Introduce strict-assertions feature flag

For now, this feature flag only enables validation
in `iced_wgpu`; which has become quite expensive
since its `0.20` release.

Cargo.toml

@@ -65,6 +65,8 @@ advanced = ["iced_core/advanced", "iced_widget/advanced"]
 fira-sans = ["iced_renderer/fira-sans"]
 # Enables auto-detecting light/dark mode for the built-in theme
 auto-detect-theme = ["iced_core/auto-detect-theme"]
+# Enables strict assertions for debugging purposes at the expense of performance
+strict-assertions = ["iced_wgpu/strict-assertions"]
 
 [dependencies]
 iced_core.workspace = true

wgpu/Cargo.toml

@@ -23,6 +23,7 @@ image = ["iced_graphics/image"]
 svg = ["iced_graphics/svg", "resvg/text"]
 web-colors = ["iced_graphics/web-colors"]
 webgl = ["wgpu/webgl"]
+strict-assertions = []
 
 [dependencies]
 iced_graphics.workspace = true

wgpu/src/window/compositor.rs

@@ -56,6 +56,11 @@ impl Compositor {
     ) -> Result<Self, Error> {
         let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
             backends: settings.backends,
+            flags: if cfg!(feature = "strict-assertions") {
+                wgpu::InstanceFlags::debugging()
+            } else {
+                wgpu::InstanceFlags::empty()
+            },
             ..Default::default()
         });