cmd/go: build fails when %go_import is used in SWIG interfaces

[i96751414]

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

go version go1.13.5 linux/amd64

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

go env Output

GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/user/.cache/go-build"
GOENV="/home/user/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/user/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
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 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build083237116=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I have created an empty package and a SWIG interface for it containing only %go_import(_ "time").

What did you expect to see?

A successful build (by doing go build).

What did you see instead?

The build failed with the following error:
/tmp/go-build220377569/b001/_dummy_swig.go:40:8: can't find import: "time"

[i96751414]

Files to reproduce this issue: dummy_test.zip

I believe this can be explained by

go/src/cmd/go/internal/load/pkg.go

Line 1657 in 98d2717

// TODO: The .swig and .swigcxx files can use

A workaround for this is to add import _ "time" on the go file.

[bcmills]

If someone would like to do that TODO, please send a CL.

[bcmills]

If someone would like to do that TODO, please send a CL.