Via setting GOCACHEPROG to a binary which speaks JSON over stdin/stdout. For now, it requires GOEXPERIMENT=cacheprog. Fixes golang/go#59719 Change-Id: I824ff04d5ebdf0ba4d1b5bc2e9fbaee26d34c80f Reviewed-on: https://go-review.googlesource.com/c/go/+/486715 Reviewed-by: Bryan Mills <bcmills@google.com> Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Russ Cox <rsc@golang.org>