1 files changed, 70 insertions, 0 deletions
diff --git a/test/fixedbugs/issue8606b.go b/test/fixedbugs/issue8606b.go
new file mode 100644
index 0000000..41b9a3d
--- /dev/null
+++ b/test/fixedbugs/issue8606b.go
@@ -0,0 +1,70 @@
+// run
+// +build linux darwin
+
+// Copyright 2020 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.
+
+// This is an optimization check. We want to make sure that we compare
+// string lengths, and other scalar fields, before checking string
+// contents.  There's no way to verify this in the language, and
+// codegen tests in test/codegen can't really detect ordering
+// optimizations like this. Instead, we generate invalid strings with
+// bad backing store pointers but nonzero length, so we can check that
+// the backing store never gets compared.
+//
+// We use two different bad strings so that pointer comparisons of
+// backing store pointers fail.
+
+package main
+
+import (
+	"fmt"
+	"reflect"
+	"syscall"
+	"unsafe"
+)
+
+type SI struct {
+	s string
+	i int
+}
+
+type SS struct {
+	s string
+	t string
+}
+
+func main() {
+	bad1 := "foo"
+	bad2 := "foo"
+
+	p := syscall.Getpagesize()
+	b, err := syscall.Mmap(-1, 0, p, syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_ANON|syscall.MAP_PRIVATE)
+	if err != nil {
+		panic(err)
+	}
+	err = syscall.Mprotect(b, syscall.PROT_NONE)
+	if err != nil {
+		panic(err)
+	}
+	// write inaccessible pointers as the data fields of bad1 and bad2.
+	(*reflect.StringHeader)(unsafe.Pointer(&bad1)).Data = uintptr(unsafe.Pointer(&b[0]))
+	(*reflect.StringHeader)(unsafe.Pointer(&bad2)).Data = uintptr(unsafe.Pointer(&b[1]))
+
+	for _, test := range []struct {
+		a, b interface{}
+	}{
+		{SI{s: bad1, i: 1}, SI{s: bad2, i: 2}},
+		{SS{s: bad1, t: "a"}, SS{s: bad2, t: "aa"}},
+		{SS{s: "a", t: bad1}, SS{s: "b", t: bad2}},
+		// This one would panic because the length of both strings match, and we check
+		// the body of the bad strings before the body of the good strings.
+		//{SS{s: bad1, t: "a"}, SS{s: bad2, t: "b"}},
+	} {
+		if test.a == test.b {
+			panic(fmt.Sprintf("values %#v and %#v should not be equal", test.a, test.b))
+		}
+	}
+
+}