x/sys/windows: correct FormatMessage parameter

Second FormatMessage parameter lpSource is uintptr not uint32.

Update golang/go#11147.

Change-Id: Icaa67abaed93efdad41564b21f8e511e8f9694b1
Reviewed-on: https://go-review.googlesource.com/11165
Reviewed-by: Yasuhiro MATSUMOTO <mattn.jp@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

windows/syscall_windows_test.go

@@ -10,6 +10,7 @@ import (
 	"path/filepath"
 	"syscall"
 	"testing"
+	"unsafe"
 
 	"golang.org/x/sys/windows"
 )
@@ -52,6 +53,38 @@ func TestWin32finddata(t *testing.T) {
 	}
 }
 
+func TestFormatMessage(t *testing.T) {
+	dll := windows.MustLoadDLL("pdh.dll")
+
+	pdhOpenQuery := func(datasrc *uint16, userdata uint32, query *windows.Handle) (errno uintptr) {
+		r0, _, _ := syscall.Syscall(dll.MustFindProc("PdhOpenQueryW").Addr(), 3, uintptr(unsafe.Pointer(datasrc)), uintptr(userdata), uintptr(unsafe.Pointer(query)))
+		return r0
+	}
+
+	pdhCloseQuery := func(query windows.Handle) (errno uintptr) {
+		r0, _, _ := syscall.Syscall(dll.MustFindProc("PdhCloseQuery").Addr(), 1, uintptr(query), 0, 0)
+		return r0
+	}
+
+	var q windows.Handle
+	name, err := windows.UTF16PtrFromString("no_such_source")
+	if err != nil {
+		t.Fatal(err)
+	}
+	errno := pdhOpenQuery(name, 0, &q)
+	if errno == 0 {
+		pdhCloseQuery(q)
+		t.Fatal("PdhOpenQuery succeeded, but expected to fail.")
+	}
+
+	const flags uint32 = syscall.FORMAT_MESSAGE_FROM_HMODULE | syscall.FORMAT_MESSAGE_ARGUMENT_ARRAY | syscall.FORMAT_MESSAGE_IGNORE_INSERTS
+	buf := make([]uint16, 300)
+	_, err = windows.FormatMessage(flags, uintptr(dll.Handle), uint32(errno), 0, buf, nil)
+	if err != nil {
+		t.Fatal("FormatMessage for handle=%x and errno=%x failed: %v", dll.Handle, errno, err)
+	}
+}
+
 func abort(funcname string, err error) {
 	panic(funcname + " failed: " + err.Error())
 }