cmd/go: use build ID as plugin symbol prefix

Updates #17821

Change-Id: Iebd2e88b2d4f3d757ffad72456f4bfc0607d8110
Reviewed-on: https://go-review.googlesource.com/33162
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/misc/cgo/testplugin/src/host/host.go b/misc/cgo/testplugin/src/host/host.go
index b3b4df3d58..898f44efa1 100644
--- a/misc/cgo/testplugin/src/host/host.go
+++ b/misc/cgo/testplugin/src/host/host.go
@@ -18,6 +18,35 @@ func init() {
 	common.X *= 5
 }
 
+// testUnnamed tests that two plugins built with .go files passed on
+// the command line do not have overlapping symbols. That is,
+// unnamed1.so/FuncInt and unnamed2.so/FuncInt should be distinct functions.
+func testUnnamed() {
+	p, err := plugin.Open("unnamed1.so")
+	if err != nil {
+		log.Fatalf(`plugin.Open("unnamed1.so"): %v`, err)
+	}
+	fn, err := p.Lookup("FuncInt")
+	if err != nil {
+		log.Fatalf(`unnamed1.so: Lookup("FuncInt") failed: %v`, err)
+	}
+	if got, want := fn.(func() int)(), 1; got != want {
+		log.Fatalf("unnamed1.so: FuncInt()=%d, want %d", got, want)
+	}
+
+	p, err = plugin.Open("unnamed2.so")
+	if err != nil {
+		log.Fatalf(`plugin.Open("unnamed2.so"): %v`, err)
+	}
+	fn, err = p.Lookup("FuncInt")
+	if err != nil {
+		log.Fatalf(`unnamed2.so: Lookup("FuncInt") failed: %v`, err)
+	}
+	if got, want := fn.(func() int)(), 2; got != want {
+		log.Fatalf("unnamed2.so: FuncInt()=%d, want %d", got, want)
+	}
+}
+
 func main() {
 	if got, want := common.X, 3*5; got != want {
 		log.Fatalf("before plugin load common.X=%d, want %d", got, want)
@@ -113,5 +142,7 @@ func main() {
 		log.Fatalf(`plugin.Open("plugin-mismatch.so"): error does not mention "different version": %v`, s)
 	}
 
+	testUnnamed()
+
 	fmt.Println("PASS")
 }