bug#25189: Use `current-global-map' in `comint-insert-input'

[Alexander Shukaev <emacs@Alexander.Shukaev.name>]

On 12/24/19 5:25 PM, Lars Ingebrigtsen wrote:
> Alexander Shukaev <emacs@Alexander.Shukaev.name> writes:
> 
>> On 7/27/19 1:29 PM, Lars Ingebrigtsen wrote:
>>> Alexander Shukaev <emacs@Alexander.Shukaev.name> writes:
>>>
>>>> I think according to Emacs documentation it's more correct to change the
>>>>
>>>> (lookup-key global-map (vector last-key))
>>>>
>>>> form to the
>>>>
>>>> (lookup-key (current-global-map) (vector last-key))
>>>>
>>>> form.
>>> (I'm going through older Emacs bug reports that have received no
>>> response.)
>>> Looking at the manual section in "Controlling Active Maps", there
>>> doesn't seem to be anything to discourage using `global-map' directly
>>> there.  I've grepped through the sources, though, and `global-map' is
>>> used all over the place (while `current-global-map' is used less).
>>> So this doesn't seem like something to be fixed, and I'm closing
>>> this
>>> bug report.
>>>
>>
>> I believe you want to read the docstring of `global-map' for that point.
> 
> It would help if you could point to where you think Emacs says this.
> 
> This is the doc string of global-map:
> 
> global-map is a variable defined in ‘subr.el’.
> Its value is shown below.
> 
>    This variable may be risky if used as a file-local variable.
>    Probably introduced at or before Emacs version 21.1.
> 
> Documentation:
> Default global keymap mapping Emacs keyboard input into commands.
> The value is a keymap that is usually (but not necessarily) Emacs’s
> global map.
> 
> 

In particular,

 > The value is a keymap that is usually (but not necessarily) Emacs’s
 > global map.

So it's not necessarily the current global keymap.  Hence, applying 
`define-key' (or any other mutating function to it), may not take any 
effect and do what is expected.  It is safer to always use 
`current-global-map'.  At least that is my understanding why there are 
special functions like `current-global-map' for accessing and 
`use-global-map' for assignment.