Fixed compilation errors

Cargo.toml

@@ -13,8 +13,7 @@ readme = "README.md"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-default-features = false
-libc = "0.2"
+libc = { version = "0.2", default-features = false }
 
 [dev-dependencies]
 expect-test = "1.4"

src/cee_based.rs

@@ -30,15 +30,15 @@ where
     }
 
     unsafe {
-        let closure_env_ptr = std::ptr::addr_of_mut!(callback);
+        let closure_env_ptr = core::ptr::addr_of_mut!(callback);
 
         // The callback is now effectively owned by `closure_env_ptr` (i.e., the
         // `closure_env_ptr.read()` call in `call_from_c_to_rust` will take a
         // direct bitwise copy of its state, and pass that ownership into the
         // FnOnce::call_once invocation.)
         //
         // Therefore, we need to forget about our own ownership of the callback now.
-        std::mem::forget(callback);
+        core::mem::forget(callback);
 
         call_closure_with_setjmp(closure_env_ptr as *mut c_void, call_from_c_to_rust::<F>)
     }
@@ -66,15 +66,15 @@ where
     let savemask: c_int = if savemask { 1 } else { 0 };
 
     unsafe {
-        let closure_env_ptr = std::ptr::addr_of_mut!(callback);
+        let closure_env_ptr = core::ptr::addr_of_mut!(callback);
 
         // The callback is now effectively owned by `closure_env_ptr` (i.e., the
         // `closure_env_ptr.read()` call in `call_from_c_to_rust` will take a
         // direct bitwise copy of its state, and pass that ownership into the
         // FnOnce::call_once invocation.)
         //
         // Therefore, we need to forget about our own ownership of the callback now.
-        std::mem::forget(callback);
+        core::mem::forget(callback);
 
         call_closure_with_sigsetjmp(savemask, closure_env_ptr as *mut c_void, call_from_c_to_rust::<F>)
     }

src/lib.rs

@@ -174,7 +174,7 @@
 //!     })
 //! });
 //! ```
-#![no_std]
+#![cfg_attr(not(test), no_std)]
 
 use libc::c_int;