cmd/go: "go mod download" doesn't fetch necessary modules in workspace mode

[h31]

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

$ go version
go version go1.18 darwin/amd64

Does this issue reproduce with the latest release?

Yes

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

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/artyom/Library/Caches/go-build"
GOENV="/Users/artyom/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/artyom/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/artyom/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/Cellar/go/1.18/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.18/libexec/pkg/tool/darwin_amd64"
GOVCS=""
GOVERSION="go1.18"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/dev/null"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch x86_64 -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/pr/5k6c2yx97cjb9t5fh0httxv80000gn/T/go-build740782791=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

• git clone https://github.com/sergunya/my_workspace; cd my_workspace/
• rm go.work.sum
• go clean -modcache
• cd cmd/my_app/
• go mod download
• go list -m -json all

What did you expect to see?

github.com/samber/lo@v1.3.2-0.20220305174447-4edabde35217 necessary to build my_app module is downloaded and has a "Dir" property in go list output.

What did you see instead?

There's no "Dir" property.

I tried to debug Go source code and found that checksumOk("") in src/cmd/go/internal/modload/build.go:275 returns false for github.com/samber/lo. Building my_app using go build adds the necessary checksum to go.work.sum and the issue disappears. It doesn't help to run go mod tidy or go work sync before go mod download.

[seankhliao]

cc @bcmills @matloob

[bcmills]

This may be a bad interaction with #44435.