I've remapped <cr> (enter) to za so I can quickly open/close folds.
However, now when I use the quickfix window and hit enter it no longer jumps to the line with the error (because it's trying to open/close a fold that does not exist in the quick fix window).
Is there a way to disable my mapping or re-set it locally when entering a quickfix window?
Using an expression mapping is the easiest way to do this:
nnoremap <expr> <CR> &buftype ==# 'quickfix' ? "\<CR>" : 'za'
This defines a mapping that checks whether you are in the quickfix window, and then performs either a <CR> or za accordingly.
See:
:h :map-expr:h 'buftype':h expr1:h stringYou can also define a function that carries out a regular enter when invoked from the quickfix window, and does 'za' otherwise. This isn't efficient for what you're trying to do, but I'm leaving it here because it's useful info for if you want to map to something more complicated than a normal mode command:
function! FoldingEnter()
if &buftype ==# 'quickfix'
execute "normal! \<CR>"
else
normal! za
endif
endfunction
nnoremap <CR> :call FoldingEnter()<CR>
<C-V><C-M> to enter the carriage return literally, but that displays as ^M and can't be easily copy/pasted outside of Vim, or we can use Vim's string constant notation. (See :help expr-string.) If we didn't include the backslash in "<CR>" then the string would instead contain the series of four characters: less-than, uppercase C, uppercase R, greater-than.
:help expr-string is important.