Release 1.0.213

Hygiene for macro-generated newtype struct deserialization with `with` attr

.github/FUNDING.yml

@@ -0,0 +1 @@
+github: dtolnay

.github/workflows/ci.yml

@@ -95,13 +95,16 @@ jobs:
       - run: cd serde && cargo build
 
   derive:
-    name: Rust 1.56.0
+    name: Rust 1.61.0
     runs-on: ubuntu-latest
     timeout-minutes: 45
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/rust-toolchain@1.56.0
+      - uses: dtolnay/rust-toolchain@1.61.0
-      - run: sed -i '/"test_suite"/d' Cargo.toml
+      - run: |
+          sed -i 's/proc-macro2 = { workspace = true/proc-macro2 = { version = "1"/' serde_derive*/Cargo.toml
+          sed -i 's/quote = { workspace = true/quote = { version = "1"/' serde_derive*/Cargo.toml
+          sed -i 's/syn = { workspace = true/syn = { version = "2"/' serde_derive*/Cargo.toml
       - run: cd serde && cargo check --no-default-features
       - run: cd serde && cargo check
       - run: cd serde_derive && cargo check

Cargo.toml

@@ -12,4 +12,4 @@ serde = { path = "serde" }
 [workspace.dependencies]
 proc-macro2 = { version = "1.0.74", default-features = false }
 quote = { version = "1.0.35", default-features = false }
-syn = { version = "2.0.46", default-features = false }
+syn = { version = "2.0.81", default-features = false }

README.md

@@ -1,4 +1,4 @@
-# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde msrv]][Rust 1.31] [![serde_derive msrv]][Rust 1.56]
+# Serde   [![Build Status]][actions] [![Latest Version]][crates.io] [![serde msrv]][Rust 1.31] [![serde_derive msrv]][Rust 1.61]
 
 [Build Status]: https://img.shields.io/github/actions/workflow/status/serde-rs/serde/ci.yml?branch=master
 [actions]: https://github.com/serde-rs/serde/actions?query=branch%3Amaster
@@ -7,7 +7,7 @@
 [serde msrv]: https://img.shields.io/crates/msrv/serde.svg?label=serde%20msrv&color=lightgray
 [serde_derive msrv]: https://img.shields.io/crates/msrv/serde_derive.svg?label=serde_derive%20msrv&color=lightgray
 [Rust 1.31]: https://blog.rust-lang.org/2018/12/06/Rust-1.31-and-rust-2018.html
-[Rust 1.56]: https://blog.rust-lang.org/2021/10/21/Rust-1.56.0.html
+[Rust 1.61]: https://blog.rust-lang.org/2022/05/19/Rust-1.61.0.html
 
 **Serde is a framework for *ser*ializing and *de*serializing Rust data structures efficiently and generically.**
 

serde/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde"
-version = "1.0.210"
+version = "1.0.213"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 build = "build.rs"
 categories = ["encoding", "no-std", "no-std::no-alloc"]
@@ -37,7 +37,7 @@ rustdoc-args = ["--generate-link-to-definition"]
 # is compatible with exactly one serde release because the generated code
 # involves nonpublic APIs which are not bound by semver.
 [target.'cfg(any())'.dependencies]
-serde_derive = { version = "=1.0.210", path = "../serde_derive" }
+serde_derive = { version = "=1.0.213", path = "../serde_derive" }
 
 
 ### FEATURES #################################################################

serde/build.rs

@@ -50,11 +50,6 @@ fn main() {
         println!("cargo:rustc-cfg=no_float_copysign");
     }
 
-    // Current minimum supported version of serde_derive crate is Rust 1.56.
-    if minor < 56 {
-        println!("cargo:rustc-cfg=no_serde_derive");
-    }
-
     // Support for #[cfg(target_has_atomic = "...")] stabilized in Rust 1.60.
     if minor < 60 {
         println!("cargo:rustc-cfg=no_target_has_atomic");
@@ -76,6 +71,11 @@ fn main() {
         }
     }
 
+    // Current minimum supported version of serde_derive crate is Rust 1.61.
+    if minor < 61 {
+        println!("cargo:rustc-cfg=no_serde_derive");
+    }
+
     // Support for core::ffi::CStr and alloc::ffi::CString stabilized in Rust 1.64.
     // https://blog.rust-lang.org/2022/09/22/Rust-1.64.0.html#c-compatible-ffi-types-in-core-and-alloc
     if minor < 64 {

serde/src/de/mod.rs

@@ -486,13 +486,13 @@ where
     }
 }
 
-impl<'a> Expected for &'a str {
+impl Expected for &str {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         formatter.write_str(self)
     }
 }
 
-impl<'a> Display for Expected + 'a {
+impl Display for Expected + '_ {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         Expected::fmt(self, formatter)
     }
@@ -1741,7 +1741,7 @@ pub trait SeqAccess<'de> {
     }
 }
 
-impl<'de, 'a, A> SeqAccess<'de> for &'a mut A
+impl<'de, A> SeqAccess<'de> for &mut A
 where
     A: ?Sized + SeqAccess<'de>,
 {
@@ -1894,7 +1894,7 @@ pub trait MapAccess<'de> {
     }
 }
 
-impl<'de, 'a, A> MapAccess<'de> for &'a mut A
+impl<'de, A> MapAccess<'de> for &mut A
 where
     A: ?Sized + MapAccess<'de>,
 {

serde/src/lib.rs

@@ -95,7 +95,7 @@
 ////////////////////////////////////////////////////////////////////////////////
 
 // Serde types in rustdoc of other crates get linked to here.
-#![doc(html_root_url = "https://docs.rs/serde/1.0.210")]
+#![doc(html_root_url = "https://docs.rs/serde/1.0.213")]
 // Support using Serde without the standard library!
 #![cfg_attr(not(feature = "std"), no_std)]
 // Show which crate feature enables conditionally compiled APIs in documentation.
@@ -144,6 +144,7 @@
     clippy::too_many_lines,
     // preference
     clippy::doc_markdown,
+    clippy::needless_lifetimes,
     clippy::unseparated_literal_suffix,
     // false positive
     clippy::needless_doctest_main,

serde/src/private/de.rs

@@ -313,6 +313,17 @@ mod content {
         }
     }
 
+    impl<'a, 'de, E> de::IntoDeserializer<'de, E> for &'a Content<'de>
+    where
+        E: de::Error,
+    {
+        type Deserializer = ContentRefDeserializer<'a, 'de, E>;
+
+        fn into_deserializer(self) -> Self::Deserializer {
+            ContentRefDeserializer::new(self)
+        }
+    }
+
     /// Used to capture data in [`Content`] from other deserializers.
     /// Cannot capture externally tagged enums, `i128` and `u128`.
     struct ContentVisitor<'de> {
@@ -476,14 +487,16 @@ mod content {
         where
             D: Deserializer<'de>,
         {
-            Deserialize::deserialize(deserializer).map(|v| Content::Some(Box::new(v)))
+            let v = tri!(Deserialize::deserialize(deserializer));
+            Ok(Content::Some(Box::new(v)))
         }
 
         fn visit_newtype_struct<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
         where
             D: Deserializer<'de>,
         {
-            Deserialize::deserialize(deserializer).map(|v| Content::Newtype(Box::new(v)))
+            let v = tri!(Deserialize::deserialize(deserializer));
+            Ok(Content::Newtype(Box::new(v)))
         }
 
         fn visit_seq<V>(self, mut visitor: V) -> Result<Self::Value, V::Error>
@@ -1098,8 +1111,7 @@ mod content {
         V: Visitor<'de>,
         E: de::Error,
     {
-        let seq = content.into_iter().map(ContentDeserializer::new);
+        let mut seq_visitor = SeqDeserializer::new(content.into_iter());
-        let mut seq_visitor = SeqDeserializer::new(seq);
         let value = tri!(visitor.visit_seq(&mut seq_visitor));
         tri!(seq_visitor.end());
         Ok(value)
@@ -1113,10 +1125,7 @@ mod content {
         V: Visitor<'de>,
         E: de::Error,
     {
-        let map = content
+        let mut map_visitor = MapDeserializer::new(content.into_iter());
-            .into_iter()
-            .map(|(k, v)| (ContentDeserializer::new(k), ContentDeserializer::new(v)));
-        let mut map_visitor = MapDeserializer::new(map);
         let value = tri!(visitor.visit_map(&mut map_visitor));
         tri!(map_visitor.end());
         Ok(value)
@@ -1694,8 +1703,7 @@ mod content {
         V: Visitor<'de>,
         E: de::Error,
     {
-        let seq = content.iter().map(ContentRefDeserializer::new);
+        let mut seq_visitor = SeqDeserializer::new(content.iter());
-        let mut seq_visitor = SeqDeserializer::new(seq);
         let value = tri!(visitor.visit_seq(&mut seq_visitor));
         tri!(seq_visitor.end());
         Ok(value)
@@ -1709,12 +1717,13 @@ mod content {
         V: Visitor<'de>,
         E: de::Error,
     {
-        let map = content.iter().map(|(k, v)| {
+        fn content_ref_deserializer_pair<'a, 'de>(
-            (
+            (k, v): &'a (Content<'de>, Content<'de>),
-                ContentRefDeserializer::new(k),
+        ) -> (&'a Content<'de>, &'a Content<'de>) {
-                ContentRefDeserializer::new(v),
+            (k, v)
-            )
+        }
-        });
+
+        let map = content.iter().map(content_ref_deserializer_pair);
         let mut map_visitor = MapDeserializer::new(map);
         let value = tri!(visitor.visit_map(&mut map_visitor));
         tri!(map_visitor.end());

serde/src/ser/fmt.rs

@@ -35,7 +35,7 @@ macro_rules! fmt_primitives {
 ///     }
 /// }
 /// ```
-impl<'a, 'b> Serializer for &'a mut fmt::Formatter<'b> {
+impl<'a> Serializer for &mut fmt::Formatter<'a> {
     type Ok = ();
     type Error = fmt::Error;
     type SerializeSeq = Impossible<(), fmt::Error>;

serde_derive/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "serde_derive"
-version = "1.0.210"
+version = "1.0.213"
 authors = ["Erick Tryzelaar <erick.tryzelaar@gmail.com>", "David Tolnay <dtolnay@gmail.com>"]
 categories = ["no-std", "no-std::no-alloc"]
 description = "Macros 1.1 implementation of #[derive(Serialize, Deserialize)]"
@@ -12,7 +12,7 @@ keywords = ["serde", "serialization", "no_std", "derive"]
 license = "MIT OR Apache-2.0"
 readme = "crates-io.md"
 repository = "https://github.com/serde-rs/serde"
-rust-version = "1.56"
+rust-version = "1.61"
 
 [features]
 default = []

serde_derive/src/bound.rs

@@ -227,7 +227,9 @@ pub fn with_bound(
             match bound {
                 #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
                 syn::TypeParamBound::Trait(bound) => self.visit_path(&bound.path),
-                syn::TypeParamBound::Lifetime(_) | syn::TypeParamBound::Verbatim(_) => {}
+                syn::TypeParamBound::Lifetime(_)
+                | syn::TypeParamBound::PreciseCapture(_)
+                | syn::TypeParamBound::Verbatim(_) => {}
                 _ => {}
             }
         }

serde_derive/src/de.rs

@@ -371,7 +371,11 @@ fn deserialize_transparent(cont: &Container, params: &Parameters) -> Fragment {
         } else {
             let value = match field.attrs.default() {
                 attr::Default::Default => quote!(_serde::__private::Default::default()),
-                attr::Default::Path(path) => quote!(#path()),
+                // If #path returns wrong type, error will be reported here (^^^^^).
+                // We attach span of the path to the function so it will be reported
+                // on the #[serde(default = "...")]
+                //                          ^^^^^
+                attr::Default::Path(path) => quote_spanned!(path.span()=> #path()),
                 attr::Default::None => quote!(_serde::__private::PhantomData),
             };
             quote!(#member: #value)
@@ -757,7 +761,11 @@ fn deserialize_seq(
         attr::Default::Default => Some(quote!(
             let __default: Self::Value = _serde::__private::Default::default();
         )),
-        attr::Default::Path(path) => Some(quote!(
+        // If #path returns wrong type, error will be reported here (^^^^^).
+        // We attach span of the path to the function so it will be reported
+        // on the #[serde(default = "...")]
+        //                          ^^^^^
+        attr::Default::Path(path) => Some(quote_spanned!(path.span()=>
             let __default: Self::Value = #path();
         )),
         attr::Default::None => {
@@ -839,7 +847,11 @@ fn deserialize_seq_in_place(
         attr::Default::Default => Some(quote!(
             let __default: #this_type #ty_generics = _serde::__private::Default::default();
         )),
-        attr::Default::Path(path) => Some(quote!(
+        // If #path returns wrong type, error will be reported here (^^^^^).
+        // We attach span of the path to the function so it will be reported
+        // on the #[serde(default = "...")]
+        //                          ^^^^^
+        attr::Default::Path(path) => Some(quote_spanned!(path.span()=>
             let __default: #this_type #ty_generics = #path();
         )),
         attr::Default::None => {
@@ -863,18 +875,23 @@ fn deserialize_newtype_struct(
 ) -> TokenStream {
     let delife = params.borrowed.de_lifetime();
     let field_ty = field.ty;
+    let deserializer_var = quote!(__e);
 
     let value = match field.attrs.deserialize_with() {
         None => {
             let span = field.original.span();
             let func = quote_spanned!(span=> <#field_ty as _serde::Deserialize>::deserialize);
             quote! {
-                #func(__e)?
+                #func(#deserializer_var)?
             }
         }
         Some(path) => {
-            quote! {
+            // If #path returns wrong type, error will be reported here (^^^^^).
-                #path(__e)?
+            // We attach span of the path to the function so it will be reported
+            // on the #[serde(with = "...")]
+            //                       ^^^^^
+            quote_spanned! {path.span()=>
+                #path(#deserializer_var)?
             }
         }
     };
@@ -890,7 +907,7 @@ fn deserialize_newtype_struct(
 
     quote! {
         #[inline]
-        fn visit_newtype_struct<__E>(self, __e: __E) -> _serde::__private::Result<Self::Value, __E::Error>
+        fn visit_newtype_struct<__E>(self, #deserializer_var: __E) -> _serde::__private::Result<Self::Value, __E::Error>
         where
             __E: _serde::Deserializer<#delife>,
         {
@@ -950,23 +967,20 @@ fn deserialize_struct(
     };
     let expecting = cattrs.expecting().unwrap_or(&expecting);
 
-    let field_names_idents: Vec<_> = fields
+    let deserialized_fields: Vec<_> = fields
         .iter()
         .enumerate()
         // Skip fields that shouldn't be deserialized or that were flattened,
         // so they don't appear in the storage in their literal form
         .filter(|&(_, field)| !field.attrs.skip_deserializing() && !field.attrs.flatten())
-        .map(|(i, field)| {
+        .map(|(i, field)| FieldWithAliases {
-            (
+            ident: field_i(i),
-                field.attrs.name().deserialize_name(),
+            aliases: field.attrs.aliases(),
-                field_i(i),
-                field.attrs.aliases(),
-            )
         })
         .collect();
 
     let has_flatten = has_flatten(fields);
-    let field_visitor = deserialize_field_identifier(&field_names_idents, cattrs, has_flatten);
+    let field_visitor = deserialize_field_identifier(&deserialized_fields, cattrs, has_flatten);
 
     // untagged struct variants do not get a visit_seq method. The same applies to
     // structs that only have a map representation.
@@ -974,7 +988,7 @@ fn deserialize_struct(
         StructForm::Untagged(..) => None,
         _ if has_flatten => None,
         _ => {
-            let mut_seq = if field_names_idents.is_empty() {
+            let mut_seq = if deserialized_fields.is_empty() {
                 quote!(_)
             } else {
                 quote!(mut __seq)
@@ -1022,9 +1036,7 @@ fn deserialize_struct(
     let fields_stmt = if has_flatten {
         None
     } else {
-        let field_names = field_names_idents
+        let field_names = deserialized_fields.iter().flat_map(|field| field.aliases);
-            .iter()
-            .flat_map(|&(_, _, aliases)| aliases);
 
         Some(quote! {
             #[doc(hidden)]
@@ -1117,31 +1129,26 @@ fn deserialize_struct_in_place(
     let expecting = format!("struct {}", params.type_name());
     let expecting = cattrs.expecting().unwrap_or(&expecting);
 
-    let field_names_idents: Vec<_> = fields
+    let deserialized_fields: Vec<_> = fields
         .iter()
         .enumerate()
         .filter(|&(_, field)| !field.attrs.skip_deserializing())
-        .map(|(i, field)| {
+        .map(|(i, field)| FieldWithAliases {
-            (
+            ident: field_i(i),
-                field.attrs.name().deserialize_name(),
+            aliases: field.attrs.aliases(),
-                field_i(i),
-                field.attrs.aliases(),
-            )
         })
         .collect();
 
-    let field_visitor = deserialize_field_identifier(&field_names_idents, cattrs, false);
+    let field_visitor = deserialize_field_identifier(&deserialized_fields, cattrs, false);
 
-    let mut_seq = if field_names_idents.is_empty() {
+    let mut_seq = if deserialized_fields.is_empty() {
         quote!(_)
     } else {
         quote!(mut __seq)
     };
     let visit_seq = Stmts(deserialize_seq_in_place(params, fields, cattrs, expecting));
     let visit_map = Stmts(deserialize_map_in_place(params, fields, cattrs));
-    let field_names = field_names_idents
+    let field_names = deserialized_fields.iter().flat_map(|field| field.aliases);
-        .iter()
-        .flat_map(|&(_, _, aliases)| aliases);
     let type_name = cattrs.name().deserialize_name();
 
     let in_place_impl_generics = de_impl_generics.in_place();
@@ -1225,39 +1232,38 @@ fn deserialize_homogeneous_enum(
 }
 
 fn prepare_enum_variant_enum(variants: &[Variant]) -> (TokenStream, Stmts) {
-    let mut deserialized_variants = variants
+    let deserialized_variants = variants
         .iter()
         .enumerate()
-        .filter(|&(_, variant)| !variant.attrs.skip_deserializing());
+        .filter(|&(_i, variant)| !variant.attrs.skip_deserializing());
-
-    let variant_names_idents: Vec<_> = deserialized_variants
-        .clone()
-        .map(|(i, variant)| {
-            (
-                variant.attrs.name().deserialize_name(),
-                field_i(i),
-                variant.attrs.aliases(),
-            )
-        })
-        .collect();
 
     let fallthrough = deserialized_variants
-        .position(|(_, variant)| variant.attrs.other())
+        .clone()
-        .map(|other_idx| {
+        .find(|(_i, variant)| variant.attrs.other())
-            let ignore_variant = variant_names_idents[other_idx].1.clone();
+        .map(|(i, _variant)| {
+            let ignore_variant = field_i(i);
             quote!(_serde::__private::Ok(__Field::#ignore_variant))
         });
 
     let variants_stmt = {
-        let variant_names = variant_names_idents.iter().map(|(name, _, _)| name);
+        let variant_names = deserialized_variants
+            .clone()
+            .flat_map(|(_i, variant)| variant.attrs.aliases());
         quote! {
             #[doc(hidden)]
             const VARIANTS: &'static [&'static str] = &[ #(#variant_names),* ];
         }
     };
 
+    let deserialized_variants: Vec<_> = deserialized_variants
+        .map(|(i, variant)| FieldWithAliases {
+            ident: field_i(i),
+            aliases: variant.attrs.aliases(),
+        })
+        .collect();
+
     let variant_visitor = Stmts(deserialize_generated_identifier(
-        &variant_names_idents,
+        &deserialized_variants,
         false, // variant identifiers do not depend on the presence of flatten fields
         true,
         None,
@@ -1994,19 +2000,27 @@ fn deserialize_untagged_newtype_variant(
     }
 }
 
+struct FieldWithAliases<'a> {
+    ident: Ident,
+    aliases: &'a BTreeSet<String>,
+}
+
 fn deserialize_generated_identifier(
-    fields: &[(&str, Ident, &BTreeSet<String>)],
+    deserialized_fields: &[FieldWithAliases],
     has_flatten: bool,
     is_variant: bool,
     ignore_variant: Option<TokenStream>,
     fallthrough: Option<TokenStream>,
 ) -> Fragment {
     let this_value = quote!(__Field);
-    let field_idents: &Vec<_> = &fields.iter().map(|(_, ident, _)| ident).collect();
+    let field_idents: &Vec<_> = &deserialized_fields
+        .iter()
+        .map(|field| &field.ident)
+        .collect();
 
     let visitor_impl = Stmts(deserialize_identifier(
         &this_value,
-        fields,
+        deserialized_fields,
         is_variant,
         fallthrough,
         None,
@@ -2052,7 +2066,7 @@ fn deserialize_generated_identifier(
 /// Generates enum and its `Deserialize` implementation that represents each
 /// non-skipped field of the struct
 fn deserialize_field_identifier(
-    fields: &[(&str, Ident, &BTreeSet<String>)],
+    deserialized_fields: &[FieldWithAliases],
     cattrs: &attr::Container,
     has_flatten: bool,
 ) -> Stmts {
@@ -2069,7 +2083,7 @@ fn deserialize_field_identifier(
     };
 
     Stmts(deserialize_generated_identifier(
-        fields,
+        deserialized_fields,
         has_flatten,
         false,
         ignore_variant,
@@ -2127,18 +2141,15 @@ fn deserialize_custom_identifier(
         (variants, None, None)
     };
 
-    let names_idents: Vec<_> = ordinary
+    let idents_aliases: Vec<_> = ordinary
         .iter()
-        .map(|variant| {
+        .map(|variant| FieldWithAliases {
-            (
+            ident: variant.ident.clone(),
-                variant.attrs.name().deserialize_name(),
+            aliases: variant.attrs.aliases(),
-                variant.ident.clone(),
-                variant.attrs.aliases(),
-            )
         })
         .collect();
 
-    let names = names_idents.iter().flat_map(|&(_, _, aliases)| aliases);
+    let names = idents_aliases.iter().flat_map(|variant| variant.aliases);
 
     let names_const = if fallthrough.is_some() {
         None
@@ -2161,7 +2172,7 @@ fn deserialize_custom_identifier(
     let delife = params.borrowed.de_lifetime();
     let visitor_impl = Stmts(deserialize_identifier(
         &this_value,
-        &names_idents,
+        &idents_aliases,
         is_variant,
         fallthrough,
         fallthrough_borrowed,
@@ -2194,20 +2205,24 @@ fn deserialize_custom_identifier(
 
 fn deserialize_identifier(
     this_value: &TokenStream,
-    fields: &[(&str, Ident, &BTreeSet<String>)],
+    deserialized_fields: &[FieldWithAliases],
     is_variant: bool,
     fallthrough: Option<TokenStream>,
     fallthrough_borrowed: Option<TokenStream>,
     collect_other_fields: bool,
     expecting: Option<&str>,
 ) -> Fragment {
-    let str_mapping = fields.iter().map(|(_, ident, aliases)| {
+    let str_mapping = deserialized_fields.iter().map(|field| {
+        let ident = &field.ident;
+        let aliases = field.aliases;
         // `aliases` also contains a main name
         quote!(#(#aliases)|* => _serde::__private::Ok(#this_value::#ident))
     });
-    let bytes_mapping = fields.iter().map(|(_, ident, aliases)| {
+    let bytes_mapping = deserialized_fields.iter().map(|field| {
+        let ident = &field.ident;
         // `aliases` also contains a main name
-        let aliases = aliases
+        let aliases = field
+            .aliases
             .iter()
             .map(|alias| Literal::byte_string(alias.as_bytes()));
         quote!(#(#aliases)|* => _serde::__private::Ok(#this_value::#ident))
@@ -2360,8 +2375,9 @@ fn deserialize_identifier(
             }
         }
     } else {
-        let u64_mapping = fields.iter().enumerate().map(|(i, (_, ident, _))| {
+        let u64_mapping = deserialized_fields.iter().enumerate().map(|(i, field)| {
             let i = i as u64;
+            let ident = &field.ident;
             quote!(#i => _serde::__private::Ok(#this_value::#ident))
         });
 
@@ -2370,7 +2386,11 @@ fn deserialize_identifier(
             fallthrough
         } else {
             let index_expecting = if is_variant { "variant" } else { "field" };
-            let fallthrough_msg = format!("{} index 0 <= i < {}", index_expecting, fields.len());
+            let fallthrough_msg = format!(
+                "{} index 0 <= i < {}",
+                index_expecting,
+                deserialized_fields.len(),
+            );
             u64_fallthrough_arm_tokens = quote! {
                 _serde::__private::Err(_serde::de::Error::invalid_value(
                     _serde::de::Unexpected::Unsigned(__value),
@@ -2647,7 +2667,11 @@ fn deserialize_map(
         attr::Default::Default => Some(quote!(
             let __default: Self::Value = _serde::__private::Default::default();
         )),
-        attr::Default::Path(path) => Some(quote!(
+        // If #path returns wrong type, error will be reported here (^^^^^).
+        // We attach span of the path to the function so it will be reported
+        // on the #[serde(default = "...")]
+        //                          ^^^^^
+        attr::Default::Path(path) => Some(quote_spanned!(path.span()=>
             let __default: Self::Value = #path();
         )),
         attr::Default::None => {
@@ -2817,7 +2841,11 @@ fn deserialize_map_in_place(
         attr::Default::Default => Some(quote!(
             let __default: #this_type #ty_generics = _serde::__private::Default::default();
         )),
-        attr::Default::Path(path) => Some(quote!(
+        // If #path returns wrong type, error will be reported here (^^^^^).
+        // We attach span of the path to the function so it will be reported
+        // on the #[serde(default = "...")]
+        //                          ^^^^^
+        attr::Default::Path(path) => Some(quote_spanned!(path.span()=>
             let __default: #this_type #ty_generics = #path();
         )),
         attr::Default::None => {
@@ -2855,7 +2883,15 @@ fn wrap_deserialize_with(
     let (de_impl_generics, de_ty_generics, ty_generics, where_clause) =
         split_with_de_lifetime(params);
     let delife = params.borrowed.de_lifetime();
+    let deserializer_var = quote!(__deserializer);
 
+    // If #deserialize_with returns wrong type, error will be reported here (^^^^^).
+    // We attach span of the path to the function so it will be reported
+    // on the #[serde(with = "...")]
+    //                       ^^^^^
+    let value = quote_spanned! {deserialize_with.span()=>
+        #deserialize_with(#deserializer_var)?
+    };
     let wrapper = quote! {
         #[doc(hidden)]
         struct __DeserializeWith #de_impl_generics #where_clause {
@@ -2865,12 +2901,12 @@ fn wrap_deserialize_with(
         }
 
         impl #de_impl_generics _serde::Deserialize<#delife> for __DeserializeWith #de_ty_generics #where_clause {
-            fn deserialize<__D>(__deserializer: __D) -> _serde::__private::Result<Self, __D::Error>
+            fn deserialize<__D>(#deserializer_var: __D) -> _serde::__private::Result<Self, __D::Error>
             where
                 __D: _serde::Deserializer<#delife>,
             {
                 _serde::__private::Ok(__DeserializeWith {
-                    value: #deserialize_with(__deserializer)?,
+                    value: #value,
                     phantom: _serde::__private::PhantomData,
                     lifetime: _serde::__private::PhantomData,
                 })
@@ -2961,7 +2997,11 @@ fn expr_is_missing(field: &Field, cattrs: &attr::Container) -> Fragment {
             return quote_expr!(#func());
         }
         attr::Default::Path(path) => {
-            return quote_expr!(#path());
+            // If #path returns wrong type, error will be reported here (^^^^^).
+            // We attach span of the path to the function so it will be reported
+            // on the #[serde(default = "...")]
+            //                          ^^^^^
+            return Fragment::Expr(quote_spanned!(path.span()=> #path()));
         }
         attr::Default::None => { /* below */ }
     }
@@ -3004,6 +3044,10 @@ fn expr_is_missing_seq(
             return quote_spanned!(span=> #assign_to _serde::__private::Default::default());
         }
         attr::Default::Path(path) => {
+            // If #path returns wrong type, error will be reported here (^^^^^).
+            // We attach span of the path to the function so it will be reported
+            // on the #[serde(default = "...")]
+            //                          ^^^^^
             return quote_spanned!(path.span()=> #assign_to #path());
         }
         attr::Default::None => { /* below */ }

serde_derive/src/internals/attr.rs

@@ -8,6 +8,7 @@ use std::iter::FromIterator;
 use syn::meta::ParseNestedMeta;
 use syn::parse::ParseStream;
 use syn::punctuated::Punctuated;
+use syn::spanned::Spanned;
 use syn::{parse_quote, token, Ident, Lifetime, Token};
 
 // This module handles parsing of `#[serde(...)]` attributes. The entrypoints
@@ -888,13 +889,13 @@ impl Variant {
                         ser_path
                             .path
                             .segments
-                            .push(Ident::new("serialize", Span::call_site()).into());
+                            .push(Ident::new("serialize", ser_path.span()).into());
                         serialize_with.set(&meta.path, ser_path);
                         let mut de_path = path;
                         de_path
                             .path
                             .segments
-                            .push(Ident::new("deserialize", Span::call_site()).into());
+                            .push(Ident::new("deserialize", de_path.span()).into());
                         deserialize_with.set(&meta.path, de_path);
                     }
                 } else if meta.path == SERIALIZE_WITH {
@@ -1170,13 +1171,13 @@ impl Field {
                         ser_path
                             .path
                             .segments
-                            .push(Ident::new("serialize", Span::call_site()).into());
+                            .push(Ident::new("serialize", ser_path.span()).into());
                         serialize_with.set(&meta.path, ser_path);
                         let mut de_path = path;
                         de_path
                             .path
                             .segments
-                            .push(Ident::new("deserialize", Span::call_site()).into());
+                            .push(Ident::new("deserialize", de_path.span()).into());
                         deserialize_with.set(&meta.path, de_path);
                     }
                 } else if meta.path == BOUND {

serde_derive/src/internals/receiver.rs

@@ -209,7 +209,9 @@ impl ReplaceReceiver<'_> {
         match bound {
             #![cfg_attr(all(test, exhaustive), deny(non_exhaustive_omitted_patterns))]
             TypeParamBound::Trait(bound) => self.visit_path_mut(&mut bound.path),
-            TypeParamBound::Lifetime(_) | TypeParamBound::Verbatim(_) => {}
+            TypeParamBound::Lifetime(_)
+            | TypeParamBound::PreciseCapture(_)
+            | TypeParamBound::Verbatim(_) => {}
             _ => {}
         }
     }

serde_derive/src/internals/symbol.rs

@@ -46,7 +46,7 @@ impl PartialEq<Symbol> for Ident {
     }
 }
 
-impl<'a> PartialEq<Symbol> for &'a Ident {
+impl PartialEq<Symbol> for &Ident {
     fn eq(&self, word: &Symbol) -> bool {
         *self == word.0
     }
@@ -58,7 +58,7 @@ impl PartialEq<Symbol> for Path {
     }
 }
 
-impl<'a> PartialEq<Symbol> for &'a Path {
+impl PartialEq<Symbol> for &Path {
     fn eq(&self, word: &Symbol) -> bool {
         self.is_ident(word.0)
     }

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/1.0.210")]
+#![doc(html_root_url = "https://docs.rs/serde_derive/1.0.213")]
 #![cfg_attr(not(check_cfg), allow(unexpected_cfgs))]
 // Ignored clippy lints
 #![allow(
@@ -27,6 +27,7 @@
     // clippy bug: https://github.com/rust-lang/rust-clippy/issues/6797
     clippy::manual_map,
     clippy::match_like_matches_macro,
+    clippy::needless_lifetimes,
     clippy::needless_pass_by_value,
     clippy::too_many_arguments,
     clippy::trivially_copy_pass_by_ref,
@@ -55,6 +56,7 @@
     clippy::single_match_else,
     clippy::struct_excessive_bools,
     clippy::too_many_lines,
+    clippy::uninlined_format_args,
     clippy::unseparated_literal_suffix,
     clippy::unused_self,
     clippy::use_self,

serde_derive/src/ser.rs

@@ -1220,6 +1220,17 @@ fn wrap_serialize_with(
         })
     });
 
+    let self_var = quote!(self);
+    let serializer_var = quote!(__s);
+
+    // If #serialize_with returns wrong type, error will be reported on here.
+    // We attach span of the path to this piece so error will be reported
+    // on the #[serde(with = "...")]
+    //                       ^^^^^
+    let wrapper_serialize = quote_spanned! {serialize_with.span()=>
+        #serialize_with(#(#self_var.values.#field_access, )* #serializer_var)
+    };
+
     quote!({
         #[doc(hidden)]
         struct __SerializeWith #wrapper_impl_generics #where_clause {
@@ -1228,11 +1239,11 @@ fn wrap_serialize_with(
         }
 
         impl #wrapper_impl_generics _serde::Serialize for __SerializeWith #wrapper_ty_generics #where_clause {
-            fn serialize<__S>(&self, __s: __S) -> _serde::__private::Result<__S::Ok, __S::Error>
+            fn serialize<__S>(&#self_var, #serializer_var: __S) -> _serde::__private::Result<__S::Ok, __S::Error>
             where
                 __S: _serde::Serializer,
             {
-                #serialize_with(#(self.values.#field_access, )* __s)
+                #wrapper_serialize
             }
         }
 

serde_derive_internals/Cargo.toml

@@ -10,7 +10,7 @@ homepage = "https://serde.rs"
 keywords = ["serde", "serialization"]
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/serde-rs/serde"
-rust-version = "1.56"
+rust-version = "1.61"
 
 [lib]
 path = "lib.rs"

serde_derive_internals/lib.rs

@@ -9,6 +9,7 @@
     // clippy bug: https://github.com/rust-lang/rust-clippy/issues/6797
     clippy::manual_map,
     clippy::missing_panics_doc,
+    clippy::needless_lifetimes,
     clippy::redundant_field_names,
     clippy::result_unit_err,
     clippy::should_implement_trait,
@@ -35,6 +36,7 @@
     clippy::single_match_else,
     clippy::struct_excessive_bools,
     clippy::too_many_lines,
+    clippy::uninlined_format_args,
     clippy::unused_self,
     clippy::wildcard_imports
 )]

test_suite/tests/regression/issue2565.rs

@@ -1,4 +1,4 @@
-use serde_derive::{Serialize, Deserialize};
+use serde_derive::{Deserialize, Serialize};
 use serde_test::{assert_tokens, Token};
 
 #[derive(Serialize, Deserialize, Debug, PartialEq)]
@@ -18,11 +18,15 @@ fn simple_variant() {
     assert_tokens(
         &Enum::Simple { a: 42 },
         &[
-            Token::StructVariant { name: "Enum", variant: "Simple", len: 1 },
+            Token::StructVariant {
+                name: "Enum",
+                variant: "Simple",
+                len: 1,
+            },
             Token::Str("a"),
             Token::I32(42),
             Token::StructVariantEnd,
-        ]
+        ],
     );
 }
 
@@ -31,11 +35,14 @@ fn flatten_variant() {
     assert_tokens(
         &Enum::Flatten { flatten: (), a: 42 },
         &[
-            Token::NewtypeVariant { name: "Enum", variant: "Flatten" },
+            Token::NewtypeVariant {
+                name: "Enum",
+                variant: "Flatten",
+            },
             Token::Map { len: None },
             Token::Str("a"),
             Token::I32(42),
             Token::MapEnd,
-        ]
+        ],
     );
 }

test_suite/tests/regression/issue2844.rs

@@ -0,0 +1,33 @@
+#![allow(clippy::trivially_copy_pass_by_ref)]
+
+use serde_derive::{Deserialize, Serialize};
+
+macro_rules! declare_in_macro {
+    ($with:literal) => {
+        #[derive(Serialize, Deserialize)]
+        pub struct S {
+            #[serde(with = $with)]
+            f: i32,
+        }
+    };
+}
+
+declare_in_macro!("with");
+
+mod with {
+    use serde::{Deserializer, Serializer};
+
+    pub fn serialize<S>(_: &i32, _: S) -> Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        unimplemented!()
+    }
+
+    pub fn deserialize<'de, D>(_: D) -> Result<i32, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        unimplemented!()
+    }
+}

test_suite/tests/regression/issue2846.rs

@@ -0,0 +1,27 @@
+#![allow(clippy::trivially_copy_pass_by_ref)]
+
+use serde_derive::Deserialize;
+
+macro_rules! declare_in_macro {
+    ($with:literal) => {
+        #[derive(Deserialize)]
+        pub struct S(
+            #[serde(with = $with)]
+            #[allow(dead_code)]
+            i32,
+        );
+    };
+}
+
+declare_in_macro!("with");
+
+mod with {
+    use serde::Deserializer;
+
+    pub fn deserialize<'de, D>(_: D) -> Result<i32, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        unimplemented!()
+    }
+}

test_suite/tests/test_annotations.rs

@@ -782,7 +782,7 @@ fn test_unknown_field_rename_enum() {
             variant: "SailorMoon",
             len: 3,
         }],
-        "unknown variant `SailorMoon`, expected `sailor_moon`",
+        "unknown variant `SailorMoon`, expected `sailor_moon` or `usagi_tsukino`",
     );
 
     assert_de_tokens_error::<AliasEnum>(

test_suite/tests/test_serde_path.rs

@@ -1,5 +1,6 @@
 #![allow(
     clippy::extra_unused_type_parameters,
+    clippy::needless_lifetimes,
     clippy::type_repetition_in_bounds
 )]
 

test_suite/tests/ui/default-attribute/incorrect_type_enum_adjacently_tagged.rs

@@ -0,0 +1,20 @@
+// Tests that type error points to the path in attribute
+
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+#[serde(tag = "tag", content = "content")]
+enum Enum {
+    // Newtype variants do not use the provided path, so it is forbidden here
+    // Newtype(#[serde(default = "main")] u8),
+    Tuple(u8, #[serde(default = "main")] i8),
+    Struct {
+        #[serde(default = "main")]
+        f1: u8,
+        f2: u8,
+        #[serde(default = "main")]
+        f3: i8,
+    },
+}
+
+fn main() {}

test_suite/tests/ui/default-attribute/incorrect_type_enum_adjacently_tagged.stderr

@@ -0,0 +1,35 @@
+error[E0308]: `match` arms have incompatible types
+  --> tests/ui/default-attribute/incorrect_type_enum_adjacently_tagged.rs:10:33
+   |
+5  | #[derive(Deserialize)]
+   |          -----------
+   |          |
+   |          this is found to be of type `i8`
+   |          `match` arms have incompatible types
+...
+10 |     Tuple(u8, #[serde(default = "main")] i8),
+   |                                 ^^^^^^ expected `i8`, found `()`
+
+error[E0308]: `match` arms have incompatible types
+  --> tests/ui/default-attribute/incorrect_type_enum_adjacently_tagged.rs:12:27
+   |
+5  | #[derive(Deserialize)]
+   |          -----------
+   |          |
+   |          this is found to be of type `u8`
+   |          `match` arms have incompatible types
+...
+12 |         #[serde(default = "main")]
+   |                           ^^^^^^ expected `u8`, found `()`
+
+error[E0308]: `match` arms have incompatible types
+  --> tests/ui/default-attribute/incorrect_type_enum_adjacently_tagged.rs:15:27
+   |
+5  | #[derive(Deserialize)]
+   |          -----------
+   |          |
+   |          this is found to be of type `i8`
+   |          `match` arms have incompatible types
+...
+15 |         #[serde(default = "main")]
+   |                           ^^^^^^ expected `i8`, found `()`

test_suite/tests/ui/default-attribute/incorrect_type_enum_externally_tagged.rs

@@ -0,0 +1,19 @@
+// Tests that type error points to the path in attribute
+
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+enum Enum {
+    // Newtype variants do not use the provided path, so it is forbidden here
+    // Newtype(#[serde(default = "main")] u8),
+    Tuple(u8, #[serde(default = "main")] i8),
+    Struct {
+        #[serde(default = "main")]
+        f1: u8,
+        f2: u8,
+        #[serde(default = "main")]
+        f3: i8,
+    },
+}
+
+fn main() {}

test_suite/tests/ui/default-attribute/incorrect_type_enum_externally_tagged.stderr

@@ -0,0 +1,35 @@
+error[E0308]: `match` arms have incompatible types
+ --> tests/ui/default-attribute/incorrect_type_enum_externally_tagged.rs:9:33
+  |
+5 | #[derive(Deserialize)]
+  |          -----------
+  |          |
+  |          this is found to be of type `i8`
+  |          `match` arms have incompatible types
+...
+9 |     Tuple(u8, #[serde(default = "main")] i8),
+  |                                 ^^^^^^ expected `i8`, found `()`
+
+error[E0308]: `match` arms have incompatible types
+  --> tests/ui/default-attribute/incorrect_type_enum_externally_tagged.rs:11:27
+   |
+5  | #[derive(Deserialize)]
+   |          -----------
+   |          |
+   |          this is found to be of type `u8`
+   |          `match` arms have incompatible types
+...
+11 |         #[serde(default = "main")]
+   |                           ^^^^^^ expected `u8`, found `()`
+
+error[E0308]: `match` arms have incompatible types
+  --> tests/ui/default-attribute/incorrect_type_enum_externally_tagged.rs:14:27
+   |
+5  | #[derive(Deserialize)]
+   |          -----------
+   |          |
+   |          this is found to be of type `i8`
+   |          `match` arms have incompatible types
+...
+14 |         #[serde(default = "main")]
+   |                           ^^^^^^ expected `i8`, found `()`

test_suite/tests/ui/default-attribute/incorrect_type_enum_internally_tagged.rs

@@ -0,0 +1,20 @@
+// Tests that type error points to the path in attribute
+
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+#[serde(tag = "tag")]
+enum Enum {
+    // Newtype variants do not use the provided path, so it is forbidden here
+    // Newtype(#[serde(default = "main")] u8),
+    // Tuple variants are not supported in internally tagged enums
+    Struct {
+        #[serde(default = "main")]
+        f1: u8,
+        f2: u8,
+        #[serde(default = "main")]
+        f3: i8,
+    },
+}
+
+fn main() {}

test_suite/tests/ui/default-attribute/incorrect_type_enum_internally_tagged.stderr

@@ -0,0 +1,23 @@
+error[E0308]: `match` arms have incompatible types
+  --> tests/ui/default-attribute/incorrect_type_enum_internally_tagged.rs:12:27
+   |
+5  | #[derive(Deserialize)]
+   |          -----------
+   |          |
+   |          this is found to be of type `u8`
+   |          `match` arms have incompatible types
+...
+12 |         #[serde(default = "main")]
+   |                           ^^^^^^ expected `u8`, found `()`
+
+error[E0308]: `match` arms have incompatible types
+  --> tests/ui/default-attribute/incorrect_type_enum_internally_tagged.rs:15:27
+   |
+5  | #[derive(Deserialize)]
+   |          -----------
+   |          |
+   |          this is found to be of type `i8`
+   |          `match` arms have incompatible types
+...
+15 |         #[serde(default = "main")]
+   |                           ^^^^^^ expected `i8`, found `()`

test_suite/tests/ui/default-attribute/incorrect_type_enum_untagged.rs

@@ -0,0 +1,20 @@
+// Tests that type error points to the path in attribute
+
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+#[serde(untagged)]
+enum Enum {
+    // Newtype variants do not use the provided path, so it is forbidden here
+    // Newtype(#[serde(default = "main")] u8),
+    Tuple(u8, #[serde(default = "main")] i8),
+    Struct {
+        #[serde(default = "main")]
+        f1: u8,
+        f2: u8,
+        #[serde(default = "main")]
+        f3: i8,
+    },
+}
+
+fn main() {}

test_suite/tests/ui/default-attribute/incorrect_type_enum_untagged.stderr

@@ -0,0 +1,35 @@
+error[E0308]: `match` arms have incompatible types
+  --> tests/ui/default-attribute/incorrect_type_enum_untagged.rs:10:33
+   |
+5  | #[derive(Deserialize)]
+   |          -----------
+   |          |
+   |          this is found to be of type `i8`
+   |          `match` arms have incompatible types
+...
+10 |     Tuple(u8, #[serde(default = "main")] i8),
+   |                                 ^^^^^^ expected `i8`, found `()`
+
+error[E0308]: `match` arms have incompatible types
+  --> tests/ui/default-attribute/incorrect_type_enum_untagged.rs:12:27
+   |
+5  | #[derive(Deserialize)]
+   |          -----------
+   |          |
+   |          this is found to be of type `u8`
+   |          `match` arms have incompatible types
+...
+12 |         #[serde(default = "main")]
+   |                           ^^^^^^ expected `u8`, found `()`
+
+error[E0308]: `match` arms have incompatible types
+  --> tests/ui/default-attribute/incorrect_type_enum_untagged.rs:15:27
+   |
+5  | #[derive(Deserialize)]
+   |          -----------
+   |          |
+   |          this is found to be of type `i8`
+   |          `match` arms have incompatible types
+...
+15 |         #[serde(default = "main")]
+   |                           ^^^^^^ expected `i8`, found `()`

test_suite/tests/ui/default-attribute/incorrect_type_newtype.rs

@@ -0,0 +1,9 @@
+// Tests that type error points to the path in attribute
+
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+#[serde(default = "main")]
+struct Newtype(#[serde(default = "main")] u8);
+
+fn main() {}

test_suite/tests/ui/default-attribute/incorrect_type_newtype.stderr

@@ -0,0 +1,37 @@
+error[E0308]: mismatched types
+ --> tests/ui/default-attribute/incorrect_type_newtype.rs:6:19
+  |
+6 | #[serde(default = "main")]
+  |                   ^^^^^^
+  |                   |
+  |                   expected `Newtype`, found `()`
+  |                   expected due to this
+
+error[E0308]: `match` arms have incompatible types
+ --> tests/ui/default-attribute/incorrect_type_newtype.rs:7:34
+  |
+5 | #[derive(Deserialize)]
+  |          -----------
+  |          |
+  |          this is found to be of type `u8`
+  |          `match` arms have incompatible types
+6 | #[serde(default = "main")]
+7 | struct Newtype(#[serde(default = "main")] u8);
+  |                                  ^^^^^^ expected `u8`, found `()`
+
+error[E0308]: mismatched types
+ --> tests/ui/default-attribute/incorrect_type_newtype.rs:6:19
+  |
+6 | #[serde(default = "main")]
+  |                   ^^^^^^ expected `Newtype`, found `()`
+7 | struct Newtype(#[serde(default = "main")] u8);
+  |        ------- expected due to this
+
+error[E0308]: mismatched types
+ --> tests/ui/default-attribute/incorrect_type_newtype.rs:7:34
+  |
+5 | #[derive(Deserialize)]
+  |          ----------- expected due to the type of this binding
+6 | #[serde(default = "main")]
+7 | struct Newtype(#[serde(default = "main")] u8);
+  |                                  ^^^^^^ expected `u8`, found `()`

test_suite/tests/ui/default-attribute/incorrect_type_struct.rs

@@ -0,0 +1,15 @@
+// Tests that type error points to the path in attribute
+
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+#[serde(default = "main")]
+struct Struct {
+    #[serde(default = "main")]
+    f1: u8,
+    f2: u8,
+    #[serde(default = "main")]
+    f3: i8,
+}
+
+fn main() {}

test_suite/tests/ui/default-attribute/incorrect_type_struct.stderr

@@ -0,0 +1,58 @@
+error[E0308]: mismatched types
+ --> tests/ui/default-attribute/incorrect_type_struct.rs:6:19
+  |
+6 | #[serde(default = "main")]
+  |                   ^^^^^^
+  |                   |
+  |                   expected `Struct`, found `()`
+  |                   expected due to this
+
+error[E0308]: `match` arms have incompatible types
+ --> tests/ui/default-attribute/incorrect_type_struct.rs:8:23
+  |
+5 | #[derive(Deserialize)]
+  |          -----------
+  |          |
+  |          this is found to be of type `u8`
+  |          `match` arms have incompatible types
+...
+8 |     #[serde(default = "main")]
+  |                       ^^^^^^ expected `u8`, found `()`
+
+error[E0308]: `match` arms have incompatible types
+  --> tests/ui/default-attribute/incorrect_type_struct.rs:11:23
+   |
+5  | #[derive(Deserialize)]
+   |          -----------
+   |          |
+   |          this is found to be of type `i8`
+   |          `match` arms have incompatible types
+...
+11 |     #[serde(default = "main")]
+   |                       ^^^^^^ expected `i8`, found `()`
+
+error[E0308]: mismatched types
+ --> tests/ui/default-attribute/incorrect_type_struct.rs:6:19
+  |
+6 | #[serde(default = "main")]
+  |                   ^^^^^^ expected `Struct`, found `()`
+7 | struct Struct {
+  |        ------ expected due to this
+
+error[E0308]: mismatched types
+ --> tests/ui/default-attribute/incorrect_type_struct.rs:8:23
+  |
+5 | #[derive(Deserialize)]
+  |          ----------- expected due to the type of this binding
+...
+8 |     #[serde(default = "main")]
+  |                       ^^^^^^ expected `u8`, found `()`
+
+error[E0308]: mismatched types
+  --> tests/ui/default-attribute/incorrect_type_struct.rs:11:23
+   |
+5  | #[derive(Deserialize)]
+   |          ----------- expected due to the type of this binding
+...
+11 |     #[serde(default = "main")]
+   |                       ^^^^^^ expected `i8`, found `()`

test_suite/tests/ui/default-attribute/incorrect_type_tuple.rs

@@ -0,0 +1,9 @@
+// Tests that type error points to the path in attribute
+
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+#[serde(default = "main")]
+struct Tuple(u8, #[serde(default = "main")] i8);
+
+fn main() {}

test_suite/tests/ui/default-attribute/incorrect_type_tuple.stderr

@@ -0,0 +1,37 @@
+error[E0308]: mismatched types
+ --> tests/ui/default-attribute/incorrect_type_tuple.rs:6:19
+  |
+6 | #[serde(default = "main")]
+  |                   ^^^^^^
+  |                   |
+  |                   expected `Tuple`, found `()`
+  |                   expected due to this
+
+error[E0308]: `match` arms have incompatible types
+ --> tests/ui/default-attribute/incorrect_type_tuple.rs:7:36
+  |
+5 | #[derive(Deserialize)]
+  |          -----------
+  |          |
+  |          this is found to be of type `i8`
+  |          `match` arms have incompatible types
+6 | #[serde(default = "main")]
+7 | struct Tuple(u8, #[serde(default = "main")] i8);
+  |                                    ^^^^^^ expected `i8`, found `()`
+
+error[E0308]: mismatched types
+ --> tests/ui/default-attribute/incorrect_type_tuple.rs:6:19
+  |
+6 | #[serde(default = "main")]
+  |                   ^^^^^^ expected `Tuple`, found `()`
+7 | struct Tuple(u8, #[serde(default = "main")] i8);
+  |        ----- expected due to this
+
+error[E0308]: mismatched types
+ --> tests/ui/default-attribute/incorrect_type_tuple.rs:7:36
+  |
+5 | #[derive(Deserialize)]
+  |          ----------- expected due to the type of this binding
+6 | #[serde(default = "main")]
+7 | struct Tuple(u8, #[serde(default = "main")] i8);
+  |                                    ^^^^^^ expected `i8`, found `()`

test_suite/tests/ui/default-attribute/union.rs

@@ -0,0 +1,9 @@
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+#[serde(default)]
+union Union {
+    f: u8,
+}
+
+fn main() {}

test_suite/tests/ui/default-attribute/union.stderr

@@ -0,0 +1,14 @@
+error: #[serde(default)] can only be used on structs
+ --> tests/ui/default-attribute/union.rs:4:9
+  |
+4 | #[serde(default)]
+  |         ^^^^^^^
+
+error: Serde does not support derive for unions
+ --> tests/ui/default-attribute/union.rs:4:1
+  |
+4 | / #[serde(default)]
+5 | | union Union {
+6 | |     f: u8,
+7 | | }
+  | |_^

test_suite/tests/ui/default-attribute/union_path.rs

@@ -0,0 +1,9 @@
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+#[serde(default = "default_u")]
+union Union {
+    f: u8,
+}
+
+fn main() {}

test_suite/tests/ui/default-attribute/union_path.stderr

@@ -0,0 +1,14 @@
+error: #[serde(default = "...")] can only be used on structs
+ --> tests/ui/default-attribute/union_path.rs:4:9
+  |
+4 | #[serde(default = "default_u")]
+  |         ^^^^^^^^^^^^^^^^^^^^^
+
+error: Serde does not support derive for unions
+ --> tests/ui/default-attribute/union_path.rs:4:1
+  |
+4 | / #[serde(default = "default_u")]
+5 | | union Union {
+6 | |     f: u8,
+7 | | }
+  | |_^

test_suite/tests/ui/default-attribute/unit.rs

@@ -0,0 +1,7 @@
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+#[serde(default)]
+struct Unit;
+
+fn main() {}

test_suite/tests/ui/default-attribute/unit.stderr

@@ -0,0 +1,7 @@
+error: #[serde(default)] can only be used on structs that have fields
+ --> tests/ui/default-attribute/unit.rs:3:10
+  |
+3 | #[derive(Deserialize)]
+  |          ^^^^^^^^^^^
+  |
+  = note: this error originates in the derive macro `Deserialize` (in Nightly builds, run with -Z macro-backtrace for more info)

test_suite/tests/ui/default-attribute/unit_path.rs

@@ -0,0 +1,7 @@
+use serde_derive::Deserialize;
+
+#[derive(Deserialize)]
+#[serde(default = "default_u")]
+struct Unit;
+
+fn main() {}

test_suite/tests/ui/default-attribute/unit_path.stderr

@@ -0,0 +1,5 @@
+error: #[serde(default = "...")] can only be used on structs that have fields
+ --> tests/ui/default-attribute/unit_path.rs:4:9
+  |
+4 | #[serde(default = "default_u")]
+  |         ^^^^^^^^^^^^^^^^^^^^^

test_suite/tests/ui/with/incorrect_type.rs

@@ -0,0 +1,23 @@
+use serde_derive::{Deserialize, Serialize};
+
+mod w {
+    use serde::{Deserializer, Serializer};
+
+    pub fn deserialize<'de, D: Deserializer<'de>>(_: D) -> Result<(), D::Error> {
+        unimplemented!()
+    }
+    pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
+        unimplemented!()
+    }
+}
+
+#[derive(Serialize, Deserialize)]
+struct W(#[serde(with = "w")] u8, u8);
+
+#[derive(Serialize, Deserialize)]
+struct S(#[serde(serialize_with = "w::serialize")] u8, u8);
+
+#[derive(Serialize, Deserialize)]
+struct D(#[serde(deserialize_with = "w::deserialize")] u8, u8);
+
+fn main() {}

test_suite/tests/ui/with/incorrect_type.stderr

@@ -0,0 +1,101 @@
+error[E0277]: the trait bound `&u8: Serializer` is not satisfied
+  --> tests/ui/with/incorrect_type.rs:14:10
+   |
+14 | #[derive(Serialize, Deserialize)]
+   |          ^^^^^^^^^ the trait `Serializer` is not implemented for `&u8`
+15 | struct W(#[serde(with = "w")] u8, u8);
+   |                         --- required by a bound introduced by this call
+   |
+   = help: the following other types implement trait `Serializer`:
+             &mut Formatter<'a>
+             FlatMapSerializer<'a, M>
+             _::_serde::__private::ser::content::ContentSerializer<E>
+note: required by a bound in `w::serialize`
+  --> tests/ui/with/incorrect_type.rs:9:28
+   |
+9  |     pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
+   |                            ^^^^^^^^^^ required by this bound in `serialize`
+
+error[E0061]: this function takes 1 argument but 2 arguments were supplied
+  --> tests/ui/with/incorrect_type.rs:15:25
+   |
+14 | #[derive(Serialize, Deserialize)]
+   |          --------- unexpected argument #2 of type `__S`
+15 | struct W(#[serde(with = "w")] u8, u8);
+   |                         ^^^
+   |
+note: function defined here
+  --> tests/ui/with/incorrect_type.rs:9:12
+   |
+9  |     pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
+   |            ^^^^^^^^^                   ----
+
+error[E0277]: the trait bound `&u8: Serializer` is not satisfied
+  --> tests/ui/with/incorrect_type.rs:15:25
+   |
+15 | struct W(#[serde(with = "w")] u8, u8);
+   |                         ^^^ the trait `Serializer` is not implemented for `&u8`
+   |
+   = help: the following other types implement trait `Serializer`:
+             &mut Formatter<'a>
+             FlatMapSerializer<'a, M>
+             _::_serde::__private::ser::content::ContentSerializer<E>
+
+error[E0308]: `?` operator has incompatible types
+  --> tests/ui/with/incorrect_type.rs:15:25
+   |
+15 | struct W(#[serde(with = "w")] u8, u8);
+   |                         ^^^ expected `u8`, found `()`
+   |
+   = note: `?` operator cannot convert from `()` to `u8`
+
+error[E0277]: the trait bound `&u8: Serializer` is not satisfied
+  --> tests/ui/with/incorrect_type.rs:17:10
+   |
+17 | #[derive(Serialize, Deserialize)]
+   |          ^^^^^^^^^ the trait `Serializer` is not implemented for `&u8`
+18 | struct S(#[serde(serialize_with = "w::serialize")] u8, u8);
+   |                                   -------------- required by a bound introduced by this call
+   |
+   = help: the following other types implement trait `Serializer`:
+             &mut Formatter<'a>
+             FlatMapSerializer<'a, M>
+             _::_serde::__private::ser::content::ContentSerializer<E>
+note: required by a bound in `w::serialize`
+  --> tests/ui/with/incorrect_type.rs:9:28
+   |
+9  |     pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
+   |                            ^^^^^^^^^^ required by this bound in `serialize`
+
+error[E0061]: this function takes 1 argument but 2 arguments were supplied
+  --> tests/ui/with/incorrect_type.rs:18:35
+   |
+17 | #[derive(Serialize, Deserialize)]
+   |          --------- unexpected argument #2 of type `__S`
+18 | struct S(#[serde(serialize_with = "w::serialize")] u8, u8);
+   |                                   ^^^^^^^^^^^^^^
+   |
+note: function defined here
+  --> tests/ui/with/incorrect_type.rs:9:12
+   |
+9  |     pub fn serialize<T, S: Serializer>(_: S) -> Result<S::Ok, S::Error> {
+   |            ^^^^^^^^^                   ----
+
+error[E0277]: the trait bound `&u8: Serializer` is not satisfied
+  --> tests/ui/with/incorrect_type.rs:18:35
+   |
+18 | struct S(#[serde(serialize_with = "w::serialize")] u8, u8);
+   |                                   ^^^^^^^^^^^^^^ the trait `Serializer` is not implemented for `&u8`
+   |
+   = help: the following other types implement trait `Serializer`:
+             &mut Formatter<'a>
+             FlatMapSerializer<'a, M>
+             _::_serde::__private::ser::content::ContentSerializer<E>
+
+error[E0308]: `?` operator has incompatible types
+  --> tests/ui/with/incorrect_type.rs:21:37
+   |
+21 | struct D(#[serde(deserialize_with = "w::deserialize")] u8, u8);
+   |                                     ^^^^^^^^^^^^^^^^ expected `u8`, found `()`
+   |
+   = note: `?` operator cannot convert from `()` to `u8`