cmd/cgo: add go:notinheap annotation to Windows handle types

Fixes #42018

Change-Id: I6a40f3effe860e67a45fca2e8ab86f3e9887ffee
Reviewed-on: https://go-review.googlesource.com/c/go/+/350070
Trust: Elias Naur <mail@eliasnaur.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>

3 files changed, 61 insertions, 0 deletions

diff --git a/misc/cgo/test/cgo_test.go b/misc/cgo/test/cgo_test.go
index 143f23f0e0..fe99e251e9 100644
--- a/misc/cgo/test/cgo_test.go
+++ b/misc/cgo/test/cgo_test.go
@@ -59,6 +59,7 @@ func Test28896(t *testing.T)                 { test28896(t) }
 func Test30065(t *testing.T)                 { test30065(t) }
 func Test32579(t *testing.T)                 { test32579(t) }
 func Test31891(t *testing.T)                 { test31891(t) }
+func Test42018(t *testing.T)                 { test42018(t) }
 func Test45451(t *testing.T)                 { test45451(t) }
 func TestAlign(t *testing.T)                 { testAlign(t) }
 func TestAtol(t *testing.T)                  { testAtol(t) }
diff --git a/misc/cgo/test/issue42018.go b/misc/cgo/test/issue42018.go
new file mode 100644
index 0000000000..fab686a678
--- /dev/null
+++ b/misc/cgo/test/issue42018.go
@@ -0,0 +1,14 @@
+// Copyright 2021 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.
+
+//go:build !windows
+// +build !windows
+
+package cgotest
+
+import "testing"
+
+func test42018(t *testing.T) {
+	t.Skip("skipping Windows-only test")
+}
diff --git a/misc/cgo/test/issue42018_windows.go b/misc/cgo/test/issue42018_windows.go
new file mode 100644
index 0000000000..8f4570ab2a
--- /dev/null
+++ b/misc/cgo/test/issue42018_windows.go
@@ -0,0 +1,46 @@
+// Copyright 2021 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 cgotest
+
+/*
+typedef void *HANDLE;
+
+struct HWND__{int unused;}; typedef struct HWND__ *HWND;
+*/
+import "C"
+
+import (
+	"testing"
+	"unsafe"
+)
+
+func test42018(t *testing.T) {
+	// Test that Windows handles are marked go:notinheap, by growing the
+	// stack and checking for pointer adjustments. Trick from
+	// test/fixedbugs/issue40954.go.
+	var i int
+	handle := C.HANDLE(unsafe.Pointer(uintptr(unsafe.Pointer(&i))))
+	recurseHANDLE(100, handle, uintptr(unsafe.Pointer(&i)))
+	hwnd := C.HWND(unsafe.Pointer(uintptr(unsafe.Pointer(&i))))
+	recurseHWND(400, hwnd, uintptr(unsafe.Pointer(&i)))
+}
+
+func recurseHANDLE(n int, p C.HANDLE, v uintptr) {
+	if n > 0 {
+		recurseHANDLE(n-1, p, v)
+	}
+	if uintptr(unsafe.Pointer(p)) != v {
+		panic("adjusted notinheap pointer")
+	}
+}
+
+func recurseHWND(n int, p C.HWND, v uintptr) {
+	if n > 0 {
+		recurseHWND(n-1, p, v)
+	}
+	if uintptr(unsafe.Pointer(p)) != v {
+		panic("adjusted notinheap pointer")
+	}
+}