feat: feature-gate the generator crates (rollout step 6)

Cargo.toml

@@ -27,8 +27,16 @@ toml = "0.8"
 # `comline-core` in the tree. Local dev: see .cargo/config.
 comline-core = { git = "https://github.com/ComlineProject/core", rev = "aa84d970d3295df59cc3e620bdb71bf96382f97b" }
 comline-codegen = { git = "https://github.com/ComlineProject/generation", rev = "4f29f4fce4e2e0b3775e4d687a7188112eaf58e3" }
-comline-codegen-rust = { git = "https://github.com/ComlineProject/comline-rust", rev = "070c77759b77f3f9a51ae217734277c95414f71f" }
-comline-codegen-typescript = { git = "https://github.com/ComlineProject/comline-typescript", rev = "97d8b2ea3db8b0489eaa8a1ad1fa2e89cfb391e6" }
+comline-codegen-rust = { git = "https://github.com/ComlineProject/comline-rust", rev = "070c77759b77f3f9a51ae217734277c95414f71f", optional = true }
+comline-codegen-typescript = { git = "https://github.com/ComlineProject/comline-typescript", rev = "97d8b2ea3db8b0489eaa8a1ad1fa2e89cfb391e6", optional = true }
+
+[features]
+# Which language generators are compiled in. Drop one to shed its whole
+# dependency tree from the build. A build with neither can compile but
+# `comline generate` will find no generator.
+default = ["gen-rust", "gen-typescript"]
+gen-rust = ["dep:comline-codegen-rust"]
+gen-typescript = ["dep:comline-codegen-typescript"]
 
 [target.'cfg(unix)'.dependencies]
 libc = "0.2"

src/commands/generate.rs

@@ -24,10 +24,15 @@ use crate::gen_config::{self, ComlineToml, DeclaredLang, Overrides, VersionSpec}
 use crate::{history, ui, watch};
 
 /// The generator registry, composed from the per-language `comline-codegen-*`
-/// crates this CLI was built with. (Feature-gating the set is rollout step 6.)
+/// crates this CLI was built with — one `register()` per crate, each behind its
+/// `gen-<lang>` cargo feature (both on by default). A build without a feature
+/// never compiles that generator crate or its dependency tree.
 pub(crate) fn generator_registry() -> Registry {
+    #[allow(unused_mut)]
     let mut registry = Registry::new();
+    #[cfg(feature = "gen-rust")]
     comline_codegen_rust::register(&mut registry);
+    #[cfg(feature = "gen-typescript")]
     comline_codegen_typescript::register(&mut registry);
     registry
 }