Tweak MapPassErr to work for both errors and results (gfx-rs#7780)

Author: andyleiserson

wgpu-core/src/command/bundle.rs

@@ -1519,15 +1519,15 @@ impl RenderBundleError {
     }
 }
 
-impl<T, E> MapPassErr<T, RenderBundleError> for Result<T, E>
+impl<E> MapPassErr<RenderBundleError> for E
 where
     E: Into<RenderBundleErrorInner>,
 {
-    fn map_pass_err(self, scope: PassErrorScope) -> Result<T, RenderBundleError> {
-        self.map_err(|inner| RenderBundleError {
+    fn map_pass_err(self, scope: PassErrorScope) -> RenderBundleError {
+        RenderBundleError {
             scope,
-            inner: inner.into(),
-        })
+            inner: self.into(),
+        }
     }
 }
 

wgpu-core/src/command/compute.rs

@@ -182,15 +182,15 @@ pub struct ComputePassError {
     pub(super) inner: ComputePassErrorInner,
 }
 
-impl<T, E> MapPassErr<T, ComputePassError> for Result<T, E>
+impl<E> MapPassErr<ComputePassError> for E
 where
     E: Into<ComputePassErrorInner>,
 {
-    fn map_pass_err(self, scope: PassErrorScope) -> Result<T, ComputePassError> {
-        self.map_err(|inner| ComputePassError {
+    fn map_pass_err(self, scope: PassErrorScope) -> ComputePassError {
+        ComputePassError {
             scope,
-            inner: inner.into(),
-        })
+            inner: self.into(),
+        }
     }
 }
 

wgpu-core/src/command/mod.rs

@@ -1029,8 +1029,17 @@ impl Default for BindGroupStateChange {
     }
 }
 
-trait MapPassErr<T, O> {
-    fn map_pass_err(self, scope: PassErrorScope) -> Result<T, O>;
+trait MapPassErr<T> {
+    fn map_pass_err(self, scope: PassErrorScope) -> T;
+}
+
+impl<T, E, F> MapPassErr<Result<T, F>> for Result<T, E>
+where
+    E: MapPassErr<F>,
+{
+    fn map_pass_err(self, scope: PassErrorScope) -> Result<T, F> {
+        self.map_err(|err| err.map_pass_err(scope))
+    }
 }
 
 #[derive(Clone, Copy, Debug)]

wgpu-core/src/command/render.rs

@@ -807,15 +807,12 @@ pub struct RenderPassError {
     pub(super) inner: RenderPassErrorInner,
 }
 
-impl<T, E> MapPassErr<T, RenderPassError> for Result<T, E>
-where
-    E: Into<RenderPassErrorInner>,
-{
-    fn map_pass_err(self, scope: PassErrorScope) -> Result<T, RenderPassError> {
-        self.map_err(|inner| RenderPassError {
+impl<E: Into<RenderPassErrorInner>> MapPassErr<RenderPassError> for E {
+    fn map_pass_err(self, scope: PassErrorScope) -> RenderPassError {
+        RenderPassError {
             scope,
-            inner: inner.into(),
-        })
+            inner: self.into(),
+        }
     }
 }