Add progress bar for go get command

[rishiloyola]

It would be good to have a bar on terminal showing progress of package downloading process.

[ALTree]

#17959 was about adding some kind of feedback/output (possibly a progress bar) to go get. It was rejected. Note that you can use -v to make get a little more verbose.

[bradfitz]

Yeah, dup of #17959

I personally think it would be okay to play terminal-detection games and only do a curses progress UI if the terminal supports such things, but the Go tools are pretty opinionated against terminals, ASCII art, and color, so I don't see this happening.

I recommend somebody prototype this first as an external tool (you could run go get -v as a child process and parse its output for the prototype?), and get a demo ready. If the demo is convincing and people like it, I'd support it, but I don't think anybody on the Go team has time to work on this itself.

I'd say come back with code, with the understanding that it might be fated to live out of tree.

[rishiloyola]

@bradfitz I guess we don't need any kind of fancy stuff. It will be just simple bar.
Let me implement it.

[bradfitz]

Prototype away.

[minux]

One simple solution is to (buffer and) show the underlying VCS command output if the commands executes longer than, say, a few seconds? Of course, we need to persuade the VCS command to always generate progress output even when its stdout is a pipe. But I think that's certainly doable.