Dep: panic: Should never need to recheck imports/constraints from root during solve

[F21]

What version of dep are you using (dep version)?

1963157

What dep command did you run?

I have a library (github.com/F21/some-lib) in my GOPATH. I then accidentally ran dep inside the project importing itself.

$ dep ensure -v -add github.com/F21/some-lib
Root project is "github.com/F21/some-lib"
 1 transitively valid internal packages
 8 external packages imported from 8 projects
(0)   ✓ select (root)
(1)     ? revisit github.com/F21/some-lib to add 1 pkgs
panic: Should never need to recheck imports/constraints from root during solve

goroutine 1 [running]:
github.com/golang/dep/internal/gps.(*solver).getImportsAndConstraintsOf(0xc042398600, 0xc0421d6060, 0x21, 0x0, 0x0, 0xb13a00, 0xb67000, 0xc04228a200, 0x1, 0x1, ...)
        D:/work/src/github.com/golang/dep/internal/gps/solver.go:617 +0xeb6
github.com/golang/dep/internal/gps.(*solver).check(0xc042398600, 0xc0421d6060, 0x21, 0x0, 0x0, 0xb13a00, 0xb67000, 0xc04228a200, 0x1, 0x1, ...)
        D:/work/src/github.com/golang/dep/internal/gps/satisfy.go:43 +0x1f7
github.com/golang/dep/internal/gps.(*solver).solve(0xc042398600, 0x0, 0x0, 0xc042381ad0)
        D:/work/src/github.com/golang/dep/internal/gps/solver.go:540 +0x33a
github.com/golang/dep/internal/gps.(*solver).Solve(0xc042398600, 0x38, 0xb0f040, 0xb667d0, 0xc04216e330)
        D:/work/src/github.com/golang/dep/internal/gps/solver.go:442 +0xb1
main.(*ensureCommand).runAdd(0xc0420e95e0, 0xc04208ee60, 0xc042072040, 0x1, 0x4, 0xc04203b440, 0xb13f80, 0xc0422d01e0, 0xc04215c040, 0x38, ...)
        D:/work/src/github.com/golang/dep/cmd/dep/ensure.go:597 +0x15f3
main.(*ensureCommand).Run(0xc0420e95e0, 0xc04208ee60, 0xc042072040, 0x1, 0x4, 0x0, 0x0)
        D:/work/src/github.com/golang/dep/cmd/dep/ensure.go:186 +0x56b
main.(*Config).Run(0xc04203ef00, 0xc04203ef00)
        D:/work/src/github.com/golang/dep/cmd/dep/main.go:159 +0x7a9
main.main()
        D:/work/src/github.com/golang/dep/cmd/dep/main.go:45 +0x203

What did you expect to see?

Maybe there should be a nicer error message rather than a panic?

What did you see instead?

There was a panic

[sdboyer]

OH, hah! yeah, this should be a simple case to guard against. just need to reject arguments to dep ensure -add that come back to the same project as we're currently in. i...guess? hmm. it's actually kinda weird we can get here at all.

well, this'll take a little tracing to see how we reach this path, but the fix should be pretty straightforward.

[sdboyer]

this'd be a really good first PR - if someone's interested, drop a note, and i'll provide more guidance.

[vedhavyas]

@sdboyer I can take it up

[sdboyer]

@vedhavyas woot!

so basically, i think this _should_ just amount to one more check in this loop, comparing the parsed root to the current project's root and failing out if they're the same.

we'll want to add another harness test to capture this specifically, too. there's a README on how to write those in general, and then lots of examples to work from. though this case may be a bit tricky, as i can't recall what the root of the project in the harness tests actually ends up being - we might have it hardcoded to github.com/golang/notexist.