Mark generated constructors as #[inline]

CHANGELOG.md

@@ -9,6 +9,7 @@
 - **[FIX]** Improve rust-analyzer resilience: when `#[nutype(...)]` arguments fail to parse (e.g. while still being typed), emit a best-effort type skeleton alongside the error so the newtype stays resolvable and downstream completions keep working (see [#178](https://github.com/greyblake/nutype/issues/178)).
 - **[FIX]** Correct the validation error `Display` message for float newtypes: `less` now reads "The value must be less than ..." and `less_or_equal` reads "The value must be less or equal to ..." (the two were previously swapped). Integer and decimal were already correct.
 - **[INTERNAL]** Consolidate the integer, float and decimal backends onto a shared numeric code-generation and validation layer (`common/generate/numeric.rs` and shared helpers in `common/validate.rs`), removing a large amount of duplicated code. No change to generated code or public API.
+- **[IMPROVEMENT]** Mark the generated `new`, `try_new` and `new_unchecked` constructors with `#[inline]` so they can be inlined across crate boundaries, matching the existing `into_inner` (see [#237](https://github.com/greyblake/nutype/issues/237)).
 
 ### v0.7.0 - 2026-04-25
 - **[BREAKING]** Rename `derive_unsafe` to `derive_unchecked` (both the feature flag and the attribute).

nutype_macros/src/any/generate/mod.rs

@@ -162,3 +162,66 @@ impl GenerateNewtype for AnyNewtype {
         }
     }
 }
+
+#[cfg(test)]
+mod inline_tests {
+    use super::*;
+    use crate::common::generate::gen_impl_into_inner;
+    use crate::common::models::{ConstructorVisibility, ErrorTypePath, Validation};
+    use quote::{format_ident, quote};
+    use syn::parse::Parser;
+
+    fn inner_type() -> AnyInnerType {
+        let field = syn::Field::parse_unnamed
+            .parse2(quote!(String))
+            .expect("field should parse");
+        AnyInnerType::new(field)
+    }
+
+    fn stripped(ts: TokenStream) -> String {
+        ts.to_string().split_whitespace().collect()
+    }
+
+    #[test]
+    fn new_is_marked_inline() {
+        let rendered = stripped(AnyNewtype::gen_new(
+            &TypeName::new(format_ident!("Foo")),
+            &Generics::default(),
+            &inner_type(),
+            &[],
+            ConstFn::NoConst,
+            &ConstructorVisibility::Public,
+        ));
+        assert!(rendered.contains("#[inline]pubfnnew"), "{rendered}");
+    }
+
+    #[test]
+    fn try_new_is_marked_inline() {
+        let error_path: syn::Path = syn::parse_quote!(FooError);
+        let validation = Validation::Standard {
+            validators: Vec::<AnyValidator>::new(),
+            error_type_path: ErrorTypePath::new(error_path),
+        };
+        let rendered = stripped(AnyNewtype::gen_try_new(
+            &TypeName::new(format_ident!("Foo")),
+            &Generics::default(),
+            &inner_type(),
+            &[],
+            &validation,
+            ConstFn::NoConst,
+            &ConstructorVisibility::Public,
+        ));
+        assert!(rendered.contains("#[inline]pubfntry_new"), "{rendered}");
+    }
+
+    #[test]
+    fn into_inner_stays_inline() {
+        let rendered = stripped(gen_impl_into_inner(
+            &TypeName::new(format_ident!("Foo")),
+            &Generics::default(),
+            inner_type(),
+            ConstFn::NoConst,
+        ));
+        assert!(rendered.contains("#[inline]pubfninto_inner"), "{rendered}");
+    }
+}

nutype_macros/src/common/generate/mod.rs

@@ -287,6 +287,7 @@ pub trait GenerateNewtype {
             #maybe_generated_validation_error
 
             impl #impl_generics #type_name #type_generics #where_clause {
+                #[inline]
                 #constructor_visibility #const_fn fn try_new(raw_value: #input_type) -> ::core::result::Result<Self, #error_type_path> {
                     #convert_raw_value_if_necessary
 
@@ -340,6 +341,7 @@ pub trait GenerateNewtype {
         // }
         quote!(
             impl #impl_generics #type_name #type_generics #where_clause {
+                #[inline]
                 #constructor_visibility #const_fn fn new(raw_value: #input_type) -> Self {
                     #convert_raw_value_if_necessary
                     Self(Self::__sanitize__(raw_value))

nutype_macros/src/common/generate/new_unchecked.rs

@@ -16,10 +16,48 @@ pub fn gen_new_unchecked(
                 /// Creates a value of type skipping the sanitization and validation
                 /// rules. Generally, you should avoid using `::new_unchecked()` without a real need.
                 /// Use `::new()` instead when it's possible.
+                #[inline]
                 #constructor_visibility #const_fn unsafe fn new_unchecked(inner_value: #inner_type) -> #type_name {
                     #type_name(inner_value)
                 }
             }
         },
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use quote::format_ident;
+
+    #[test]
+    fn new_unchecked_is_marked_inline() {
+        let type_name = TypeName::new(format_ident!("Foo"));
+        let inner_type = quote!(String);
+        let rendered = gen_new_unchecked(
+            &type_name,
+            inner_type,
+            NewUnchecked::On,
+            ConstFn::NoConst,
+            &ConstructorVisibility::Public,
+        )
+        .to_string();
+
+        let stripped: String = rendered.split_whitespace().collect();
+        assert!(stripped.contains("#[inline]pubunsafefnnew_unchecked"));
+    }
+
+    #[test]
+    fn off_generates_nothing() {
+        let type_name = TypeName::new(format_ident!("Foo"));
+        let rendered = gen_new_unchecked(
+            &type_name,
+            quote!(String),
+            NewUnchecked::Off,
+            ConstFn::NoConst,
+            &ConstructorVisibility::Public,
+        )
+        .to_string();
+        assert!(rendered.is_empty());
+    }
+}