From 130c9fdfb2294c0f93a2f07b431191089da5e554 Mon Sep 17 00:00:00 2001
From: Alex Sayers <alex.sayers@gmail.com>
Date: Sat, 29 Sep 2018 20:23:57 +0900
Subject: [PATCH 01/11] Factor out dummy_const_trick()

---
 src/lib.rs | 101 +++++++++++++++++++++++++++++++----------------------
 1 file changed, 60 insertions(+), 41 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 8269eb8..9e2e771 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -50,6 +50,43 @@ use proc_macro2::Span;
 
 use syn::{Data, Fields, Ident};
 
+// Within `exp`, you can bring things into scope with `extern crate`.
+//
+// We don't want to assume that `num_traits::` is in scope - the user may have imported it under a
+// different name, or may have imported it in a non-toplevel module (common when putting impls
+// behind a feature gate).
+//
+// Solution: let's just generate `extern crate num_traits as _num_traits` and then refer to
+// `_num_traits` in the derived code.  However, macros are not allowed to produce `extern crate`
+// statements at the toplevel.
+//
+// Solution: let's generate `mod _impl_foo` and import num_traits within that.  However, now we
+// lose access to private members of the surrounding module.  This is a problem if, for example,
+// 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
+// here, but everything from the surrounding module is in scope.  This trick is taken from serde.
+fn dummy_const_trick<T: quote::ToTokens>(
+    trait_: &str,
+    name: &proc_macro2::Ident,
+    exp: T,
+) -> proc_macro2::TokenStream {
+    let dummy_const = Ident::new(
+        &format!(
+            "_IMPL_NUM_{}_FOR_{}",
+            trait_.to_uppercase(),
+            format!("{}", name).to_uppercase()
+        ),
+        Span::call_site(),
+    );
+    quote! {
+        const #dummy_const: () = {
+            #exp
+        };
+    }
+}
+
 /// Derives [`num_traits::FromPrimitive`][from] for simple enums.
 ///
 /// [from]: https://docs.rs/num-traits/0.2/num_traits/cast/trait.FromPrimitive.html
@@ -102,10 +139,6 @@ use syn::{Data, Fields, Ident};
 pub fn from_primitive(input: TokenStream) -> TokenStream {
     let ast: syn::DeriveInput = syn::parse(input).unwrap();
     let name = &ast.ident;
-    let dummy_const = Ident::new(
-        &format!("_IMPL_NUM_FROM_PRIMITIVE_FOR_{}", name),
-        Span::call_site(),
-    );
 
     let variants = match ast.data {
         Data::Enum(ref data_enum) => &data_enum.variants,
@@ -143,28 +176,23 @@ pub fn from_primitive(input: TokenStream) -> TokenStream {
         from_i64_var
     };
 
-    let res = quote! {
-        #[allow(non_upper_case_globals)]
+    dummy_const_trick("FromPrimative", &name, quote! {
         #[allow(unused_qualifications)]
-        const #dummy_const: () = {
-            extern crate num_traits as _num_traits;
+        extern crate num_traits as _num_traits;
 
-            impl _num_traits::FromPrimitive for #name {
-                #[allow(trivial_numeric_casts)]
-                fn from_i64(#from_i64_var: i64) -> Option<Self> {
-                    #(#clauses else)* {
-                        None
-                    }
-                }
-
-                fn from_u64(n: u64) -> Option<Self> {
-                    Self::from_i64(n as i64)
+        impl _num_traits::FromPrimitive for #name {
+            #[allow(trivial_numeric_casts)]
+            fn from_i64(#from_i64_var: i64) -> Option<Self> {
+                #(#clauses else)* {
+                    None
                 }
             }
-        };
-    };
 
-    res.into()
+            fn from_u64(n: u64) -> Option<Self> {
+                Self::from_i64(n as i64)
+            }
+        }
+    }).into()
 }
 
 /// Derives [`num_traits::ToPrimitive`][to] for simple enums.
@@ -219,10 +247,6 @@ pub fn from_primitive(input: TokenStream) -> TokenStream {
 pub fn to_primitive(input: TokenStream) -> TokenStream {
     let ast: syn::DeriveInput = syn::parse(input).unwrap();
     let name = &ast.ident;
-    let dummy_const = Ident::new(
-        &format!("_IMPL_NUM_TO_PRIMITIVE_FOR_{}", name),
-        Span::call_site(),
-    );
 
     let variants = match ast.data {
         Data::Enum(ref data_enum) => &data_enum.variants,
@@ -263,24 +287,19 @@ pub fn to_primitive(input: TokenStream) -> TokenStream {
         }
     };
 
-    let res = quote! {
-        #[allow(non_upper_case_globals)]
+    dummy_const_trick("ToPrimative", &name, quote! {
         #[allow(unused_qualifications)]
-        const #dummy_const: () = {
-            extern crate num_traits as _num_traits;
-
-            impl _num_traits::ToPrimitive for #name {
-                #[allow(trivial_numeric_casts)]
-                fn to_i64(&self) -> Option<i64> {
-                    #match_expr
-                }
+        extern crate num_traits as _num_traits;
 
-                fn to_u64(&self) -> Option<u64> {
-                    self.to_i64().map(|x| x as u64)
-                }
+        impl _num_traits::ToPrimitive for #name {
+            #[allow(trivial_numeric_casts)]
+            fn to_i64(&self) -> Option<i64> {
+                #match_expr
             }
-        };
-    };
 
-    res.into()
+            fn to_u64(&self) -> Option<u64> {
+                self.to_i64().map(|x| x as u64)
+            }
+        }
+    }).into()
 }

From 9a9c80c1bb84535195578ac40e0c5c51004c3311 Mon Sep 17 00:00:00 2001
From: Alex Sayers <alex.sayers@gmail.com>
Date: Wed, 3 Oct 2018 15:59:45 +0900
Subject: [PATCH 02/11] Add the standard num-* build.rs file

---
 build.rs | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)
 create mode 100644 build.rs

diff --git a/build.rs b/build.rs
new file mode 100644
index 0000000..fd60866
--- /dev/null
+++ b/build.rs
@@ -0,0 +1,35 @@
+use std::env;
+use std::io::Write;
+use std::process::{Command, Stdio};
+
+fn main() {
+    if probe("fn main() { 0i128; }") {
+        println!("cargo:rustc-cfg=has_i128");
+    } else if env::var_os("CARGO_FEATURE_I128").is_some() {
+        panic!("i128 support was not detected!");
+    }
+}
+
+/// Test if a code snippet can be compiled
+fn probe(code: &str) -> bool {
+    let rustc = env::var_os("RUSTC").unwrap_or_else(|| "rustc".into());
+    let out_dir = env::var_os("OUT_DIR").expect("environment variable OUT_DIR");
+
+    let mut child = Command::new(rustc)
+        .arg("--out-dir")
+        .arg(out_dir)
+        .arg("--emit=obj")
+        .arg("-")
+        .stdin(Stdio::piped())
+        .spawn()
+        .expect("rustc probe");
+
+    child
+        .stdin
+        .as_mut()
+        .expect("rustc stdin")
+        .write_all(code.as_bytes())
+        .expect("write rustc stdin");
+
+    child.wait().expect("rustc probe").success()
+}

From 75b897241ff896f650cd99291f80ba52e0e8f99a Mon Sep 17 00:00:00 2001
From: Alex Sayers <alex.sayers@gmail.com>
Date: Sat, 29 Sep 2018 20:36:09 +0900
Subject: [PATCH 03/11] Derive {To,From}Primitive for newtypes

---
 src/lib.rs       | 318 ++++++++++++++++++++++++++++++++++-------------
 tests/newtype.rs |  26 ++++
 2 files changed, 257 insertions(+), 87 deletions(-)
 create mode 100644 tests/newtype.rs

diff --git a/src/lib.rs b/src/lib.rs
index 9e2e771..65d7812 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,6 +10,7 @@
 
 #![crate_type = "proc-macro"]
 #![doc(html_root_url = "https://docs.rs/num-derive/0.2")]
+#![recursion_limit="256"]
 
 //! Procedural macros to derive numeric traits in Rust.
 //!
@@ -87,7 +88,31 @@ fn dummy_const_trick<T: quote::ToTokens>(
     }
 }
 
-/// Derives [`num_traits::FromPrimitive`][from] for simple enums.
+// If `data` is a newtype, return the type it's wrapping.
+fn newtype_inner(data: &syn::Data) -> Option<syn::Type> {
+    match data {
+        &Data::Struct(ref s) => match s.fields {
+            Fields::Unnamed(ref fs) => {
+                if fs.unnamed.len() == 1 {
+                    Some(fs.unnamed[0].ty.clone())
+                } else {
+                    None
+                }
+            }
+            Fields::Named(ref fs) => {
+                if fs.named.len() == 1 {
+                    panic!("num-derive doesn't know how to handle newtypes with named fields yet. \
+                           Please use a tuple-style newtype, or submit a PR!");
+                }
+                None
+            }
+            _ => None,
+        },
+        _ => None,
+    }
+}
+
+/// Derives [`num_traits::FromPrimitive`][from] for simple enums and newtypes.
 ///
 /// [from]: https://docs.rs/num-traits/0.2/num_traits/cast/trait.FromPrimitive.html
 ///
@@ -140,62 +165,121 @@ pub fn from_primitive(input: TokenStream) -> TokenStream {
     let ast: syn::DeriveInput = syn::parse(input).unwrap();
     let name = &ast.ident;
 
-    let variants = match ast.data {
-        Data::Enum(ref data_enum) => &data_enum.variants,
-        _ => panic!(
-            "`FromPrimitive` can be applied only to the enums, {} is not an enum",
-            name
-        ),
-    };
-
-    let from_i64_var = quote! { n };
-    let clauses: Vec<_> = variants
-        .iter()
-        .map(|variant| {
-            let ident = &variant.ident;
-            match variant.fields {
-                Fields::Unit => (),
-                _ => panic!(
-                    "`FromPrimitive` can be applied only to unitary enums, \
-                     {}::{} is either struct or tuple",
-                    name, ident
-                ),
-            }
-
+    let impl_ = if let Some(inner_ty) = newtype_inner(&ast.data) {
+        let i128_fns = if cfg!(has_i128) {
             quote! {
-                if #from_i64_var == #name::#ident as i64 {
-                    Some(#name::#ident)
+                fn from_i128(n: i128) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_i128(n).map(#name)
+                }
+                fn from_u128(n: u128) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_u128(n).map(#name)
                 }
             }
-        })
-        .collect();
+        } else {
+            quote! {}
+        };
 
-    let from_i64_var = if clauses.is_empty() {
-        quote!(_)
+        quote! {
+            extern crate num_traits as _num_traits;
+            impl _num_traits::FromPrimitive for #name {
+                fn from_i64(n: i64) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_i64(n).map(#name)
+                }
+                fn from_u64(n: u64) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_u64(n).map(#name)
+                }
+                fn from_isize(n: isize) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_isize(n).map(#name)
+                }
+                fn from_i8(n: i8) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_i8(n).map(#name)
+                }
+                fn from_i16(n: i16) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_i16(n).map(#name)
+                }
+                fn from_i32(n: i32) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_i32(n).map(#name)
+                }
+                fn from_usize(n: usize) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_usize(n).map(#name)
+                }
+                fn from_u8(n: u8) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_u8(n).map(#name)
+                }
+                fn from_u16(n: u16) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_u16(n).map(#name)
+                }
+                fn from_u32(n: u32) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_u32(n).map(#name)
+                }
+                fn from_f32(n: f32) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_f32(n).map(#name)
+                }
+                fn from_f64(n: f64) -> Option<Self> {
+                    <#inner_ty as _num_traits::FromPrimitive>::from_f64(n).map(#name)
+                }
+                #i128_fns
+            }
+        }
     } else {
-        from_i64_var
-    };
+        let variants = match ast.data {
+            Data::Enum(ref data_enum) => &data_enum.variants,
+            _ => panic!(
+                "`FromPrimitive` can be applied only to enums and newtypes, {} is neither",
+                name
+            ),
+        };
 
-    dummy_const_trick("FromPrimative", &name, quote! {
-        #[allow(unused_qualifications)]
-        extern crate num_traits as _num_traits;
+        let from_i64_var = quote! { n };
+        let clauses: Vec<_> = variants
+            .iter()
+            .map(|variant| {
+                let ident = &variant.ident;
+                match variant.fields {
+                    Fields::Unit => (),
+                    _ => panic!(
+                        "`FromPrimitive` can be applied only to unitary enums and newtypes, \
+                         {}::{} is either struct or tuple",
+                        name, ident
+                    ),
+                }
 
-        impl _num_traits::FromPrimitive for #name {
-            #[allow(trivial_numeric_casts)]
-            fn from_i64(#from_i64_var: i64) -> Option<Self> {
-                #(#clauses else)* {
-                    None
+                quote! {
+                    if #from_i64_var == #name::#ident as i64 {
+                        Some(#name::#ident)
+                    }
                 }
-            }
+            }).collect();
+
+        let from_i64_var = if clauses.is_empty() {
+            quote!(_)
+        } else {
+            from_i64_var
+        };
 
-            fn from_u64(n: u64) -> Option<Self> {
-                Self::from_i64(n as i64)
+        quote! {
+            #[allow(unused_qualifications)]
+            extern crate num_traits as _num_traits;
+
+            impl _num_traits::FromPrimitive for #name {
+                #[allow(trivial_numeric_casts)]
+                fn from_i64(#from_i64_var: i64) -> Option<Self> {
+                    #(#clauses else)* {
+                        None
+                    }
+                }
+
+                fn from_u64(n: u64) -> Option<Self> {
+                    Self::from_i64(n as i64)
+                }
             }
         }
-    }).into()
+    };
+
+    dummy_const_trick("FromPrimitive", &name, impl_).into()
 }
 
-/// Derives [`num_traits::ToPrimitive`][to] for simple enums.
+/// Derives [`num_traits::ToPrimitive`][to] for simple enums and newtypes.
 ///
 /// [to]: https://docs.rs/num-traits/0.2/num_traits/cast/trait.ToPrimitive.html
 ///
@@ -248,58 +332,118 @@ pub fn to_primitive(input: TokenStream) -> TokenStream {
     let ast: syn::DeriveInput = syn::parse(input).unwrap();
     let name = &ast.ident;
 
-    let variants = match ast.data {
-        Data::Enum(ref data_enum) => &data_enum.variants,
-        _ => panic!(
-            "`ToPrimitive` can be applied only to the enums, {} is not an enum",
-            name
-        ),
-    };
-
-    let variants: Vec<_> = variants
-        .iter()
-        .map(|variant| {
-            let ident = &variant.ident;
-            match variant.fields {
-                Fields::Unit => (),
-                _ => {
-                    panic!("`ToPrimitive` can be applied only to unitary enums, {}::{} is either struct or tuple", name, ident)
-                },
+    let impl_ = if let Some(inner_ty) = newtype_inner(&ast.data) {
+        let i128_fns = if cfg!(has_i128) {
+            quote! {
+                fn to_i128(&self) -> Option<i128> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_i128(&self.0)
+                }
+                fn to_u128(&self) -> Option<u128> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_u128(&self.0)
+                }
             }
+        } else {
+            quote! {}
+        };
 
-            // NB: We have to check each variant individually, because we'll only have `&self`
-            // for the input.  We can't move from that, and it might not be `Clone` or `Copy`.
-            // (Otherwise we could just do `*self as i64` without a `match` at all.)
-            quote!(#name::#ident => #name::#ident as i64)
-        })
-        .collect();
-
-    let match_expr = if variants.is_empty() {
-        // No variants found, so do not use Some to not to trigger `unreachable_code` lint
         quote! {
-            match *self {}
+            extern crate num_traits as _num_traits;
+            impl _num_traits::ToPrimitive for #name {
+                fn to_i64(&self) -> Option<i64> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_i64(&self.0)
+                }
+                fn to_u64(&self) -> Option<u64> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_u64(&self.0)
+                }
+                fn to_isize(&self) -> Option<isize> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_isize(&self.0)
+                }
+                fn to_i8(&self) -> Option<i8> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_i8(&self.0)
+                }
+                fn to_i16(&self) -> Option<i16> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_i16(&self.0)
+                }
+                fn to_i32(&self) -> Option<i32> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_i32(&self.0)
+                }
+                fn to_usize(&self) -> Option<usize> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_usize(&self.0)
+                }
+                fn to_u8(&self) -> Option<u8> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_u8(&self.0)
+                }
+                fn to_u16(&self) -> Option<u16> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_u16(&self.0)
+                }
+                fn to_u32(&self) -> Option<u32> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_u32(&self.0)
+                }
+                fn to_f32(&self) -> Option<f32> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_f32(&self.0)
+                }
+                fn to_f64(&self) -> Option<f64> {
+                    <#inner_ty as _num_traits::ToPrimitive>::to_f64(&self.0)
+                }
+                #i128_fns
+            }
         }
     } else {
-        quote! {
-            Some(match *self {
-                #(#variants,)*
-            })
-        }
-    };
+        let variants = match ast.data {
+            Data::Enum(ref data_enum) => &data_enum.variants,
+            _ => panic!(
+                "`ToPrimitive` can be applied only to enums and newtypes, {} is neither",
+                name
+            ),
+        };
 
-    dummy_const_trick("ToPrimative", &name, quote! {
-        #[allow(unused_qualifications)]
-        extern crate num_traits as _num_traits;
+        let variants: Vec<_> = variants
+            .iter()
+            .map(|variant| {
+                let ident = &variant.ident;
+                match variant.fields {
+                    Fields::Unit => (),
+                    _ => {
+                        panic!("`ToPrimitive` can be applied only to unitary enums and newtypes, {}::{} is either struct or tuple", name, ident)
+                    },
+                }
 
-        impl _num_traits::ToPrimitive for #name {
-            #[allow(trivial_numeric_casts)]
-            fn to_i64(&self) -> Option<i64> {
-                #match_expr
+                // NB: We have to check each variant individually, because we'll only have `&self`
+                // for the input.  We can't move from that, and it might not be `Clone` or `Copy`.
+                // (Otherwise we could just do `*self as i64` without a `match` at all.)
+                quote!(#name::#ident => #name::#ident as i64)
+            })
+            .collect();
+
+        let match_expr = if variants.is_empty() {
+            // No variants found, so do not use Some to not to trigger `unreachable_code` lint
+            quote! {
+                match *self {}
             }
+        } else {
+            quote! {
+                Some(match *self {
+                    #(#variants,)*
+                })
+            }
+        };
+
+        quote! {
+            #[allow(unused_qualifications)]
+            extern crate num_traits as _num_traits;
 
-            fn to_u64(&self) -> Option<u64> {
-                self.to_i64().map(|x| x as u64)
+            impl _num_traits::ToPrimitive for #name {
+                #[allow(trivial_numeric_casts)]
+                fn to_i64(&self) -> Option<i64> {
+                    #match_expr
+                }
+
+                fn to_u64(&self) -> Option<u64> {
+                    self.to_i64().map(|x| x as u64)
+                }
             }
         }
-    }).into()
+    };
+
+    dummy_const_trick("ToPrimitive", &name, impl_).into()
 }
diff --git a/tests/newtype.rs b/tests/newtype.rs
new file mode 100644
index 0000000..75f4008
--- /dev/null
+++ b/tests/newtype.rs
@@ -0,0 +1,26 @@
+extern crate num as num_renamed;
+#[macro_use]
+extern crate num_derive;
+
+use num_renamed::{FromPrimitive, ToPrimitive};
+
+#[derive(
+    Debug,
+    Clone,
+    Copy,
+    PartialEq,
+    PartialOrd,
+    ToPrimitive,
+    FromPrimitive,
+)]
+struct MyFloat(f64);
+
+#[test]
+fn test_from_primitive() {
+    assert_eq!(MyFloat::from_u32(25), Some(MyFloat(25.0)));
+}
+
+#[test]
+fn test_to_primitive() {
+    assert_eq!(MyFloat(25.0).to_u32(), Some(25));
+}

From 52e86e241dfcb9137f32d7b853247e092ddf13dd Mon Sep 17 00:00:00 2001
From: Alex Sayers <alex.sayers@gmail.com>
Date: Sat, 29 Sep 2018 21:10:19 +0900
Subject: [PATCH 04/11] Derive NumOps<Self, Self> for newtypes

This equates to deriving Add, Sub, Mul, Div, and Rem, where RHS=Self and
Output=Self.
---
 src/lib.rs       | 49 ++++++++++++++++++++++++++++++++++++++++++++++++
 tests/newtype.rs | 10 ++++++++++
 2 files changed, 59 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index 65d7812..f5efb99 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -447,3 +447,52 @@ pub fn to_primitive(input: TokenStream) -> TokenStream {
 
     dummy_const_trick("ToPrimitive", &name, impl_).into()
 }
+
+const NEWTYPE_ONLY: &'static str = "This trait can only be derived for newtypes";
+
+/// Derives [`num_traits::NumOps`][num_ops] for newtypes.  The inner type must already implement
+/// `NumOps`.
+///
+/// [num_ops]: https://docs.rs/num-traits/0.2/num_traits/trait.NumOps.html
+///
+/// Note that, since `NumOps` is really a trait alias for `Add + Sub + Mul + Div + Rem`, this macro
+/// generates impls for _those_ traits.  Furthermore, in all generated impls, `RHS=Self` and
+/// `Output=Self`.
+#[proc_macro_derive(NumOps)]
+pub fn num_ops(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput = syn::parse(input).unwrap();
+    let name = &ast.ident;
+    let inner_ty = newtype_inner(&ast.data).expect(NEWTYPE_ONLY);
+    dummy_const_trick("NumOps", &name, quote! {
+        impl ::std::ops::Add for #name {
+            type Output = Self;
+            fn add(self, other: Self) -> Self {
+                #name(<#inner_ty as ::std::ops::Add>::add(self.0, other.0))
+            }
+        }
+        impl ::std::ops::Sub for #name {
+            type Output = Self;
+            fn sub(self, other: Self) -> Self {
+                #name(<#inner_ty as ::std::ops::Sub>::sub(self.0, other.0))
+            }
+        }
+        impl ::std::ops::Mul for #name {
+            type Output = Self;
+            fn mul(self, other: Self) -> Self {
+                #name(<#inner_ty as ::std::ops::Mul>::mul(self.0, other.0))
+            }
+        }
+        impl ::std::ops::Div for #name {
+            type Output = Self;
+            fn div(self, other: Self) -> Self {
+                #name(<#inner_ty as ::std::ops::Div>::div(self.0, other.0))
+            }
+        }
+        impl ::std::ops::Rem for #name {
+            type Output = Self;
+            fn rem(self, other: Self) -> Self {
+                #name(<#inner_ty as ::std::ops::Rem>::rem(self.0, other.0))
+            }
+        }
+    }).into()
+}
diff --git a/tests/newtype.rs b/tests/newtype.rs
index 75f4008..1880c1b 100644
--- a/tests/newtype.rs
+++ b/tests/newtype.rs
@@ -12,6 +12,7 @@ use num_renamed::{FromPrimitive, ToPrimitive};
     PartialOrd,
     ToPrimitive,
     FromPrimitive,
+    NumOps,
 )]
 struct MyFloat(f64);
 
@@ -24,3 +25,12 @@ fn test_from_primitive() {
 fn test_to_primitive() {
     assert_eq!(MyFloat(25.0).to_u32(), Some(25));
 }
+
+#[test]
+fn test_num_ops() {
+    assert_eq!(MyFloat(25.0) + MyFloat(10.0), MyFloat(35.0));
+    assert_eq!(MyFloat(25.0) - MyFloat(10.0), MyFloat(15.0));
+    assert_eq!(MyFloat(25.0) * MyFloat(2.0), MyFloat(50.0));
+    assert_eq!(MyFloat(25.0) / MyFloat(10.0), MyFloat(2.5));
+    assert_eq!(MyFloat(25.0) % MyFloat(10.0), MyFloat(5.0));
+}

From e4d40fe6b6c39d19f83bc5b34450d5087507447e Mon Sep 17 00:00:00 2001
From: Alex Sayers <alex.sayers@gmail.com>
Date: Sat, 29 Sep 2018 21:19:23 +0900
Subject: [PATCH 05/11] Derive NumCast for newtypes

---
 src/lib.rs       | 19 +++++++++++++++++++
 tests/newtype.rs |  8 +++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/lib.rs b/src/lib.rs
index f5efb99..6579d30 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -496,3 +496,22 @@ pub fn num_ops(input: TokenStream) -> TokenStream {
         }
     }).into()
 }
+
+/// Derives [`num_traits::NumCast`][num_cast] for newtypes.  The inner type must already implement
+/// `NumCast`.
+///
+/// [num_cast]: https://docs.rs/num-traits/0.2/num_traits/cast/trait.NumCast.html
+#[proc_macro_derive(NumCast)]
+pub fn num_cast(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput = syn::parse(input).unwrap();
+    let name = &ast.ident;
+    let inner_ty = newtype_inner(&ast.data).expect(NEWTYPE_ONLY);
+    dummy_const_trick("NumCast", &name, quote! {
+        extern crate num_traits as _num_traits;
+        impl _num_traits::NumCast for #name {
+            fn from<T: _num_traits::ToPrimitive>(n: T) -> Option<Self> {
+                <#inner_ty as _num_traits::NumCast>::from(n).map(#name)
+            }
+        }
+    }).into()
+}
diff --git a/tests/newtype.rs b/tests/newtype.rs
index 1880c1b..7ba0926 100644
--- a/tests/newtype.rs
+++ b/tests/newtype.rs
@@ -2,7 +2,7 @@ extern crate num as num_renamed;
 #[macro_use]
 extern crate num_derive;
 
-use num_renamed::{FromPrimitive, ToPrimitive};
+use num_renamed::{FromPrimitive, ToPrimitive, NumCast};
 
 #[derive(
     Debug,
@@ -13,6 +13,7 @@ use num_renamed::{FromPrimitive, ToPrimitive};
     ToPrimitive,
     FromPrimitive,
     NumOps,
+    NumCast,
 )]
 struct MyFloat(f64);
 
@@ -34,3 +35,8 @@ fn test_num_ops() {
     assert_eq!(MyFloat(25.0) / MyFloat(10.0), MyFloat(2.5));
     assert_eq!(MyFloat(25.0) % MyFloat(10.0), MyFloat(5.0));
 }
+
+#[test]
+fn test_num_cast() {
+    assert_eq!(<MyFloat as NumCast>::from(25u8), Some(MyFloat(25.0)));
+}

From b0999000f7aaf12e7d73f5a2cb78e3263ad67f81 Mon Sep 17 00:00:00 2001
From: Alex Sayers <alex.sayers@gmail.com>
Date: Sat, 29 Sep 2018 21:24:25 +0900
Subject: [PATCH 06/11] Derive Zero and One for newtypes

---
 src/lib.rs       | 42 ++++++++++++++++++++++++++++++++++++++++++
 tests/newtype.rs | 14 +++++++++++++-
 2 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/src/lib.rs b/src/lib.rs
index 6579d30..be45dcf 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -515,3 +515,45 @@ pub fn num_cast(input: TokenStream) -> TokenStream {
         }
     }).into()
 }
+
+/// Derives [`num_traits::Zero`][zero] for newtypes.  The inner type must already implement `Zero`.
+///
+/// [zero]: https://docs.rs/num-traits/0.2/num_traits/identities/trait.Zero.html
+#[proc_macro_derive(Zero)]
+pub fn zero(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput = syn::parse(input).unwrap();
+    let name = &ast.ident;
+    let inner_ty = newtype_inner(&ast.data).expect(NEWTYPE_ONLY);
+    dummy_const_trick("Zero", &name, quote! {
+        extern crate num_traits as _num_traits;
+        impl _num_traits::Zero for #name {
+            fn zero() -> Self {
+                #name(<#inner_ty as _num_traits::Zero>::zero())
+            }
+            fn is_zero(&self) -> bool {
+                <#inner_ty as _num_traits::Zero>::is_zero(&self.0)
+            }
+        }
+    }).into()
+}
+
+/// Derives [`num_traits::One`][one] for newtypes.  The inner type must already implement `One`.
+///
+/// [one]: https://docs.rs/num-traits/0.2/num_traits/identities/trait.One.html
+#[proc_macro_derive(One)]
+pub fn one(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput = syn::parse(input).unwrap();
+    let name = &ast.ident;
+    let inner_ty = newtype_inner(&ast.data).expect(NEWTYPE_ONLY);
+    dummy_const_trick("One", &name, quote! {
+        extern crate num_traits as _num_traits;
+        impl _num_traits::One for #name {
+            fn one() -> Self {
+                #name(<#inner_ty as _num_traits::One>::one())
+            }
+            fn is_one(&self) -> bool {
+                <#inner_ty as _num_traits::One>::is_one(&self.0)
+            }
+        }
+    }).into()
+}
diff --git a/tests/newtype.rs b/tests/newtype.rs
index 7ba0926..cbdff4d 100644
--- a/tests/newtype.rs
+++ b/tests/newtype.rs
@@ -2,7 +2,7 @@ extern crate num as num_renamed;
 #[macro_use]
 extern crate num_derive;
 
-use num_renamed::{FromPrimitive, ToPrimitive, NumCast};
+use num_renamed::{FromPrimitive, ToPrimitive, NumCast, One, Zero};
 
 #[derive(
     Debug,
@@ -14,6 +14,8 @@ use num_renamed::{FromPrimitive, ToPrimitive, NumCast};
     FromPrimitive,
     NumOps,
     NumCast,
+    One,
+    Zero,
 )]
 struct MyFloat(f64);
 
@@ -40,3 +42,13 @@ fn test_num_ops() {
 fn test_num_cast() {
     assert_eq!(<MyFloat as NumCast>::from(25u8), Some(MyFloat(25.0)));
 }
+
+#[test]
+fn test_zero() {
+    assert_eq!(MyFloat::zero(), MyFloat(0.0));
+}
+
+#[test]
+fn test_one() {
+    assert_eq!(MyFloat::one(), MyFloat(1.0));
+}

From a2887aca12b8a3031bb981dc3f88f445b8d2d69c Mon Sep 17 00:00:00 2001
From: Alex Sayers <alex.sayers@gmail.com>
Date: Sat, 29 Sep 2018 21:28:07 +0900
Subject: [PATCH 07/11] Derive Num for newtypes

---
 src/lib.rs       | 19 +++++++++++++++++++
 tests/newtype.rs |  8 +++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/lib.rs b/src/lib.rs
index be45dcf..9ec13db 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -557,3 +557,22 @@ pub fn one(input: TokenStream) -> TokenStream {
         }
     }).into()
 }
+
+/// Derives [`num_traits::Num`][num] for newtypes.  The inner type must already implement `Num`.
+///
+/// [num]: https://docs.rs/num-traits/0.2/num_traits/trait.Num.html
+#[proc_macro_derive(Num)]
+pub fn num(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput = syn::parse(input).unwrap();
+    let name = &ast.ident;
+    let inner_ty = newtype_inner(&ast.data).expect(NEWTYPE_ONLY);
+    dummy_const_trick("Num", &name, quote! {
+        extern crate num_traits as _num_traits;
+        impl _num_traits::Num for #name {
+            type FromStrRadixErr = <#inner_ty as _num_traits::Num>::FromStrRadixErr;
+            fn from_str_radix(s: &str, radix: u32) -> Result<Self, Self::FromStrRadixErr> {
+                <#inner_ty as _num_traits::Num>::from_str_radix(s, radix).map(#name)
+            }
+        }
+    }).into()
+}
diff --git a/tests/newtype.rs b/tests/newtype.rs
index cbdff4d..7136357 100644
--- a/tests/newtype.rs
+++ b/tests/newtype.rs
@@ -2,7 +2,7 @@ extern crate num as num_renamed;
 #[macro_use]
 extern crate num_derive;
 
-use num_renamed::{FromPrimitive, ToPrimitive, NumCast, One, Zero};
+use num_renamed::{FromPrimitive, ToPrimitive, NumCast, One, Zero, Num};
 
 #[derive(
     Debug,
@@ -16,6 +16,7 @@ use num_renamed::{FromPrimitive, ToPrimitive, NumCast, One, Zero};
     NumCast,
     One,
     Zero,
+    Num,
 )]
 struct MyFloat(f64);
 
@@ -52,3 +53,8 @@ fn test_zero() {
 fn test_one() {
     assert_eq!(MyFloat::one(), MyFloat(1.0));
 }
+
+#[test]
+fn test_num() {
+    assert_eq!(MyFloat::from_str_radix("25", 10).ok(), Some(MyFloat(25.0)));
+}

From 2e751bf960515a6c14559a381aa0cc10076b1e0a Mon Sep 17 00:00:00 2001
From: Alex Sayers <alex.sayers@gmail.com>
Date: Sat, 29 Sep 2018 21:39:24 +0900
Subject: [PATCH 08/11] Derive Float for newtypes

---
 src/lib.rs       | 190 ++++++++++++++++++++++++++++++++++++++++++++++-
 tests/newtype.rs |  16 +++-
 2 files changed, 204 insertions(+), 2 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 9ec13db..ed8997a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,7 +10,7 @@
 
 #![crate_type = "proc-macro"]
 #![doc(html_root_url = "https://docs.rs/num-derive/0.2")]
-#![recursion_limit="256"]
+#![recursion_limit="512"]
 
 //! Procedural macros to derive numeric traits in Rust.
 //!
@@ -576,3 +576,191 @@ pub fn num(input: TokenStream) -> TokenStream {
         }
     }).into()
 }
+
+/// Derives [`num_traits::Float`][float] for newtypes.  The inner type must already implement
+/// `Float`.
+///
+/// [float]: https://docs.rs/num-traits/0.2/num_traits/float/trait.Float.html
+#[proc_macro_derive(Float)]
+pub fn float(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput = syn::parse(input).unwrap();
+    let name = &ast.ident;
+    let inner_ty = newtype_inner(&ast.data).expect(NEWTYPE_ONLY);
+    dummy_const_trick("Float", &name, quote! {
+        extern crate num_traits as _num_traits;
+        impl _num_traits::Float for #name {
+            fn nan() -> Self {
+                #name(<#inner_ty as _num_traits::Float>::nan())
+            }
+            fn infinity() -> Self {
+                #name(<#inner_ty as _num_traits::Float>::infinity())
+            }
+            fn neg_infinity() -> Self {
+                #name(<#inner_ty as _num_traits::Float>::neg_infinity())
+            }
+            fn neg_zero() -> Self {
+                #name(<#inner_ty as _num_traits::Float>::neg_zero())
+            }
+            fn min_value() -> Self {
+                #name(<#inner_ty as _num_traits::Float>::min_value())
+            }
+            fn min_positive_value() -> Self {
+                #name(<#inner_ty as _num_traits::Float>::min_positive_value())
+            }
+            fn max_value() -> Self {
+                #name(<#inner_ty as _num_traits::Float>::max_value())
+            }
+            fn is_nan(self) -> bool {
+                <#inner_ty as _num_traits::Float>::is_nan(self.0)
+            }
+            fn is_infinite(self) -> bool {
+                <#inner_ty as _num_traits::Float>::is_infinite(self.0)
+            }
+            fn is_finite(self) -> bool {
+                <#inner_ty as _num_traits::Float>::is_finite(self.0)
+            }
+            fn is_normal(self) -> bool {
+                <#inner_ty as _num_traits::Float>::is_normal(self.0)
+            }
+            fn classify(self) -> ::std::num::FpCategory {
+                <#inner_ty as _num_traits::Float>::classify(self.0)
+            }
+            fn floor(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::floor(self.0))
+            }
+            fn ceil(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::ceil(self.0))
+            }
+            fn round(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::round(self.0))
+            }
+            fn trunc(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::trunc(self.0))
+            }
+            fn fract(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::fract(self.0))
+            }
+            fn abs(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::abs(self.0))
+            }
+            fn signum(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::signum(self.0))
+            }
+            fn is_sign_positive(self) -> bool {
+                <#inner_ty as _num_traits::Float>::is_sign_positive(self.0)
+            }
+            fn is_sign_negative(self) -> bool {
+                <#inner_ty as _num_traits::Float>::is_sign_negative(self.0)
+            }
+            fn mul_add(self, a: Self, b: Self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::mul_add(self.0, a.0, b.0))
+            }
+            fn recip(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::recip(self.0))
+            }
+            fn powi(self, n: i32) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::powi(self.0, n))
+            }
+            fn powf(self, n: Self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::powf(self.0, n.0))
+            }
+            fn sqrt(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::sqrt(self.0))
+            }
+            fn exp(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::exp(self.0))
+            }
+            fn exp2(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::exp2(self.0))
+            }
+            fn ln(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::ln(self.0))
+            }
+            fn log(self, base: Self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::log(self.0, base.0))
+            }
+            fn log2(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::log2(self.0))
+            }
+            fn log10(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::log10(self.0))
+            }
+            fn max(self, other: Self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::max(self.0, other.0))
+            }
+            fn min(self, other: Self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::min(self.0, other.0))
+            }
+            fn abs_sub(self, other: Self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::abs_sub(self.0, other.0))
+            }
+            fn cbrt(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::cbrt(self.0))
+            }
+            fn hypot(self, other: Self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::hypot(self.0, other.0))
+            }
+            fn sin(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::sin(self.0))
+            }
+            fn cos(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::cos(self.0))
+            }
+            fn tan(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::tan(self.0))
+            }
+            fn asin(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::asin(self.0))
+            }
+            fn acos(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::acos(self.0))
+            }
+            fn atan(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::atan(self.0))
+            }
+            fn atan2(self, other: Self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::atan2(self.0, other.0))
+            }
+            fn sin_cos(self) -> (Self, Self) {
+                let (x, y) = <#inner_ty as _num_traits::Float>::sin_cos(self.0);
+                (#name(x), #name(y))
+            }
+            fn exp_m1(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::exp_m1(self.0))
+            }
+            fn ln_1p(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::ln_1p(self.0))
+            }
+            fn sinh(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::sinh(self.0))
+            }
+            fn cosh(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::cosh(self.0))
+            }
+            fn tanh(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::tanh(self.0))
+            }
+            fn asinh(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::asinh(self.0))
+            }
+            fn acosh(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::acosh(self.0))
+            }
+            fn atanh(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::atanh(self.0))
+            }
+            fn integer_decode(self) -> (u64, i16, i8) {
+                <#inner_ty as _num_traits::Float>::integer_decode(self.0)
+            }
+            fn epsilon() -> Self {
+                #name(<#inner_ty as _num_traits::Float>::epsilon())
+            }
+            fn to_degrees(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::to_degrees(self.0))
+            }
+            fn to_radians(self) -> Self {
+                #name(<#inner_ty as _num_traits::Float>::to_radians(self.0))
+            }
+        }
+    }).into()
+}
diff --git a/tests/newtype.rs b/tests/newtype.rs
index 7136357..c08aec7 100644
--- a/tests/newtype.rs
+++ b/tests/newtype.rs
@@ -2,7 +2,8 @@ extern crate num as num_renamed;
 #[macro_use]
 extern crate num_derive;
 
-use num_renamed::{FromPrimitive, ToPrimitive, NumCast, One, Zero, Num};
+use num_renamed::{FromPrimitive, ToPrimitive, NumCast, One, Zero, Num, Float};
+use std::ops::Neg;
 
 #[derive(
     Debug,
@@ -17,9 +18,17 @@ use num_renamed::{FromPrimitive, ToPrimitive, NumCast, One, Zero, Num};
     One,
     Zero,
     Num,
+    Float,
 )]
 struct MyFloat(f64);
 
+impl Neg for MyFloat {
+    type Output = MyFloat;
+    fn neg(self) -> Self {
+        MyFloat(self.0.neg())
+    }
+}
+
 #[test]
 fn test_from_primitive() {
     assert_eq!(MyFloat::from_u32(25), Some(MyFloat(25.0)));
@@ -58,3 +67,8 @@ fn test_one() {
 fn test_num() {
     assert_eq!(MyFloat::from_str_radix("25", 10).ok(), Some(MyFloat(25.0)));
 }
+
+#[test]
+fn test_float() {
+    assert_eq!(MyFloat(4.0).log(MyFloat(2.0)), MyFloat(2.0));
+}

From 8f54ad2231b056106e29a7f2e65d1043cedf94d2 Mon Sep 17 00:00:00 2001
From: Alex Sayers <alex.sayers@gmail.com>
Date: Sun, 30 Sep 2018 12:59:24 +0900
Subject: [PATCH 09/11] Add "newtype deriving" entry to RELEASES

---
 RELEASES.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/RELEASES.md b/RELEASES.md
index 17f97e3..fc9a10d 100644
--- a/RELEASES.md
+++ b/RELEASES.md
@@ -1,3 +1,10 @@
+# Unreleased
+
+- [Added newtype deriving][17] for `FromPrimitive`, `ToPrimitive`,
+  `NumOps<Self, Self>`, `NumCast`, `Zero`, `One`, `Num`, and `Float`.
+
+[17]: https://github.com/rust-num/num-derive/pull/17
+
 # Release 0.2.2 (2018-05-22)
 
 - [Updated dependencies][14].

From 203a3db0280256eee60925e535df2a57e930eca2 Mon Sep 17 00:00:00 2001
From: Josh Stone <cuviper@gmail.com>
Date: Wed, 3 Oct 2018 09:58:05 -0700
Subject: [PATCH 10/11] Explicitly use build.rs in Cargo.toml

This is needed for older compilers, even though we know they won't have
i128 support anyway...
---
 Cargo.toml | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Cargo.toml b/Cargo.toml
index a2c7a7d..204ff58 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,6 +10,7 @@ name = "num-derive"
 repository = "https://github.com/rust-num/num-derive"
 version = "0.2.2"
 readme = "README.md"
+build = "build.rs"
 
 [dependencies]
 num-traits = "0.2"

From 706ea88d1459ea9e803249eff5a3790295b302c4 Mon Sep 17 00:00:00 2001
From: Josh Stone <cuviper@gmail.com>
Date: Wed, 3 Oct 2018 09:59:51 -0700
Subject: [PATCH 11/11] Add explicit tests of has_i128-derived methods

---
 tests/newtype.rs | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tests/newtype.rs b/tests/newtype.rs
index c08aec7..98d77c8 100644
--- a/tests/newtype.rs
+++ b/tests/newtype.rs
@@ -34,11 +34,25 @@ fn test_from_primitive() {
     assert_eq!(MyFloat::from_u32(25), Some(MyFloat(25.0)));
 }
 
+#[test]
+#[cfg(has_i128)]
+fn test_from_primitive_128() {
+    assert_eq!(MyFloat::from_i128(std::i128::MIN), Some(MyFloat(-2.0.powi(127))));
+}
+
 #[test]
 fn test_to_primitive() {
     assert_eq!(MyFloat(25.0).to_u32(), Some(25));
 }
 
+#[test]
+#[cfg(has_i128)]
+fn test_to_primitive_128() {
+    let f = MyFloat::from_f32(std::f32::MAX).unwrap();
+    assert_eq!(f.to_i128(), None);
+    assert_eq!(f.to_u128(), Some(0xffff_ff00_0000_0000_0000_0000_0000_0000));
+}
+
 #[test]
 fn test_num_ops() {
     assert_eq!(MyFloat(25.0) + MyFloat(10.0), MyFloat(35.0));