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

[Alexander Shukaev]

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.