trivially implement PassByValue for usize

lib/src/atomic.rs

@@ -0,0 +1,15 @@
+//! Trait implementations for a few atomic types
+
+use crate::traits::*;
+
+impl PassByValue for usize {
+    type CType = usize;
+
+    unsafe fn from_ctype(arg: usize) -> usize {
+        arg
+    }
+
+    fn as_ctype(self) -> usize {
+        self
+    }
+}

lib/src/lib.rs

@@ -4,6 +4,7 @@ mod traits;
 mod util;
 
 pub mod arrays;
+pub mod atomic;
 pub mod replica;
 pub mod result;
 pub mod status;

lib/src/string.rs

@@ -248,15 +248,14 @@ pub extern "C" fn tc_string_content_with_len(
     //  - lifetime of tcstring outlives the lifetime of this function
     //  - lifetime of tcstring outlives the lifetime of the returned pointer (promised by caller)
     let tcstring = unsafe { TCString::from_arg_ref(tcstring) };
-    debug_assert!(!len_out.is_null());
 
     let bytes = tcstring.as_bytes();
 
     // SAFETY:
-    //  - len_out is not NULL (checked by assertion, promised by caller)
+    //  - len_out is not NULL (promised by caller)
     //  - len_out points to valid memory (promised by caller)
     //  - len_out is properly aligned (C convention)
-    unsafe { *len_out = bytes.len() };
+    unsafe { bytes.len().to_arg_out(len_out) };
     bytes.as_ptr() as *const libc::c_char
 }