bug#55097: 29.0.50; flymake-show-buffer-diagnostics does not enable flymake-mode

bug#55097: 29.0.50; flymake-show-buffer-diagnostics does not enable flymake-mode

[No Wayman]

flymake-show-buffer-diagnostics will display an empty diagnostics 
buffer if flymake-mode is not enabled in that buffer. This is 
confusing, as it makes it appear as if there are no issues, when 
that may not be the case.
The command should either signal a user-error or (IMO better) 
enable flymake mode in the buffer if it is not already enabled.

In GNU Emacs 29.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 
3.24.33, cairo version 1.17.6)
 of 2022-04-20 built on arch
Repository revision: f98c3f4426fecf794f47f27aebe1f3b854fb1bfd
Repository branch: master
System Description: Arch Linux

bug#55097: 29.0.50; flymake-show-buffer-diagnostics does not enable flymake-mode

[Lars Ingebrigtsen]

No Wayman <iarchivedmywholelife@gmail.com> writes:

> flymake-show-buffer-diagnostics will display an empty diagnostics
> buffer if flymake-mode is not enabled in that buffer. This is
> confusing, as it makes it appear as if there are no issues, when that
> may not be the case.
> The command should either signal a user-error or (IMO better) enable
> flymake mode in the buffer if it is not already enabled.

Commands tied to certain modes aren't supposed to be used outside of
those modes, and will usually give nonsensical results if you do that.
So this is one of those "well, don't do that, then" situations.

But on the other hand, I can see that this is a command that people
might be calling spuriously, so I've made it error out in these
situations.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no