Can't hide quickfix before executing makeprg

Question

I'm trying to hide the quickfix window while building, so that it doesn't show outdated info.

I can, of course, execute :ccl at any time to close quickfix. Additionally, I've used autocmd to call a function BeforeQuickFix which is successfully executed when prior to the execution of makeprg:

"hide quickfix when re-compiling
function BeforeQuickFix()
    :ccl
    :echom "hello test"
endfunction

autocmd QuickFixCmdPre * :call BeforeQuickFix()

However, while I see "hello test" printed prior to the execution of makeprg, the quickfix window never closes.

I've also tried to clear its contents instead with :cexpr [], but puzzlingly that also has no effect:

"hide quickfix when re-compiling
function BeforeQuickFix()
    :noautocmd cexpr []
endfunction

autocmd QuickFixCmdPre * :call BeforeQuickFix()

I'm sure I can manually hack at makeprg to get it to do what I want, but there has to be a cleaner way than that, right?