ui: Make a no_std build possible.

The part that we can neatly cut off, in this case, is `Session`
and its associated UI -- stuff that requires channels and mutexes.
What we keep is the `vui` and `logo` modules.

.github/workflows/ci.yml

@@ -467,13 +467,13 @@ jobs:
 
     - name: no_std lint
       run: |
-        cargo clippy --target=thumbv7em-none-eabihf --no-default-features -p all-is-cubes -p all-is-cubes-render -p all-is-cubes-mesh
+        cargo clippy --target=thumbv7em-none-eabihf --no-default-features -p all-is-cubes -p all-is-cubes-render -p all-is-cubes-ui -p all-is-cubes-mesh
 
     - name: no_std build
       # This is `cargo build`, not `cargo check`, because `cargo check` won't detect problems like
       # use of undefined linker symbols. Not sure if that matters.
       run: |
-        cargo build --target=thumbv7em-none-eabihf --no-default-features -p all-is-cubes -p all-is-cubes-render -p all-is-cubes-mesh
+        cargo build --target=thumbv7em-none-eabihf --no-default-features -p all-is-cubes -p all-is-cubes-render -p all-is-cubes-ui -p all-is-cubes-mesh
 
   fuzz:
     # Don't spend time on fuzzing if the build failed indicating the code is bad other ways

all-is-cubes-desktop/Cargo.toml

@@ -70,7 +70,7 @@ all-is-cubes-mesh = { workspace = true, optional = true, features = ["dynamic"]
 all-is-cubes-port = { workspace = true, features = ["import", "native"] }
 # TODO: make raytracer optional
 all-is-cubes-render = { workspace = true, features = ["raytracer"] }
-all-is-cubes-ui = { workspace = true }
+all-is-cubes-ui = { workspace = true, features = ["session"] }
 anyhow = { workspace = true }
 cfg-if = { workspace = true }
 clap = { workspace = true }

all-is-cubes-port/Cargo.toml

@@ -57,7 +57,7 @@ dot-vox = [
 
 [dependencies]
 # Non-optional generally required dependencies
-# need all-is-cubes/std because we have boxed Send futures
+# need all-is-cubes/std because we have boxed Send futures and errors
 all-is-cubes = { workspace = true, features = ["std"] }
 cfg-if = { workspace = true }
 futures-core = { workspace = true }

all-is-cubes-ui/Cargo.toml

@@ -12,27 +12,41 @@ categories = ["games", "gui"]
 keywords = ["all-is-cubes", "voxel"]
 
 [package.metadata.docs.rs]
-features = []
+features = ["session"]
 
 [lib]
 # Disable running as benchmark so that the default doesn't interfere with Criterion usage.
 bench = false
 
+[features]
+# Enable the `apps` and `notification` modules, particularly including the `Session` type,
+# and require `std` support.
+session = [
+    "all-is-cubes/std",
+    "dep:async_fn_traits",
+    "dep:flume",
+    "dep:futures-core",
+    "dep:futures-task",
+    "dep:futures-util",
+    "dep:scopeguard",
+    "dep:sync_wrapper",
+]
+
 [dependencies]
-# TODO: Disable default features. Requires more `maybe_sync` work.
-all-is-cubes = { workspace = true, default-features = true }
-all-is-cubes-render = { workspace = true, default-features = true }
-async_fn_traits = { workspace = true }
+all-is-cubes = { workspace = true, default-features = false }
+all-is-cubes-render = { workspace = true, default-features = false }
+async_fn_traits = { workspace = true, optional = true }
 displaydoc = { workspace = true }
 exhaust = { workspace = true }
-flume = { workspace = true }
-futures-core = { workspace = true }
-futures-task = { workspace = true }
-futures-util = { workspace = true }
+flume = { workspace = true, optional = true }
+futures-core = { workspace = true, optional = true }
+futures-task = { workspace = true, optional = true }
+futures-util = { workspace = true, optional = true }
 indoc = { workspace = true }
 log = { workspace = true }
-scopeguard = { workspace = true }
-sync_wrapper = { workspace = true }
+num-traits = { workspace = true }
+scopeguard = { workspace = true, optional = true }
+sync_wrapper = { workspace = true, optional = true }
 
 [dev-dependencies]
 futures-channel = { workspace = true }

all-is-cubes-ui/src/apps/input.rs

@@ -3,6 +3,8 @@
     reason = "module is private; https://github.com/rust-lang/rust-clippy/issues/8524"
 )]
 
+
+use alloc::vec::Vec;
 use core::time::Duration;
 use std::collections::{HashMap, HashSet};
 

all-is-cubes-ui/src/apps/session.rs

@@ -3,6 +3,8 @@
     reason = "module is private; https://github.com/rust-lang/rust-clippy/issues/8524"
 )]
 
+use alloc::boxed::Box;
+use alloc::string::ToString as _;
 use alloc::sync::{Arc, Weak};
 use core::fmt;
 use core::future::Future;

all-is-cubes-ui/src/editor.rs

@@ -1,13 +1,15 @@
 //! VUI components related to allowing the user to inspect universe contents.
 
-use all_is_cubes::universe::Handle;
 use alloc::sync::Arc;
+use alloc::vec;
+use alloc::vec::Vec;
 
 use all_is_cubes::arcstr::{self, literal, ArcStr};
 use all_is_cubes::block::{self, Block};
 use all_is_cubes::character::Cursor;
 use all_is_cubes::euclid::size3;
 use all_is_cubes::math::Face6;
+use all_is_cubes::universe::Handle;
 
 use crate::ui_content::hud::HudInputs;
 use crate::ui_content::pages::back_button;

all-is-cubes-ui/src/inv_watch.rs

@@ -4,7 +4,7 @@
 //! "derived information from a `ListenableSource` that requires computation" and should become
 //! general code that handles the re-listening problem.
 
-use std::sync::Arc;
+use alloc::sync::Arc;
 
 use all_is_cubes::character::{Character, CharacterChange};
 use all_is_cubes::inv::{Inventory, TOOL_SELECTIONS};

all-is-cubes-ui/src/lib.rs

@@ -18,21 +18,29 @@
 //! [`Space`]: all_is_cubes::space::Space
 //! [`Universe`]: all_is_cubes::universe::Universe
 
-// This crate is not `no_std` because it currently uses `std::sync::mpsc`.
-
+#![no_std]
 // Crate-specific lint settings. (General settings can be found in the workspace manifest.)
 #![forbid(unsafe_code)]
 
 extern crate alloc;
 
+#[cfg(any(test, feature = "session"))]
+#[macro_use]
+extern crate std;
+
+#[cfg(feature = "session")]
 mod editor;
+#[cfg(feature = "session")]
 mod inv_watch;
 
+#[cfg(feature = "session")]
 pub mod apps;
 
 pub mod logo;
 
+#[cfg(feature = "session")]
 mod ui_content;
+#[cfg(feature = "session")]
 pub use ui_content::notification;
 
 pub mod vui;

all-is-cubes-ui/src/ui_content/notification.rs

@@ -1,6 +1,7 @@
 //! Types used to create notifications displayed to the user.
 
 use alloc::sync::{Arc, Weak};
+use alloc::vec::Vec;
 use std::sync::Mutex;
 
 use all_is_cubes::listen;

all-is-cubes-ui/src/ui_content/options.rs

@@ -1,4 +1,6 @@
+use alloc::boxed::Box;
 use alloc::sync::Arc;
+use alloc::vec::Vec;
 use core::fmt;
 
 use all_is_cubes::arcstr::{self, literal};

all-is-cubes-ui/src/ui_content/pages.rs

@@ -1,5 +1,6 @@
 //! Contents of various UI pages.
 
+use alloc::string::String;
 use alloc::sync::Arc;
 
 use all_is_cubes::arcstr::{literal, ArcStr};

all-is-cubes-ui/src/ui_content/vui_manager.rs

@@ -1,3 +1,4 @@
+use alloc::string::{String, ToString as _};
 use alloc::sync::Arc;
 use core::future::Future;
 use flume::TryRecvError;

all-is-cubes-ui/src/vui/layout.rs

@@ -3,8 +3,11 @@
     reason = "module is private; https://github.com/rust-lang/rust-clippy/issues/8524"
 )]
 
+use alloc::boxed::Box;
 use alloc::rc::Rc;
 use alloc::sync::Arc;
+use alloc::vec;
+use alloc::vec::Vec;
 use core::fmt;
 
 use all_is_cubes::euclid::{self, size3, Size3D, Vector3D};

all-is-cubes-ui/src/vui/mod.rs

@@ -6,10 +6,13 @@
 
 #[doc(hidden)] // public for use by test-renderers only
 pub mod blocks;
+#[cfg(feature = "session")]
 pub(crate) use blocks::UiBlocks;
 mod layout;
 pub use layout::*;
+#[cfg(feature = "session")]
 mod page;
+#[cfg(feature = "session")]
 pub(crate) use page::*;
 mod widget_trait;
 pub use widget_trait::*;

all-is-cubes-ui/src/vui/page.rs

@@ -1,4 +1,5 @@
 use alloc::sync::Arc;
+use alloc::vec;
 
 use all_is_cubes::arcstr::ArcStr;
 use all_is_cubes::block::{text, AIR};
@@ -336,6 +337,7 @@ pub(crate) mod parts {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use alloc::vec::Vec;
 
     #[test]
     fn ui_size() {

all-is-cubes-ui/src/vui/widget_trait.rs

@@ -1,6 +1,7 @@
 //! UI [`Widget`] trait and related glue.
 
 use all_is_cubes::time::Tick;
+use alloc::boxed::Box;
 use alloc::sync::Arc;
 use core::error::Error;
 use core::fmt::Debug;
@@ -10,7 +11,7 @@ use all_is_cubes::math::GridAab;
 use all_is_cubes::space::{self, Space, SpaceTransaction};
 use all_is_cubes::transaction::{self, Merge as _};
 use all_is_cubes::universe::{HandleVisitor, UniverseTransaction, VisitHandles};
-use all_is_cubes::util::maybe_sync::{Mutex, SendSyncIfStd};
+use all_is_cubes::util::maybe_sync::{self, SendSyncIfStd};
 
 // reused for WidgetController
 pub use all_is_cubes::behavior::Then;
@@ -112,7 +113,9 @@ pub type StepSuccess = (WidgetTransaction, Then);
 /// Error return of [`WidgetController::step()`].
 ///
 /// TODO: This should become a more specific error type.
-pub type StepError = Box<dyn Error + Send + Sync>;
+//---
+// This is a type alias to cope with the maybe-Sync kludge without exposing that everywhere.
+pub type StepError = maybe_sync::BoxError;
 
 impl WidgetController for Box<dyn WidgetController> {
     fn step(&mut self, context: &WidgetContext<'_>) -> Result<StepSuccess, StepError> {
@@ -136,7 +139,7 @@ impl WidgetController for Box<dyn WidgetController> {
 pub(super) struct WidgetBehavior {
     /// Original widget -- not used directly but for error reporting
     widget: Positioned<Arc<dyn Widget>>,
-    controller: Mutex<Box<dyn WidgetController>>,
+    controller: maybe_sync::Mutex<Box<dyn WidgetController>>,
 }
 
 impl WidgetBehavior {
@@ -163,7 +166,7 @@ impl WidgetBehavior {
             space::SpaceBehaviorAttachment::new(widget.position.bounds),
             Arc::new(WidgetBehavior {
                 widget,
-                controller: Mutex::new(controller),
+                controller: maybe_sync::Mutex::new(controller),
             }),
         );
         init_txn
@@ -324,11 +327,11 @@ pub(crate) fn instantiate_widget<W: Widget + 'static>(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use all_is_cubes::util::assert_send_sync;
+    use all_is_cubes::util::assert_conditional_send_sync;
 
     #[test]
     fn error_is_send_sync() {
-        assert_send_sync::<InstallVuiError>()
+        assert_conditional_send_sync::<InstallVuiError>()
     }
 
     fn _assert_widget_trait_is_object_safe(_: &dyn Widget) {}

all-is-cubes-ui/src/vui/widgets/button.rs

@@ -3,6 +3,9 @@
     reason = "module is private; https://github.com/rust-lang/rust-clippy/issues/8524"
 )]
 
+use alloc::borrow::ToOwned as _;
+use alloc::boxed::Box;
+use alloc::format;
 use alloc::sync::Arc;
 use core::fmt;
 use core::hash::Hash;
@@ -549,7 +552,7 @@ mod theme {
     /// Build a [`Block`] for [`ButtonBase`].
     pub fn common_block(space: Handle<Space>, name: &str) -> Block {
         Block::builder()
-            .display_name(name.to_string())
+            .display_name(name)
             .voxels_handle(MULTI_RESOLUTION, space)
             .animation_hint(block::AnimationHint::replacement(
                 block::AnimationChange::Shape,

all-is-cubes-ui/src/vui/widgets/crosshair.rs

@@ -1,3 +1,4 @@
+use alloc::boxed::Box;
 use alloc::sync::Arc;
 
 use all_is_cubes::block::{Block, AIR};

all-is-cubes-ui/src/vui/widgets/debug.rs

@@ -1,3 +1,4 @@
+use alloc::boxed::Box;
 use alloc::sync::Arc;
 
 use all_is_cubes::block::{self, text, Block, Resolution::R64};

all-is-cubes-ui/src/vui/widgets/frame.rs

@@ -1,4 +1,6 @@
+use alloc::boxed::Box;
 use alloc::sync::Arc;
+use alloc::vec;
 
 use all_is_cubes::block::Block;
 use all_is_cubes::euclid::size3;

all-is-cubes-ui/src/vui/widgets/mod.rs

@@ -1,5 +1,6 @@
 //! Specific UI widgets.
 
+use alloc::boxed::Box;
 use alloc::sync::Arc;
 
 use all_is_cubes::block::Block;
@@ -8,7 +9,9 @@ use all_is_cubes::space::SpaceTransaction;
 
 use crate::vui;
 
+#[cfg(feature = "session")]
 mod crosshair;
+#[cfg(feature = "session")]
 pub(crate) use crosshair::*;
 mod frame;
 pub use frame::*;
@@ -22,9 +25,13 @@ mod progress_bar;
 pub use progress_bar::*;
 mod theme;
 pub use theme::*;
+#[cfg(feature = "session")]
 mod toolbar;
+#[cfg(feature = "session")]
 pub(crate) use toolbar::*;
+#[cfg(feature = "session")]
 mod tooltip;
+#[cfg(feature = "session")]
 pub(crate) use tooltip::*;
 mod voxels;
 pub use voxels::*;

all-is-cubes-ui/src/vui/widgets/progress_bar.rs

@@ -3,7 +3,13 @@
     reason = "module is private; https://github.com/rust-lang/rust-clippy/issues/8524"
 )]
 
-use std::sync::Arc;
+use alloc::boxed::Box;
+use alloc::sync::Arc;
+
+/// Acts as polyfill for float methods
+#[cfg(not(feature = "session"))]
+#[allow(unused_imports)]
+use num_traits::float::FloatCore as _;
 
 use all_is_cubes::block::{self, Block, Composite, CompositeOperator, AIR};
 use all_is_cubes::color_block;
@@ -208,6 +214,8 @@ mod tests {
     use all_is_cubes::transaction::Transaction as _;
     use all_is_cubes::util::yield_progress_for_testing;
     use all_is_cubes::{transaction, universe};
+    use alloc::string::String;
+    use alloc::vec::Vec;
 
     #[tokio::test]
     async fn progress_output() {