docs: update placement visibility (#11)

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde-inline-default"
-version = "0.2.1"
+version = "0.2.3"
 authors = ["bytedream"]
 edition = "2021"
 description = "Serde default values via inline declaration"

README.md

@@ -1,4 +1,4 @@
-# serde-inline-default [![ci](https://github.com/ByteDream/serde-inline-default/actions/workflows/ci.yml/badge.svg)](https://github.com/ByteDream/serde-inline-default/actions/workflows/ci.yml) [![crates.io](https://img.shields.io/crates/v/serde-inline-default)](https://crates.io/crates/serde-inline-default) [![docs](https://img.shields.io/docsrs/serde-inline-default)](https://docs.rs/serde-inline-default/latest/serde_inline_default/)
+# serde-inline-default [![ci](https://github.com/ByteDream/serde-inline-default/actions/workflows/ci.yml/badge.svg)](https://github.com/ByteDream/serde-inline-default/actions/workflows/ci.yml) [![crates.io](https://img.shields.io/crates/v/serde-inline-default)](https://crates.io/crates/serde-inline-default) [![crates.io downloads](https://img.shields.io/crates/d/serde-inline-default)](https://crates.io/crates/serde-inline-default) [![docs](https://img.shields.io/docsrs/serde-inline-default)](https://docs.rs/serde-inline-default/latest/serde_inline_default/)
 
 Tiny crate to set default values for serde fields via inline attribute declaration.
 
@@ -19,7 +19,7 @@ fn value_default() -> u32 { 42 }
 
 That can get quiet messy if you have many fields with many (different) default values.
 This crate tries to solve this issue by providing the `#[serde_inline_default]` proc macro.
-With this macro set at the struct level (_**before `#[derive(Deserialize)]`/`#[derive(Serialize)]`!, otherwise it's not working correctly**_), you can set default values via `#[serde_inline_default(...)]` for your serde fields inline, without creating an extra function.
+With this macro set at the struct level, you can set default values via `#[serde_inline_default(...)]` for your serde fields inline, without creating an extra function.
 
 ```rust
 #[serde_inline_default]
@@ -30,9 +30,54 @@ struct Test {
 }
 ```
 
+> [!IMPORTANT]
+> **`#[serde_inline_default]` must be set before `#[derive(Deserialize)]`/`#[derive(Serialize)]`, otherwise it's not working correctly!**
+
 Internally, `#[serde_inline_default(...)]` gets expanded to a function which returns the set value and the attribute is replaced with `#[serde(default = "<function name>")]`.
 So this macro is just some syntax sugar for you, but can get quiet handy if you want to keep your code clean or write declarative macros / `macro_rules!`.
 
+## Alternatives
+
+This crate isn't perfect. Thus, you might be more satisfied with alternatives `serde` provides.
+
+With `#[serde(default)]` + `impl Default` on a struct, `serde` uses the default implementation of the struct to get default values for each field ([docs](https://serde.rs/container-attrs.html#default)):
+```rust
+#[derive(Deserialize)]
+#[serde(default)]
+struct Test {
+    value: u32
+}
+
+impl Default for Test {
+    fn default() -> Self {
+        Self {
+            value: 42
+        }
+    }
+}
+```
+
+If you still need/want `serde-inline-default` features, you also can combine them with `#[serde(default))` and `impl Default`:
+```rust
+#[serde_inline_default]
+#[derive(Deserialize)]
+#[serde(default)]
+struct Test {
+    value: u32,
+    #[serde_inline_default(0)]
+    other_value: u32,
+}
+
+impl Default for Test {
+    fn default() -> Self {
+        Self {
+            value: 42,
+            other_value: 42
+        }
+    }
+}
+```
+
 ## License
 
 This project is licensed under either of the following licenses, at your option:

src/expand.rs

@@ -1,9 +1,10 @@
+use crate::utils::type_lifetimes_to_static;
 use proc_macro2::{Ident, Span, TokenStream};
 use quote::quote;
 use syn::{parse_quote, ItemStruct};
 
 pub(crate) fn expand_struct(mut item: ItemStruct) -> proc_macro::TokenStream {
-    let mut inline_fns: Vec<(String, TokenStream, TokenStream)> = vec![];
+    let mut inline_fns: Vec<TokenStream> = vec![];
 
     for (i, field) in item.fields.iter_mut().enumerate() {
         for (j, attr) in field.attrs.iter_mut().enumerate() {
@@ -13,28 +14,21 @@ pub(crate) fn expand_struct(mut item: ItemStruct) -> proc_macro::TokenStream {
 
             let default: TokenStream = attr.parse_args().unwrap();
 
-            // we check here if a function with the exact same return value already exists. if so,
+            let fn_name_lit = format!("__serde_inline_default_{}_{}", item.ident, i);
-            // this function gets used.
+            let fn_name_ident = Ident::new(&fn_name_lit, Span::call_site());
-            let fn_name_lit = if let Some((fn_name_lit, _, _)) = inline_fns
+            let mut return_type = field.ty.clone();
-                .iter()
+
-                .find(|(_, def, _)| def.to_string() == default.to_string())
+            // replaces most lifetimes with 'static
-            {
+            type_lifetimes_to_static(&mut return_type);
-                fn_name_lit.clone()
+
-            } else {
+            inline_fns.push(quote! {
-                let fn_name_lit = format!("__serde_inline_default_{}_{}", item.ident, i);
+                #[doc(hidden)]
-                let fn_name_ident = Ident::new(&fn_name_lit, Span::call_site());
+                #[allow(non_snake_case)]
-                let return_type = &field.ty;
+                fn #fn_name_ident () -> #return_type {
+                    #default
+                }
+            });
 
-                let inline_fn = quote! {
-                    #[doc(hidden)]
-                    #[allow(non_snake_case)]
-                    fn #fn_name_ident () -> #return_type {
-                        #default
-                    }
-                };
-                inline_fns.push((fn_name_lit.clone(), default, inline_fn));
-                fn_name_lit
-            };
             field.attrs.remove(j);
             field
                 .attrs
@@ -43,10 +37,8 @@ pub(crate) fn expand_struct(mut item: ItemStruct) -> proc_macro::TokenStream {
         }
     }
 
-    let real_inline_fns: Vec<TokenStream> =
-        inline_fns.into_iter().map(|(_, _, func)| func).collect();
     let expanded = quote! {
-        #( #real_inline_fns )*
+        #( #inline_fns )*
 
         #item
     };

src/lib.rs

@@ -4,6 +4,7 @@ use proc_macro::TokenStream;
 use syn::{parse_macro_input, Item};
 
 mod expand;
+mod utils;
 
 /// The main macro of this crate.
 /// Use it to define default values of fields in structs you [`Serialize`] or [`Deserialize`].

src/utils.rs

@@ -0,0 +1,40 @@
+use syn::{parse_quote, GenericArgument, PathArguments, Type};
+
+pub(crate) fn type_lifetimes_to_static(ty: &mut Type) {
+    match ty {
+        Type::Array(array) => type_lifetimes_to_static(array.elem.as_mut()),
+        Type::Group(group) => type_lifetimes_to_static(&mut group.elem),
+        Type::Path(path) => {
+            for segment in &mut path.path.segments {
+                match &mut segment.arguments {
+                    PathArguments::None => (),
+                    PathArguments::AngleBracketed(angle_bracketed) => {
+                        for arg in &mut angle_bracketed.args {
+                            match arg {
+                                GenericArgument::Lifetime(lifetime) => {
+                                    *lifetime = parse_quote!('static);
+                                }
+                                GenericArgument::Type(ty) => type_lifetimes_to_static(ty),
+                                _ => (),
+                            }
+                        }
+                    }
+                    PathArguments::Parenthesized(parenthesized) => {
+                        for input in &mut parenthesized.inputs {
+                            type_lifetimes_to_static(input)
+                        }
+                    }
+                }
+            }
+        }
+        Type::Ptr(ptr) => type_lifetimes_to_static(&mut ptr.elem),
+        Type::Reference(reference) => reference.lifetime = Some(parse_quote!('static)),
+        Type::Slice(slice) => type_lifetimes_to_static(&mut slice.elem),
+        Type::Tuple(tuple) => {
+            for elem in &mut tuple.elems {
+                type_lifetimes_to_static(elem)
+            }
+        }
+        _ => (),
+    }
+}

tests/test_serde_inline_default.rs

@@ -1,6 +1,7 @@
 use serde::Deserialize;
 use serde_inline_default::serde_inline_default;
 use serde_json::json;
+use std::borrow::Cow;
 
 #[test]
 fn test_serde_inline_default() {
@@ -28,3 +29,17 @@ fn test_serde_inline_default() {
     assert_eq!(test.inline_negative, -1337);
     assert_eq!(test.string, "string".to_string());
 }
+
+#[test]
+fn test_lifetime() {
+    #[serde_inline_default]
+    #[derive(Deserialize)]
+    struct LifetimeTest<'a> {
+        #[serde_inline_default("test".into())]
+        test_str: Cow<'a, str>,
+    }
+
+    let lifetime_test: LifetimeTest = serde_json::from_value(json!({})).unwrap();
+
+    assert_eq!(lifetime_test.test_str, "test");
+}