_, nullptr)->resume_with< fiber >( std::forward< Fn >( fn) );
-#else
-        detail::fiber_activation_record * ptr =
-            std::exchange( ptr_, nullptr)->resume_with< fiber >( std::forward< Fn >( fn) );
-#endif
-        if ( BOOST_UNLIKELY( detail::fiber_activation_record::current()->force_unwind) ) {
-            throw detail::forced_unwind{ ptr};
-        } else if ( BOOST_UNLIKELY( nullptr != detail::fiber_activation_record::current()->ontop) ) {
-            ptr = detail::fiber_activation_record::current()->ontop( ptr);
-            detail::fiber_activation_record::current()->ontop = nullptr;
-        }
-        return { ptr };
-    }
-
-    explicit operator bool() const noexcept {
-        return nullptr != ptr_ && ! ptr_->terminated;
-    }
-
-    bool operator!() const noexcept {
-        return nullptr == ptr_ || ptr_->terminated;
-    }
-
-    bool operator<( fiber const& other) const noexcept {
-        return ptr_ < other.ptr_;
-    }
-    
-    #if !defined(BOOST_EMBTC)
-    
-    template< typename charT, class traitsT >
-    friend std::basic_ostream< charT, traitsT > &
-    operator<<( std::basic_ostream< charT, traitsT > & os, fiber const& other) {
-        if ( nullptr != other.ptr_) {
-            return os << other.ptr_;
-        } else {
-            return os << "{not-a-context}";
-        }
-    }
-
-    #else
-    
-    template< typename charT, class traitsT >
-    friend std::basic_ostream< charT, traitsT > &
-    operator<<( std::basic_ostream< charT, traitsT > & os, fiber const& other);
-
-    #endif
-
-    void swap( fiber & other) noexcept {
-        std::swap( ptr_, other.ptr_);
-    }
-};
-
-#if defined(BOOST_EMBTC)
-
-    template< typename charT, class traitsT >
-    inline std::basic_ostream< charT, traitsT > &
-    operator<<( std::basic_ostream< charT, traitsT > & os, fiber const& other) {
-        if ( nullptr != other.ptr_) {
-            return os << other.ptr_;
-        } else {
-            return os << "{not-a-context}";
-        }
-    }
-
-#endif
-
-inline
-void swap( fiber & l, fiber & r) noexcept {
-    l.swap( r);
-}
-
-typedef fiber fiber_context;
-
-}}
-
-#if defined(BOOST_MSVC)
-# pragma warning(pop)
-#endif
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_SUFFIX
-#endif
-
-#endif // BOOST_CONTEXT_FIBER_H
diff --git a/contrib/restricted/boost/context/include/boost/context/fixedsize_stack.hpp b/contrib/restricted/boost/context/include/boost/context/fixedsize_stack.hpp
deleted file mode 100644
index c309347935a..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/fixedsize_stack.hpp
+++ /dev/null
@@ -1,97 +0,0 @@
-
-//          Copyright Oliver Kowalke 2014.
-// 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)
-
-#ifndef BOOST_CONTEXT_FIXEDSIZE_H
-#define BOOST_CONTEXT_FIXEDSIZE_H
-
-#include <cstddef>
-#include <cstdlib>
-#include <new>
-
-#include <boost/assert.hpp>
-#include <boost/config.hpp>
-
-#include <boost/context/detail/config.hpp>
-#include <boost/context/stack_context.hpp>
-#include <boost/context/stack_traits.hpp>
-
-#if defined(BOOST_CONTEXT_USE_MAP_STACK)
-extern "C" {
-#include <sys/mman.h>
-}
-#endif
-
-#if defined(BOOST_USE_VALGRIND)
-#include <valgrind/valgrind.h>
-#endif
-
-#ifdef BOOST_HAS_ABI_HEADERS
-#  include BOOST_ABI_PREFIX
-#endif
-
-namespace boost {
-namespace context {
-
-template< typename traitsT >
-class basic_fixedsize_stack {
-private:
-    std::size_t     size_;
-
-public:
-    typedef traitsT traits_type;
-
-    basic_fixedsize_stack( std::size_t size = traits_type::default_size() ) BOOST_NOEXCEPT_OR_NOTHROW :
-        size_( size) {
-    }
-
-    stack_context allocate() {
-#if defined(BOOST_CONTEXT_USE_MAP_STACK)
-        void * vp = ::mmap( 0, size_, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON | MAP_STACK, -1, 0);
-        if ( vp == MAP_FAILED) {
-            throw std::bad_alloc();
-        }
-#else
-        void * vp = std::malloc( size_);
-        if ( ! vp) {
-            throw std::bad_alloc();
-        }
-#endif
-        stack_context sctx;
-        sctx.size = size_;
-        sctx.sp = static_cast< char * >( vp) + sctx.size;
-#if defined(BOOST_USE_VALGRIND)
-        sctx.valgrind_stack_id = VALGRIND_STACK_REGISTER( sctx.sp, vp);
-#endif
-        return sctx;
-    }
-
-    void deallocate( stack_context & sctx) BOOST_NOEXCEPT_OR_NOTHROW {
-        BOOST_ASSERT( sctx.sp);
-
-#if defined(BOOST_USE_VALGRIND)
-        VALGRIND_STACK_DEREGISTER( sctx.valgrind_stack_id);
-#endif
-        void * vp = static_cast< char * >( sctx.sp) - sctx.size;
-#if defined(BOOST_CONTEXT_USE_MAP_STACK)
-        ::munmap( vp, sctx.size);
-#else
-        std::free( vp);
-#endif
-    }
-};
-
-typedef basic_fixedsize_stack< stack_traits >  fixedsize_stack;
-# if ! defined(BOOST_USE_SEGMENTED_STACKS)
-typedef fixedsize_stack default_stack;
-# endif
-
-}}
-
-#ifdef BOOST_HAS_ABI_HEADERS
-#  include BOOST_ABI_SUFFIX
-#endif
-
-#endif // BOOST_CONTEXT_FIXEDSIZE_H
diff --git a/contrib/restricted/boost/context/include/boost/context/flags.hpp b/contrib/restricted/boost/context/include/boost/context/flags.hpp
deleted file mode 100644
index c7ff1179da5..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/flags.hpp
+++ /dev/null
@@ -1,28 +0,0 @@
-
-//          Copyright Oliver Kowalke 2014.
-// 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)
-
-#ifndef BOOST_CONTEXT_FLAGS_H
-#define BOOST_CONTEXT_FLAGS_H
-
-# include <boost/config.hpp>
-
-# ifdef BOOST_HAS_ABI_HEADERS
-#  include BOOST_ABI_PREFIX
-# endif
-
-namespace boost {
-namespace context {
-
-struct exec_ontop_arg_t {};
-const exec_ontop_arg_t exec_ontop_arg{};
-
-}}
-
-# ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_SUFFIX
-# endif
-
-#endif // BOOST_CONTEXT_FLAGS_H
diff --git a/contrib/restricted/boost/context/include/boost/context/posix/segmented_stack.hpp b/contrib/restricted/boost/context/include/boost/context/posix/segmented_stack.hpp
deleted file mode 100644
index e3d2efcb5b1..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/posix/segmented_stack.hpp
+++ /dev/null
@@ -1,82 +0,0 @@
-
-//          Copyright Oliver Kowalke 2014.
-// 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)
-
-#ifndef BOOST_CONTEXT_SEGMENTED_H
-#define BOOST_CONTEXT_SEGMENTED_H
-
-#include <cstddef>
-#include <new>
-
-#include <boost/config.hpp>
-
-#include <boost/context/detail/config.hpp>
-#include <boost/context/stack_context.hpp>
-#include <boost/context/stack_traits.hpp>
-
-#ifdef BOOST_HAS_ABI_HEADERS
-#  include BOOST_ABI_PREFIX
-#endif
-
-// forward declaration for splitstack-functions defined in libgcc
-extern "C" {
-void *__splitstack_makecontext( std::size_t,
-                                void * [BOOST_CONTEXT_SEGMENTS],
-                                std::size_t *);
-
-void __splitstack_releasecontext( void * [BOOST_CONTEXT_SEGMENTS]);
-
-void __splitstack_resetcontext( void * [BOOST_CONTEXT_SEGMENTS]);
-
-void __splitstack_block_signals_context( void * [BOOST_CONTEXT_SEGMENTS],
-                                         int * new_value, int * old_value);
-}
-
-namespace boost {
-namespace context {
-
-template< typename traitsT >
-class basic_segmented_stack {
-private:
-    std::size_t     size_;
-
-public:
-    typedef traitsT traits_type;
-
-    basic_segmented_stack( std::size_t size = traits_type::default_size() ) BOOST_NOEXCEPT_OR_NOTHROW :
-        size_( size) {
-    }
-
-    stack_context allocate() {
-        stack_context sctx;
-        void * vp = __splitstack_makecontext( size_, sctx.segments_ctx, & sctx.size);
-        if ( ! vp) throw std::bad_alloc();
-
-        // sctx.size is already filled by __splitstack_makecontext
-        sctx.sp = static_cast< char * >( vp) + sctx.size;
-
-        int off = 0;
-        __splitstack_block_signals_context( sctx.segments_ctx, & off, 0);
-
-        return sctx;
-    }
-
-    void deallocate( stack_context & sctx) BOOST_NOEXCEPT_OR_NOTHROW {
-        __splitstack_releasecontext( sctx.segments_ctx);
-    }
-};
-
-typedef basic_segmented_stack< stack_traits > segmented_stack;
-# if defined(BOOST_USE_SEGMENTED_STACKS)
-typedef segmented_stack default_stack;
-# endif
-
-}}
-
-#ifdef BOOST_HAS_ABI_HEADERS
-#  include BOOST_ABI_SUFFIX
-#endif
-
-#endif // BOOST_CONTEXT_SEGMENTED_H
diff --git a/contrib/restricted/boost/context/include/boost/context/preallocated.hpp b/contrib/restricted/boost/context/include/boost/context/preallocated.hpp
deleted file mode 100644
index 862a6a5060f..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/preallocated.hpp
+++ /dev/null
@@ -1,39 +0,0 @@
-
-//          Copyright Oliver Kowalke 2014.
-// 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)
-
-#ifndef BOOST_CONTEXT_PREALLOCATED_H
-#define BOOST_CONTEXT_PREALLOCATED_H
-
-#include <cstddef>
-
-#include <boost/config.hpp>
-
-#include <boost/context/detail/config.hpp>
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_PREFIX
-#endif
-
-namespace boost {
-namespace context {
-
-struct preallocated {
-    void        *   sp;
-    std::size_t     size;
-    stack_context   sctx;
-
-    preallocated( void * sp_, std::size_t size_, stack_context sctx_) noexcept :
-        sp( sp_), size( size_), sctx( sctx_) {
-    }
-};
-
-}}
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_SUFFIX
-#endif
-
-#endif // BOOST_CONTEXT_PREALLOCATED_H
diff --git a/contrib/restricted/boost/context/include/boost/context/segmented_stack.hpp b/contrib/restricted/boost/context/include/boost/context/segmented_stack.hpp
deleted file mode 100644
index 88e3e6a61f5..00000000000
--- a/contrib/restricted/boost/context/include/boost/context/segmented_stack.hpp
+++ /dev/null
@@ -1,13 +0,0 @@
-
-//          Copyright Oliver Kowalke 2014.
-// 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/config.hpp>
-
-#if defined(BOOST_USE_SEGMENTED_STACKS)
-# if ! defined(BOOST_WINDOWS)
-#  include <boost/context/posix/segmented_stack.hpp>
-# endif
-#endif
diff --git a/contrib/restricted/boost/context/src/continuation.cpp b/contrib/restricted/boost/context/src/continuation.cpp
deleted file mode 100644
index 2d7769602a7..00000000000
--- a/contrib/restricted/boost/context/src/continuation.cpp
+++ /dev/null
@@ -1,58 +0,0 @@
-
-//          Copyright Oliver Kowalke 2017.
-// 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)
-
-#if defined(BOOST_USE_UCONTEXT)
-#include "boost/context/continuation_ucontext.hpp"
-#elif defined(BOOST_USE_WINFIB)
-#include "boost/context/continuation_winfib.hpp"
-#endif
-
-#include <boost/config.hpp>
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_PREFIX
-#endif
-
-namespace boost {
-namespace context {
-namespace detail {
-
-// zero-initialization
-thread_local activation_record * current_rec;
-thread_local static std::size_t counter;
-
-// schwarz counter
-activation_record_initializer::activation_record_initializer() noexcept {
-    if ( 0 == counter++) {
-        current_rec = new activation_record();
-    }
-}
-
-activation_record_initializer::~activation_record_initializer() {
-    if ( 0 == --counter) {
-        BOOST_ASSERT( current_rec->is_main_context() );
-        delete current_rec;
-    }
-}
-
-}
-
-namespace detail {
-
-activation_record *&
-activation_record::current() noexcept {
-    // initialized the first time control passes; per thread
-    thread_local static activation_record_initializer initializer;
-    return current_rec;
-}
-
-}
-
-}}
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_SUFFIX
-#endif
diff --git a/contrib/restricted/boost/context/src/fiber.cpp b/contrib/restricted/boost/context/src/fiber.cpp
deleted file mode 100644
index b6b790df544..00000000000
--- a/contrib/restricted/boost/context/src/fiber.cpp
+++ /dev/null
@@ -1,58 +0,0 @@
-
-//          Copyright Oliver Kowalke 2017.
-// 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)
-
-#if defined(BOOST_USE_UCONTEXT)
-#include "boost/context/fiber_ucontext.hpp"
-#elif defined(BOOST_USE_WINFIB)
-#include "boost/context/fiber_winfib.hpp"
-#endif
-
-#include <boost/config.hpp>
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_PREFIX
-#endif
-
-namespace boost {
-namespace context {
-namespace detail {
-
-// zero-initialization
-thread_local fiber_activation_record * fib_current_rec;
-thread_local static std::size_t counter;
-
-// schwarz counter
-fiber_activation_record_initializer::fiber_activation_record_initializer() noexcept {
-    if ( 0 == counter++) {
-        fib_current_rec = new fiber_activation_record();
-    }
-}
-
-fiber_activation_record_initializer::~fiber_activation_record_initializer() {
-    if ( 0 == --counter) {
-        BOOST_ASSERT( fib_current_rec->is_main_context() );
-        delete fib_current_rec;
-    }
-}
-
-}
-
-namespace detail {
-
-fiber_activation_record *&
-fiber_activation_record::current() noexcept {
-    // initialized the first time control passes; per thread
-    thread_local static fiber_activation_record_initializer initializer;
-    return fib_current_rec;
-}
-
-}
-
-}}
-
-#ifdef BOOST_HAS_ABI_HEADERS
-# include BOOST_ABI_SUFFIX
-#endif