Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

5 files changed, 648 insertions, 0 deletions

diff --git a/third_party/rust/scroll_derive/.cargo-checksum.json b/third_party/rust/scroll_derive/.cargo-checksum.json
new file mode 100644
index 0000000000..8c6b3b87c4
--- /dev/null
+++ b/third_party/rust/scroll_derive/.cargo-checksum.json
@@ -0,0 +1 @@
+{"files":{"Cargo.toml":"9fbb5068c3ffbf2c357f4068f854f439bae4999e04527e2dedc6758fa37a9807","LICENSE":"afb11426e09da40a1ae4f8fa17ddcc6b6a52d14df04c29bc5bcd06eb8730624d","README.md":"f89c7768454b0d2b9db816afe05db3a4cea1125bef87f08ed3eefd65e9e2b180","src/lib.rs":"a9cabe3c0b373f352357745b817f188ab841e9445056014dee9cc83c4d167483"},"package":"1db149f81d46d2deba7cd3c50772474707729550221e69588478ebf9ada425ae"}
\ No newline at end of file
diff --git a/third_party/rust/scroll_derive/Cargo.toml b/third_party/rust/scroll_derive/Cargo.toml
new file mode 100644
index 0000000000..71f40a7e6c
--- /dev/null
+++ b/third_party/rust/scroll_derive/Cargo.toml
@@ -0,0 +1,53 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2018"
+name = "scroll_derive"
+version = "0.11.1"
+authors = [
+    "m4b <m4b.github.io@gmail.com>",
+    "Ted Mielczarek <ted@mielczarek.org>",
+    "Systemcluster <me@systemcluster.me>",
+]
+include = [
+    "src/**/*",
+    "Cargo.toml",
+    "LICENSE",
+    "README.md",
+]
+description = "A macros 1.1 derive implementation for Pread and Pwrite traits from the scroll crate"
+documentation = "https://docs.rs/scroll_derive"
+readme = "README.md"
+keywords = [
+    "derive",
+    "macros",
+    "pread",
+    "pwrite",
+    "bytes",
+]
+license = "MIT"
+repository = "https://github.com/m4b/scroll"
+
+[lib]
+proc-macro = true
+
+[dependencies.proc-macro2]
+version = "1"
+
+[dependencies.quote]
+version = "1"
+
+[dependencies.syn]
+version = "2"
+
+[dev-dependencies.scroll]
+version = "0.11"
diff --git a/third_party/rust/scroll_derive/LICENSE b/third_party/rust/scroll_derive/LICENSE
new file mode 100644
index 0000000000..8864d4a396
--- /dev/null
+++ b/third_party/rust/scroll_derive/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2017 
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/third_party/rust/scroll_derive/README.md b/third_party/rust/scroll_derive/README.md
new file mode 100644
index 0000000000..a7f7e85f0e
--- /dev/null
+++ b/third_party/rust/scroll_derive/README.md
@@ -0,0 +1,35 @@
+# scroll_derive
+Macros 1.1 implementing #[derive(Pread, Pwrite)] for https://github.com/m4b/scroll
+
+Add derive annotations to your POD seamlessly and easily:
+
+```rust
+extern crate scroll;
+#[macro_use]
+extern crate scroll_derive;
+
+#[derive(Debug, PartialEq, Pread, Pwrite, IOread, IOwrite, SizeWith)]
+#[repr(C)]
+struct Data {
+    id: u32,
+    timestamp: f64,
+    arr: [u16; 2],
+}
+
+use scroll::{Pread, Pwrite, Cread, LE};
+
+fn main (){
+    let bytes = [0xefu8, 0xbe, 0xad, 0xde, 0, 0, 0, 0, 0, 0, 224, 63, 0xad, 0xde, 0xef, 0xbe];
+    let data: Data = bytes.pread_with(0, LE).unwrap();
+    println!("data: {:?}", &data);
+    assert_eq!(data.id, 0xdeadbeefu32);
+    let mut bytes2 = vec![0; ::std::mem::size_of::<Data>()];
+    bytes2.pwrite_with(data, 0, LE).unwrap();
+    let data: Data = bytes.pread_with(0, LE).unwrap();
+    let data2: Data = bytes2.pread_with(0, LE).unwrap();
+    assert_eq!(data, data2);
+
+    let data: Data = bytes.cread_with(0, LE);
+    assert_eq!(data, data2);
+}
+```
diff --git a/third_party/rust/scroll_derive/src/lib.rs b/third_party/rust/scroll_derive/src/lib.rs
new file mode 100644
index 0000000000..a2ba6692df
--- /dev/null
+++ b/third_party/rust/scroll_derive/src/lib.rs
@@ -0,0 +1,538 @@
+#![recursion_limit = "1024"]
+
+extern crate proc_macro;
+use proc_macro2;
+use quote::quote;
+
+use proc_macro::TokenStream;
+
+fn impl_field(ident: &proc_macro2::TokenStream, ty: &syn::Type) -> proc_macro2::TokenStream {
+    match *ty {
+        syn::Type::Array(ref array) => match array.len {
+            syn::Expr::Lit(syn::ExprLit {
+                lit: syn::Lit::Int(ref int),
+                ..
+            }) => {
+                let size = int.base10_parse::<usize>().unwrap();
+                quote! {
+                    #ident: { let mut __tmp: #ty = [0u8.into(); #size]; src.gread_inout_with(offset, &mut __tmp, ctx)?; __tmp }
+                }
+            }
+            _ => panic!("Pread derive with bad array constexpr"),
+        },
+        syn::Type::Group(ref group) => impl_field(ident, &group.elem),
+        _ => {
+            quote! {
+                #ident: src.gread_with::<#ty>(offset, ctx)?
+            }
+        }
+    }
+}
+
+fn impl_struct(
+    name: &syn::Ident,
+    fields: &syn::punctuated::Punctuated<syn::Field, syn::Token![,]>,
+    generics: &syn::Generics,
+) -> proc_macro2::TokenStream {
+    let items: Vec<_> = fields
+        .iter()
+        .enumerate()
+        .map(|(i, f)| {
+            let ident = &f.ident.as_ref().map(|i| quote! {#i}).unwrap_or({
+                let t = proc_macro2::Literal::usize_unsuffixed(i);
+                quote! {#t}
+            });
+            let ty = &f.ty;
+            impl_field(ident, ty)
+        })
+        .collect();
+
+    let gl = &generics.lt_token;
+    let gp = &generics.params;
+    let gg = &generics.gt_token;
+    let gn = gp.iter().map(|param: &syn::GenericParam| match param {
+        syn::GenericParam::Type(ref t) => {
+            let ident = &t.ident;
+            quote! { #ident }
+        }
+        p => quote! { #p },
+    });
+    let gn = quote! { #gl #( #gn ),* #gg };
+    let gw = if !gp.is_empty() {
+        let gi = gp.iter().map(|param: &syn::GenericParam| match param {
+            syn::GenericParam::Type(ref t) => {
+                let ident = &t.ident;
+                quote! {
+                    #ident : ::scroll::ctx::TryFromCtx<'a, ::scroll::Endian> + ::std::convert::From<u8> + ::std::marker::Copy,
+                    ::scroll::Error : ::std::convert::From<< #ident as ::scroll::ctx::TryFromCtx<'a, ::scroll::Endian>>::Error>,
+                    < #ident as ::scroll::ctx::TryFromCtx<'a, ::scroll::Endian>>::Error : ::std::convert::From<scroll::Error>
+                }
+            },
+            p => quote! { #p }
+        });
+        quote! { #( #gi ),* , }
+    } else {
+        quote! {}
+    };
+
+    quote! {
+        impl<'a, #gp > ::scroll::ctx::TryFromCtx<'a, ::scroll::Endian> for #name #gn where #gw #name #gn : 'a {
+            type Error = ::scroll::Error;
+            #[inline]
+            fn try_from_ctx(src: &'a [u8], ctx: ::scroll::Endian) -> ::scroll::export::result::Result<(Self, usize), Self::Error> {
+                use ::scroll::Pread;
+                let offset = &mut 0;
+                let data  = Self { #(#items,)* };
+                Ok((data, *offset))
+            }
+        }
+    }
+}
+
+fn impl_try_from_ctx(ast: &syn::DeriveInput) -> proc_macro2::TokenStream {
+    let name = &ast.ident;
+    let generics = &ast.generics;
+    match ast.data {
+        syn::Data::Struct(ref data) => match data.fields {
+            syn::Fields::Named(ref fields) => impl_struct(name, &fields.named, generics),
+            syn::Fields::Unnamed(ref fields) => impl_struct(name, &fields.unnamed, generics),
+            _ => {
+                panic!("Pread can not be derived for unit structs")
+            }
+        },
+        _ => panic!("Pread can only be derived for structs"),
+    }
+}
+
+#[proc_macro_derive(Pread)]
+pub fn derive_pread(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput = syn::parse(input).unwrap();
+    let gen = impl_try_from_ctx(&ast);
+    gen.into()
+}
+
+fn impl_pwrite_field(ident: &proc_macro2::TokenStream, ty: &syn::Type) -> proc_macro2::TokenStream {
+    match ty {
+        syn::Type::Array(ref array) => match array.len {
+            syn::Expr::Lit(syn::ExprLit {
+                lit: syn::Lit::Int(ref int),
+                ..
+            }) => {
+                let size = int.base10_parse::<usize>().unwrap();
+                quote! {
+                    for i in 0..#size {
+                        dst.gwrite_with(&self.#ident[i], offset, ctx)?;
+                    }
+                }
+            }
+            _ => panic!("Pwrite derive with bad array constexpr"),
+        },
+        syn::Type::Group(group) => impl_pwrite_field(ident, &group.elem),
+        _ => {
+            quote! {
+                dst.gwrite_with(&self.#ident, offset, ctx)?
+            }
+        }
+    }
+}
+
+fn impl_try_into_ctx(
+    name: &syn::Ident,
+    fields: &syn::punctuated::Punctuated<syn::Field, syn::Token![,]>,
+    generics: &syn::Generics,
+) -> proc_macro2::TokenStream {
+    let items: Vec<_> = fields
+        .iter()
+        .enumerate()
+        .map(|(i, f)| {
+            let ident = &f.ident.as_ref().map(|i| quote! {#i}).unwrap_or({
+                let t = proc_macro2::Literal::usize_unsuffixed(i);
+                quote! {#t}
+            });
+            let ty = &f.ty;
+            impl_pwrite_field(ident, ty)
+        })
+        .collect();
+
+    let gl = &generics.lt_token;
+    let gp = &generics.params;
+    let gg = &generics.gt_token;
+    let gn = gp.iter().map(|param: &syn::GenericParam| match param {
+        syn::GenericParam::Type(ref t) => {
+            let ident = &t.ident;
+            quote! { #ident }
+        }
+        p => quote! { #p },
+    });
+    let gn = quote! { #gl #( #gn ),* #gg };
+    let gwref = if !gp.is_empty() {
+        let gi = gp.iter().map(|param: &syn::GenericParam| match param {
+            syn::GenericParam::Type(ref t) => {
+                let ident = &t.ident;
+                quote! {
+                    &'a #ident : ::scroll::ctx::TryIntoCtx<::scroll::Endian>,
+                    ::scroll::Error: ::std::convert::From<<&'a #ident as ::scroll::ctx::TryIntoCtx<::scroll::Endian>>::Error>,
+                    <&'a #ident as ::scroll::ctx::TryIntoCtx<::scroll::Endian>>::Error: ::std::convert::From<scroll::Error>
+                }
+            },
+            p => quote! { #p }
+        });
+        quote! { where #( #gi ),* }
+    } else {
+        quote! {}
+    };
+    let gw = if !gp.is_empty() {
+        let gi = gp.iter().map(|param: &syn::GenericParam| match param {
+            syn::GenericParam::Type(ref t) => {
+                let ident = &t.ident;
+                quote! {
+                    #ident : ::scroll::ctx::TryIntoCtx<::scroll::Endian>,
+                    ::scroll::Error: ::std::convert::From<<#ident as ::scroll::ctx::TryIntoCtx<::scroll::Endian>>::Error>,
+                    <#ident as ::scroll::ctx::TryIntoCtx<::scroll::Endian>>::Error: ::std::convert::From<scroll::Error>
+                }
+            },
+            p => quote! { #p }
+        });
+        quote! { where Self: ::std::marker::Copy, #( #gi ),* }
+    } else {
+        quote! {}
+    };
+
+    quote! {
+        impl<'a, #gp > ::scroll::ctx::TryIntoCtx<::scroll::Endian> for &'a #name #gn #gwref {
+            type Error = ::scroll::Error;
+            #[inline]
+            fn try_into_ctx(self, dst: &mut [u8], ctx: ::scroll::Endian) -> ::scroll::export::result::Result<usize, Self::Error> {
+                use ::scroll::Pwrite;
+                let offset = &mut 0;
+                #(#items;)*;
+                Ok(*offset)
+            }
+        }
+
+        impl #gl #gp #gg ::scroll::ctx::TryIntoCtx<::scroll::Endian> for #name #gn #gw {
+            type Error = ::scroll::Error;
+            #[inline]
+            fn try_into_ctx(self, dst: &mut [u8], ctx: ::scroll::Endian) -> ::scroll::export::result::Result<usize, Self::Error> {
+                (&self).try_into_ctx(dst, ctx)
+            }
+        }
+    }
+}
+
+fn impl_pwrite(ast: &syn::DeriveInput) -> proc_macro2::TokenStream {
+    let name = &ast.ident;
+    let generics = &ast.generics;
+    match ast.data {
+        syn::Data::Struct(ref data) => match data.fields {
+            syn::Fields::Named(ref fields) => impl_try_into_ctx(name, &fields.named, generics),
+            syn::Fields::Unnamed(ref fields) => impl_try_into_ctx(name, &fields.unnamed, generics),
+            _ => {
+                panic!("Pwrite can not be derived for unit structs")
+            }
+        },
+        _ => panic!("Pwrite can only be derived for structs"),
+    }
+}
+
+#[proc_macro_derive(Pwrite)]
+pub fn derive_pwrite(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput = syn::parse(input).unwrap();
+    let gen = impl_pwrite(&ast);
+    gen.into()
+}
+
+fn size_with(
+    name: &syn::Ident,
+    fields: &syn::punctuated::Punctuated<syn::Field, syn::Token![,]>,
+    generics: &syn::Generics,
+) -> proc_macro2::TokenStream {
+    let items: Vec<_> = fields
+        .iter()
+        .map(|f| {
+            let ty = &f.ty;
+            match *ty {
+                syn::Type::Array(ref array) => {
+                    let elem = &array.elem;
+                    match array.len {
+                        syn::Expr::Lit(syn::ExprLit {
+                            lit: syn::Lit::Int(ref int),
+                            ..
+                        }) => {
+                            let size = int.base10_parse::<usize>().unwrap();
+                            quote! {
+                                (#size * <#elem>::size_with(ctx))
+                            }
+                        }
+                        _ => panic!("Pread derive with bad array constexpr"),
+                    }
+                }
+                _ => {
+                    quote! {
+                        <#ty>::size_with(ctx)
+                    }
+                }
+            }
+        })
+        .collect();
+
+    let gl = &generics.lt_token;
+    let gp = &generics.params;
+    let gg = &generics.gt_token;
+    let gn = gp.iter().map(|param: &syn::GenericParam| match param {
+        syn::GenericParam::Type(ref t) => {
+            let ident = &t.ident;
+            quote! { #ident }
+        }
+        p => quote! { #p },
+    });
+    let gn = quote! { #gl #( #gn ),* #gg };
+    let gw = if !gp.is_empty() {
+        let gi = gp.iter().map(|param: &syn::GenericParam| match param {
+            syn::GenericParam::Type(ref t) => {
+                let ident = &t.ident;
+                quote! {
+                    #ident : ::scroll::ctx::SizeWith<::scroll::Endian>
+                }
+            }
+            p => quote! { #p },
+        });
+        quote! { where #( #gi ),* }
+    } else {
+        quote! {}
+    };
+
+    quote! {
+        impl #gl #gp #gg ::scroll::ctx::SizeWith<::scroll::Endian> for #name #gn #gw {
+            #[inline]
+            fn size_with(ctx: &::scroll::Endian) -> usize {
+                0 #(+ #items)*
+            }
+        }
+    }
+}
+
+fn impl_size_with(ast: &syn::DeriveInput) -> proc_macro2::TokenStream {
+    let name = &ast.ident;
+    let generics = &ast.generics;
+    match ast.data {
+        syn::Data::Struct(ref data) => match data.fields {
+            syn::Fields::Named(ref fields) => size_with(name, &fields.named, generics),
+            syn::Fields::Unnamed(ref fields) => size_with(name, &fields.unnamed, generics),
+            _ => {
+                panic!("SizeWith can not be derived for unit structs")
+            }
+        },
+        _ => panic!("SizeWith can only be derived for structs"),
+    }
+}
+
+#[proc_macro_derive(SizeWith)]
+pub fn derive_sizewith(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput = syn::parse(input).unwrap();
+    let gen = impl_size_with(&ast);
+    gen.into()
+}
+
+fn impl_cread_struct(
+    name: &syn::Ident,
+    fields: &syn::punctuated::Punctuated<syn::Field, syn::Token![,]>,
+    generics: &syn::Generics,
+) -> proc_macro2::TokenStream {
+    let items: Vec<_> = fields.iter().enumerate().map(|(i, f)| {
+        let ident = &f.ident.as_ref().map(|i|quote!{#i}).unwrap_or({let t = proc_macro2::Literal::usize_unsuffixed(i); quote!{#t}});
+        let ty = &f.ty;
+        match *ty {
+            syn::Type::Array(ref array) => {
+                let arrty = &array.elem;
+                match array.len {
+                    syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(ref int), ..}) => {
+                        let size = int.base10_parse::<usize>().unwrap();
+                        let incr = quote! { ::scroll::export::mem::size_of::<#arrty>() };
+                        quote! {
+                            #ident: {
+                                let mut __tmp: #ty = [0u8.into(); #size];
+                                for i in 0..__tmp.len() {
+                                    __tmp[i] = src.cread_with(*offset, ctx);
+                                    *offset += #incr;
+                                }
+                                __tmp
+                            }
+                        }
+                    },
+                    _ => panic!("IOread derive with bad array constexpr")
+                }
+            },
+            _ => {
+                let size = quote! { ::scroll::export::mem::size_of::<#ty>() };
+                quote! {
+                    #ident: { let res = src.cread_with::<#ty>(*offset, ctx); *offset += #size; res }
+                }
+            }
+        }
+    }).collect();
+
+    let gl = &generics.lt_token;
+    let gp = &generics.params;
+    let gg = &generics.gt_token;
+    let gn = gp.iter().map(|param: &syn::GenericParam| match param {
+        syn::GenericParam::Type(ref t) => {
+            let ident = &t.ident;
+            quote! { #ident }
+        }
+        p => quote! { #p },
+    });
+    let gn = quote! { #gl #( #gn ),* #gg };
+    let gw = if !gp.is_empty() {
+        let gi = gp.iter().map(|param: &syn::GenericParam| match param {
+            syn::GenericParam::Type(ref t) => {
+                let ident = &t.ident;
+                quote! {
+                    #ident : ::scroll::ctx::FromCtx<::scroll::Endian> + ::std::convert::From<u8> + ::std::marker::Copy
+                }
+            },
+            p => quote! { #p }
+        });
+        quote! { where #( #gi ),* , }
+    } else {
+        quote! {}
+    };
+
+    quote! {
+        impl #gl #gp #gg ::scroll::ctx::FromCtx<::scroll::Endian> for #name #gn #gw {
+            #[inline]
+            fn from_ctx(src: &[u8], ctx: ::scroll::Endian) -> Self {
+                use ::scroll::Cread;
+                let offset = &mut 0;
+                let data = Self { #(#items,)* };
+                data
+            }
+        }
+    }
+}
+
+fn impl_from_ctx(ast: &syn::DeriveInput) -> proc_macro2::TokenStream {
+    let name = &ast.ident;
+    let generics = &ast.generics;
+    match ast.data {
+        syn::Data::Struct(ref data) => match data.fields {
+            syn::Fields::Named(ref fields) => impl_cread_struct(name, &fields.named, generics),
+            syn::Fields::Unnamed(ref fields) => impl_cread_struct(name, &fields.unnamed, generics),
+            _ => {
+                panic!("IOread can not be derived for unit structs")
+            }
+        },
+        _ => panic!("IOread can only be derived for structs"),
+    }
+}
+
+#[proc_macro_derive(IOread)]
+pub fn derive_ioread(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput = syn::parse(input).unwrap();
+    let gen = impl_from_ctx(&ast);
+    gen.into()
+}
+
+fn impl_into_ctx(
+    name: &syn::Ident,
+    fields: &syn::punctuated::Punctuated<syn::Field, syn::Token![,]>,
+    generics: &syn::Generics,
+) -> proc_macro2::TokenStream {
+    let items: Vec<_> = fields
+        .iter()
+        .enumerate()
+        .map(|(i, f)| {
+            let ident = &f.ident.as_ref().map(|i| quote! {#i}).unwrap_or({
+                let t = proc_macro2::Literal::usize_unsuffixed(i);
+                quote! {#t}
+            });
+            let ty = &f.ty;
+            let size = quote! { ::scroll::export::mem::size_of::<#ty>() };
+            match *ty {
+                syn::Type::Array(ref array) => {
+                    let arrty = &array.elem;
+                    quote! {
+                        let size = ::scroll::export::mem::size_of::<#arrty>();
+                        for i in 0..self.#ident.len() {
+                            dst.cwrite_with(self.#ident[i], *offset, ctx);
+                            *offset += size;
+                        }
+                    }
+                }
+                _ => {
+                    quote! {
+                        dst.cwrite_with(self.#ident, *offset, ctx);
+                        *offset += #size;
+                    }
+                }
+            }
+        })
+        .collect();
+
+    let gl = &generics.lt_token;
+    let gp = &generics.params;
+    let gg = &generics.gt_token;
+    let gn = gp.iter().map(|param: &syn::GenericParam| match param {
+        syn::GenericParam::Type(ref t) => {
+            let ident = &t.ident;
+            quote! { #ident }
+        }
+        p => quote! { #p },
+    });
+    let gw = if !gp.is_empty() {
+        let gi = gp.iter().map(|param: &syn::GenericParam| match param {
+            syn::GenericParam::Type(ref t) => {
+                let ident = &t.ident;
+                quote! {
+                    #ident : ::scroll::ctx::IntoCtx<::scroll::Endian> + ::std::marker::Copy
+                }
+            }
+            p => quote! { #p },
+        });
+        quote! { where #( #gi ),* }
+    } else {
+        quote! {}
+    };
+    let gn = quote! { #gl #( #gn ),* #gg };
+
+    quote! {
+        impl<'a, #gp > ::scroll::ctx::IntoCtx<::scroll::Endian> for &'a #name #gn #gw {
+            #[inline]
+            fn into_ctx(self, dst: &mut [u8], ctx: ::scroll::Endian) {
+                use ::scroll::Cwrite;
+                let offset = &mut 0;
+                #(#items;)*;
+                ()
+            }
+        }
+
+        impl #gl #gp #gg ::scroll::ctx::IntoCtx<::scroll::Endian> for #name #gn #gw {
+            #[inline]
+            fn into_ctx(self, dst: &mut [u8], ctx: ::scroll::Endian) {
+                (&self).into_ctx(dst, ctx)
+            }
+        }
+    }
+}
+
+fn impl_iowrite(ast: &syn::DeriveInput) -> proc_macro2::TokenStream {
+    let name = &ast.ident;
+    let generics = &ast.generics;
+    match ast.data {
+        syn::Data::Struct(ref data) => match data.fields {
+            syn::Fields::Named(ref fields) => impl_into_ctx(name, &fields.named, generics),
+            syn::Fields::Unnamed(ref fields) => impl_into_ctx(name, &fields.unnamed, generics),
+            _ => {
+                panic!("IOwrite can not be derived for unit structs")
+            }
+        },
+        _ => panic!("IOwrite can only be derived for structs"),
+    }
+}
+
+#[proc_macro_derive(IOwrite)]
+pub fn derive_iowrite(input: TokenStream) -> TokenStream {
+    let ast: syn::DeriveInput = syn::parse(input).unwrap();
+    let gen = impl_iowrite(&ast);
+    gen.into()
+}