Relax derive for structs by only requiring Atom field

Before, `PrimitiveAtom` was required. But `Atom` is absolutely enough.

Author: LukasKalbertodt

atomig-macro/src/lib.rs

@@ -105,7 +105,7 @@ fn atom_impl_for_struct(s: &DataStruct) -> Result<TokenStream2, Error> {
         return Err(Error::new(s.fields.span(), msg));
     }
 
-    // Generate the code for `pack` and `unpack` which depends on weather it is
+    // Generate the code for `pack` and `unpack` which depends on whether it is
     // a named or tuple-struct field.
     let (field_access, struct_init) = match &field.ident {
         Some(name) => (quote! { self.#name }, quote! { Self { #name: src } }),
@@ -114,12 +114,13 @@ fn atom_impl_for_struct(s: &DataStruct) -> Result<TokenStream2, Error> {
 
     let field_type = &field.ty;
     Ok(quote! {
-        type Repr = #field_type;
+        type Repr = <#field_type as atomig::Atom>::Repr;
 
         fn pack(self) -> Self::Repr {
-            #field_access
+            <#field_type as atomig::Atom>::pack(#field_access)
         }
         fn unpack(src: Self::Repr) -> Self {
+            let src = <#field_type as atomig::Atom>::unpack(src);
             #struct_init
         }
     })

examples/custom_type.rs

@@ -2,6 +2,7 @@
 //! deriving `Atom`.
 
 use std::{
+    num::NonZeroU16,
     sync::Arc,
     thread,
     time::Duration,
@@ -20,6 +21,9 @@ enum Animal {
 #[derive(Debug, PartialEq, Atom, AtomLogic)]
 struct BitSet(u16);
 
+// The inner type only has to implement `Atom`, not `PrimitiveAtom`.
+#[derive(Debug, PartialEq, Atom)]
+struct Port(NonZeroU16);
 
 fn main() {
     // Example with `Animal`

src/lib.rs

@@ -163,8 +163,7 @@ pub use atomig_macro::{Atom, AtomInteger, AtomLogic};
 ///
 /// The trait can be automatically derived for two kinds of types:
 /// - `struct` types with only *one* field. That field's type has to implement
-///   `PrimitiveAtom` and is used as `Repr` type. Works with tuple structs or
-///   normal structs with named fields.
+///   `Atom`. Works with tuple structs or normal structs with one named field.
 /// - `enum` types that have a `#[repr(_)]` attribute specified and are C-like
 ///   (i.e. no variant has any fields). The primitive type specified in the
 ///   `#[repr(_)]` attribute is used as `Repr` type.