Re: TAP test breakage on MacOS X

On Wed, Oct 29, 2014 at 08:14:07PM -0400, Peter Eisentraut wrote:
> On 10/28/14 9:09 PM, Peter Eisentraut wrote:
> > I have looked into IPC::Cmd, but the documentation keeps telling me that
> > to do anything interesting I have to have IPC::Run anyway. I'll give it
> > a try, though.
>
> I tried this, but I'm not optimistic about it. While parts of IPC::Cmd
> are actually a bit nicer than IPC::Run, other parts are weird. For
> example, with most packages and functions in Perl that run a command,
> you can pass the command as a string or as a list (or array reference).
> The latter is preferred because it avoids issues with quoting, word
> splitting, spaces, etc. In IPC::Run, I can use the "run" function in
> the latter way, but I cannot use the "run_forked" function like that,
> and I need that one to get the exit code of a command. It's possible to
> work around that, but I'm getting the feeling that this is not very well
> designed.

Ick; I concur with your judgment on those aspects of the IPC::Cmd design.
Thanks for investigating. So, surviving options include:

1. Require IPC::Run.
2. Write our own run() that reports the raw exit code.
3. Distill the raw exit code from the IPC::Cmd::run() error string.
4. Pass IPC::Run::run_forked() a subroutine that execs an argument list.

Any others worth noting?

> Also, IPC::Cmd is a wrapper module, and it passes the hard work down to
> other modules, depending on what's available. I think that sounds like
> a portability problem waiting to happen.

Assuming test suite code doesn't modify $IPC::Cmd::USE_* variables, the two
relevant backends are IPC::Run on Windows and IPC::Open3 everywhere else.
That's not bad.