Drop Default supertrait from Settings

foundations-macros/src/settings.rs

@@ -7,7 +7,7 @@ use syn::parse::{Parse, ParseStream};
 use syn::spanned::Spanned;
 use syn::{
     Attribute, Expr, ExprLit, Field, Fields, Ident, Item, ItemEnum, ItemStruct, Lit, LitStr, Meta,
-    MetaNameValue, Path, Type, parse_macro_input, parse_quote,
+    MetaNameValue, Path, parse_macro_input, parse_quote,
 };
 
 const ERR_NOT_STRUCT_OR_ENUM: &str = "Settings should be either structure or enum.";
@@ -265,18 +265,9 @@ fn impl_settings_trait_for_field(
     let mut impl_for_field = quote_spanned! { span=>
         let mut key = parent_key.to_vec();
         key.push(#name_str.into());
+        #crate_path::settings::Settings::add_docs(&self.#name, &key, docs);
     };
 
-    // foundations#150: `[T; 0]` used to impl Settings for `T: !Default`, but this
-    // is not possible anymore. We thus can't call `Settings::add_docs` for such
-    // fields, but it was a noop anyway.
-    // TODO(lblocher): Remove this compatibility hack with the next major release
-    if !is_array_zst(&field.ty) {
-        impl_for_field.append_all(quote_spanned! { span =>
-            #crate_path::settings::Settings::add_docs(&self.#name, &key, docs);
-        });
-    }
-
     if !docs.is_empty() {
         impl_for_field.append_all(quote! {
             docs.insert(key, &[#(#docs,)*][..]);
@@ -319,30 +310,6 @@ fn extract_doc_comments(attrs: &[Attribute]) -> Vec<LitStr> {
     comments
 }
 
-/// Returns whether `ty` is exactly `[T; 0]` (for some T)
-fn is_array_zst(ty: &Type) -> bool {
-    let Type::Array(array) = ty else {
-        return false;
-    };
-
-    let mut expr = &array.len;
-    while let Expr::Cast(cast) = expr {
-        expr = &cast.expr;
-    }
-
-    let Expr::Lit(ExprLit {
-        lit: Lit::Int(len_lit),
-        ..
-    }) = expr
-    else {
-        return false;
-    };
-    len_lit
-        .base10_parse::<usize>()
-        .map(|len| len == 0)
-        .unwrap_or(false)
-}
-
 /// Returns whether `attrs` contains `serde(flatten)`.
 fn is_serde_flattened(attrs: &[Attribute]) -> bool {
     matches!(

foundations/src/cli.rs

@@ -29,15 +29,15 @@ const USE_CONFIG_OPT_ID: &str = "config";
 /// Additional arguments can be added via `custom_args` argument of the [`Cli::new`] function.
 ///
 /// [`Settings`]: crate::settings::Settings
-pub struct Cli<S: Settings> {
+pub struct Cli<S> {
     /// Parsed service settings.
     pub settings: S,
 
     /// Parsed service arguments.
     pub arg_matches: ArgMatches,
 }
 
-impl<S: Settings> Cli<S> {
+impl<S: Settings + Default> Cli<S> {
     /// Bootstraps a new command line interface (CLI) for the service.
     ///
     /// `custom_args` argument can be used to add extra service-specific arguments to the CLI.
@@ -116,7 +116,7 @@ fn get_arg_matches(
     })
 }
 
-fn get_settings<S: Settings>(arg_matches: &ArgMatches) -> BootstrapResult<S> {
+fn get_settings<S: Settings + Default>(arg_matches: &ArgMatches) -> BootstrapResult<S> {
     if let Some(path) = arg_matches.get_one::<String>(GENERATE_CONFIG_OPT_ID) {
         let settings = S::default();
 

foundations/src/settings/basic_impls.rs

@@ -13,7 +13,7 @@ use std::ops::Range;
 use std::path::PathBuf;
 use std::rc::Rc;
 use std::sync::Arc;
-use std::time::Duration;
+use std::time::{Duration, SystemTime};
 
 macro_rules! impl_noop {
     ( $( $impl_desc:tt )* ) => {
@@ -30,7 +30,8 @@ macro_rules! impl_noop {
 }
 
 impl_noop!(<T> Settings for PhantomData<T> where T: 'static);
-impl_noop!(<Idx> Settings for Range<Idx> where Idx: Debug + Serialize + DeserializeOwned + Clone + Default + 'static);
+impl_noop!(<T> Settings for [T; 0] where T: Debug + Clone + 'static);
+impl_noop!(<Idx> Settings for Range<Idx> where Idx: Debug + Serialize + DeserializeOwned + Clone + 'static);
 impl_noop!(<T> Settings for Reverse<T> where T: Settings);
 impl_noop!(<T> Settings for Wrapping<T> where T: Settings);
 
@@ -39,7 +40,7 @@ macro_rules! impl_for_num {
     ( $( $Ty:ty )* ) => { $(
         impl_noop!(Settings for $Ty);
         impl_noop!(Settings for Saturating<$Ty>);
-        impl_noop!(Settings for Option<NonZero<$Ty>>);
+        impl_noop!(Settings for NonZero<$Ty>);
     )* };
 }
 
@@ -64,7 +65,14 @@ impl_for_non_generic! {
     CString,
     OsString,
     Duration,
-    PathBuf
+    SystemTime,
+    PathBuf,
+    std::net::IpAddr,
+    std::net::Ipv4Addr,
+    std::net::Ipv6Addr,
+    std::net::SocketAddr,
+    std::net::SocketAddrV4,
+    std::net::SocketAddrV6
 }
 
 macro_rules! impl_for_ref {
@@ -120,10 +128,10 @@ macro_rules! impl_for_array {
 }
 
 impl_for_array! {
-     0  1  2  3  4  5  6  7  8  9
-    10 11 12 13 14 15 16 17 18 19
-    20 21 22 23 24 25 26 27 28 29
-    30 31 32
+     1  2  3  4  5  6  7  8  9 10
+    11 12 13 14 15 16 17 18 19 20
+    21 22 23 24 25 26 27 28 29 30
+    31 32
 }
 
 impl<T: Settings> Settings for Option<T> {

foundations/src/settings/mod.rs

@@ -343,7 +343,7 @@ pub use foundations_macros::settings;
 /// [`settings`] macro.
 ///
 /// [`settings`]: crate::settings::settings
-pub trait Settings: Default + Clone + Serialize + DeserializeOwned + Debug + 'static {
+pub trait Settings: Clone + Serialize + DeserializeOwned + Debug + 'static {
     /// Add Rust doc comments for the settings fields.
     ///
     /// Docs for each field need to be added to the provided hashmap with the key consisting of the