From 5ffc2906bf58452166262bfa61f1751a179feefd Mon Sep 17 00:00:00 2001
From: Josh Stone <cuviper@gmail.com>
Date: Tue, 6 Feb 2024 12:50:12 -0800
Subject: [PATCH 1/2] Replace dummy-const with anon-const

This has been supported since Rust 1.37, and the old way is about to
start raising a warning from [RFC 3373][1].

[1]: https://rust-lang.github.io/rfcs/3373-avoid-nonlocal-definitions-in-fns.html
---
 src/lib.rs | 36 ++++++++++++++----------------------
 1 file changed, 14 insertions(+), 22 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index b6f7785..207602b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -97,16 +97,12 @@ macro_rules! parse {
 // we're deriving for a newtype, where the inner type is defined in the same module, but not
 // exported.
 //
-// Solution: use the dummy const trick.  For some reason, `extern crate` statements are allowed
+// Solution: use the anonymous const trick.  For some reason, `extern crate` statements are allowed
 // here, but everything from the surrounding module is in scope.  This trick is taken from serde.
-fn dummy_const_trick(trait_: &str, name: &Ident, exp: TokenStream2) -> TokenStream2 {
-    let dummy_const = Ident::new(
-        &format!("_IMPL_NUM_{}_FOR_{}", trait_, unraw(name)),
-        Span::call_site(),
-    );
+fn anon_const_trick(exp: TokenStream2) -> TokenStream2 {
     quote! {
         #[allow(non_upper_case_globals, unused_qualifications)]
-        const #dummy_const: () = {
+        const _: () = {
             #[allow(clippy::useless_attribute)]
             #[allow(rust_2018_idioms)]
             extern crate num_traits as _num_traits;
@@ -115,10 +111,6 @@ fn dummy_const_trick(trait_: &str, name: &Ident, exp: TokenStream2) -> TokenStre
     }
 }
 
-fn unraw(ident: &Ident) -> String {
-    ident.to_string().trim_start_matches("r#").to_owned()
-}
-
 // If `data` is a newtype, return the type it's wrapping.
 fn newtype_inner(data: &syn::Data) -> Option<syn::Type> {
     match *data {
@@ -189,11 +181,11 @@ impl NumTraits {
         }
     }
 
-    fn wrap(&self, trait_: &str, name: &Ident, output: TokenStream2) -> TokenStream2 {
+    fn wrap(&self, output: TokenStream2) -> TokenStream2 {
         if self.explicit {
             output
         } else {
-            dummy_const_trick(trait_, name, output)
+            anon_const_trick(output)
         }
     }
 }
@@ -369,7 +361,7 @@ pub fn from_primitive(input: TokenStream) -> TokenStream {
         }
     };
 
-    import.wrap("FromPrimitive", name, impl_).into()
+    import.wrap(impl_).into()
 }
 
 /// Derives [`num_traits::ToPrimitive`][to] for simple enums and newtypes.
@@ -544,7 +536,7 @@ pub fn to_primitive(input: TokenStream) -> TokenStream {
         }
     };
 
-    import.wrap("ToPrimitive", name, impl_).into()
+    import.wrap(impl_).into()
 }
 
 const NEWTYPE_ONLY: &str = "This trait can only be derived for newtypes";
@@ -623,7 +615,7 @@ pub fn num_cast(input: TokenStream) -> TokenStream {
         }
     };
 
-    import.wrap("NumCast", name, impl_).into()
+    import.wrap(impl_).into()
 }
 
 /// Derives [`num_traits::Zero`][zero] for newtypes.  The inner type must already implement `Zero`.
@@ -650,7 +642,7 @@ pub fn zero(input: TokenStream) -> TokenStream {
         }
     };
 
-    import.wrap("Zero", name, impl_).into()
+    import.wrap(impl_).into()
 }
 
 /// Derives [`num_traits::One`][one] for newtypes.  The inner type must already implement `One`.
@@ -677,7 +669,7 @@ pub fn one(input: TokenStream) -> TokenStream {
         }
     };
 
-    import.wrap("One", name, impl_).into()
+    import.wrap(impl_).into()
 }
 
 /// Derives [`num_traits::Num`][num] for newtypes.  The inner type must already implement `Num`.
@@ -701,7 +693,7 @@ pub fn num(input: TokenStream) -> TokenStream {
         }
     };
 
-    import.wrap("Num", name, impl_).into()
+    import.wrap(impl_).into()
 }
 
 /// Derives [`num_traits::Float`][float] for newtypes.  The inner type must already implement
@@ -950,7 +942,7 @@ pub fn float(input: TokenStream) -> TokenStream {
         }
     };
 
-    import.wrap("Float", name, impl_).into()
+    import.wrap(impl_).into()
 }
 
 /// Derives [`num_traits::Signed`][signed] for newtypes.  The inner type must already implement
@@ -990,7 +982,7 @@ pub fn signed(input: TokenStream) -> TokenStream {
         }
     };
 
-    import.wrap("Signed", &name, impl_).into()
+    import.wrap(impl_).into()
 }
 
 /// Derives [`num_traits::Unsigned`][unsigned].  The inner type must already implement
@@ -1008,5 +1000,5 @@ pub fn unsigned(input: TokenStream) -> TokenStream {
         impl #import::Unsigned for #name {}
     };
 
-    import.wrap("Unsigned", &name, impl_).into()
+    import.wrap(impl_).into()
 }

From b5b7ee907e23238966d2a7d8f8de93146a6c311f Mon Sep 17 00:00:00 2001
From: Josh Stone <cuviper@gmail.com>
Date: Tue, 6 Feb 2024 12:56:59 -0800
Subject: [PATCH 2/2] Release 0.4.2

---
 Cargo.toml  | 2 +-
 RELEASES.md | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/Cargo.toml b/Cargo.toml
index cfa35ab..40dcc07 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,7 +8,7 @@ categories = [ "science" ]
 license = "MIT OR Apache-2.0"
 name = "num-derive"
 repository = "https://github.com/rust-num/num-derive"
-version = "0.4.1"
+version = "0.4.2"
 readme = "README.md"
 exclude = ["/bors.toml", "/ci/*", "/.github/*"]
 edition = "2021"
diff --git a/RELEASES.md b/RELEASES.md
index d0ae55d..bbf6d53 100644
--- a/RELEASES.md
+++ b/RELEASES.md
@@ -1,3 +1,9 @@
+# Release 0.4.2 (2024-02-06)
+
+- [Use anon-const to avoid RFC 3373 warnings.][62]
+
+[62]: https://github.com/rust-num/num-derive/pull/62
+
 # Release 0.4.1 (2023-10-07)
 
 - [Make `Float` work with `no_std`][56] -- thanks @vkahl!