syntax: printer breaks certain arithmetic expressions

[musjj]

By default, shfmt removes brackets within parentheses, but this breaks certain kinds of expressions.

For example:

(( ! 0 )) && echo true || echo false # true

shfmt will format this into:

((!0)) && echo true || echo false # bash: !0: event not found

[mvdan]

Thanks for reporting - this does indeed look like a bug. Happy to review a PR, as this one shouldn't be hard to fix.

[kiyoon]

I realised in zsh, the expression like this would be treated as + operation and will make spaces in between, breaking the script.

if (($+commands[exa])); then

[mikeBashStuff]

((!0)) && echo true || echo false # bash: !0: event not found

I believe this is only true for interactive shells since this syntax triggers history expansion. It's perfectly fine to use it from within a script by the very default, unless you explicitly enable histexpand|history there as well (which I guess is a valid use-case, though I personally prefer to trace the entire thing rather then save a history of it).