Composer does not properly determine version of mercurial

[exteon]

When compiling mercurial from, say, https://www.mercurial-scm.org/repo/hg/archive/stable.tar.gz :

hg --version
Mercurial Distributed SCM (version 6.2+hg7.4a1f0bc0713e)

\Composer\Util\Hg::getVersion doesn't parse that, resulting in

[RuntimeException]                                       
  hg was not found in your PATH, skipping source download 

I don't know what the check is for anyway, the actual version doesn't seem used further... I would remove the check altogether, or usehg --version -q and update the parsing to allow for 6.2+.

I would also add a mechanism to specify hg, git etc. path, but especially hg because a lot of people use chg ( see https://www.mercurial-scm.org/wiki/CHg ) and alias hg=chg doesn't seem to work with symfony process.

[stof]

and alias hg=chg doesn't seem to work with symfony process.

bash aliases indeed don't work when launching a subprocess, because bash is not involved to process the command. However, if you create hg executable in your PATH that is a symlink to chg, this would work (for any tool relying on the PATH).

Regarding the version parsing, it indeed seems to missed support non-tag versions.

[exteon]

bash aliases indeed don't work when launching a subprocess

Yes, sometimes process helpers do sh -c command to get around this... I personally don't find it a good idea, and anyway, this is beyond the point.

A way to specify the hg path via env or config variables seems more than welcome though. I see in Fedora 36, it seems we have mercurial and mercurial-chg packages... chg needs the path to hg... While it can be compiled with an absolute path to /usr/local/bin/hg, I don't think it is (too lazy to check right now), so it might go into a self-loop trying to call the original hg.

I don't use the official repos and routinely compile from the stable branch with rust, so I did a mv hg hg_slow && mv chg hg (and compiled chg with the path to hg_slow) to get around hardcoded hg calls.

[Seldaek]

Fixed the version parsing as that's an easy one and definitely a bug. Allowing customizing path though is more work and frankly I am not sure it's needed/worth it. The PATH is how this should work.

Adding support for chg might be a thing.. but that also sounds like more work I'd like to do on this given 99% of Composer users are using git.