Re: `gzip` dependency

[Phillip Lord]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>>> > The gzip thing is again your call (having gzip in the package is no
>>> > big deal, IMO).
>>> BTW, we don't really need a `gzip` executable as long as we have the
>>> `zlib-decompress-region` function, right?
>> Not necessarily, because Info files can be read outside Emacs.
>
> I don't think we should worry about that: those who want to read Info
> files with something else than Emacs may need to have `gzip` installed,
> and I think it's perfectly acceptable.
>
> My question was instead about whether or not Emacs does indeed make use
> of `zlib-decompress-region` when it tries to read a gzipped Info file,
> and whether the Windows build does always provide
> `zlib-decompress-region` or whether that function also requires an
> external dependency that may or may not be available (in which case
> it's no better than using the `gzip` executable in this respect).



zlib is not given as an explicit dependency of Emacs on Windows at the
moment, although perhaps it should be. However, it is included as a
transitive dependency.

If I gzip all the info files then do M-x info and look into a node, I
get an error with message "Unpression program `gzip' not found". If I
open a gzip node with find-file-literally then do eval
(zlib-decompress-region (point-min) (point-max)), I get the contents of
the info file.

Conclusions:

1) Emacs uses gzip to decompress but doesn't need to.

2) zlib should probably be added an explicit dependency regardless,
since it's a feature of Emacs that can be disabled.

Phil