vcpkg/scripts/cmake/execute_process.cmake

## # execute_process
##
## Intercepts all calls to execute_process() inside portfiles and fails when Download Mode
## is enabled.
##
## In order to execute a process in Download Mode call `_execute_process()` instead.
##
if (NOT DEFINED OVERRIDEN_EXECUTE_PROCESS)
  set(OVERRIDEN_EXECUTE_PROCESS ON)

  if (DEFINED VCPKG_DOWNLOAD_MODE)
    macro(execute_process)
      message(FATAL_ERROR "This command cannot be executed in Download Mode.\nHalting portfile execution.\n")
    endmacro()
  else()
    macro(execute_process)
      _execute_process(${ARGV})
    endmacro()
  endif()
endif()