cmd/go: confusing error on mod edit -replace=old=.. #30514
Description
What version of Go are you using (go version)?
go version devel +44d3bb998c Fri Mar 1 07:45:00 2019 +0000 linux/amd64
Does this issue reproduce with the latest release?
Yes.
What did you do?
$ mkdir test
$ cd test
$ go mod init test
go: creating new go.mod: module test
$ go mod edit -replace=foo.com/bar=..
go mod: -replace=foo.com/bar=..: invalid new path: malformed module path "..": double dot
$ go mod edit -replace=foo.com/bar=../
$ cat go.mod
module test
go 1.13
replace foo.com/bar => ../
What did you expect to see?
Replacing a module to .. would either succeed or give a useful error.
What did you see instead?
An error saying "double dot", which makes no sense to me as a user. It was @myitcv who pointed out that adding a trailing slash would fix the problem.
From go help go mod:
If the @v in new@v is omitted, the new path hould be a local module root directory, not a module path.
So nothing in the error nor the docs seemed to point me at the missing slash.
/cc @bcmills