Fix Issue 17090 - dmd -transition=? needs quoting => make it -transition=help

[wilzbach]

There's still a lot more that could be done:

• create usage pages for other switches
• Trigger a message like "See -transition=help for an overview of all valid options" if an incorrect option has been provided
• ...

but this is a small start. I changed the ? as default in the docs as its very problematic in most shells. I added a test to ensure that it will continue to be accepted though.

[dlang-bot]

Thanks for your pull request, @wilzbach!

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	17090	normal	dmd -transition=? needs quoting => make it -transition=help
✓	19552	enhancement	-transition is non-intuitive to use - the flag should list options by default

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub fetch digger
dub run digger -- build "master + dmd#9205"

[PetarKirov]

I think part of the reason for the =? syntax comes from the long tradition of using /? as the help switch in dos and later windows cli programs. As far as I know =? should work in command prompt and powershell and it works in bash, but not in my fish shell. =help should everywhere, so I'm fine with changing it. Let's wait to see what other think.

[PetarKirov]

On second thought, with this function I'm all in.

[WalterBright]

Yeah, just accept all three. I know I try them in sequence (for random utilities) until one of them works.

[WalterBright]

Why not [?|h|help] ?

[PetarKirov]

Perhaps because ? needs to be quoted on some shells, but some users won't immediately figure out that they need to use -mcpu='?'. So instead, the suggestion would become ['?'|h|help].

[wilzbach]

Because I wanted to phase out ? as it's problematic on many shells. Anyhow I now changed it to: mcpu=h|help|?, s.t. it's still mentioned but not as first choice.