libgo: update to go1.9

    
    Reviewed-on: https://go-review.googlesource.com/63753

From-SVN: r252767

1 files changed, 54 insertions, 0 deletions

diff --git a/libgo/go/runtime/example_test.go b/libgo/go/runtime/example_test.go
new file mode 100644
index 0000000..e4912a5
--- /dev/null
+++ b/libgo/go/runtime/example_test.go
@@ -0,0 +1,54 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime_test
+
+import (
+	"fmt"
+	"runtime"
+	"strings"
+)
+
+func ExampleFrames() {
+	c := func() {
+		// Ask runtime.Callers for up to 10 pcs, including runtime.Callers itself.
+		pc := make([]uintptr, 10)
+		n := runtime.Callers(0, pc)
+		if n == 0 {
+			// No pcs available. Stop now.
+			// This can happen if the first argument to runtime.Callers is large.
+			return
+		}
+
+		pc = pc[:n] // pass only valid pcs to runtime.CallersFrames
+		frames := runtime.CallersFrames(pc)
+
+		// Loop to get frames.
+		// A fixed number of pcs can expand to an indefinite number of Frames.
+		for {
+			frame, more := frames.Next()
+			// To keep this example's output stable
+			// even if there are changes in the testing package,
+			// stop unwinding when we leave package runtime.
+			if !strings.Contains(frame.File, "runtime/") {
+				break
+			}
+			fmt.Printf("- more:%v | %s\n", more, frame.Function)
+			if !more {
+				break
+			}
+		}
+	}
+
+	b := func() { c() }
+	a := func() { b() }
+
+	a()
+	// Output:
+	// - more:true | runtime.Callers
+	// - more:true | runtime_test.ExampleFrames.func1
+	// - more:true | runtime_test.ExampleFrames.func2
+	// - more:true | runtime_test.ExampleFrames.func3
+	// - more:true | runtime_test.ExampleFrames
+}