From 4e3ab7fa6a11e481198aee57cdd907b258c80e64 Mon Sep 17 00:00:00 2001
From: Stephen Chung <schungx@live.com>
Date: Fri, 19 Feb 2021 15:49:51 +0800
Subject: [PATCH] Add compiler guards for mutually-exclusive features.

---
 src/lib.rs | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/src/lib.rs b/src/lib.rs
index 04f494c6..db6e4687 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -41,7 +41,7 @@
 //!     engine.register_fn("compute", compute_something);
 //!
 //! #   #[cfg(not(feature = "no_std"))]
-//! #   #[cfg(not(target_arch = "wasm32"))]
+//! #   #[cfg(not(any(target_arch = "wasm32", target_arch = "wasm64")))]
 //!     assert_eq!(
 //!         // Evaluate the script, expects a 'bool' return
 //!         engine.eval_file::<bool>("my_script.rhai".into())?,
@@ -61,6 +61,8 @@
 #[cfg(feature = "no_std")]
 extern crate alloc;
 
+// Internal modules
+
 mod ast;
 mod dynamic;
 mod engine;
@@ -207,3 +209,29 @@ type StaticVec<T> = smallvec::SmallVec<[T; 4]>;
 /// Exported under the `internals` feature only.
 #[cfg(feature = "internals")]
 pub type StaticVec<T> = smallvec::SmallVec<[T; 4]>;
+
+// Compiler guards against mutually-exclusive feature flags
+
+#[cfg(feature = "no_float")]
+#[cfg(feature = "f32_float")]
+compile_error!("'f32_float' cannot be used with 'no_float'");
+
+#[cfg(feature = "no_std")]
+#[cfg(feature = "wasm-bindgen")]
+compile_error!("'wasm-bindgen' cannot be used with 'no-std'");
+
+#[cfg(feature = "no_std")]
+#[cfg(feature = "stdweb")]
+compile_error!("'stdweb' cannot be used with 'no-std'");
+
+#[cfg(any(target_arch = "wasm32", target_arch = "wasm64"))]
+#[cfg(feature = "no_std")]
+compile_error!("'no_std' cannot be used for WASM target");
+
+#[cfg(not(any(target_arch = "wasm32", target_arch = "wasm64")))]
+#[cfg(feature = "wasm-bindgen")]
+compile_error!("'wasm-bindgen' should not be used non-WASM target");
+
+#[cfg(not(any(target_arch = "wasm32", target_arch = "wasm64")))]
+#[cfg(feature = "stdweb")]
+compile_error!("'stdweb' should not be used non-WASM target");