I cannot type left open bracket into buffer

Question

I have a very weird problem, I cannot type left open bracket character ([) into any buffer. Bracket itself is recognized when I:

• type anywhere outside emacs
• type in minibuffer
• use it as part of command ([[ in evil normal state or C-c [ in reftex work as expected)
• launch emacs -Q, then it works in buffers

After typing [ it looks like this:

When I try to describe [ with C-h k, it's treated as prefix, not as all the other chars (which do self-insert-command).

I can't manually bind inserting [ to [, it's not recognized. My current workaround is like this:

(global-set-key (kbd "M-[") (kbd "C-x 8 RET L S B R RET")) This interactively selects "LEFT SQUARE BRACKET" in C-x 8 RET (insert char) command in my ivy-flx, but it's slower and annoying.

I'm not on macbook, as they seem to have related problems (https://stackoverflow.com/questions/3376863/unable-to-type-braces-and-square-braces-in-emacs), I'm on Arch Linux, with emacs 25.2.1.

After turning evil-mode off the problem persists, so I guess that's not that.

My config is here: https://pastebin.com/8FLSkbAA.

Any feedback really appreciated!

Answer 1

EDIT and final answer: Okay, so thanks to the @npostavs (can't thank you enough :D) I can finally tell the real problem was me not understanding the use-package binding syntax, we can have either

• ("C-c x" . some-fun) "string syntax" or
• ([tab] . some-fun) "vector syntax" (mainly for special characters)

Syntax is based on this part of manual.

I was mixing both and in the process use-package interpreted my shortcut "[backtab]" as literal sequence of 9 characters [ b a c k t a b ], which was quite far from what I was trying to do :D.

As a bonus, working code (can be launched in emacs -Q and M-x eval-buffer to properly rebind yasnippet tab and shift tab using use-package.

(package-initialize)
(require 'use-package)
(require 'bind-key)
(use-package yasnippet
  :bind
  (:map yas-minor-mode-map
    ([tab] . nil)
    ([?\t] . nil)
    ([(shift tab)] . nil)
    ([backtab] . nil)
    ("C-c r" . yas-prev-field)
    ("C-c t" . yas-next-field-or-maybe-expand)
    :map yas-keymap
    ([tab] . nil)
    ([?\t] . nil)
    ([(shift tab)] . nil)
    ([backtab] . nil)
    ("C-c r" . yas-prev-field)
    ("C-c t" . yas-next-field-or-maybe-expand)))

(yas-minor-mode 1)

Initial post:

Okay, the reason was in yasnippet's interpretation of this part of my config:

(use-package yasnippet
  :diminish yas-minor-mode
  :bind
  (:map yas-minor-mode-map
  ("<tab>" . yas-expand)
  ("TAB" . yas-expand)
  ;; ("[(shift tab)]" . nil) ;; THIS made "[" act like prefix
  ;; ("[backtab]" . nil) ;; THIS made "[" act like prefix
  ("<S-iso-lefttab>" . yas-prev-field))
  :config
  (yas-global-mode 1))

My keyboard on Shift+Tab is understood by emacs as <S-iso-lefttab> (as described in this comment), so, according to yasnippet faq I tried to unbind other keys with notation they provided, but well, that bug was really unexpected. Maybe a bug with interaction with use-package's bind macro? I'll try to provide minimal config to reproduce it, and file an issue on yasnippet.

Huge thanks to @npostavs for suggestion that if [ acted as prefix, hitting [ <f1> allows to quickly find what follows after it, in my case: