Changed most instances of var to const in the Windows code. Only one left...

comctl_windows.go

@@ -50,8 +50,8 @@ References:
 - http://support.microsoft.com/kb/830033
 */
 func forceCommonControls6() (err error) {
-	var (
-		// from winbase.h; var because Go won't let me convert this constant
+	const (
+		// from winbase.h
 		_INVALID_HANDLE_VALUE = -1
 	)
 
@@ -85,7 +85,7 @@ func forceCommonControls6() (err error) {
 	actctx.lpSource = syscall.StringToUTF16Ptr(filename)
 
 	r1, _, err := _createActCtx.Call(uintptr(unsafe.Pointer(&actctx)))
-	if r1 == uintptr(_INVALID_HANDLE_VALUE) {		// failure
+	if r1 == negConst(_INVALID_HANDLE_VALUE) {		// failure
 		return fmt.Errorf("error creating activation context for synthesized manifest file: %v", err)
 	}
 	r1, _, err = _activateActCtx.Call(

common_windows.go

@@ -76,6 +76,12 @@ type _RECT struct {
 	bottom	int32
 }
 
+// Go doesn't allow negative constants to be forced into unsigned types at compile-time; this will do it at runtime.
+// TODO make sure sign extension works fine here (check Go's rules and ABI sign extension rules)
+func negConst(c int) uintptr {
+	return uintptr(c)
+}
+
 // Predefined cursor resource IDs.
 const (
 	_IDC_APPSTARTING = 32650

controls_windows.go

@@ -179,7 +179,7 @@ const (
 )
 
 // Combobox errors.
-var (		// var so they can be cast to uintptr
+const (
 	// from winuser.h
 	_CB_ERR = (-1)
 	_CB_ERRSPACE = (-2)
@@ -356,7 +356,7 @@ const (
 )
 
 // Listbox errors.
-var (		// var so they can be cast to uintptr
+const (
 	// from winuser.h
 	_LB_OKAY = 0
 	_LB_ERR = (-1)

sysdata_windows.go

@@ -35,8 +35,8 @@ type classData struct {
 	insertBeforeMsg	uintptr
 	deleteMsg			uintptr
 	selectedIndexMsg	uintptr
-	selectedIndexErr	int
-	addSpaceErr		int
+	selectedIndexErr	uintptr
+	addSpaceErr		uintptr
 	lenMsg			uintptr
 }
 
@@ -69,8 +69,8 @@ var classTypes = [nctypes]*classData{
 		insertBeforeMsg:	_CB_INSERTSTRING,
 		deleteMsg:		_CB_DELETESTRING,
 		selectedIndexMsg:	_CB_GETCURSEL,
-		selectedIndexErr:	_CB_ERR,
-		addSpaceErr:		_CB_ERRSPACE,
+		selectedIndexErr:	negConst(_CB_ERR),
+		addSpaceErr:		negConst(_CB_ERRSPACE),
 		lenMsg:			_CB_GETCOUNT,
 	},
 	c_lineedit:		&classData{
@@ -100,8 +100,8 @@ var classTypes = [nctypes]*classData{
 		insertBeforeMsg:	_LB_INSERTSTRING,
 		deleteMsg:		_LB_DELETESTRING,
 		selectedIndexMsg:	_LB_GETCURSEL,
-		selectedIndexErr:	_LB_ERR,
-		addSpaceErr:		_LB_ERRSPACE,
+		selectedIndexErr:	negConst(_LB_ERR),
+		addSpaceErr:		negConst(_LB_ERRSPACE),
 		lenMsg:			_LB_GETCOUNT,
 	},
 	c_progressbar:		&classData{
@@ -422,7 +422,7 @@ func (s *sysData) selectedIndices() []int {
 		ret:		ret,
 	}
 	r := <-ret
-	if r.ret == uintptr(_LB_ERR) {
+	if r.ret == negConst(_LB_ERR) {
 		panic("UI library internal error: LB_ERR from LB_GETSELCOUNT in what we know is a multi-selection listbox")
 	}
 	if r.ret == 0 {		// nothing selected
@@ -440,7 +440,7 @@ func (s *sysData) selectedIndices() []int {
 		ret:		ret,
 	}
 	r = <-ret
-	if r.ret == uintptr(_LB_ERR) {
+	if r.ret == negConst(_LB_ERR) {
 		panic("UI library internal error: LB_ERR from LB_GETSELITEMS in what we know is a multi-selection listbox")
 	}
 	return indices
@@ -463,7 +463,7 @@ func (s *sysData) selectedTexts() []string {
 			ret:		ret,
 		}
 		r := <-ret
-		if r.ret == uintptr(_LB_ERR) {
+		if r.ret == negConst(_LB_ERR) {
 			panic("UI library internal error: LB_ERR from LB_GETTEXTLEN in what we know is a valid listbox index (came from LB_GETSELITEMS)")
 		}
 		str := make([]uint16, r.ret)
@@ -478,7 +478,7 @@ func (s *sysData) selectedTexts() []string {
 			ret:		ret,
 		}
 		r = <-ret
-		if r.ret == uintptr(_LB_ERR) {
+		if r.ret == negConst(_LB_ERR) {
 			panic("UI library internal error: LB_ERR from LB_GETTEXT in what we know is a valid listbox index (came from LB_GETSELITEMS)")
 		}
 		strings[i] = syscall.UTF16ToString(str)
@@ -537,7 +537,7 @@ func (s *sysData) setIndeterminate() {
 		call:		_setWindowLong,
 		p:		[]uintptr{
 			uintptr(s.hwnd),
-			uintptr(_GWL_STYLE),
+			negConst(_GWL_STYLE),
 			uintptr(classTypes[s.ctype].style | _PBS_MARQUEE),
 		},
 		ret:		ret,
@@ -584,7 +584,7 @@ func (s *sysData) setProgress(percent int) {
 			call:		_setWindowLong,
 			p:		[]uintptr{
 				uintptr(s.hwnd),
-				uintptr(_GWL_STYLE),
+				negConst(_GWL_STYLE),
 				uintptr(classTypes[s.ctype].style),
 			},
 			ret:		ret,

uitask_windows.go

@@ -133,8 +133,8 @@ const (
 	msghandlerclass = "gomsghandler"
 )
 
-var (
-	// fron winuser.h; var because Go won't let me
+const (
+	// fron winuser.h
 	_HWND_MESSAGE = -3
 )
 
@@ -162,7 +162,7 @@ func makeMessageHandler() (hwnd _HWND, err error) {
 		uintptr(_CW_USEDEFAULT),
 		uintptr(_CW_USEDEFAULT),
 		uintptr(_CW_USEDEFAULT),
-		uintptr(_HWND_MESSAGE),
+		negConst(_HWND_MESSAGE),
 		uintptr(_NULL),
 		uintptr(hInstance),
 		uintptr(_NULL))

windows_windows.go

@@ -121,14 +121,6 @@ const (
 	_HWND_TOP = _HWND(0)
 )
 
-// SetWindowPos hWndInsertAfter values that Go won't allow as constants.
-var (
-	__HWND_NOTOPMOST = -2
-	_HWND_NOTOPMOST = _HWND(__HWND_NOTOPMOST)
-	__HWND_TOPMOST = -1
-	_HWND_TOPMOST = _HWND(__HWND_TOPMOST)
-)
-
 // SetWindowPos uFlags values.
 const (
 	_SWP_DRAWFRAME = 0x0020
@@ -244,7 +236,7 @@ const (
 )
 
 // WM_STYLECHANGED and WM_STYLECHANGING values (wParam).
-var (		// var because Go won't let me cast a negative const to a uintptr
+const (
 	_GWL_EXSTYLE = -20
 	_GWL_STYLE = -16
 )