app crashes if build with --release

[dumdrak]

Hi,

When I use Tab and TabsContainer my app works in debug but crashes in release mode with the error
(exit code: 0xc000001d, STATUS_ILLEGAL_INSTRUCTION)

putting

[profile.release]
opt-level = 0

in cargo.toml makes the app work again in --release but its not optimized

any idea what I'm doing wrong?

the code that makes this happen is

<-- window, layout, file dialogs
//tabs
#[nwg_control()]
#[nwg_layout_item(layout: grid, row: 0, col: 0, col_span: 5, row_span: 9)]
tabs_container: nwg::TabsContainer,
//tab proveedors
#[nwg_control(text: "Proveedors",parent: tabs_container)]
tab_proveedors: nwg::Tab,
-->more controls

[w-flo]

I noticed the same issue with code that was working on a previous rustc version. I cross-compile from Ubuntu to the x86_64-pc-windows-gnu target.

After some investigation, I found some suspicious transmute()s in controls/tabs.rs. This fixes some of the crashes for me, but I'm not sure it's enough. There are quite a few transmute()s in the code base that probably shouldn't be there. The docs say:

Transmuting integers to pointers is a largely unspecified operation. It is likely not equivalent to an as cast. Doing non-zero-sized memory accesses with a pointer constructed this way is currently considered undefined behavior.
[..] In particular, doing a pointer-to-integer-to-pointer roundtrip via transmute is not a lossless process

diff --git a/native-windows-gui/src/controls/tabs.rs b/native-windows-gui/src/controls/tabs.rs
index feafa8c..fe438d5 100644
--- a/native-windows-gui/src/controls/tabs.rs
+++ b/native-windows-gui/src/controls/tabs.rs
@@ -265,7 +265,7 @@ impl TabsContainer {
         let handler0 = bind_raw_event_handler_inner(&parent_handle, handle as usize, move |_hwnd, msg, _w, l| { unsafe {
             match msg {
                 WM_NOTIFY => {
-                    let nmhdr: &NMHDR = mem::transmute(l);
+                    let nmhdr: &NMHDR = &*(l as *const NMHDR);
                     if nmhdr.code == TCN_SELCHANGE {
                         let index = SendMessageW(handle, TCM_GETCURSEL, 0, 0) as i32;
                         let data: (HWND, i32) = (handle, index);
@@ -318,7 +318,7 @@ impl TabsContainer {
                     data.tab_offset_y = tab_height;
                     
                     let data_ptr = &data as *const ResizeDirectChildrenParams;
-                    EnumChildWindows(hwnd, Some(resize_direct_children), mem::transmute(data_ptr));
+                    EnumChildWindows(hwnd, Some(resize_direct_children), data_ptr as isize);
                 },
                 _ => {}
             }
@@ -612,7 +612,7 @@ impl Tab {
         let count_ptr = &mut count as *mut usize;
 
         unsafe {
-            EnumChildWindows(tab_view_handle, Some(count_children), mem::transmute(count_ptr));
+            EnumChildWindows(tab_view_handle, Some(count_children), count_ptr as isize);
         }
 
         count
@@ -757,7 +757,7 @@ unsafe extern "system" fn count_children(handle: HWND, params: LPARAM) -> BOOL {
 
     if &wh::get_window_class_name(handle) == "NWG_TAB" {
         let tab_index = (wh::get_window_long(handle, GWL_USERDATA)) as WPARAM;
-        let count: &mut usize = ::std::mem::transmute(params);
+        let count: &mut usize = &mut *(params as *mut usize);
         *count = usize::max(tab_index+1, *count);
     }
     
@@ -768,7 +768,7 @@ unsafe extern "system" fn count_children(handle: HWND, params: LPARAM) -> BOOL {
 unsafe extern "system" fn toggle_children_tabs(handle: HWND, params: LPARAM) -> BOOL {
     use winapi::um::winuser::GWL_USERDATA;
     
-    let &(parent, index): &(HWND, i32) = mem::transmute(params);
+    let &(parent, index): &(HWND, i32) = &*(params as *const (HWND, i32));
     if wh::get_window_parent(handle) == parent {
         let tab_index = wh::get_window_long(handle, GWL_USERDATA) as i32;
         let visible = tab_index == index + 1;

[dumdrak]

I tried using the pull request #308 and the crash stoped.

to do so you have to put in your Cargo.toml the dependence:
native-windows-gui = { git = "https://github.com/nickbeth/native-windows-gui.git", branch = "transmute-ub" }

its only in the 1.0.12 version (main its 1.0.13) but works with optimizations.

[nickbeth]

Hi, I'm the author of #308.

Since I'm using this library in my app, I've made a fork of this repo with the "transmute fix" applied. Just wanted to clarify how the fork works:

• Branch transmute-ub is version 1.0.13 (latest) with the fix applied
• Branch transmute-ub-1.0.12 is version 1.0.12 with the fix applied

I had to make a fix for v1.0.12 as well because v1.0.13 broke nested flex layouts, which I was using in my app.