crown: Do not check trait item projections. (#36095)

Signed-off-by: Josh Matthews <josh@joshmatthews.net>

components/script/dom/canvasrenderingcontext2d.rs

@@ -127,7 +127,6 @@ impl LayoutCanvasRenderingContextHelpers for LayoutDom<'_, CanvasRenderingContex
 impl CanvasContext for CanvasRenderingContext2D {
     type ID = CanvasId;
 
-    #[cfg_attr(crown, allow(crown::unrooted_must_root))] // Crown is wrong here #35570
     fn context_id(&self) -> Self::ID {
         self.canvas_state.get_canvas_id()
     }

components/script/dom/testbindingmaplikewithinterface.rs

@@ -89,9 +89,6 @@ impl TestBindingMaplikeWithInterfaceMethods<crate::DomTypeHolder>
     }
 }
 
-// this error is wrong because if we inline Self::Key and Self::Value all errors are gone
-// TODO: FIX THIS
-#[cfg_attr(crown, allow(crown::unrooted_must_root))]
 impl Maplike for TestBindingMaplikeWithInterface {
     type Key = DOMString;
     type Value = DomRoot<TestBinding>;

components/script/dom/testbindingmaplikewithprimitive.rs

@@ -87,9 +87,6 @@ impl TestBindingMaplikeWithPrimitiveMethods<crate::DomTypeHolder>
     }
 }
 
-// this error is wrong because if we inline Self::Key and Self::Value all errors are gone
-// TODO: FIX THIS
-#[cfg_attr(crown, allow(crown::unrooted_must_root))]
 impl Maplike for TestBindingMaplikeWithPrimitive {
     type Key = DOMString;
     type Value = i32;

components/script/dom/testbindingsetlikewithinterface.rs

@@ -61,9 +61,6 @@ impl TestBindingSetlikeWithInterfaceMethods<crate::DomTypeHolder>
     }
 }
 
-// this error is wrong because if we inline Self::Key and Self::Value all errors are gone
-// TODO: FIX THIS
-#[cfg_attr(crown, allow(crown::unrooted_must_root))]
 impl Setlike for TestBindingSetlikeWithInterface {
     type Key = DomRoot<TestBinding>;
 

components/script/dom/testbindingsetlikewithprimitive.rs

@@ -61,9 +61,6 @@ impl TestBindingSetlikeWithPrimitiveMethods<crate::DomTypeHolder>
     }
 }
 
-// this error is wrong because if we inline Self::Key and Self::Value all errors are gone
-// TODO: FIX THIS
-#[cfg_attr(crown, allow(crown::unrooted_must_root))]
 impl Setlike for TestBindingSetlikeWithPrimitive {
     type Key = DOMString;
 

components/script/dom/webgl2renderingcontext.rs

@@ -903,7 +903,6 @@ impl WebGL2RenderingContext {
 impl CanvasContext for WebGL2RenderingContext {
     type ID = WebGLContextId;
 
-    #[cfg_attr(crown, allow(crown::unrooted_must_root))] // Crown is wrong here #35570
     fn context_id(&self) -> Self::ID {
         self.base.context_id()
     }

components/script/dom/webglrenderingcontext.rs

@@ -1864,7 +1864,6 @@ impl WebGLRenderingContext {
 impl CanvasContext for WebGLRenderingContext {
     type ID = WebGLContextId;
 
-    #[cfg_attr(crown, allow(crown::unrooted_must_root))] // Crown is wrong here #35570
     fn context_id(&self) -> Self::ID {
         self.webgl_sender.context_id()
     }

components/script/dom/webgpu/gpucanvascontext.rs

@@ -253,7 +253,6 @@ impl GPUCanvasContext {
 impl CanvasContext for GPUCanvasContext {
     type ID = WebGPUContextId;
 
-    #[cfg_attr(crown, allow(crown::unrooted_must_root))] // Crown is wrong here #35570
     fn context_id(&self) -> WebGPUContextId {
         self.context_id
     }

components/script/dom/webgpu/gpusupportedfeatures.rs

@@ -139,8 +139,6 @@ pub(crate) fn gpu_to_wgt_feature(feature: GPUFeatureName) -> Option<Features> {
     }
 }
 
-// this error is wrong because if we inline Self::Key and Self::Value all errors are gone
-#[cfg_attr(crown, allow(crown::unrooted_must_root))]
 impl Setlike for GPUSupportedFeatures {
     type Key = DOMString;
 

components/script/dom/webgpu/wgsllanguagefeatures.rs

@@ -54,8 +54,6 @@ impl WGSLLanguageFeaturesMethods<crate::DomTypeHolder> for WGSLLanguageFeatures
     }
 }
 
-// this error is wrong because if we inline Self::Key and Self::Value all errors are gone
-#[cfg_attr(crown, allow(crown::unrooted_must_root))]
 impl Setlike for WGSLLanguageFeatures {
     type Key = DOMString;
 

support/crown/src/unrooted_must_root.rs

@@ -192,7 +192,9 @@ fn is_unrooted_ty<'tcx>(
             ty::RawPtr(..) => false, // don't recurse down *ptrs
             ty::FnDef(..) | ty::FnPtr(..) => false,
             ty::Alias(
-                ty::AliasTyKind::Projection | ty::AliasTyKind::Inherent | ty::AliasTyKind::Weak,
+                kind @ ty::AliasTyKind::Projection |
+                kind @ ty::AliasTyKind::Inherent |
+                kind @ ty::AliasTyKind::Weak,
                 ty,
             ) => {
                 if has_attr(ty.def_id, sym.must_root) {
@@ -201,7 +203,10 @@ fn is_unrooted_ty<'tcx>(
                 } else if has_attr(ty.def_id, sym.allow_unrooted_interior) {
                     false
                 } else {
-                    true
+                    // If this is a projection (i.e. Self::FOO), recursing will
+                    // make us consider Self, which is overly conservative for
+                    // this analysys.
+                    *kind != ty::AliasTyKind::Projection
                 }
             },
             _ => true,

support/crown/tests/run-pass/alias-projection-ignored.rs

@@ -0,0 +1,25 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+//@rustc-env:RUSTC_BOOTSTRAP=1
+
+#![allow(dead_code)]
+
+fn main() {}
+
+struct CanvasId(u64);
+
+trait CanvasContext {
+    type ID;
+
+    fn context_id(&self) -> Self::ID;
+}
+
+#[crown::unrooted_must_root_lint::must_root]
+struct Context;
+
+impl CanvasContext for Context {
+    type ID = CanvasId;
+
+    fn context_id(&self) -> Self::ID { CanvasId(0) }
+}