cmd/compile,cmd/internal/objabi: abstract out object header string

Change-Id: Idbbb4cb7127b93afa34a8aa18bbdaad1f206ab6a
Reviewed-on: https://go-review.googlesource.com/c/go/+/308090
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/cmd/internal/objabi/util.go b/src/cmd/internal/objabi/util.go
index 76c56dab27..c2c05bd1b2 100644
--- a/src/cmd/internal/objabi/util.go
+++ b/src/cmd/internal/objabi/util.go
@@ -5,6 +5,7 @@
 package objabi
 
 import (
+	"fmt"
 	"log"
 	"os"
 	"strings"
@@ -121,3 +122,11 @@ func gowasm() (f gowasmFeatures) {
 func Getgoextlinkenabled() string {
 	return envOr("GO_EXTLINK_ENABLED", defaultGO_EXTLINK_ENABLED)
 }
+
+// HeaderString returns the toolchain configuration string written in
+// Go object headers. This string ensures we don't attempt to import
+// or link object files that are incompatible with each other. This
+// string always starts with "go object ".
+func HeaderString() string {
+	return fmt.Sprintf("go object %s %s %s %s\n", GOOS, GOARCH, Version, Expstring())
+}