From 44f961975dac6cf464a77b5f6dd0c47cc192c4fd Mon Sep 17 00:00:00 2001
From: Matt Madison <matt@madison.systems>
Date: Wed, 13 Sep 2017 08:19:52 -0700
Subject: [PATCH 5/7] cmd/go: make GOROOT precious by default

For OE builds, we never want packages that have
already been installed into the build root to be
modified, so prevent the go build tool from checking
if they should be rebuilt.

Also add an environment variable to override this
behavior, just for building the Go runtime.

Upstream-Status: Pending

Signed-off-by: Matt Madison <matt@madison.systems>
---
 src/cmd/go/internal/load/pkg.go | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index 60de666..2660d3f 100644
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -1530,6 +1530,13 @@ func isStale(p *Package) (bool, string) {
 		return true, "build ID mismatch"
 	}
 
+	// For OE builds, make anything in GOROOT non-stale,
+	// to prevent a package build from overwriting the
+	// build root.
+	if p.Goroot && os.Getenv("GOROOT_OVERRIDE") != "1" {
+		return false, "GOROOT-resident packages do not get rebuilt"
+	}
+
 	// Package is stale if a dependency is.
 	for _, p1 := range p.Internal.Deps {
 		if p1.Stale {
-- 
2.7.4