bug#63235: 29.0.90; makefile-mode does not recognize Plan 9's mk, mkfile

[Po Lu via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Van Ly <van.ly@sdf.org> writes:

> The makefile-mode is not general enough to make use of Plan 9's user
> space mkfile format and mk command.
>
> This is likely to be considered not a bug.  The expected behavior is
> Emacs would be smart with Plan 9's user space tools.  Specifically,
> the mk command and mkfile format in this case.
>
> The unexpected behavior attempts to compile using the make command and
> not the mk command.  I tried to locate a PLAN9Makefile-mode but didn't
> find one in the command completion mechanism.
>
> steps to reproduce
>  - set PLAN9 and PATH environment variables in shell
>  - verify, mk all, works at the plain shell
>  - start, emacs -Q
>  - visit /tmp/mkfile; makefile-mode does not recognize mkfile
>  - M-x makefile-mode
>  - M-x compile RET; Compile command: make -k, should adapt to mk command
>
> quote
> # example /tmp/mkfile
> all:V:
>   echo This line is left blank intentionally.
>   
> quote ends

The way I understand it, mk is not a variant of Make, and is certainly
not close enough to be supported by Makefile mode.  For starters,
commands are not indented with tabs, but with spaces.

Besides, who uses it in the real world?