cmd/dist: set GOPROXY=off when GOPATH is set to be in GOROOT

Avoid downloading modules into a modcache in the GOROOT directory. That
creates read only files in GOROOT, which is undesirable.

Fixes #67463

Change-Id: I6d10c605be5eba967648d823ee8fc915716b4b5b
Reviewed-on: https://go-review.googlesource.com/c/go/+/586078
Reviewed-by: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

diff --git a/src/cmd/dist/build.go b/src/cmd/dist/build.go
index 99f517e7588c79b3569b3064788317c74608f703..c033beabdbb37470c97ee38ab82ceff48331392b 100644 (file)
--- a/src/cmd/dist/build.go
+++ b/src/cmd/dist/build.go
@@ -1394,6 +1394,12 @@ func cmdbootstrap() {
        // go tool may complain.
        os.Setenv("GOPATH", pathf("%s/pkg/obj/gopath", goroot))
 
+       // Set GOPROXY=off to avoid downloading modules to the modcache in
+       // the GOPATH set above to be inside GOROOT. The modcache is read
+       // only so if we downloaded to the modcache, we'd create readonly
+       // files in GOROOT, which is undesirable. See #67463)
+       os.Setenv("GOPROXY", "off")
+
        // Use a build cache separate from the default user one.
        // Also one that will be wiped out during startup, so that
        // make.bash really does start from a clean slate.