Build: drop the unused egui patches and fail CI on [[patch.unused]] (#3404)

Removes the unused egui_demo_lib, egui_inspection and egui_system_font_provider patches and adds cargo xtask lock-patches to cargo xtask ci. Fixes #3403.

Cargo.lock

@@ -8037,18 +8037,3 @@ dependencies = [
  "syn 3.0.6",
  "winnow",
 ]
-
-[[patch.unused]]
-name = "egui_demo_lib"
-version = "0.37.0"
-source = "git+https://github.com/storytold/egui.git?rev=6d518fc799681571963842f95b55a6b68431b15a#6d518fc799681571963842f95b55a6b68431b15a"
-
-[[patch.unused]]
-name = "egui_inspection"
-version = "0.37.0"
-source = "git+https://github.com/storytold/egui.git?rev=6d518fc799681571963842f95b55a6b68431b15a#6d518fc799681571963842f95b55a6b68431b15a"
-
-[[patch.unused]]
-name = "egui_system_font_provider"
-version = "0.37.0"
-source = "git+https://github.com/storytold/egui.git?rev=6d518fc799681571963842f95b55a6b68431b15a#6d518fc799681571963842f95b55a6b68431b15a"

Cargo.toml

@@ -254,8 +254,7 @@ egui-wgpu = { git = "https://github.com/storytold/egui.git", rev = "6d518fc79968
 egui_glow = { git = "https://github.com/storytold/egui.git", rev = "6d518fc799681571963842f95b55a6b68431b15a" }
 egui_extras = { git = "https://github.com/storytold/egui.git", rev = "6d518fc799681571963842f95b55a6b68431b15a" }
 egui_kittest = { git = "https://github.com/storytold/egui.git", rev = "6d518fc799681571963842f95b55a6b68431b15a" }
-egui_system_font_provider = { git = "https://github.com/storytold/egui.git", rev = "6d518fc799681571963842f95b55a6b68431b15a" }
 eframe = { git = "https://github.com/storytold/egui.git", rev = "6d518fc799681571963842f95b55a6b68431b15a" }
-egui_demo_lib = { git = "https://github.com/storytold/egui.git", rev = "6d518fc799681571963842f95b55a6b68431b15a" }
-egui_inspection = { git = "https://github.com/storytold/egui.git", rev = "6d518fc799681571963842f95b55a6b68431b15a" }
+# Patch a crate only together with the dependency that needs it: an unused patch makes the Nix
+# build, which uses vendored sources, fail (`cargo xtask lock-patches`).
 winit = { git = "https://github.com/storytold/winit.git", rev = "a517b3846ee8457d84ee4975110bfda6797c44dc" }

docs/testing.md

@@ -2,7 +2,7 @@
 
 ```sh
 cargo test --workspace     # everything
-cargo xtask ci             # fmt, clippy -D warnings, tests, pdf-deps, layers, assets, wasm
+cargo xtask ci             # fmt, clippy -D warnings, tests, pdf-deps, lock-patches, layers, assets, wasm
 ```
 
 The After Effects test projects of `crates/aep` are not in the repository; without them the

xtask/src/lock_patches.rs

@@ -0,0 +1,71 @@
+//! Fail when `Cargo.lock` records a `[patch]` entry nothing uses.
+//!
+//! An unused patch only makes cargo warn, but the Nix package builds offline from vendored
+//! sources, which hold only the packages the build uses: it cannot find the patched package and
+//! refuses to build (#3403). Patch a crate together with the dependency that needs it.
+
+use std::path::Path;
+
+pub fn run(root: &Path) -> Result<(), String> {
+    let lock = std::fs::read_to_string(root.join("Cargo.lock")).map_err(|e| format!("Cargo.lock: {e}"))?;
+    let unused = unused_patches(&lock);
+    if unused.is_empty() {
+        println!("Cargo.lock: every [patch] entry is used");
+        return Ok(());
+    }
+    Err(format!(
+        "Cargo.lock has [[patch.unused]] entries: {}. Remove them from [patch] in Cargo.toml (add a patch together with the dependency that needs it); the Nix build, which uses vendored sources, fails on them (#3403)",
+        unused.join(", ")
+    ))
+}
+
+/// The package names of the `[[patch.unused]]` entries in the text of a `Cargo.lock`.
+fn unused_patches(lock: &str) -> Vec<String> {
+    let mut names = Vec::new();
+    let mut in_unused = false;
+    for line in lock.lines() {
+        let line = line.trim();
+        if line.starts_with('[') {
+            in_unused = line == "[[patch.unused]]";
+        } else if let Some(name) = line.strip_prefix("name = ").filter(|_| in_unused) {
+            names.push(name.trim_matches('"').to_string());
+        }
+    }
+    names
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const LOCK: &str = r#"
+[[package]]
+name = "egui"
+version = "0.37.0"
+
+[[patch.unused]]
+name = "egui_demo_lib"
+version = "0.37.0"
+source = "git+https://github.com/storytold/egui.git?rev=6d518fc#6d518fc"
+
+[[patch.unused]]
+name = "egui_inspection"
+version = "0.37.0"
+"#;
+
+    #[test]
+    fn lists_the_unused_patches_and_only_those() {
+        assert_eq!(unused_patches(LOCK), ["egui_demo_lib", "egui_inspection"]);
+    }
+
+    #[test]
+    fn a_lock_without_unused_patches_is_accepted() {
+        assert!(unused_patches("[[package]]\nname = \"egui\"\nversion = \"0.37.0\"\n").is_empty());
+    }
+
+    #[test]
+    fn the_repository_lock_has_no_unused_patches() {
+        let root = Path::new(env!("CARGO_MANIFEST_DIR")).join("..");
+        assert!(run(&root).is_ok(), "{:?}", run(&root));
+    }
+}

xtask/src/main.rs

@@ -1,4 +1,4 @@
-//! Workspace automation: `cargo xtask <layers|assets|pdf-deps|aep-corpus|wasm|web|ico|ci>`.
+//! Workspace automation: `cargo xtask <layers|assets|pdf-deps|lock-patches|aep-corpus|wasm|web|ico|ci>`.
 //!
 //! - `layers`: enforces the dependency layering of `docs/architecture.md` §1 (downward-only edges,
 //!   listed same-layer edges, no UI/OS crates below L5).
@@ -6,6 +6,7 @@
 //!   and the web app.
 //! - `web [--dev] [--serve PORT]`: build the web app (`apps/effectcraft-web`) into
 //!   `<target>/web/dist` with `wasm-bindgen` (docs/web.md); `--serve` serves it on localhost.
+//! - `lock-patches`: `Cargo.lock` records no unused `[patch]` entry (the Nix build cannot vendor one).
 //! - `assets`: every asset file (image, icon, font, LUT, audio, video…) has a complete
 //!   `<file>.attribution` sidecar and an entry in `ATTRIBUTION.md` (AGENTS.md §1).
 //! - `aep-corpus [--dir DIR]`: fetch the After Effects test corpus at the commit pinned in
@@ -19,6 +20,7 @@
 mod aep_corpus;
 mod bench;
 mod ico;
+mod lock_patches;
 mod pdf_deps;
 mod version;
 
@@ -534,12 +536,13 @@ type Stage = fn() -> Result<(), String>;
 
 /// Every stage runs even when an earlier one fails, so one run reports all the problems.
 fn ci() -> Result<(), String> {
-    let stages: [(&str, Stage); 8] = [
+    let stages: [(&str, Stage); 9] = [
         ("audio backend", audio_backend),
         ("fmt", || run(Command::new(env!("CARGO")).args(["fmt", "--check"]))),
         ("clippy", || run(Command::new(env!("CARGO")).args(["clippy", "--workspace", "--all-targets", "--", "-D", "warnings"]))),
         ("tests", tests),
         ("pdf-deps", || pdf_deps::run(&root())),
+        ("lock-patches", || lock_patches::run(&root())),
         ("layers", layers),
         ("assets", assets),
         ("wasm", wasm),
@@ -555,6 +558,7 @@ fn main() -> ExitCode {
         "wasm" => wasm(),
         "assets" => assets(),
         "pdf-deps" => pdf_deps::run(&root()),
+        "lock-patches" => lock_patches::run(&root()),
         "aep-corpus" => aep_corpus::run(&root(), &std::env::args().skip(2).collect::<Vec<_>>()),
         "ci" => ci(),
         "audio-backend" => audio_backend(),
@@ -568,7 +572,7 @@ fn main() -> ExitCode {
             let rest: Vec<String> = std::env::args().skip(2).collect();
             version::run(&root(), &rest.iter().map(String::as_str).collect::<Vec<_>>())
         }
-        _ => Err("usage: cargo xtask <layers|assets|pdf-deps|aep-corpus [--dir DIR]|wasm|web [--dev] [--serve PORT]|ico OUT.ico IN.png…|version [set X.Y.Z]|ci|audio-backend|bench [--bin CLI] [--quick] [--project F --comp C] [--compare OLD.jsonl] (--help)>".into()),
+        _ => Err("usage: cargo xtask <layers|assets|pdf-deps|lock-patches|aep-corpus [--dir DIR]|wasm|web [--dev] [--serve PORT]|ico OUT.ico IN.png…|version [set X.Y.Z]|ci|audio-backend|bench [--bin CLI] [--quick] [--project F --comp C] [--compare OLD.jsonl] (--help)>".into()),
     };
     match r {
         Ok(()) => ExitCode::SUCCESS,