From 627ea86a841a289f84c00fce0e6ebf7747193f4a Mon Sep 17 00:00:00 2001
From: Kevin Reid <kpreid@switchb.org>
Date: Mon, 11 Dec 2023 13:36:05 -0800
Subject: [PATCH] port: Fix `export_to_path` producing a `!Send` future.

---
 all-is-cubes-port/src/gltf.rs  | 57 ++++++++++++++++++----------------
 all-is-cubes-port/src/tests.rs | 17 ++++++++++
 2 files changed, 47 insertions(+), 27 deletions(-)

diff --git a/all-is-cubes-port/src/gltf.rs b/all-is-cubes-port/src/gltf.rs
index 15d54e141..eccdd2e5a 100644
--- a/all-is-cubes-port/src/gltf.rs
+++ b/all-is-cubes-port/src/gltf.rs
@@ -395,37 +395,40 @@ pub(crate) async fn export_gltf(
     let mesh_options = MeshOptions::new(&GraphicsOptions::default());
 
     for (mut p, block_def_ref) in progress.split_evenly(block_defs.len()).zip(block_defs) {
-        let block_def = block_def_ref.read()?;
         let name = block_def_ref.name();
         p.set_label(&name);
         p.progress(0.01).await;
-        let mesh = SpaceMesh::<GltfMt>::from(&BlockMesh::new(
-            &block_def
-                .evaluate()
-                .map_err(|eve| ExportError::NotRepresentable {
-                    name: Some(name.clone()),
-                    reason: format!("block evaluation failed: {eve}"),
-                })?,
-            &writer.texture_allocator(),
-            &mesh_options,
-        ));
-
-        let mesh_index = writer.add_mesh(&name, &mesh);
-        // TODO: if the mesh is empty/None, should we include the node anyway or not?
-        let mesh_node = push_and_return_index(
-            &mut writer.root.nodes,
-            gltf_json::Node {
-                mesh: mesh_index,
-                ..empty_node(Some(name.to_string()))
-            },
-        );
+        {
+            // constrained scope so we don't hold UBorrow over an await
+            let block_def = block_def_ref.read()?;
+            let mesh = SpaceMesh::<GltfMt>::from(&BlockMesh::new(
+                &block_def
+                    .evaluate()
+                    .map_err(|eve| ExportError::NotRepresentable {
+                        name: Some(name.clone()),
+                        reason: format!("block evaluation failed: {eve}"),
+                    })?,
+                &writer.texture_allocator(),
+                &mesh_options,
+            ));
+
+            let mesh_index = writer.add_mesh(&name, &mesh);
+            // TODO: if the mesh is empty/None, should we include the node anyway or not?
+            let mesh_node = push_and_return_index(
+                &mut writer.root.nodes,
+                gltf_json::Node {
+                    mesh: mesh_index,
+                    ..empty_node(Some(name.to_string()))
+                },
+            );
 
-        writer.root.scenes.push(json::Scene {
-            name: Some(format!("{name} display scene")),
-            nodes: vec![mesh_node],
-            extensions: None,
-            extras: Default::default(),
-        });
+            writer.root.scenes.push(json::Scene {
+                name: Some(format!("{name} display scene")),
+                nodes: vec![mesh_node],
+                extensions: None,
+                extras: Default::default(),
+            });
+        }
 
         p.finish().await;
     }
diff --git a/all-is-cubes-port/src/tests.rs b/all-is-cubes-port/src/tests.rs
index 6f53c4f8f..4415ec56e 100644
--- a/all-is-cubes-port/src/tests.rs
+++ b/all-is-cubes-port/src/tests.rs
@@ -20,6 +20,12 @@ fn errors_are_send_sync() {
     assert_send_sync::<ExportError>();
 }
 
+/// This function won't compile if `load_universe_from_file`'s future isn't Send
+fn _load_universe_from_file_future_is_send() {
+    #![allow(unreachable_code, clippy::diverging_sub_expression)]
+    tokio::spawn(load_universe_from_file(unreachable!(), unreachable!()));
+}
+
 #[tokio::test]
 async fn import_unknown_format() {
     let error = load_universe_from_file(
@@ -38,6 +44,17 @@ async fn import_unknown_format() {
     );
 }
 
+/// This function won't compile if `export_to_path`'s future isn't Send
+fn _export_to_path_future_is_send() {
+    #![allow(unreachable_code, clippy::diverging_sub_expression)]
+    tokio::spawn(export_to_path(
+        unreachable!(),
+        unreachable!(),
+        unreachable!(),
+        unreachable!(),
+    ));
+}
+
 #[test]
 fn member_export_path() {
     let mut universe = Universe::new();