check package existence with govendor if installed

[genzj]

also take the vendor dir into consider at command completing

try to fix #1709

[bhcleek]

The problem this PR attempts to solve is not specific to govendor. The right solution to the problem is to parse the output of go list correctly.

From https://golang.org/cmd/go/#hdr-Vendor_Directories:

Packages stored in vendor directories report an ImportPath that includes the path to the vendor directory (for example, "d/vendor/p" instead of "p"), so that the ImportPath uniquely identifies a given copy of a package. The Imports, Deps, TestImports, and XTestImports lists also contain these expanded imports paths. See golang.org/s/go15vendor for more about vendoring.

[genzj]

@bhcleek but the output of go list some/dep/package doesn't return a line. do you mean the call should be go list proj/vendor/some/dep/package instead?

[bhcleek]

To find a package that's only in a vendor directory, the vendor directories in each of the parent directories would need to be searched. govendor isn't needed to do that.

[genzj]

@bhcleek I understood the govender isn't needed for that, I think you made the point really clear. I just want to know the preferred methodology so that I may be able to help. By

the vendor directories in each of the parent directories would need to be searched

do you mean searching by go list with specific arguments/options, by other go xxx commands or by walking/globing in different directories with vimscript?

I don't mean any step-by-step solution. just let me know the preferred or ideal way. I will do further research and test.

you may have noticed i sent same pr years ago, but no more feedback due to busy project schedule that makes it impossible to digging on this problem so we continued the go vendor way. Since it can lock the dependency versions and isolate different projects, glide/go vendor mean a lot to me. I believe so as to many gophers. So I hope I can make even a small contribution to this issue, not only a private workaround patch.

thanks a lot.

[bhcleek]

Assuming the current file is within GOPATH, I think the right solution would be to walk the directories up to the src that's in GOPATH, looking for vendor directory. For each vendor directory, if go list $relative_dir_path/vendor/$pkg returns 0, then the package exists.

[genzj]

@bhcleek good one! thanks! I'll try that.

[bhcleek]

Closing due to inactivity.