Question: Below is the error message when I run "scons" to compiler in windows7:

```
-----------------------------------------------------------------------------------
'cl' is not recognized as an internal or external command,
operable program or batch file.
scons: *** [out\windows-x86-MD-unicode-vs2008-rel\obj-static\src\featuresets\ada                                      pters\im-history\AddToChatRoomHistoryVisitor.obj] Error 1
scons: building terminated because of errors.
-----------------------------------------------------------------------------------

```

I have added path to environment variables already, but still met this problem.

Below is the PATH info of environment variables:

```
--------------------------------------------------------------------------------------------
PATH=C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v
1.0\;C:\Program Files\CREDANT\Shield v7.1\;C:\Program Files (x86)\QuickTime\QTSystem\;C:\Program Fil
es\Microsoft SQL Server\110\Tools\Binn\;C:\Program Files\TortoiseSVN\bin;C:\Python27;C:\cygwin64\bin
;C:\Python27\scons-2.3.1;c:\Program Files (x86)\Microsoft SQL Server\100\Tools\Binn\;c:\Program File
s\Microsoft SQL Server\100\Tools\Binn\;c:\Program Files\Microsoft SQL Server\100\DTS\Binn\;C:\Progra
m Files (x86)\Microsoft Visual Studio 10.0\VC\bin;C:\Python27\Scripts;C:\Program Files (x86)\Microso
ft Visual Studio 10.0\VC\lib;C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include
--------------------------------------------------------------------------------------------

```

Answer: 
Simply do window search for cl.exe, and add that path to PATH variable, save it. Close the existing open command and reopen it it before executing cl.exe. Hope this will work.
I was having the same issue and found a better way to fix it from @bdbaddog answer to get the debug log from `set SCONS_MSCOMMON_DEBUG=%TEMP%\SCONS_MSVS_DEBUG.log` SCons seem to find the cl.exe

```
00073ms:MSCommon/vc.py:_check_cl_exists_in_vc_dir#588:checking for cl.exe at C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.26.28801\bin\Hostx64\x64\cl.exe: 
00073ms:MSCommon/vc.py:_check_cl_exists_in_vc_dir#590:found cl.exe!: 

```

And scons env `env['ENV']['PATH']` has the `cl.exe` path but it doesn't use it, So I just updated the session path using scons path like below and it worked

```py
os.environ['PATH'] = env['ENV']['PATH']

```