WSL user .profile file to enable the MS compiler in the WSL shell

profile.sh

# shellcheck shell=bash 
# ~/.profile: executed by the command interpreter for login shells.
# This file is not read by bash(1), if ~/.bash_profile or ~/.bash_login
# exists.
# see /usr/share/doc/bash/examples/startup-files for examples.
# the files are located in the bash-doc package.

# this file is symlinked to /home/<user>/.profile
# Jerker Bäck 2017

# the default umask is set in /etc/profile; for setting the umask
# for ssh logins, install and configure the libpam-umask package.
#umask 022

# if running bash
if [ -n "$BASH_VERSION" ]; then
    # include .bashrc if it exists
    if [ -f "$HOME/.bashrc" ]; then
	. "$HOME/.bashrc"
    fi
fi

export TMPDIR="/mnt/c/TEMP/apptemp/unixtmp"
export TMP=$TMPDIR  # override
vswhere='/mnt/c/Program Files (x86)/Microsoft Visual Studio/Installer/vswhere.exe'
vsinstalldir=$(wslpath "$("$vswhere" -latest -property installationPath 2>/dev/null | sed 's:\\:/:g' | tr -d '\r\n')")
vctoolsversion=$(head -n 1 "${vsinstalldir}/VC/Auxiliary/Build/Microsoft.VCToolsVersion.default.txt" | tr -d '\r\n')
export VCToolsInstallDir="$vsinstalldir/VC/Tools/MSVC/$vctoolsversion"  # used by clang
kitskey='HKLM\SOFTWARE\WOW6432Node\Microsoft\Windows Kits\Installed Roots'
kitsroot10="$(wslpath "$(/mnt/c/Windows/System32/reg.exe query "$kitskey" -f 'KitsRoot10' 2>/dev/null | sed -n 's:.*REG_SZ *\([[:print:]]*\).*:\1:p' | sed 's:\\:/:g')")"
kitsversion=$(sed -n -e '/PlatformIdentity/ s:.*Version\=*::p' "${kitsroot10}SDKManifest.xml" | sed 's:"[[:space:]]*::g')
export kitsroot10
export kitsversion
#export INCLUDE="$VCToolsInstallDir/include:${kitsroot10}Include/$kitsversion/ucrt:${kitsroot10}Include/$kitsversion/um:${kitsroot10}Include/$kitsversion/shared:$VCToolsInstallDir/atlmfc/include:/mnt/f/libraries/include"
#export LIB="$VCToolsInstallDir/lib/x64:${kitsroot10}Lib/$kitsversion/ucrt/x64:${kitsroot10}Lib/$kitsversion/um/x64:${kitsroot10}Lib/$kitsversion/shared/x64:/mnt/f/libraries/lib/x64"
export INCLUDE="$VCToolsInstallDir/include;${kitsroot10}Include/$kitsversion/ucrt;${kitsroot10}Include/$kitsversion/um;${kitsroot10}Include/$kitsversion/shared;$VCToolsInstallDir/atlmfc/include;/mnt/f/libraries/include"
export LIB="$VCToolsInstallDir/lib/x64;${kitsroot10}Lib/$kitsversion/ucrt/x64;${kitsroot10}Lib/$kitsversion/um/x64;${kitsroot10}Lib/$kitsversion/shared/x64;/mnt/f/libraries/lib/x64"
export CL="-O1 -Oi -EHsc -std:c++17 -W4 -MD"
export _CL_="-link -subsystem:console -machine:x64"
#export CFLAGS="--target=x86_64-pc-windows-msvc -std=c++20 -isystem"$VCToolsInstallDir/include" -isystem"${kitsroot10}Include/$kitsversion/ucrt" -isystem"${kitsroot10}Include/$kitsversion/um" -isystem"${kitsroot10}Include/$kitsversion/shared" -isystem"$VCToolsInstallDir/atlmfc/include" -isystem"/mnt/f/libraries/include""
export WSLENV=$WSLENV:INCLUDE/l:LIB/l:CL:_CL_:TMPDIR/p:TMP/p
# strip path to Ubuntu system to avoid pollution of Windows versions of tools
wslsys="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/mnt/c/Windows/System32:/mnt/c/Windows:/mnt/c/Windows/System32/WindowsPowerShell/v1.0"
export PATH="$VCToolsInstallDir/bin/Hostx64/x64:${kitsroot10}bin/$kitsversion/x64:/mnt/c/develop/vscode/bin:$wslsys"
unset vswhere vsinstalldir vctoolsversion kitskey wslsys

I finally understood why clang couldn't parse the INCLUDE and LIB environment variables. The parser expects a semicolon ; instead of a colon : even in UNIX environments. I therefore added INCLUDEtmp and LIBtmp with semicolon delimiters. To let clang compile successfully using INCLUDE and LIB, do:

$ cl.exe test.cpp
$ export INCLUDE=$INCLUDEtmp
$ clang -target x86_64-pc-windows-msvc -std=c++17 -Wall -pedantic -Wextra -save-temps=obj -v test.cpp

The compile will then use WSL clang using INCLUDE with UNIX paths and semicolons and Windows link.exe using LIB and WSLENV.

See WSLENV for an explanation. Share Environment Vars between WSL and Windows. Test the effect by running cmd.exe env from WSL.

The cl.exe compile will use CL and _CL_ which expands to:
cl.exe -O1 -Oi -EHsc -std:c++17 -W4 -MD test.cpp -link -subsystem:console -machine:x64