bug#50244: 28.0.50; Support project-wide diagnostics reports in flymake.el

[Dmitry Gutov <dgutov@yandex.ru>]

On 14.09.2021 11:20, João Távora wrote:
>> Like mentioned previously, I think using project.el for this is
>> probably not ideal (rather, the diagnostic source can decide which
>> diagnostics belong to the current default-directory),
> Yes, it can, and it does (have you read the change?) In fact the
> diagnostic source knows nothing about projects.  But at a certain point,
> someone will have to know about "projects", because the request is not
> for "default-directory-wide diagnostics", it's for project-wide
> diagnostics.  I don't know what better library to use for segregating
> diagnostics into projects other than project.el: it works quite well, to
> be frank.

When I said "belong to default-directory", I didn't mean "reside 
inside". I meant "all diagnostics that, in the opinion of the 
diagnostics source, relate to the specified default-directory".

Basically all diagnostics belonging to the project which 
default-directory belongs to (with implicit assumption that 
default-directory can uniquely identify the project).

 > Indeed, I even thought that flymake-show-project-diagnostics could go
into the 'C-x p' map.  But users can do that easily if they want to, so
I won't argue for that now.

Uh, maybe. I was thinking we'd rather add a new keymap (in the spirit of 
Flycheck's 'C-c !') with Flymake-related commands. Then the "aggregated 
diagnostics" could be on its own button, or they could even be displayed 
by 'M-x flymake-show-diagnostics-buffer'.