cmd/go: actually allow "go run" without any arguments nor flags

[mvdan]

#22726 was accepted and implemented a while ago. I'm really happy with it, because go run . is pretty useful.

I also understand the point that @rsc brought up about ambiguous flags. Not accepting go run -foo is reasonable, instead forcing the user to write go run -foo . or go run . -foo to clarify if the flag is for the Go tool or for the main package.

However, I don't quite undrestand why go run without any flags or arguments was left out:

$ go run
go run: no go files listed

The only reason I can think of is consistency, to make go run always require file or package arguments. Still, I'd argue that this form alone should be allowed. It's pretty convenient, and we could simply point the user in the right direction if they try to add a flag alone:

$ go run -foo
go run: specify a package or list of Go files to use flags

This would also actually mark the original proposal as implemented. I was pretty confused that the original proposal was accepted and closed, while the very idea in the title was never implemented.

At the very least, if this proposal is rejected, I think the original proposal should be retitled.

/cc @myitcv @rogpeppe @broady @rsc

[mvdan]

This got pretty much all positive feedback and no complaints, so we agreed with @bcmills to just move it to a regular issue to be fixed.

[gopherbot]

Change https://golang.org/cl/342389 mentions this issue: cmd/go: allow go run without arguments

[rsc]

Please don't do this. It seems like a good idea, and then the very next thing someone wants to do is pass a single argument, whether a flag or not, and it all breaks.

[rsc]

If go run . is not discoverable enough, it would be fine to change the message

go run: no go files listed (use 'go run .' for current package)

[mvdan]

That's fair. It's been some time since I filed this, and I feel less strongly about it now. We now also have go run pkg@version, so I think it's going to be expected that one always gives arguments to go run.

At the very least, if this proposal is rejected, I think the original proposal should be retitled.

I think we should still do this, though. We have an accepted and closed proposal titled proposal: cmd/go: allow "go run" without arguments, which is clearly not the current state of affairs.

[seankhliao]

I've retitled the other issue, closing this one as we're not doing it