cl.exe long file name issues

testcase.bat

@ECHO OFF

SET WORKDIR=C:\Temp

::SET DIR=short
:: 64 + 64 + 64 + 64
SET DIR=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb\cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc\dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd

CD /D %WORKDIR%
MKDIR %DIR%

ECHO.>foo.cpp

ECHO Test 1 - use very long file name on command line
cl.exe /c /Fo%DIR%\foo1.o foo.cpp

ECHO Test 2 - use UNC file name on command line
cl.exe /c /Fo\\?\%WORKDIR%\%DIR%\foo2.o foo.cpp

ECHO Test 3 - use response file with regular file
ECHO /c /Fo%DIR%\foo3.o foo.cpp>resp3.txt
cl.exe @resp3.txt

ECHO Test 4 - use response file with UNC file name
ECHO /c /Fo\\?\%WORKDIR%\%DIR%\foo4.o foo.cpp>resp4.txt
cl.exe @resp4.txt

Test 1 - use very long file name on command line
Microsoft (R) C/C++ Optimizing Compiler Version 19.12.25831 for x64
Copyright (C) Microsoft Corporation.  All rights reserved.

foo.cpp
c1xx: fatal error C1081: 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb\cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc\dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd\foo1.o': file name too long
Test 2 - use UNC file name on command line
Microsoft (R) C/C++ Optimizing Compiler Version 19.12.25831 for x64
Copyright (C) Microsoft Corporation.  All rights reserved.

foo.cpp
c1xx: fatal error C1081: '\\?\C:\Temp\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb\cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc\dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd\foo2.o': file name too long
Test 3 - use response file with regular file
Microsoft (R) C/C++ Optimizing Compiler Version 19.12.25831 for x64
Copyright (C) Microsoft Corporation.  All rights reserved.

cl /c /Foaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb\cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc\dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd\foo3.o foo.cpp

foo.cpp
c1xx: fatal error C1081: 'aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb\cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc\dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd\foo3.o': file name too long
Test 4 - use response file with UNC file name
Microsoft (R) C/C++ Optimizing Compiler Version 19.12.25831 for x64
Copyright (C) Microsoft Corporation.  All rights reserved.

cl /c /Fo\\?\C:\Temp\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb\cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc\dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd\foo4.o foo.cpp

foo.cpp
c1xx: fatal error C1081: '\\?\C:\Temp\aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb\cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc\dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd\foo4.o': file name too long

PS V:\> Get-Item -Path Registry::HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem


    Hive: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control


Name                           Property
----                           --------
...
                               LongPathsEnabled                      : 1
...