Escape `^@` in a variable

Question

Goal: print git diffs of pwd in a popup

let diff = system('git diff')
call popup_create(diff, {})

Problem: It prints ^@(I've got to know that is newline chars):

diff --git a/.config/fish/config.fish b/.config/fish/config.fish^@deleted file mode 100644^@...(ellipsis)

How could I escape the newline chars in the variable diff?

I tried substitute and it does not work:

let diff = system('git diff')
let diff = substitute(diff, '^@', '\n', 'g')
call popup_create(diff, {})

Answer 1

I don't know if it's documented, but if I see ^@ in the output because of newlines, what I'd do is see if a list of strings is allowed instead, and if so, the split the string on newline and pass that list instead:

:call popup_create(split(diff, "\n"), {})

It seems popup_create() does support a list of strings, so I'd expect this to then show the output the way you expect to see it.