option to auto-choose serial port if only one matches a known USB device

[jneem]

Because I often have a few USB-serial devices connected, my esp device gets a path like /dev/ttyACMn but the n is unpredictable. This prevents me from using the serial option in my espflash.toml file, and the presence of multiple serial ports also prevents cargo espflash from auto-connecting to one. But I usually connect only a single esp device, and so cargo espflash always highlights a single "known common dev board", and it's always the one I want.

Would you accept a PR to add an option (either a CLI flag or something in the config file) to say that if there's a single known dev board then auto-connect to it?

[jessebraham]

Sorry for taking so long to get to this, thanks for opening this issue.

I would be happy to accept a PR for this functionality, I think it makes sense from a UX perspective. I'm not entirely sure how to go about doing this, maybe if there's only a single recommended device we can just select it regardless, no setting/flag required. I'm not really sure if there are any downsides to this, I'll have to think about it a bit I suppose. If you have any further input on this I'd be glad to hear it!

[jneem]

Yeah, I don't have a real motivation for making it a flag; I mainly just suggested it to be conservative. I'll put up a PR that enables the auto-selection with no flag, but if you decide you'd rather go with one I'd be happy to change it.

I think the only downside of having a flag is increased complexity. As far as UX goes, I was just planning to add runner = "espflash --monitor --enable-auto-whatever" to my .cargo/config.toml, so I'll never have to type out that flag anyway 🤷