C ++: Компиляция независимости единиц перевода и ошибка переопределения старых типов winsock2.h

Насколько мне известно, единицы перевода ничего не говорят друг о друге на этапе компиляции. Можете ли вы объяснить, почему у меня такое странное поведение: после включения windows.h в один A.cpp (который на самом деле не использует сокет api и не включает winsock2.h) я получаю ошибку при компиляции ДРУГОГО B.cpp с winsock2.h конфликт winsock.h. Этот B.cpp вообще не был изменен. Заранее спасибо.

РЕДАКТИРОВАТЬ: на самом деле это ошибка КОМПИЛЯЦИИ, а не ссылка. Я поставил компилятор msvc в подробный режим, здесь заголовок включает дерево:

2>perfomancemeter.cpp
2>Note: including file: C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\numeric
2>Note: including file:  C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\iterator
2>Note: including file:   C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\xutility
2>Note: including file:    C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\climits
2>Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\yvals.h
2>Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdefs.h
2>Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\sal.h
2>Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtassem.h
2>Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\vadefs.h
2>Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\use_ansi.h
2>Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\limits.h
2>Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdefs.h
2>Note: including file:    C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\utility
2>Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\iosfwd
2>Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\cstdio
2>Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\stdio.h
2>Note: including file:        C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdefs.h
2>Note: including file:        C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\swprintf.inl
2>Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\cstring
2>Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\string.h
2>Note: including file:        C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdefs.h
2>Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\cwchar
2>Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\wchar.h
2>Note: including file:        C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdefs.h
2>Note: including file:        C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\wtime.inl
2>Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\xstddef
2>Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\cstddef
2>Note: including file:        C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\stddef.h
2>Note: including file:         C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdefs.h
2>Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdbg.h
2>Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdefs.h
2>Note: including file: C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\algorithm
2>Note: including file:  C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\memory
2>Note: including file:   C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\xmemory
2>Note: including file:    C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\cstdlib
2>Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\stdlib.h
2>Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdefs.h
2>Note: including file:    C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\exception
2>Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\eh.h
2>Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdefs.h
2>Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\malloc.h
2>Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdefs.h
2>Note: including file:    C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\new
2>Note: including file: d:\repos\cbs\billing\common\perfomancemeter.h
2>Note: including file:  C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\vector
2>Note: including file:   C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\stdexcept
2>Note: including file:    C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\xstring
2>Note: including file: d:\repos\cbs\billing\common\util.h
2>Note: including file:  d:\repos\cbs\billing\common\framework\include\types/types.h
2>Note: including file:  C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\string
2>Note: including file:   C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\istream
2>Note: including file:    C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\ostream
2>Note: including file:     C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\ios
2>Note: including file:      C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\xlocnum
2>Note: including file:       C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\streambuf
2>Note: including file:        C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\xiosbase
2>Note: including file:         C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\xlocale
2>Note: including file:          C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\typeinfo
2>Note: including file:          C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\xdebug
2>Note: including file:          C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\xlocinfo
2>Note: including file:           C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\xlocinfo.h
2>Note: including file:            C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\ctype.h
2>Note: including file:             C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdefs.h
2>Note: including file:            C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\locale.h
2>Note: including file:             C:\Program Files (x86)\Microsoft Visual Studio 8\VC\include\crtdefs.h
1>c:\program files (x86)\microsoft visual studio 8\vc\platformsdk\include\winsock2.h(112) : error C2011: 'fd_set' : 'struct' type redefinition
1>        c:\program files (x86)\microsoft visual studio 8\vc\platformsdk\include\winsock.h(54) : see declaration of 'fd_set'

Я сталкивался с этой проблемой раньше и знаю, что #define WIN32_LEAN_AND_MEAN перед включением заголовка Windows исправляет ее. Но почему это происходит в данном случае?