Espero que sirva de guía, hace años compile los fuentes Harbour del sitio oficial
con Visual Studio C++ 2010 Express 32 bit, en Windows 10, tal vez tengas problemas con
las librerías de contribución, para tu caso no los incluyas (coméntalos con REM).
abre consola de windows y busca algo similar a vcvarsall.bat , para que VS2019 tome el control
"%C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\vcvarsall.bat"
@echo off
REM Harbour-32bit with VS2010
REM -------------------------
set PATH=C:\Harbour\library\curl-3\bin;C:\Harbour\library\curl-3\lib;%PATH%
set PATH=C:\Harbour\library\openssl-3\x86\bin;C:\Harbour\library\openssl-3\x86\lib;%PATH%
set PATH=C:\Harbour\core-master\bin\win\msvc;%PATH%
CALL "%C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\vcvarsall.bat"
REM SET HB_INSTALL_PREFIX=C:\HB32
SET HB_WITH_FREEIMAGE=C:\HARBOUR\HBLIB\FreeImage\Dist
SET HB_WITH_OCILIB=C:\HARBOUR\HBLIB\ocilib\include
SET HB_WITH_OPENSSL=C:\Harbour\library\openssl-3\x86\include
SET HB_WITH_CURL=C:\HARBOUR\HBLIB\curl-3\include
SET HB_STATIC_OPENSSL=yes
SET HB_STATIC_CURL=yes
set HB_COMPILER=msvc
cd C:\Harbour\core-master
"C:\WINDOWS\system32\cmd.exe" /k win-make