Release 1.0.130

Enable unsized Map/SeqAccess types to use the impl for &mut

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "1.0.128" # remember to update html_root_url and serde_derive dependency
+version = "1.0.130" # remember to update html_root_url and serde_derive dependency
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "A generic serialization/deserialization framework"
@@ -14,7 +14,7 @@ include = ["build.rs", "src/**/*.rs", "crates-io.md", "README.md", "LICENSE-APAC
 build = "build.rs"
 
 [dependencies]
-serde_derive = { version = "=1.0.128", optional = true, path = "../serde_derive" }
+serde_derive = { version = "=1.0.130", optional = true, path = "../serde_derive" }
 
 [dev-dependencies]
 serde_derive = { version = "1.0", path = "../serde_derive" }

serde/build.rs

@@ -62,8 +62,11 @@ fn main() {
 
     // Inclusive ranges methods stabilized in Rust 1.27:
     // https://github.com/rust-lang/rust/pull/50758
+    // Also Iterator::try_for_each:
+    // https://blog.rust-lang.org/2018/06/21/Rust-1.27.html#library-stabilizations
     if minor >= 27 {
         println!("cargo:rustc-cfg=range_inclusive");
+        println!("cargo:rustc-cfg=iterator_try_fold");
     }
 
     // Non-zero integers stabilized in Rust 1.28:

serde/src/de/mod.rs

@@ -1714,7 +1714,7 @@ pub trait SeqAccess<'de> {
     }
 }
 
-impl<'de, 'a, A> SeqAccess<'de> for &'a mut A
+impl<'de, 'a, A: ?Sized> SeqAccess<'de> for &'a mut A
 where
     A: SeqAccess<'de>,
 {
@@ -1867,7 +1867,7 @@ pub trait MapAccess<'de> {
     }
 }
 
-impl<'de, 'a, A> MapAccess<'de> for &'a mut A
+impl<'de, 'a, A: ?Sized> MapAccess<'de> for &'a mut A
 where
     A: MapAccess<'de>,
 {

serde/src/lib.rs

@@ -84,7 +84,7 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.128")]
+#![doc(html_root_url = "https://docs.rs/serde/1.0.130")]
 // Support using Serde without the standard library!
 #![cfg_attr(not(feature = "std"), no_std)]
 // Unstable functionality only if the user asks for it. For tracking and
@@ -157,7 +157,7 @@ mod lib {
         pub use std::*;
     }
 
-    pub use self::core::{cmp, iter, mem, num, slice, str};
+    pub use self::core::{cmp, iter, mem, num, ptr, slice, str};
     pub use self::core::{f32, f64};
     pub use self::core::{i16, i32, i64, i8, isize};
     pub use self::core::{u16, u32, u64, u8, usize};

serde/src/private/mod.rs

@@ -14,6 +14,7 @@ pub use lib::default::Default;
 pub use lib::fmt::{self, Formatter};
 pub use lib::marker::PhantomData;
 pub use lib::option::Option::{self, None, Some};
+pub use lib::ptr;
 pub use lib::result::Result::{self, Err, Ok};
 
 pub use self::string::from_utf8_lossy;

serde/src/ser/mod.rs

@@ -1279,9 +1279,20 @@ pub trait Serializer: Sized {
     {
         let iter = iter.into_iter();
         let mut serializer = try!(self.serialize_seq(iterator_len_hint(&iter)));
-        for item in iter {
-            try!(serializer.serialize_element(&item));
+
+        #[cfg(iterator_try_fold)]
+        {
+            let mut iter = iter;
+            try!(iter.try_for_each(|item| serializer.serialize_element(&item)));
         }
+
+        #[cfg(not(iterator_try_fold))]
+        {
+            for item in iter {
+                try!(serializer.serialize_element(&item));
+            }
+        }
+
         serializer.end()
     }
 
@@ -1319,9 +1330,20 @@ pub trait Serializer: Sized {
     {
         let iter = iter.into_iter();
         let mut serializer = try!(self.serialize_map(iterator_len_hint(&iter)));
-        for (key, value) in iter {
-            try!(serializer.serialize_entry(&key, &value));
+
+        #[cfg(iterator_try_fold)]
+        {
+            let mut iter = iter;
+            try!(iter.try_for_each(|(key, value)| serializer.serialize_entry(&key, &value)));
         }
+
+        #[cfg(not(iterator_try_fold))]
+        {
+            for (key, value) in iter {
+                try!(serializer.serialize_entry(&key, &value));
+            }
+        }
+
         serializer.end()
     }
 

serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.128" # remember to update html_root_url
+version = "1.0.130" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"

serde_derive/build.rs

@@ -16,6 +16,12 @@ fn main() {
     if minor >= 37 {
         println!("cargo:rustc-cfg=underscore_consts");
     }
+
+    // The ptr::addr_of! macro stabilized in Rust 1.51:
+    // https://blog.rust-lang.org/2021/03/25/Rust-1.51.0.html#stabilized-apis
+    if minor >= 51 {
+        println!("cargo:rustc-cfg=ptr_addr_of");
+    }
 }
 
 fn rustc_minor_version() -> Option<u32> {

serde_derive/src/de.rs

@@ -36,7 +36,7 @@ pub fn expand_derive_deserialize(
 
     let impl_block = if let Some(remote) = cont.attrs.remote() {
         let vis = &input.vis;
-        let used = pretend::pretend_used(&cont);
+        let used = pretend::pretend_used(&cont, params.is_packed);
         quote! {
             impl #de_impl_generics #ident #ty_generics #where_clause {
                 #vis fn deserialize<__D>(__deserializer: __D) -> #serde::__private::Result<#remote #ty_generics, __D::Error>
@@ -125,6 +125,9 @@ struct Parameters {
     /// At least one field has a serde(getter) attribute, implying that the
     /// remote type has a private field.
     has_getter: bool,
+
+    /// Type has a repr(packed) attribute.
+    is_packed: bool,
 }
 
 impl Parameters {
@@ -137,6 +140,7 @@ impl Parameters {
         let borrowed = borrowed_lifetimes(cont);
         let generics = build_generics(cont, &borrowed);
         let has_getter = cont.data.has_getter();
+        let is_packed = cont.attrs.is_packed();
 
         Parameters {
             local,
@@ -144,6 +148,7 @@ impl Parameters {
             generics,
             borrowed,
             has_getter,
+            is_packed,
         }
     }
 
@@ -1728,6 +1733,8 @@ fn deserialize_externally_tagged_variant(
     }
 }
 
+// Generates significant part of the visit_seq and visit_map bodies of visitors
+// for the variants of internally tagged enum.
 fn deserialize_internally_tagged_variant(
     params: &Parameters,
     variant: &Variant,
@@ -1779,11 +1786,9 @@ fn deserialize_untagged_variant(
     deserializer: TokenStream,
 ) -> Fragment {
     if let Some(path) = variant.attrs.deserialize_with() {
-        let (wrapper, wrapper_ty, unwrap_fn) = wrap_deserialize_variant_with(params, variant, path);
+        let unwrap_fn = unwrap_to_variant_closure(params, variant, false);
         return quote_block! {
-            #wrapper
-            _serde::__private::Result::map(
-                <#wrapper_ty as _serde::Deserialize>::deserialize(#deserializer), #unwrap_fn)
+            _serde::__private::Result::map(#path(#deserializer), #unwrap_fn)
         };
     }
 
@@ -2883,44 +2888,61 @@ fn wrap_deserialize_variant_with(
     variant: &Variant,
     deserialize_with: &syn::ExprPath,
 ) -> (TokenStream, TokenStream, TokenStream) {
-    let this = &params.this;
-    let variant_ident = &variant.ident;
-
     let field_tys = variant.fields.iter().map(|field| field.ty);
     let (wrapper, wrapper_ty) =
         wrap_deserialize_with(params, &quote!((#(#field_tys),*)), deserialize_with);
 
+    let unwrap_fn = unwrap_to_variant_closure(params, variant, true);
+
+    (wrapper, wrapper_ty, unwrap_fn)
+}
+
+// Generates closure that converts single input parameter to the final value.
+fn unwrap_to_variant_closure(
+    params: &Parameters,
+    variant: &Variant,
+    with_wrapper: bool,
+) -> TokenStream {
+    let this = &params.this;
+    let variant_ident = &variant.ident;
+
+    let (arg, wrapper) = if with_wrapper {
+        (quote! { __wrap }, quote! { __wrap.value })
+    } else {
+        let field_tys = variant.fields.iter().map(|field| field.ty);
+        (quote! { __wrap: (#(#field_tys),*) }, quote! { __wrap })
+    };
+
     let field_access = (0..variant.fields.len()).map(|n| {
         Member::Unnamed(Index {
             index: n as u32,
             span: Span::call_site(),
         })
     });
-    let unwrap_fn = match variant.style {
+
+    match variant.style {
         Style::Struct if variant.fields.len() == 1 => {
             let member = &variant.fields[0].member;
             quote! {
-                |__wrap| #this::#variant_ident { #member: __wrap.value }
+                |#arg| #this::#variant_ident { #member: #wrapper }
             }
         }
         Style::Struct => {
             let members = variant.fields.iter().map(|field| &field.member);
             quote! {
-                |__wrap| #this::#variant_ident { #(#members: __wrap.value.#field_access),* }
+                |#arg| #this::#variant_ident { #(#members: #wrapper.#field_access),* }
             }
         }
         Style::Tuple => quote! {
-            |__wrap| #this::#variant_ident(#(__wrap.value.#field_access),*)
+            |#arg| #this::#variant_ident(#(#wrapper.#field_access),*)
         },
         Style::Newtype => quote! {
-            |__wrap| #this::#variant_ident(__wrap.value)
+            |#arg| #this::#variant_ident(#wrapper)
         },
         Style::Unit => quote! {
-            |__wrap| #this::#variant_ident
+            |#arg| #this::#variant_ident
         },
-    };
-
-    (wrapper, wrapper_ty, unwrap_fn)
+    }
 }
 
 fn expr_is_missing(field: &Field, cattrs: &attr::Container) -> Fragment {

serde_derive/src/lib.rs

@@ -13,7 +13,7 @@
 //!
 //! [https://serde.rs/derive.html]: https://serde.rs/derive.html
 
-#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.128")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.130")]
 #![allow(unknown_lints, bare_trait_objects)]
 #![deny(clippy::all, clippy::pedantic)]
 // Ignored clippy lints

serde_derive/src/pretend.rs

@@ -1,7 +1,7 @@
-use proc_macro2::{Span, TokenStream};
-use syn::Ident;
+use proc_macro2::TokenStream;
+use quote::format_ident;
 
-use internals::ast::{Container, Data, Field, Style};
+use internals::ast::{Container, Data, Field, Style, Variant};
 
 // Suppress dead_code warnings that would otherwise appear when using a remote
 // derive. Other than this pretend code, a struct annotated with remote derive
@@ -20,8 +20,8 @@ use internals::ast::{Container, Data, Field, Style};
 //     8 | enum EnumDef { V }
 //       |                ^
 //
-pub fn pretend_used(cont: &Container) -> TokenStream {
-    let pretend_fields = pretend_fields_used(cont);
+pub fn pretend_used(cont: &Container, is_packed: bool) -> TokenStream {
+    let pretend_fields = pretend_fields_used(cont, is_packed);
     let pretend_variants = pretend_variants_used(cont);
 
     quote! {
@@ -32,49 +32,115 @@ pub fn pretend_used(cont: &Container) -> TokenStream {
 
 // For structs with named fields, expands to:
 //
+//     match None::<&T> {
+//         Some(T { a: __v0, b: __v1 }) => {}
+//         _ => {}
+//     }
+//
+// For packed structs on sufficiently new rustc, expands to:
+//
+//     match None::<&T> {
+//         Some(__v @ T { a: _, b: _ }) => {
+//             let _ = addr_of!(__v.a);
+//             let _ = addr_of!(__v.b);
+//         }
+//         _ => {}
+//     }
+//
+// For packed structs on older rustc, we assume Sized and !Drop, and expand to:
+//
 //     match None::<T> {
-//         Some(T { a: ref __v0, b: ref __v1 }) => {}
+//         Some(T { a: __v0, b: __v1 }) => {}
 //         _ => {}
 //     }
 //
 // For enums, expands to the following but only including struct variants:
 //
-//     match None::<T> {
-//         Some(T::A { a: ref __v0 }) => {}
-//         Some(T::B { b: ref __v0 }) => {}
+//     match None::<&T> {
+//         Some(T::A { a: __v0 }) => {}
+//         Some(T::B { b: __v0 }) => {}
 //         _ => {}
 //     }
 //
-// The `ref` is important in case the user has written a Drop impl on their
-// type. Rust does not allow destructuring a struct or enum that has a Drop
-// impl.
-fn pretend_fields_used(cont: &Container) -> TokenStream {
+fn pretend_fields_used(cont: &Container, is_packed: bool) -> TokenStream {
+    match &cont.data {
+        Data::Enum(variants) => pretend_fields_used_enum(cont, variants),
+        Data::Struct(Style::Struct, fields) => if is_packed {
+            pretend_fields_used_struct_packed(cont, fields)
+        } else {
+            pretend_fields_used_struct(cont, fields)
+        },
+        Data::Struct(_, _) => quote!(),
+    }
+}
+
+fn pretend_fields_used_struct(cont: &Container, fields: &[Field]) -> TokenStream {
     let type_ident = &cont.ident;
     let (_, ty_generics, _) = cont.generics.split_for_impl();
 
-    let patterns = match &cont.data {
-        Data::Enum(variants) => variants
-            .iter()
-            .filter_map(|variant| match variant.style {
-                Style::Struct => {
-                    let variant_ident = &variant.ident;
-                    let pat = struct_pattern(&variant.fields);
-                    Some(quote!(#type_ident::#variant_ident #pat))
-                }
-                _ => None,
-            })
-            .collect::<Vec<_>>(),
-        Data::Struct(Style::Struct, fields) => {
-            let pat = struct_pattern(fields);
-            vec![quote!(#type_ident #pat)]
-        }
-        Data::Struct(_, _) => {
-            return quote!();
-        }
-    };
+    let members = fields.iter().map(|field| &field.member);
+    let placeholders = (0usize..).map(|i| format_ident!("__v{}", i));
 
     quote! {
-        match _serde::__private::None::<#type_ident #ty_generics> {
+        match _serde::__private::None::<&#type_ident #ty_generics> {
+            _serde::__private::Some(#type_ident { #(#members: #placeholders),* }) => {}
+            _ => {}
+        }
+    }
+}
+
+fn pretend_fields_used_struct_packed(cont: &Container, fields: &[Field]) -> TokenStream {
+    let type_ident = &cont.ident;
+    let (_, ty_generics, _) = cont.generics.split_for_impl();
+
+    let members = fields.iter().map(|field| &field.member).collect::<Vec<_>>();
+
+    #[cfg(ptr_addr_of)]
+    {
+        quote! {
+            match _serde::__private::None::<&#type_ident #ty_generics> {
+                _serde::__private::Some(__v @ #type_ident { #(#members: _),* }) => {
+                    #(
+                        let _ = _serde::__private::ptr::addr_of!(__v.#members);
+                    )*
+                }
+                _ => {}
+            }
+        }
+    }
+
+    #[cfg(not(ptr_addr_of))]
+    {
+        let placeholders = (0usize..).map(|i| format_ident!("__v{}", i));
+
+        quote! {
+            match _serde::__private::None::<#type_ident #ty_generics> {
+                _serde::__private::Some(#type_ident { #(#members: #placeholders),* }) => {}
+                _ => {}
+            }
+        }
+    }
+}
+
+fn pretend_fields_used_enum(cont: &Container, variants: &[Variant]) -> TokenStream {
+    let type_ident = &cont.ident;
+    let (_, ty_generics, _) = cont.generics.split_for_impl();
+
+    let patterns = variants
+        .iter()
+        .filter_map(|variant| match variant.style {
+            Style::Struct => {
+                let variant_ident = &variant.ident;
+                let members = variant.fields.iter().map(|field| &field.member);
+                let placeholders = (0usize..).map(|i| format_ident!("__v{}", i));
+                Some(quote!(#type_ident::#variant_ident { #(#members: #placeholders),* }))
+            }
+            _ => None,
+        })
+        .collect::<Vec<_>>();
+
+    quote! {
+        match _serde::__private::None::<&#type_ident #ty_generics> {
             #(
                 _serde::__private::Some(#patterns) => {}
             )*
@@ -107,7 +173,7 @@ fn pretend_variants_used(cont: &Container) -> TokenStream {
     let cases = variants.iter().map(|variant| {
         let variant_ident = &variant.ident;
         let placeholders = &(0..variant.fields.len())
-            .map(|i| Ident::new(&format!("__v{}", i), Span::call_site()))
+            .map(|i| format_ident!("__v{}", i))
             .collect::<Vec<_>>();
 
         let pat = match variant.style {
@@ -131,10 +197,3 @@ fn pretend_variants_used(cont: &Container) -> TokenStream {
 
     quote!(#(#cases)*)
 }
-
-fn struct_pattern(fields: &[Field]) -> TokenStream {
-    let members = fields.iter().map(|field| &field.member);
-    let placeholders =
-        (0..fields.len()).map(|i| Ident::new(&format!("__v{}", i), Span::call_site()));
-    quote!({ #(#members: ref #placeholders),* })
-}

serde_derive/src/ser.rs

@@ -30,7 +30,7 @@ pub fn expand_derive_serialize(
 
     let impl_block = if let Some(remote) = cont.attrs.remote() {
         let vis = &input.vis;
-        let used = pretend::pretend_used(&cont);
+        let used = pretend::pretend_used(&cont, params.is_packed);
         quote! {
             impl #impl_generics #ident #ty_generics #where_clause {
                 #vis fn serialize<__S>(__self: &#remote #ty_generics, __serializer: __S) -> #serde::__private::Result<__S::Ok, __S::Error>

serde_test/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_test"
-version = "1.0.128" # remember to update html_root_url
+version = "1.0.130" # remember to update html_root_url
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "Token De/Serializer for testing De/Serialize implementations"

serde_test/src/lib.rs

@@ -144,7 +144,7 @@
 //! # }
 //! ```
 
-#![doc(html_root_url = "https://docs.rs/serde_test/1.0.128")]
+#![doc(html_root_url = "https://docs.rs/serde_test/1.0.130")]
 #![cfg_attr(feature = "cargo-clippy", allow(renamed_and_removed_lints))]
 #![cfg_attr(feature = "cargo-clippy", deny(clippy, clippy_pedantic))]
 // Ignored clippy lints

test_suite/tests/test_gen.rs

@@ -823,3 +823,64 @@ where
 {
     vec.first().serialize(serializer)
 }
+
+//////////////////////////////////////////////////////////////////////////
+
+#[derive(Debug, PartialEq, Deserialize)]
+#[serde(tag = "tag")]
+enum InternallyTagged {
+    #[serde(deserialize_with = "deserialize_generic")]
+    Unit,
+
+    #[serde(deserialize_with = "deserialize_generic")]
+    Newtype(i32),
+
+    #[serde(deserialize_with = "deserialize_generic")]
+    Struct { f1: String, f2: u8 },
+}
+
+fn deserialize_generic<'de, T, D>(deserializer: D) -> StdResult<T, D::Error>
+where
+    T: Deserialize<'de>,
+    D: Deserializer<'de>,
+{
+    T::deserialize(deserializer)
+}
+
+//////////////////////////////////////////////////////////////////////////
+
+#[repr(packed)]
+pub struct RemotePacked {
+    pub a: u16,
+    pub b: u32,
+}
+
+#[derive(Serialize)]
+#[repr(packed)]
+#[serde(remote = "RemotePacked")]
+pub struct RemotePackedDef {
+    a: u16,
+    b: u32,
+}
+
+impl Drop for RemotePackedDef {
+    fn drop(&mut self) {}
+}
+
+#[repr(packed)]
+pub struct RemotePackedNonCopy {
+    pub a: u16,
+    pub b: String,
+}
+
+#[derive(Deserialize)]
+#[repr(packed)]
+#[serde(remote = "RemotePackedNonCopy")]
+pub struct RemotePackedNonCopyDef {
+    a: u16,
+    b: String,
+}
+
+impl Drop for RemotePackedNonCopyDef {
+    fn drop(&mut self) {}
+}