From 6bdd6405ce63c7aa4b35cd85833d03c7f1b9109a Mon Sep 17 00:00:00 2001
From: Richard Purdie <richard.purdie@linuxfoundation.org>
Date: Sat, 2 Jul 2022 23:08:13 +0100
Subject: [PATCH] go: Filter build paths on staticly linked arches

Filter out build time paths from ldflags and other flags variables when they're
embedded in the go binary so that builds are reproducible regardless of build
location. This codepath is hit for statically linked go binaries such as those
on mips/ppc.

Upstream-Status: Submitted [https://github.com/golang/go/pull/56410]

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Jose Quaresma <jose.quaresma@foundries.io>
---
 src/cmd/go/internal/load/pkg.go | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index 1549800..f41fb2c 100644
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -2277,6 +2277,17 @@ func appendBuildSetting(info *debug.BuildInfo, key, value string) {
 	info.Settings = append(info.Settings, debug.BuildSetting{Key: key, Value: value})
 }
 
+func filterCompilerFlags(flags string) string {
+	var newflags []string
+	for _, flag := range strings.Fields(flags) {
+		if strings.HasPrefix(flag, "--sysroot") || strings.HasPrefix(flag, "-fmacro-prefix-map") || strings.HasPrefix(flag, "-fdebug-prefix-map") {
+			continue
+		}
+		newflags = append(newflags, flag)
+	}
+	return strings.Join(newflags, " ")
+}
+
 // setBuildInfo gathers build information and sets it into
 // p.Internal.BuildInfo, which will later be formatted as a string and embedded
 // in the binary. setBuildInfo should only be called on a main package with no
@@ -2384,7 +2395,7 @@ func (p *Package) setBuildInfo(ctx context.Context, autoVCS bool) {
 	if gcflags := BuildGcflags.String(); gcflags != "" && cfg.BuildContext.Compiler == "gc" {
 		appendSetting("-gcflags", gcflags)
 	}
-	if ldflags := BuildLdflags.String(); ldflags != "" {
+	if ldflags := filterCompilerFlags(BuildLdflags.String()); ldflags != "" {
 		// https://go.dev/issue/52372: only include ldflags if -trimpath is not set,
 		// since it can include system paths through various linker flags (notably
 		// -extar, -extld, and -extldflags).
@@ -2427,7 +2438,7 @@ func (p *Package) setBuildInfo(ctx context.Context, autoVCS bool) {
 	// subset of flags that are known not to be paths?
 	if cfg.BuildContext.CgoEnabled && !cfg.BuildTrimpath {
 		for _, name := range []string{"CGO_CFLAGS", "CGO_CPPFLAGS", "CGO_CXXFLAGS", "CGO_LDFLAGS"} {
-			appendSetting(name, cfg.Getenv(name))
+			appendSetting(name, filterCompilerFlags(cfg.Getenv(name)))
 		}
 	}
 	appendSetting("GOARCH", cfg.BuildContext.GOARCH)
