Unbuildable: github.com/klauspost/pgzip

[simulance]

Attempt 1: on darwin_arm64

$ plz build ///third_party/go/github.com_klauspost_pgzip//:pgzip
Build stopped after 8.29s. 1 target failed:
    ///third_party/go/github.com_klauspost_pgzip//:pgzip
Error building target ///third_party/go/github.com_klauspost_pgzip//:pgzip: exit status 1
pkg/darwin_amd64/github.com/klauspost/pgzip/gunzip.go, line 26, column 2: could not import github.com/klauspost/compress/flate (open : no such file or directory)
$ 

Attempt 2: on darwin_arm64 cross-compiling to linux_amd64

$ plz build ///third_party/go/github.com_klauspost_pgzip//:pgzip -a linux_amd64
Build stopped after 40ms. 1 target failed:
    ///third_party/go/github.com_klauspost_pgzip_linux_amd64//:pgzip
Subrepo third_party/go/github.com_klauspost_pgzip_linux_amd64 is not defined (referenced by command-line targets)
$ 

Attempt 3: on linux_amd64

$ plz build ///third_party/go/github.com_klauspost_pgzip//:pgzip
Build stopped after 23.32s. 1 target failed:
    ///third_party/go/github.com_klauspost_pgzip//:pgzip
Error building target ///third_party/go/github.com_klauspost_pgzip//:pgzip: exit status 1
pkg/linux_amd64/github.com/klauspost/pgzip/gunzip.go, line 26, column 2: could not import github.com/klauspost/compress/flate (open : no such file or directory)
$ 

The standard go command builds it fine but there appears to be no way of building it using Please 17.3.0.

Repro script

``` plz init mkdir plugins cat > plugins/BUILD << EOF plugin_repo( name = "go", revision="v1.8.1", ) EOF cat >> .plzconfig << EOF [Plugin "go"] Target = //plugins:go GoTool = //third_party/go:toolchain|go EOF mkdir -p third_party/go cat > third_party/go/BUILD << EOF subinclude('///go//build_defs:go') go_toolchain(name='toolchain', version='1.20.7') go_repo(module="github.com/klauspost/compress", version="v1.16.7") go_repo(module="github.com/klauspost/pgzip", version="v1.2.6") EOF plz build ///third_party/go/github.com_klauspost_pgzip//:pgzip plz build ///third_party/go/github.com_klauspost_pgzip//:pgzip -a linux_amd64 ```

[peterebden]

This appears to be because github.com/klauspost/pgzip doesn't have a go.mod file so we don't attach dependencies properly.

I suppose it needs to try to figure out that it should be doing that from the source, which I think might be tricky to fully generalise (the module location isn't extant in the import path). Alternatively maybe we allow a deps argument on go_repo to let the user hint this where necessary.

[peterebden]

Ah ok we already have that, it's requirements. The following works:

go_repo(
    module = "github.com/klauspost/compress",
    version = "v1.16.7",
)

go_repo(
    module="github.com/klauspost/pgzip",
    version="v1.2.6",
    requirements = ["github.com/klauspost/compress"],
)

$ plz build ///third_party/go/github.com_klauspost_pgzip//:pgzip
Build finished; total time 11.95s, incrementality 62.5%. Outputs:
///third_party/go/github.com_klauspost_pgzip//:pgzip:
  plz-out/gen/third_party/go/github.com_klauspost_pgzip/pgzip.a

I don't think that fixes the cross-compile issue which seems more generic... We've talked a few times about revisiting how architectures work in the face of things like go_repo that extensively use subrepos.