Can't exit buffer using leader mapping - 'cannot make changes'

Question

I have a leader key set up, and a mapping that allows me to exit windows without typing ::

let mapleader = 'f'
map <leader>q = :q<CR>

Today I installed MattesGroeger/vim-bookmarks using Vundle, and everything went fine. However when I view the annotations list using ma, and then I try to exit it using fq, vim spits out this error phrase:

E21: Cannot make changes, 'modifiable' is off

But I can exit it just fine if I manually type out :q

The other answers I've seen so far regarding the modifiable/nonmodifiable attributes of buffers imply that a solution is to set the buffer as modifiable, however that seems like a hack. It looks like map and friends are restricted in use in buffers without modifiable set, so is there a specific kind of map that will allow me to use this mapping across all buffers?

Answer 1

The problem is with the = in your command. It's being taken as part of the expansion for the mapping.

That's triggering the = command, which typically reformats a block of code. Since you have a space after the =, that's being swallowed as the "motion" for = (which is roughly equivalent to the motion of going right one character.)

I guess this reformatting wasn't doing anything on your regular buffers, so it wasn't leaving your buffer in a modified state, which would have interfered with the second part of the command.

But with a read-only buffer, that's likely to be a problem, since the command will fail early, in the way you experienced.

To fix it:

map <leader>q :q<CR>

But you might also want to make this mapping non-recursive (usually a best practice) and probably only allow it in normal mode (and not visual or select modes):

nnoremap <leader>q :q<CR>