go/build: Default.Import fails for standard-library packages when built with -trimpath #51483
Description
What version of Go are you using (go version)?
$ go version go version devel go1.19-81767e23c Fri Mar 4 01:18:57 2022 +0000 linux/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="/usr/local/google/home/bcmills/.cache/go-build" GOENV="/usr/local/google/home/bcmills/.config/go/env" GOEXE="" GOEXPERIMENT="" GOFLAGS="" GOHOSTARCH="amd64" GOHOSTOS="linux" GOINSECURE="" GOMODCACHE="/tmp/tmp.LHtt2MlVH3/.gopath/pkg/mod" GONOPROXY="" GONOSUMDB="" GOOS="linux" GOPATH="/tmp/tmp.LHtt2MlVH3/.gopath" GOPRIVATE="" GOPROXY="https://proxy.golang.org,direct" GOROOT="/usr/local/google/home/bcmills/sdk/gotip" GOSUMDB="sum.golang.org" GOTMPDIR="" GOTOOLDIR="/usr/local/google/home/bcmills/sdk/gotip/pkg/tool/linux_amd64" GOVCS="" GOVERSION="devel go1.19-81767e23c Fri Mar 4 01:18:57 2022 +0000" GCCGO="/usr/local/google/home/bcmills/bin/gccgo" GOAMD64="v1" AR="ar" CC="gcc" CXX="c++" CGO_ENABLED="1" GOMOD="/tmp/tmp.LHtt2MlVH3/go.mod" 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 -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build2171881965=/tmp/go-build -gno-record-gcc-switches"
What did you do?
Execute go run for the following program, with or without -trimpath.
-- go.mod --
module example
go 1.19
-- main.go --
package main
import (
"go/build"
"log"
"os"
)
func main() {
p, err := build.Default.Import("runtime", "", build.FindOnly)
if err != nil {
log.Fatal(err)
}
os.Stdout.WriteString(p.Dir)
}
What did you expect to see?
Successful output in both cases: go/build already falls back to go list in some cases, and go list knows where to find its own GOROOT.
What did you see instead?
$ go run .
/usr/local/google/home/bcmills/sdk/gotip/src/runtime
$ go run -trimpath .
2022/03/04 13:01:41 go/build: go list runtime: exit status 2
go: cannot find GOROOT directory: go
exit status 1