build(sim): scope objc2/private-framework deps to macOS so Linux CI skips the ObjC helper

Author: AprilNEA

crates/linkcode-sim/Cargo.toml

@@ -14,10 +14,15 @@ name = "linkcode-sim"
 path = "src/main.rs"
 
 [dependencies]
-block2 = "0.6.2"
 libc = "0.2.189"
+serde = { version = "1.0.228", features = ["derive"] }
+serde_json = "1.0.150"
+
+# The private-framework layer (CoreSimulator/SimulatorKit via objc2/block2) is macOS-only and its
+# use is all behind `#[cfg(target_os = "macos")]`. Scope these deps to macOS so a Linux CI build
+# doesn't compile objc2's Objective-C exception helper, which needs an ObjC toolchain (cc1obj).
+[target.'cfg(target_os = "macos")'.dependencies]
+block2 = "0.6.2"
 objc2 = { version = "0.6.4", features = ["exception"] }
 objc2-core-foundation = "0.3.2"
 objc2-foundation = "0.3.2"
-serde = { version = "1.0.228", features = ["derive"] }
-serde_json = "1.0.150"