x/vgo: go.mod files in subdirectories are ignored when building the whole directory

[blueimp]

What version of Go are you using (go version)?

go version go1.10 darwin/amd64 vgo:2018-02-20.1

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/blueimp/Library/Caches/go-build"
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/blueimp/Development/gocode"
GORACE=""
GOROOT="/usr/local/Cellar/go/1.10/libexec"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.10/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/pp/2fr7691n1j741m0xfz7pklx00000gn/T/go-build670014762=/tmp/go-build -gno-record-gcc-switches -fno-common"
VGOMODROOT=""

What did you do?

In a new directory, create a simple go file and a go.mod file and use vgo to build it:

mkdir main
cd main
nano main.go

package main // import "example.org/main"
func main(){}

touch go.mod
vgo build
cat go.mod

The output is as expected:

module "example.org/main"

Next, in a subdirectory add another vgo module and build it:

mkdir sub
cd sub
nano sub.go

package sub // import "example.org/main/sub"
import (
	"fmt"
	"rsc.io/quote"
)
func main() {
	fmt.Println(quote.Hello())
}

touch go.mod
vgo build
cat go.mod

The output is as expected:

module "example.org/main/sub"

require "rsc.io/quote" v1.5.2

Now back in the parent directory, execute vgo build ./... and retrieve the now unexpectedly changed contents of the go.mod file:

cd ..
vgo build ./...
cat go.mod

What did you expect to see?

module "example.org/main"

What did you see instead?

module "example.org/main"

require "rsc.io/quote" v1.5.2

[rsc]

Nice bug.

The problem is that each build always runs in the context of a single top-level repo. There's no direct connection between the parent dir and the sub dir (it's not like the parent dir mentions the sub dir in a replace directive or other connection).

At least for now I think the answer is that ./... should stop matching when it finds a directory containing a go.mod. That is, ./... can only match packages in the module where "." is, and sub would therefore be excluded.

[blueimp]

Thanks for the quick response!

I think ideally, running vgo build ./... would build all the modules in the directory, with automatic dependency resolution for each module separately.

But I'm also not 100% sure what users expect as outcome for building this way with multiple modules in the directory.

[freddy33]

Same need here on this repo: https://github.com/JFrogDev/gofrog
Like to have a go.mod for each folder creating 5 separate modules.

[tcolgate]

Same here, don't want deps for individual adapters to pollute the top level https://github.com/tcolgate/hugot. (will push go.mod attempt later today if I get a chance)

[gopherbot]

Change https://golang.org/cl/117257 mentions this issue: cmd/go/internal/vgo: do not scan submodules in file system scans

[gopherbot]

Change https://golang.org/cl/122397 mentions this issue: cmd/go/internal/search: ignore submodules in ./... patterns