Note (probably harmless): No library found for -lX11
Note (probably harmless): No library found for -lXtst
Writing Makefile for X11::GUITest

Microsoft (R) Program Maintenance Utility   Version 6.00.8168.0
Copyright (C) Microsoft Corp 1988-1998. All rights reserved.

Math::BigInt: couldn't load specified math lib(s), fallback to Math::BigInt::FastCalc at C:/cpanrun/build/5-10-0/site/lib/Win32API/File.pm line 20
cp GUITest.pm blib\lib\X11\GUITest.pm
AutoSplitting blib\lib\X11\GUITest.pm (blib\lib\auto\X11\GUITest)
	C:\cpanrun\build\5-10-0\bin\perl.exe C:\cpanrun\build\5-10-0\lib\ExtUtils\xsubpp  -typemap C:\cpanrun\build\5-10-0\lib\ExtUtils\typemap -typemap typemap  GUITest.xs > GUITest.xsc && C:\cpanrun\build\5-10-0\bin\perl.exe -MExtUtils::Command -e mv GUITest.xsc GUITest.c
	cl -c  -I/usr/X11R6/include  -Werror -MD -Zi -DNDEBUG -O1    -DVERSION=\"0.10\"  -DXS_VERSION=\"0.10\"  "-IC:\cpanrun\build\5-10-0\lib\CORE"  -DNDEBUG GUITest.c
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8804 for 80x86
Copyright (C) Microsoft Corp 1984-1998. All rights reserved.

Command line error D2021 : invalid numeric argument '/Werror'
NMAKE : fatal error U1077: 'cl' : return code '0x2'
Stop.