macOS: open the window on Intel Metal by skipping indirect-call validation

wgpu validates indirect draw and dispatch arguments with a compute shader it
compiles when the device is created. Metal on an Intel Iris Pro (MacBookPro11,3,
macOS 12.7.6) fails to compile it ("Compiler encountered an internal error" in
MTLCompilerService), the device is lost, and the window never opens.

FilmCraft draws and dispatches nothing indirectly, so leave the check out of the
instance flags. WGPU_VALIDATION_INDIRECT_CALL=1 turns it back on. VectorCraft
does the same (storytold/vectorcraft#651).

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/filmcraft/src/graphics.rs

@@ -427,6 +427,11 @@ fn apply_for(options: &mut NativeOptions, mode: Mode, backend_override: Option<B
     let WgpuSetup::CreateNew(create) = &mut options.wgpu_options.wgpu_setup else {
         return;
     };
+    // Nothing draws or dispatches indirectly, so wgpu's check of indirect arguments only costs a
+    // compute shader when the device is created, one that Metal can't compile on an Intel Iris
+    // Pro: the device is lost and the window never opens. `WGPU_VALIDATION_INDIRECT_CALL=1` turns
+    // the check back on.
+    create.instance_descriptor.flags = create.instance_descriptor.flags.difference(wgpu::InstanceFlags::VALIDATION_INDIRECT_CALL).with_env();
     match mode {
         // eframe's default (`WGPU_BACKEND`, else PRIMARY | GL), except on Windows: there it
         // includes GL. Creating that backend can crash inside AMD's atio6axx.dll before adapter
@@ -484,6 +489,22 @@ mod tests {
         (create.instance_descriptor.backends, create.native_adapter_selector.is_some())
     }
 
+    #[test]
+    fn no_mode_validates_indirect_calls() {
+        if std::env::var_os("WGPU_VALIDATION_INDIRECT_CALL").is_some() {
+            return;
+        }
+        for mode in [Mode::Default, Mode::Dx12, Mode::Software] {
+            let mut options = NativeOptions::default();
+            apply_for(&mut options, mode, None, false);
+            let WgpuSetup::CreateNew(create) = options.wgpu_options.wgpu_setup else {
+                panic!("default native options must create a wgpu instance");
+            };
+            // Intel Metal can't compile the validation's compute shader, and the device is lost.
+            assert!(!create.instance_descriptor.flags.contains(wgpu::InstanceFlags::VALIDATION_INDIRECT_CALL), "{mode:?}");
+        }
+    }
+
     #[test]
     fn windows_default_leaves_out_gl() {
         // eframe's own default (PRIMARY | GL) would initialize OpenGL as well.