I'd like to assign [[ to leader[ and ]] to leader].
I've tried the obvious:
let mapleader=" " nnoremap <leader>[ [[ nnoremap <leader>] ]]
but the former mapping doesn't work.
I've tried with just those lines in _vimrc, and can reproduce this on both Vim8 on windows and Neovim (reasonably recent build from source) on RHEL.
Note: The obvious duplicate question doesn't apply to this one because I have no problem when not using the leader key.