From: Robert Griesemer <gri@golang.org>
Date: Tue, 26 Apr 2016 22:18:48 +0000 (-0700)
Subject: cmd/dist: sort entries in zcgo.go generated file for deterministic build
X-Git-Tag: go1.7beta1~480
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=19912e1d0a0739cd8a3214de994f7e9ecb656e1d;p=gostls13.git

cmd/dist: sort entries in zcgo.go generated file for deterministic build

This simplifies comparison of object files across different builds
by ensuring that the strings in the zcgo.go always appear in the
same order.

Change-Id: I3639ea4fd10e0d645b838d1bbb03cd33deca340e
Reviewed-on: https://go-review.googlesource.com/22478
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
---

diff --git a/src/cmd/dist/buildgo.go b/src/cmd/dist/buildgo.go
index af33ecd66d..2b68fc2224 100644
--- a/src/cmd/dist/buildgo.go
+++ b/src/cmd/dist/buildgo.go
@@ -7,6 +7,7 @@ package main
 import (
 	"bytes"
 	"fmt"
+	"sort"
 )
 
 /*
@@ -48,6 +49,15 @@ func mkzdefaultcc(dir, file string) {
 //
 // It is invoked to write go/build/zcgo.go.
 func mkzcgo(dir, file string) {
+	// sort for deterministic zcgo.go file
+	var list []string
+	for plat, hasCgo := range cgoEnabled {
+		if hasCgo {
+			list = append(list, plat)
+		}
+	}
+	sort.Strings(list)
+
 	var buf bytes.Buffer
 
 	fmt.Fprintf(&buf,
@@ -56,10 +66,8 @@ func mkzcgo(dir, file string) {
 			"package build\n"+
 			"\n"+
 			"var cgoEnabled = map[string]bool{\n")
-	for plat, hasCgo := range cgoEnabled {
-		if hasCgo {
-			fmt.Fprintf(&buf, "\t%q: true,\n", plat)
-		}
+	for _, plat := range list {
+		fmt.Fprintf(&buf, "\t%q: true,\n", plat)
 	}
 	fmt.Fprintf(&buf, "}")