fix: convert callback lifetimes to 'static

Except for ev.on_tick which has a test against use-after-free in
compile_tests.rs.

Author: NoraCodes

CONTRIBUTING/callbacks.md

@@ -15,7 +15,7 @@ Their intended use is for `to_heap_ptr` to turn a Rust function into a bag of bi
 by "generic locking" the user and wrapper functions, like so:
 
 ```rust
-fn on_whatever<'ctx, F: FnMut(&Whatever)>(&mut self, _ctx: &'ctx UI, callback: F) {
+fn on_whatever<'ctx, F: FnMut(&Whatever) + 'static>(&mut self, _ctx: &'ctx UI, callback: F) {
 
     fn c_callback<G: FnMut(&Whatever)> { /* ... do stuff ... */ }
 
@@ -26,5 +26,5 @@ fn on_whatever<'ctx, F: FnMut(&Whatever)>(&mut self, _ctx: &'ctx UI, callback: F
 This is somewhat verbose but ensures that the types do not deviate, which would be unsafe.
 
 Callbacks should be named `on_event` where `event` is, for instance, `clicked` or
-`closing`.
+`closing`. The functions taken by callbacks must always have the `'static` bound.
 

iui/src/compile_tests.rs

@@ -1,39 +1,21 @@
 //! Examples of unsound code that IUI statically prevents from compiling.
 //!
-//! Here, we attempt to place use-after-free some callbacks.
+//! Here, we attempt to use-after-free some callbacks.
 //!
 //! ```compile_fail
-//! let ev = iui::UI::init().unwrap();
+//! let ui = iui::UI::init().unwrap();
 //!
 //! {
 //!     let v = vec![1, 2, 3, 4];
-//!     ev.queue_main(|| {
+//!     ui.queue_main(|| {
 //!         for i in &v {
 //!             println!("{}", i);
 //!         }
 //!     });
 //! }
-//!
-//! ev.quit();
-//! ev.main();
-//! ```
-//!
-//! ```compile_fail
-//! let ev = iui::UI::init().unwrap();
-//!
-//! {
-//!     let v = vec![1, 2, 3, 4];
-//!     ev.on_should_quit(|| {
-//!         for i in &v {
-//!             println!("{}", i);
-//!         }
-//!     });
-//! }
-//!
-//! ev.quit();
-//! ev.main();
 //! ```
 //!
+//! This one is OK, because it moves the `Vec` into the closure's scope.
 //! ```
 //! let ev = iui::UI::init().unwrap();
 //!
@@ -47,3 +29,41 @@
 //! ev.quit();
 //! ev.main();
 //! ```
+//! 
+//! This one tries to use a reference to a string that is dropped out of scope.
+//! ```compile_fail
+//! # use iui::prelude::*;
+//! # use iui::controls::{Button};
+//! let ui = UI::init().unwrap();
+//! let mut win = Window::new(&ui, "Test App", 200, 200, WindowType::NoMenubar);
+//! let mut button = Button::new(&ui, "Button");
+//!
+//! {
+//!     let s = String::from("Whatever!");
+//!     let callback =  |b: &mut Button| { println!("{}", s)};
+//!     button.on_clicked(&ui, callback);
+//! }
+//!
+//! win.set_child(&ui, button);
+//! ```
+//! 
+//! Here we try to use-after-free data in the on-tick callback.
+//! 
+//! ```compile_fail
+//! # use iui::prelude::*;
+//! # use iui::controls::{Button};
+//! let ui = UI::init().unwrap();
+//! let mut ev = ui.event_loop();
+//! let win = Window::new(&ui, "Test App", 200, 200, WindowType::NoMenubar);
+//!
+//! {
+//!     let s = String::from("Whatever!");
+//!     let callback =  || { println!("{}", s) };
+//!     ev.on_tick(&ui, callback);
+//! }
+//! 
+//! ev.next_tick(&ui);
+//! ui.quit();
+//! ev.next_tick(&ui);
+//!
+//! ```

iui/src/controls/button.rs

@@ -46,7 +46,7 @@ impl Button {
     /// Run the given callback when the button is clicked.
     pub fn on_clicked<'ctx, F>(&mut self, _ctx: &'ctx UI, callback: F)
     where
-        F: FnMut(&mut Button) + 'ctx,
+        F: FnMut(&mut Button) + 'static,
     {
         extern "C" fn c_callback<G>(button: *mut uiButton, data: *mut c_void)
         where

iui/src/controls/entry.rs

@@ -19,13 +19,13 @@ use str_tools::{from_toolkit_string, to_toolkit_string};
 pub trait NumericEntry {
     fn value(&self, ctx: &UI) -> i32;
     fn set_value(&mut self, ctx: &UI, value: i32);
-    fn on_changed<'ctx, F: FnMut(i32) + 'ctx>(&mut self, ctx: &'ctx UI, callback: F);
+    fn on_changed<'ctx, F: FnMut(i32) + 'static>(&mut self, ctx: &'ctx UI, callback: F);
 }
 
 pub trait TextEntry {
     fn value(&self, ctx: &UI) -> String;
     fn set_value(&mut self, ctx: &UI, value: &str);
-    fn on_changed<'ctx, F: FnMut(String) + 'ctx>(&mut self, ctx: &'ctx UI, callback: F);
+    fn on_changed<'ctx, F: FnMut(String) + 'static>(&mut self, ctx: &'ctx UI, callback: F);
 }
 
 define_control! {
@@ -70,7 +70,7 @@ impl NumericEntry for Spinbox {
 
     fn on_changed<'ctx, F>(&mut self, _ctx: &'ctx UI, callback: F)
     where
-        F: FnMut(i32) + 'ctx,
+        F: FnMut(i32) + 'static
     {
         extern "C" fn c_callback<G>(spinbox: *mut uiSpinbox, data: *mut c_void)
         where
@@ -103,7 +103,7 @@ impl NumericEntry for Slider {
 
     fn on_changed<'ctx, F>(&mut self, _ctx: &'ctx UI, callback: F)
     where
-        F: FnMut(i32) + 'ctx,
+        F: FnMut(i32) + 'static
     {
         extern "C" fn c_callback<G>(slider: *mut uiSlider, data: *mut c_void)
         where
@@ -169,7 +169,7 @@ impl TextEntry for Entry {
 
         fn on_changed<'ctx, F>(&mut self, _ctx: &'ctx UI, callback: F)
     where
-        F: FnMut(String) + 'ctx,
+        F: FnMut(String) + 'static,
     {
         extern "C" fn c_callback<G>(entry: *mut uiEntry, data: *mut c_void)
         where
@@ -235,7 +235,7 @@ impl TextEntry for MultilineEntry {
 
     fn on_changed<'ctx, F>(&mut self, _ctx: &'ctx UI, callback: F)
     where
-        F: FnMut(String) + 'ctx,
+        F: FnMut(String) + 'static,
     {
         extern "C" fn c_callback<G>(entry: *mut uiMultilineEntry, data: *mut c_void)
         where
@@ -288,7 +288,7 @@ impl Combobox {
 
     pub fn on_selected<'ctx, F>(&mut self, _ctx: &'ctx UI, callback: F)
     where
-        F: FnMut(i32) + 'ctx,
+        F: FnMut(i32) + 'static,
     {
         extern "C" fn c_callback<G>(combobox: *mut uiCombobox, data: *mut c_void)
         where
@@ -331,7 +331,7 @@ impl Checkbox {
 
     pub fn on_toggled<'ctx, F>(&mut self, _ctx: &'ctx UI, callback: F)
     where
-        F: FnMut(bool) + 'ctx,
+        F: FnMut(bool) + 'static,
     {
         extern "C" fn c_callback<G>(checkbox: *mut uiCheckbox, data: *mut c_void)
         where
@@ -376,7 +376,7 @@ impl RadioButtons {
         unsafe { ui_sys::uiRadioButtonsSetSelected(self.uiRadioButtons, idx); }
     }
 
-    pub fn on_selected<'ctx, F: FnMut(i32) + 'ctx>(&self, _ctx: &'ctx UI, callback: F) {
+    pub fn on_selected<'ctx, F: FnMut(i32) + 'static>(&self, _ctx: &'ctx UI, callback: F) {
         unsafe {
             let mut data: Box<Box<dyn FnMut(i32)>> = Box::new(Box::new(callback));
             ui_sys::uiRadioButtonsOnSelected(

iui/src/controls/window.rs

@@ -90,7 +90,7 @@ impl Window {
     /// the application when the window is closed.
     pub fn on_closing<'ctx, F>(&mut self, _ctx: &'ctx UI, callback: F)
     where
-        F: FnMut(&mut Window) + 'ctx,
+        F: FnMut(&mut Window) + 'static,
     {
         extern "C" fn c_callback<G>(window: *mut uiWindow, data: *mut c_void) -> i32
         where

iui/src/menus.rs

@@ -48,7 +48,7 @@ impl MenuItem {
     /// Sets the function to be executed when the item is clicked/selected.
     pub fn on_clicked<'ctx, F>(&self, _ctx: &'ctx UI, callback: F)
     where
-        F: FnMut(&MenuItem, &Window) + 'ctx,
+        F: FnMut(&MenuItem, &Window) + 'static,
     {
         extern "C" fn c_callback<G: FnMut(&MenuItem, &Window)>(
             menu_item: *mut uiMenuItem,