feat: add --no-build to cook

src/main.rs

@@ -149,6 +149,11 @@ pub struct Cook {
     /// the `cargo-zigbuild` crate and the Zig compiler toolchain separately
     #[clap(long)]
     zigbuild: bool,
+    /// Modify the current workspace to maximise cache reuse, but don't invoke `cargo build`.
+    /// This option exist to leverage `cargo-chef` when trying to cache dependencies in Rust
+    /// projects that rely on a custom build system (i.e. not `cargo`).
+    #[clap(long)]
+    no_build: bool,
 }
 
 fn _main() -> Result<(), anyhow::Error> {
@@ -189,6 +194,7 @@ fn _main() -> Result<(), anyhow::Error> {
             bin,
             zigbuild,
             bins,
+            no_build,
         }) => {
             if std::io::stdout().is_terminal() {
                 eprintln!("WARNING stdout appears to be a terminal.");
@@ -235,12 +241,13 @@ fn _main() -> Result<(), anyhow::Error> {
                 (false, Some(custom_profile)) => OptimisationProfile::Other(custom_profile),
                 (true, Some(_)) => Err(anyhow!("You specified both --release and --profile arguments. Please remove one of them, or both"))?
             };
-            let command = match (check, clippy, zigbuild) {
-                (true, false, false) => CommandArg::Check,
-                (false, true, false) => CommandArg::Clippy,
-                (false, false, true) => CommandArg::Zigbuild,
-                (false, false, false) => CommandArg::Build,
-                _ => Err(anyhow!("Only one (or none) of the  `clippy`, `check` and `zigbuild` arguments are allowed. Please remove some of them, or all"))?,
+            let command = match (check, clippy, zigbuild, no_build) {
+                (true, false, false, false) => CommandArg::Check,
+                (false, true, false, false) => CommandArg::Clippy,
+                (false, false, true, false) => CommandArg::Zigbuild,
+                (false, false, false, true) => CommandArg::NoBuild,
+                (false, false, false, false) => CommandArg::Build,
+                _ => Err(anyhow!("Only one (or none) of the  `clippy`, `check`, `zigbuild`, and `no-build` arguments are allowed. Please remove some of them, or all"))?,
             };
 
             let default_features = if no_default_features {
@@ -287,6 +294,7 @@ fn _main() -> Result<(), anyhow::Error> {
                     frozen,
                     verbose,
                     bins,
+                    no_build,
                 })
                 .context("Failed to cook recipe.")?;
         }

src/recipe.rs

@@ -22,6 +22,7 @@ pub enum CommandArg {
     Check,
     Clippy,
     Zigbuild,
+    NoBuild,
 }
 
 pub struct CookArgs {
@@ -45,6 +46,7 @@ pub struct CookArgs {
     pub no_std: bool,
     pub bin: Option<Vec<String>>,
     pub bins: bool,
+    pub no_build: bool,
 }
 
 impl Recipe {
@@ -57,6 +59,9 @@ impl Recipe {
         let current_directory = std::env::current_dir()?;
         self.skeleton
             .build_minimum_project(&current_directory, args.no_std)?;
+        if args.no_build {
+            return Ok(());
+        }
         build_dependencies(&args);
         self.skeleton
             .remove_compiled_dummies(
@@ -111,6 +116,7 @@ fn build_dependencies(args: &CookArgs) {
         bin,
         no_std: _no_std,
         bins,
+        no_build: _no_build,
     } = args;
     let cargo_path = std::env::var("CARGO").expect("The `CARGO` environment variable was not set. This is unexpected: it should always be provided by `cargo` when invoking a custom sub-command, allowing `cargo-chef` to correctly detect which toolchain should be used. Please file a bug.");
     let mut command = Command::new(cargo_path);
@@ -119,6 +125,7 @@ fn build_dependencies(args: &CookArgs) {
         CommandArg::Check => command.arg("check"),
         CommandArg::Clippy => command.arg("clippy"),
         CommandArg::Zigbuild => command.arg("zigbuild"),
+        CommandArg::NoBuild => return,
     };
     if profile == &OptimisationProfile::Release {
         command_with_args.arg("--release");