Use pointers for CLI flags

[lion7]

urfave/cli v2 has an incompatible change, for details see https://github.com/urfave/cli/issues/459

[lion7]

Hmm, after opening this PR I discovered the existence of Go Modules and that you explicitly have to enable them (sorry, n00b Go user here).

Anyway, just installing the latest Go binary and running the go get github.com/whyrusleeping/gx command doesn't work. I first had to run set GO111MODULE=on (on Windows) or export GO111MODULE=on (on Linux). Maybe this should be added to the README instead of this PR? Or maybe complementary?

[Stebalien]

It should work with GO111MODULE=auto, which has been the default since go 1.13. Is that not the case?

[Stebalien]

Anyways, I'd actually be happy to upgrade to cli v2 (but the go.mod file needs to be updated as well).

[lion7]

I double checked the Go documentation and it does indeed state that auto should be the default for GO111MODULE. But apparently that doesn't work for me. Steps I took to install gx:

• Download and install the latest (1.14.1) Go binary for Windows (MSI) from https://golang.org/dl/
• Open up a cmd.exe
• Run go get github.com/whyrusleeping/gx
• See these errors:

  C:\Users\gerar>go get github.com/whyrusleeping/gx
  # github.com/whyrusleeping/gx
  go\src\github.com\whyrusleeping\gx\main.go:154:15: cannot use cli.BoolFlag literal (type cli.BoolFlag) as type cli.Flag in slice literal:
      cli.BoolFlag does not implement cli.Flag (Apply method has pointer receiver)
  go\src\github.com\whyrusleeping\gx\main.go:243:3: undefined: cli.BoolTFlag
  go\src\github.com\whyrusleeping\gx\main.go:247:15: cannot use cli.BoolFlag literal (type cli.BoolFlag) as type cli.Flag in slice literal:
      cli.BoolFlag does not implement cli.Flag (Apply method has pointer receiver)
  go\src\github.com\whyrusleeping\gx\main.go:327:3: undefined: cli.BoolTFlag
  go\src\github.com\whyrusleeping\gx\main.go:331:15: cannot use cli.BoolFlag literal (type cli.BoolFlag) as type cli.Flag in slice literal:
      cli.BoolFlag does not implement cli.Flag (Apply method has pointer receiver)
  go\src\github.com\whyrusleeping\gx\main.go:335:15: cannot use cli.BoolFlag literal (type cli.BoolFlag) as type cli.Flag in slice literal:
      cli.BoolFlag does not implement cli.Flag (Apply method has pointer receiver)
  go\src\github.com\whyrusleeping\gx\main.go:339:15: cannot use cli.BoolFlag literal (type cli.BoolFlag) as type cli.Flag in slice literal:
      cli.BoolFlag does not implement cli.Flag (Apply method has pointer receiver)
  go\src\github.com\whyrusleeping\gx\main.go:432:17: cannot use cli.StringFlag literal (type cli.StringFlag) as type cli.Flag in slice literal:
      cli.StringFlag does not implement cli.Flag (Apply method has pointer receiver)
  go\src\github.com\whyrusleeping\gx\main.go:465:17: cannot use cli.StringFlag literal (type cli.StringFlag) as type cli.Flag in slice literal:
      cli.StringFlag does not implement cli.Flag (Apply method has pointer receiver)
  go\src\github.com\whyrusleeping\gx\main.go:514:3: undefined: cli.BoolTFlag
  go\src\github.com\whyrusleeping\gx\main.go:514:3: too many errors

[lion7]

I tried to upgrade the CLI to v2, but ran into more and more issues. Let me try some more tomorrow.

Oh, and I also made the commit history a mess, so I'll probably squash them and do a force push somewhere. Or just a new PR if that doesn't work.

[Stebalien]

Can you double check go version?

[lion7]

Sure:

C:\Users\gerar>go version
go version go1.14.1 windows/amd64

[lion7]

Ok, I think I now properly upgraded the dependency and fixed all compile errors. Force pushing also worked so the commit log should be clean now.

@Stebalien Can you please do a thorough review? This is my first time ever doing something in Go 😉

[lion7]

Oh lol, you already reviewed while I was typing this 😆 Anyway, Travis CI still fails because the way short flags work have changed. Gonna fix that first.

[Stebalien]

Lol, we keep speaking past each other.

C:\Users\gerar>go version go version go1.14.1 windows/amd64

:man_shrugging:

[lion7]

Travis says OK :) BTW, the tests don't work locally on Windows. I think that's not really an issue, but just wanted to mention it.

[Stebalien]

BTW, the tests don't work locally on Windows. I think that's not really an issue, but just wanted to mention it.

That's not all that surprising.

[Stebalien]

If you want to try to fix the tests on windows, that would be awesome! But we've never bothered putting any work into them.

[lion7]

Haha, sure. If I get bored of sitting at home all day I might take a look at it 😉