"could not load export data: no export data" in test-only packages

[bconway]

Summary:

I have some packages that contain only *_test.go files. When run with the release.2019.2 there are no issues:

$ staticcheck -checks all,-ST1000 -unused.whole-program ./...
$

Shortly after 2019.2 was branched, I noticed the following on master:

$ staticcheck -checks all,-ST1000 -unused.whole-program ./...
-: could not load export data: no export data for "github.com/x/y/z/app1/test" (compile)
-: could not load export data: no export data for "github.com/x/y/z/app2/test" (compile)
-: could not load export data: no export data for "github.com/x/y/z/app3/test" (compile)
$ echo ${?}
1
$

Please make sure to include the following information in your issue report:

• The output of 'staticcheck -version'

staticcheck (no version)

• The output of 'staticcheck -debug.version' (it is fine if this command fails)

staticcheck (no version)

Compiled with Go version: go1.13.4
Built without Go modules

• The output of 'go version'

go version go1.13.4 darwin/amd64

• The output of 'go env'

GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/bconway/Library/Caches/go-build"
GOENV="/Users/bconway/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/bconway/.go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/Users/bconway/homebrew/Cellar/go/1.13.4/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/Users/bconway/homebrew/Cellar/go/1.13.4/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/bconway/code/go/x/y/go.mod"
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/dg/vgb4f3j95md47ltbzf2s5z_80000gp/T/go-build226170866=/tmp/go-build -gno-record-gcc-switches -fno-common"

• Exactly which command you ran
  See above.

• Output of the command and what's wrong with the output
  See above.

• Where we can read the code you're running staticcheck on
  Currently private, but I'm optimistic this is trivial to reproduce.

[dominikh]

Thanks for filing the issue. This is the same as #646.

[bconway]

Curses, I tried searching a few ways. Thanks.