Improve overall quality of compile_error! errors

Also updates UI tests.

serde_derive/Cargo.toml

@@ -26,7 +26,7 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "0.4"
 quote = "0.6.3"
-syn = { version = "0.15", features = ["visit"] }
+syn = { version = "0.15.22", features = ["visit"] }
 
 [dev-dependencies]
 serde = { version = "1.0", path = "../serde" }

serde_derive/src/de.rs

@@ -13,9 +13,12 @@ use try;
 
 use std::collections::BTreeSet;
 
-pub fn expand_derive_deserialize(input: &syn::DeriveInput) -> Result<TokenStream, String> {
+pub fn expand_derive_deserialize(input: &syn::DeriveInput) -> Result<TokenStream, Vec<syn::Error>> {
     let ctxt = Ctxt::new();
-    let cont = Container::from_ast(&ctxt, input, Derive::Deserialize);
+    let cont = match Container::from_ast(&ctxt, input, Derive::Deserialize) {
+        Some(cont) => cont,
+        None => return Err(ctxt.check().unwrap_err()),
+    };
     precondition(&ctxt, &cont);
     try!(ctxt.check());
 
@@ -86,7 +89,7 @@ fn precondition_sized(cx: &Ctxt, cont: &Container) {
     if let Data::Struct(_, ref fields) = cont.data {
         if let Some(last) = fields.last() {
             if let syn::Type::Slice(_) = *last.ty {
-                cx.error("cannot deserialize a dynamically sized struct");
+                cx.error_spanned_by(cont.original, "cannot deserialize a dynamically sized struct");
             }
         }
     }
@@ -96,7 +99,10 @@ fn precondition_no_de_lifetime(cx: &Ctxt, cont: &Container) {
     if let BorrowedLifetimes::Borrowed(_) = borrowed_lifetimes(cont) {
         for param in cont.generics.lifetimes() {
             if param.lifetime.to_string() == "'de" {
-                cx.error("cannot deserialize when there is a lifetime parameter called 'de");
+                cx.error_spanned_by(
+                    &param.lifetime,
+                    "cannot deserialize when there is a lifetime parameter called 'de",
+                );
                 return;
             }
         }

serde_derive/src/internals/ast.rs

@@ -17,6 +17,8 @@ pub struct Container<'a> {
     pub data: Data<'a>,
     /// Any generics on the struct or enum.
     pub generics: &'a syn::Generics,
+    /// Original input.
+    pub original: &'a syn::DeriveInput,
 }
 
 /// The fields of a struct or enum.
@@ -33,6 +35,7 @@ pub struct Variant<'a> {
     pub attrs: attr::Variant,
     pub style: Style,
     pub fields: Vec<Field<'a>>,
+    pub original: &'a syn::Variant,
 }
 
 /// A field of a struct.
@@ -57,7 +60,7 @@ pub enum Style {
 
 impl<'a> Container<'a> {
     /// Convert the raw Syn ast into a parsed container object, collecting errors in `cx`.
-    pub fn from_ast(cx: &Ctxt, item: &'a syn::DeriveInput, derive: Derive) -> Container<'a> {
+    pub fn from_ast(cx: &Ctxt, item: &'a syn::DeriveInput, derive: Derive) -> Option<Container<'a>> {
         let mut attrs = attr::Container::from_ast(cx, item);
 
         let mut data = match item.data {
@@ -69,7 +72,8 @@ impl<'a> Container<'a> {
                 Data::Struct(style, fields)
             }
             syn::Data::Union(_) => {
-                panic!("Serde does not support derive for unions");
+                cx.error_spanned_by(item, "Serde does not support derive for unions");
+                return None;
             }
         };
 
@@ -105,9 +109,10 @@ impl<'a> Container<'a> {
             attrs: attrs,
             data: data,
             generics: &item.generics,
+            original: item,
         };
         check::check(cx, &mut item, derive);
-        item
+        Some(item)
     }
 }
 
@@ -142,6 +147,7 @@ fn enum_from_ast<'a>(
                 attrs: attrs,
                 style: style,
                 fields: fields,
+                original: variant,
             }
         })
         .collect()

serde_derive/src/internals/attr.rs

@@ -1,5 +1,6 @@
 use internals::Ctxt;
 use proc_macro2::{Group, Span, TokenStream, TokenTree};
+use quote::ToTokens;
 use std::collections::BTreeSet;
 use std::str::FromStr;
 use syn;
@@ -19,10 +20,11 @@ use syn::NestedMeta::{Literal, Meta};
 
 pub use internals::case::RenameRule;
 
-#[derive(Copy, Clone)]
+#[derive(Clone)]
 struct Attr<'c, T> {
     cx: &'c Ctxt,
     name: &'static str,
+    tokens: TokenStream,
     value: Option<T>,
 }
 
@@ -31,22 +33,28 @@ impl<'c, T> Attr<'c, T> {
         Attr {
             cx: cx,
             name: name,
+            tokens: TokenStream::new(),
             value: None,
         }
     }
 
-    fn set(&mut self, value: T) {
+    fn set<A: ToTokens>(&mut self, obj: A, value: T) {
+        let tokens = obj.into_token_stream();
+
         if self.value.is_some() {
-            self.cx
+            self.cx.error_spanned_by(
-                .error(format!("duplicate serde attribute `{}`", self.name));
+                tokens,
+                format!("duplicate serde attribute `{}`", self.name),
+            );
         } else {
+            self.tokens = tokens;
             self.value = Some(value);
         }
     }
 
-    fn set_opt(&mut self, value: Option<T>) {
+    fn set_opt<A: ToTokens>(&mut self, obj: A, value: Option<T>) {
         if let Some(value) = value {
-            self.set(value);
+            self.set(obj, value);
         }
     }
 
@@ -59,6 +67,13 @@ impl<'c, T> Attr<'c, T> {
     fn get(self) -> Option<T> {
         self.value
     }
+
+    fn get_with_tokens(self) -> Option<(TokenStream, T)> {
+        match self.value {
+            Some(v) => Some((self.tokens, v)),
+            None    => None,
+        }
+    }
 }
 
 struct BoolAttr<'c>(Attr<'c, ()>);
@@ -68,8 +83,8 @@ impl<'c> BoolAttr<'c> {
         BoolAttr(Attr::none(cx, name))
     }
 
-    fn set_true(&mut self) {
+    fn set_true<A: ToTokens>(&mut self, obj: A) {
-        self.0.set(());
+        self.0.set(obj, ());
     }
 
     fn get(&self) -> bool {
@@ -199,16 +214,16 @@ impl Container {
                     // Parse `#[serde(rename = "foo")]`
                     Meta(NameValue(ref m)) if m.ident == "rename" => {
                         if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
-                            ser_name.set(s.value());
+                            ser_name.set(&m.ident, s.value());
-                            de_name.set(s.value());
+                            de_name.set(&m.ident, s.value());
                         }
                     }
 
                     // Parse `#[serde(rename(serialize = "foo", deserialize = "bar"))]`
                     Meta(List(ref m)) if m.ident == "rename" => {
                         if let Ok((ser, de)) = get_renames(cx, &m.nested) {
-                            ser_name.set_opt(ser.map(syn::LitStr::value));
+                            ser_name.set_opt(&m.ident, ser.map(syn::LitStr::value));
-                            de_name.set_opt(de.map(syn::LitStr::value));
+                            de_name.set_opt(&m.ident, de.map(syn::LitStr::value));
                         }
                     }
 
@@ -216,11 +231,11 @@ impl Container {
                     Meta(NameValue(ref m)) if m.ident == "rename_all" => {
                         if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
                             match RenameRule::from_str(&s.value()) {
-                                Ok(rename_rule) => rename_all.set(rename_rule),
+                                Ok(rename_rule) => rename_all.set(&m.ident, rename_rule),
-                                Err(()) => cx.error(format!(
+                                Err(()) => cx.error_spanned_by(s, format!(
                                     "unknown rename rule for #[serde(rename_all \
                                      = {:?})]",
-                                    s.value()
+                                    s.value(),
                                 )),
                             }
                         }
@@ -228,23 +243,33 @@ impl Container {
 
                     // Parse `#[serde(transparent)]`
                     Meta(Word(ref word)) if word == "transparent" => {
-                        transparent.set_true();
+                        transparent.set_true(word);
                     }
 
                     // Parse `#[serde(deny_unknown_fields)]`
                     Meta(Word(ref word)) if word == "deny_unknown_fields" => {
-                        deny_unknown_fields.set_true();
+                        deny_unknown_fields.set_true(word);
                     }
 
                     // Parse `#[serde(default)]`
                     Meta(Word(ref word)) if word == "default" => match item.data {
-                        syn::Data::Struct(syn::DataStruct {
+                        syn::Data::Struct(syn::DataStruct { ref fields, .. }) => match *fields {
-                            fields: syn::Fields::Named(_),
+                            syn::Fields::Named(_) => {
-                            ..
+                                default.set(word, Default::Default);
-                        }) => {
+                            }
-                            default.set(Default::Default);
+                            syn::Fields::Unnamed(_) | syn::Fields::Unit => cx.error_spanned_by(
-                        }
+                                fields,
-                        _ => cx.error(
+                                "#[serde(default)] can only be used on structs \
+                                 with named fields",
+                            )
+                        },
+                        syn::Data::Enum(syn::DataEnum { ref enum_token, .. }) => cx.error_spanned_by(
+                            enum_token,
+                            "#[serde(default)] can only be used on structs \
+                             with named fields",
+                        ),
+                        syn::Data::Union(syn::DataUnion { ref union_token, .. }) => cx.error_spanned_by(
+                            union_token,
                             "#[serde(default)] can only be used on structs \
                              with named fields",
                         ),
@@ -254,13 +279,23 @@ impl Container {
                     Meta(NameValue(ref m)) if m.ident == "default" => {
                         if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
                             match item.data {
-                                syn::Data::Struct(syn::DataStruct {
+                                syn::Data::Struct(syn::DataStruct { ref fields, .. }) => match *fields {
-                                    fields: syn::Fields::Named(_),
+                                    syn::Fields::Named(_) => {
-                                    ..
+                                        default.set(&m.ident, Default::Path(path));
-                                }) => {
+                                    }
-                                    default.set(Default::Path(path));
+                                    syn::Fields::Unnamed(_) | syn::Fields::Unit => cx.error_spanned_by(
-                                }
+                                        fields,
-                                _ => cx.error(
+                                        "#[serde(default = \"...\")] can only be used \
+                                         on structs with named fields",
+                                    )
+                                },
+                                syn::Data::Enum(syn::DataEnum { ref enum_token, .. }) => cx.error_spanned_by(
+                                    enum_token,
+                                    "#[serde(default = \"...\")] can only be used \
+                                     on structs with named fields",
+                                ),
+                                syn::Data::Union(syn::DataUnion { ref union_token, .. }) => cx.error_spanned_by(
+                                    union_token,
                                     "#[serde(default = \"...\")] can only be used \
                                      on structs with named fields",
                                 ),
@@ -273,26 +308,35 @@ impl Container {
                         if let Ok(where_predicates) =
                             parse_lit_into_where(cx, &m.ident, &m.ident, &m.lit)
                         {
-                            ser_bound.set(where_predicates.clone());
+                            ser_bound.set(&m.ident, where_predicates.clone());
-                            de_bound.set(where_predicates);
+                            de_bound.set(&m.ident, where_predicates);
                         }
                     }
 
                     // Parse `#[serde(bound(serialize = "...", deserialize = "..."))]`
                     Meta(List(ref m)) if m.ident == "bound" => {
                         if let Ok((ser, de)) = get_where_predicates(cx, &m.nested) {
-                            ser_bound.set_opt(ser);
+                            ser_bound.set_opt(&m.ident, ser);
-                            de_bound.set_opt(de);
+                            de_bound.set_opt(&m.ident, de);
                         }
                     }
 
                     // Parse `#[serde(untagged)]`
                     Meta(Word(ref word)) if word == "untagged" => match item.data {
                         syn::Data::Enum(_) => {
-                            untagged.set_true();
+                            untagged.set_true(word);
                         }
-                        syn::Data::Struct(_) | syn::Data::Union(_) => {
+                        syn::Data::Struct(syn::DataStruct { ref struct_token, .. }) => {
-                            cx.error("#[serde(untagged)] can only be used on enums")
+                            cx.error_spanned_by(
+                                struct_token,
+                                "#[serde(untagged)] can only be used on enums",
+                            );
+                        }
+                        syn::Data::Union(syn::DataUnion { ref union_token, .. }) => {
+                            cx.error_spanned_by(
+                                union_token,
+                                "#[serde(untagged)] can only be used on enums",
+                            );
                         }
                     },
 
@@ -301,11 +345,20 @@ impl Container {
                         if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
                             match item.data {
                                 syn::Data::Enum(_) => {
-                                    internal_tag.set(s.value());
+                                    internal_tag.set(&m.ident, s.value());
-                                }
-                                syn::Data::Struct(_) | syn::Data::Union(_) => {
-                                    cx.error("#[serde(tag = \"...\")] can only be used on enums")
                                 }
+                                syn::Data::Struct(syn::DataStruct { ref struct_token, .. }) => {
+                                    cx.error_spanned_by(
+                                        struct_token,
+                                        "#[serde(tag = \"...\")] can only be used on enums",
+                                    );
+                                },
+                                syn::Data::Union(syn::DataUnion { ref union_token, .. }) => {
+                                    cx.error_spanned_by(
+                                        union_token,
+                                        "#[serde(tag = \"...\")] can only be used on enums",
+                                    );
+                                },
                             }
                         }
                     }
@@ -315,12 +368,20 @@ impl Container {
                         if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
                             match item.data {
                                 syn::Data::Enum(_) => {
-                                    content.set(s.value());
+                                    content.set(&m.ident, s.value());
                                 }
-                                syn::Data::Struct(_) | syn::Data::Union(_) => cx.error(
+                                syn::Data::Struct(syn::DataStruct { ref struct_token, .. }) => {
-                                    "#[serde(content = \"...\")] can only be used on \
+                                    cx.error_spanned_by(
-                                     enums",
+                                        struct_token,
-                                ),
+                                        "#[serde(content = \"...\")] can only be used on enums",
+                                    );
+                                },
+                                syn::Data::Union(syn::DataUnion { ref union_token, .. }) => {
+                                    cx.error_spanned_by(
+                                        union_token,
+                                        "#[serde(content = \"...\")] can only be used on enums",
+                                    );
+                                },
                             }
                         }
                     }
@@ -328,14 +389,14 @@ impl Container {
                     // Parse `#[serde(from = "Type")]
                     Meta(NameValue(ref m)) if m.ident == "from" => {
                         if let Ok(from_ty) = parse_lit_into_ty(cx, &m.ident, &m.lit) {
-                            type_from.set_opt(Some(from_ty));
+                            type_from.set_opt(&m.ident, Some(from_ty));
                         }
                     }
 
                     // Parse `#[serde(into = "Type")]
                     Meta(NameValue(ref m)) if m.ident == "into" => {
                         if let Ok(into_ty) = parse_lit_into_ty(cx, &m.ident, &m.lit) {
-                            type_into.set_opt(Some(into_ty));
+                            type_into.set_opt(&m.ident, Some(into_ty));
                         }
                     }
 
@@ -343,32 +404,32 @@ impl Container {
                     Meta(NameValue(ref m)) if m.ident == "remote" => {
                         if let Ok(path) = parse_lit_into_path(cx, &m.ident, &m.lit) {
                             if is_primitive_path(&path, "Self") {
-                                remote.set(item.ident.clone().into());
+                                remote.set(&m.ident, item.ident.clone().into());
                             } else {
-                                remote.set(path);
+                                remote.set(&m.ident, path);
                             }
                         }
                     }
 
                     // Parse `#[serde(field_identifier)]`
                     Meta(Word(ref word)) if word == "field_identifier" => {
-                        field_identifier.set_true();
+                        field_identifier.set_true(word);
                     }
 
                     // Parse `#[serde(variant_identifier)]`
                     Meta(Word(ref word)) if word == "variant_identifier" => {
-                        variant_identifier.set_true();
+                        variant_identifier.set_true(word);
                     }
 
                     Meta(ref meta_item) => {
-                        cx.error(format!(
+                        cx.error_spanned_by(meta_item.name(), format!(
                             "unknown serde container attribute `{}`",
                             meta_item.name()
                         ));
                     }
 
-                    Literal(_) => {
+                    Literal(ref lit) => {
-                        cx.error("unexpected literal in serde container attribute");
+                        cx.error_spanned_by(lit, "unexpected literal in serde container attribute");
                     }
                 }
             }
@@ -385,11 +446,11 @@ impl Container {
             rename_all: rename_all.get().unwrap_or(RenameRule::None),
             ser_bound: ser_bound.get(),
             de_bound: de_bound.get(),
-            tag: decide_tag(cx, item, &untagged, internal_tag, content),
+            tag: decide_tag(cx, item, untagged, internal_tag, content),
             type_from: type_from.get(),
             type_into: type_into.get(),
             remote: remote.get(),
-            identifier: decide_identifier(cx, item, &field_identifier, &variant_identifier),
+            identifier: decide_identifier(cx, item, field_identifier, variant_identifier),
             has_flatten: false,
         }
     }
@@ -454,14 +515,14 @@ impl Container {
 fn decide_tag(
     cx: &Ctxt,
     item: &syn::DeriveInput,
-    untagged: &BoolAttr,
+    untagged: BoolAttr,
     internal_tag: Attr<String>,
     content: Attr<String>,
 ) -> EnumTag {
-    match (untagged.get(), internal_tag.get(), content.get()) {
+    match (untagged.0.get_with_tokens(), internal_tag.get_with_tokens(), content.get_with_tokens()) {
-        (false, None, None) => EnumTag::External,
+        (None, None, None) => EnumTag::External,
-        (true, None, None) => EnumTag::None,
+        (Some(_), None, None) => EnumTag::None,
-        (false, Some(tag), None) => {
+        (None, Some((_, tag)), None) => {
             // Check that there are no tuple variants.
             if let syn::Data::Enum(ref data) = item.data {
                 for variant in &data.variants {
@@ -469,7 +530,8 @@ fn decide_tag(
                         syn::Fields::Named(_) | syn::Fields::Unit => {}
                         syn::Fields::Unnamed(ref fields) => {
                             if fields.unnamed.len() != 1 {
-                                cx.error(
+                                cx.error_spanned_by(
+                                    variant,
                                     "#[serde(tag = \"...\")] cannot be used with tuple \
                                      variants",
                                 );
@@ -481,24 +543,52 @@ fn decide_tag(
             }
             EnumTag::Internal { tag: tag }
         }
-        (true, Some(_), None) => {
+        (Some((untagged_tokens, _)), Some((tag_tokens, _)), None) => {
-            cx.error("enum cannot be both untagged and internally tagged");
+            cx.error_spanned_by(
+                untagged_tokens,
+                "enum cannot be both untagged and internally tagged",
+            );
+            cx.error_spanned_by(
+                tag_tokens,
+                "enum cannot be both untagged and internally tagged",
+            );
             EnumTag::External // doesn't matter, will error
         }
-        (false, None, Some(_)) => {
+        (None, None, Some((content_tokens, _))) => {
-            cx.error("#[serde(tag = \"...\", content = \"...\")] must be used together");
+            cx.error_spanned_by(
+                content_tokens,
+                "#[serde(tag = \"...\", content = \"...\")] must be used together",
+            );
             EnumTag::External
         }
-        (true, None, Some(_)) => {
+        (Some((untagged_tokens, _)), None, Some((content_tokens, _))) => {
-            cx.error("untagged enum cannot have #[serde(content = \"...\")]");
+            cx.error_spanned_by(
+                untagged_tokens,
+                "untagged enum cannot have #[serde(content = \"...\")]",
+            );
+            cx.error_spanned_by(
+                content_tokens,
+                "untagged enum cannot have #[serde(content = \"...\")]",
+            );
             EnumTag::External
         }
-        (false, Some(tag), Some(content)) => EnumTag::Adjacent {
+        (None, Some((_, tag)), Some((_, content))) => EnumTag::Adjacent {
             tag: tag,
             content: content,
         },
-        (true, Some(_), Some(_)) => {
+        (Some((untagged_tokens, _)), Some((tag_tokens, _)), Some((content_tokens, _))) => {
-            cx.error("untagged enum cannot have #[serde(tag = \"...\", content = \"...\")]");
+            cx.error_spanned_by(
+                untagged_tokens,
+                "untagged enum cannot have #[serde(tag = \"...\", content = \"...\")]",
+            );
+            cx.error_spanned_by(
+                tag_tokens,
+                "untagged enum cannot have #[serde(tag = \"...\", content = \"...\")]",
+            );
+            cx.error_spanned_by(
+                content_tokens,
+                "untagged enum cannot have #[serde(tag = \"...\", content = \"...\")]",
+            );
             EnumTag::External
         }
     }
@@ -507,23 +597,50 @@ fn decide_tag(
 fn decide_identifier(
     cx: &Ctxt,
     item: &syn::DeriveInput,
-    field_identifier: &BoolAttr,
+    field_identifier: BoolAttr,
-    variant_identifier: &BoolAttr,
+    variant_identifier: BoolAttr,
 ) -> Identifier {
-    match (&item.data, field_identifier.get(), variant_identifier.get()) {
+    match (&item.data, field_identifier.0.get_with_tokens(), variant_identifier.0.get_with_tokens()) {
-        (_, false, false) => Identifier::No,
+        (_, None, None) => Identifier::No,
-        (_, true, true) => {
+        (_, Some((field_identifier_tokens, _)), Some((variant_identifier_tokens, _))) => {
-            cx.error("`field_identifier` and `variant_identifier` cannot both be set");
+            cx.error_spanned_by(
+                field_identifier_tokens,
+                "#[serde(field_identifier)] and #[serde(variant_identifier)] cannot both be set",
+            );
+            cx.error_spanned_by(
+                variant_identifier_tokens,
+                "#[serde(field_identifier)] and #[serde(variant_identifier)] cannot both be set",
+            );
             Identifier::No
         }
-        (&syn::Data::Enum(_), true, false) => Identifier::Field,
+        (&syn::Data::Enum(_), Some(_), None) => Identifier::Field,
-        (&syn::Data::Enum(_), false, true) => Identifier::Variant,
+        (&syn::Data::Enum(_), None, Some(_)) => Identifier::Variant,
-        (&syn::Data::Struct(_), true, false) | (&syn::Data::Union(_), true, false) => {
+        (&syn::Data::Struct(syn::DataStruct { ref struct_token, .. }), Some(_), None) => {
-            cx.error("`field_identifier` can only be used on an enum");
+            cx.error_spanned_by(
+                struct_token,
+                "#[serde(field_identifier)] can only be used on an enum",
+            );
             Identifier::No
         }
-        (&syn::Data::Struct(_), false, true) | (&syn::Data::Union(_), false, true) => {
+        (&syn::Data::Union(syn::DataUnion { ref union_token, .. }), Some(_), None) => {
-            cx.error("`variant_identifier` can only be used on an enum");
+            cx.error_spanned_by(
+                union_token,
+                "#[serde(field_identifier)] can only be used on an enum",
+            );
+            Identifier::No
+        }
+        (&syn::Data::Struct(syn::DataStruct { ref struct_token, .. }), None, Some(_)) => {
+            cx.error_spanned_by(
+                struct_token,
+                "#[serde(variant_identifier)] can only be used on an enum",
+            );
+            Identifier::No
+        }
+        (&syn::Data::Union(syn::DataUnion { ref union_token, .. }), None, Some(_)) => {
+            cx.error_spanned_by(
+                union_token,
+                "#[serde(variant_identifier)] can only be used on an enum",
+            );
             Identifier::No
         }
     }
@@ -565,16 +682,16 @@ impl Variant {
                     // Parse `#[serde(rename = "foo")]`
                     Meta(NameValue(ref m)) if m.ident == "rename" => {
                         if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
-                            ser_name.set(s.value());
+                            ser_name.set(&m.ident, s.value());
-                            de_name.set(s.value());
+                            de_name.set(&m.ident, s.value());
                         }
                     }
 
                     // Parse `#[serde(rename(serialize = "foo", deserialize = "bar"))]`
                     Meta(List(ref m)) if m.ident == "rename" => {
                         if let Ok((ser, de)) = get_renames(cx, &m.nested) {
-                            ser_name.set_opt(ser.map(syn::LitStr::value));
+                            ser_name.set_opt(&m.ident, ser.map(syn::LitStr::value));
-                            de_name.set_opt(de.map(syn::LitStr::value));
+                            de_name.set_opt(&m.ident, de.map(syn::LitStr::value));
                         }
                     }
 
@@ -582,8 +699,8 @@ impl Variant {
                     Meta(NameValue(ref m)) if m.ident == "rename_all" => {
                         if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
                             match RenameRule::from_str(&s.value()) {
-                                Ok(rename_rule) => rename_all.set(rename_rule),
+                                Ok(rename_rule) => rename_all.set(&m.ident, rename_rule),
-                                Err(()) => cx.error(format!(
+                                Err(()) => cx.error_spanned_by(s, format!(
                                     "unknown rename rule for #[serde(rename_all \
                                      = {:?})]",
                                     s.value()
@@ -594,23 +711,23 @@ impl Variant {
 
                     // Parse `#[serde(skip)]`
                     Meta(Word(ref word)) if word == "skip" => {
-                        skip_serializing.set_true();
+                        skip_serializing.set_true(word);
-                        skip_deserializing.set_true();
+                        skip_deserializing.set_true(word);
                     }
 
                     // Parse `#[serde(skip_deserializing)]`
                     Meta(Word(ref word)) if word == "skip_deserializing" => {
-                        skip_deserializing.set_true();
+                        skip_deserializing.set_true(word);
                     }
 
                     // Parse `#[serde(skip_serializing)]`
                     Meta(Word(ref word)) if word == "skip_serializing" => {
-                        skip_serializing.set_true();
+                        skip_serializing.set_true(word);
                     }
 
                     // Parse `#[serde(other)]`
                     Meta(Word(ref word)) if word == "other" => {
-                        other.set_true();
+                        other.set_true(word);
                     }
 
                     // Parse `#[serde(bound = "T: SomeBound")]`
@@ -618,16 +735,16 @@ impl Variant {
                         if let Ok(where_predicates) =
                             parse_lit_into_where(cx, &m.ident, &m.ident, &m.lit)
                         {
-                            ser_bound.set(where_predicates.clone());
+                            ser_bound.set(&m.ident, where_predicates.clone());
-                            de_bound.set(where_predicates);
+                            de_bound.set(&m.ident, where_predicates);
                         }
                     }
 
                     // Parse `#[serde(bound(serialize = "...", deserialize = "..."))]`
                     Meta(List(ref m)) if m.ident == "bound" => {
                         if let Ok((ser, de)) = get_where_predicates(cx, &m.nested) {
-                            ser_bound.set_opt(ser);
+                            ser_bound.set_opt(&m.ident, ser);
-                            de_bound.set_opt(de);
+                            de_bound.set_opt(&m.ident, de);
                         }
                     }
 
@@ -639,49 +756,55 @@ impl Variant {
                                 .path
                                 .segments
                                 .push(Ident::new("serialize", Span::call_site()).into());
-                            serialize_with.set(ser_path);
+                            serialize_with.set(&m.ident, ser_path);
                             let mut de_path = path;
                             de_path
                                 .path
                                 .segments
                                 .push(Ident::new("deserialize", Span::call_site()).into());
-                            deserialize_with.set(de_path);
+                            deserialize_with.set(&m.ident, de_path);
                         }
                     }
 
                     // Parse `#[serde(serialize_with = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "serialize_with" => {
                         if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
-                            serialize_with.set(path);
+                            serialize_with.set(&m.ident, path);
                         }
                     }
 
                     // Parse `#[serde(deserialize_with = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "deserialize_with" => {
                         if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
-                            deserialize_with.set(path);
+                            deserialize_with.set(&m.ident, path);
                         }
                     }
 
                     // Defer `#[serde(borrow)]` and `#[serde(borrow = "'a + 'b")]`
                     Meta(ref m) if m.name() == "borrow" => match variant.fields {
                         syn::Fields::Unnamed(ref fields) if fields.unnamed.len() == 1 => {
-                            borrow.set(m.clone());
+                            borrow.set(m.name(), m.clone());
                         }
                         _ => {
-                            cx.error("#[serde(borrow)] may only be used on newtype variants");
+                            cx.error_spanned_by(
+                                variant,
+                                "#[serde(borrow)] may only be used on newtype variants",
+                            );
                         }
                     },
 
                     Meta(ref meta_item) => {
-                        cx.error(format!(
+                        cx.error_spanned_by(meta_item.name(), format!(
                             "unknown serde variant attribute `{}`",
                             meta_item.name()
                         ));
                     }
 
-                    Literal(_) => {
+                    Literal(ref lit) => {
-                        cx.error("unexpected literal in serde variant attribute");
+                        cx.error_spanned_by(
+                            lit,
+                            "unexpected literal in serde variant attribute",
+                        );
                     }
                 }
             }
@@ -837,65 +960,65 @@ impl Field {
                     // Parse `#[serde(rename = "foo")]`
                     Meta(NameValue(ref m)) if m.ident == "rename" => {
                         if let Ok(s) = get_lit_str(cx, &m.ident, &m.ident, &m.lit) {
-                            ser_name.set(s.value());
+                            ser_name.set(&m.ident, s.value());
-                            de_name.set(s.value());
+                            de_name.set(&m.ident, s.value());
                         }
                     }
 
                     // Parse `#[serde(rename(serialize = "foo", deserialize = "bar"))]`
                     Meta(List(ref m)) if m.ident == "rename" => {
                         if let Ok((ser, de)) = get_renames(cx, &m.nested) {
-                            ser_name.set_opt(ser.map(syn::LitStr::value));
+                            ser_name.set_opt(&m.ident, ser.map(syn::LitStr::value));
-                            de_name.set_opt(de.map(syn::LitStr::value));
+                            de_name.set_opt(&m.ident, de.map(syn::LitStr::value));
                         }
                     }
 
                     // Parse `#[serde(default)]`
                     Meta(Word(ref word)) if word == "default" => {
-                        default.set(Default::Default);
+                        default.set(word, Default::Default);
                     }
 
                     // Parse `#[serde(default = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "default" => {
                         if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
-                            default.set(Default::Path(path));
+                            default.set(&m.ident, Default::Path(path));
                         }
                     }
 
                     // Parse `#[serde(skip_serializing)]`
                     Meta(Word(ref word)) if word == "skip_serializing" => {
-                        skip_serializing.set_true();
+                        skip_serializing.set_true(word);
                     }
 
                     // Parse `#[serde(skip_deserializing)]`
                     Meta(Word(ref word)) if word == "skip_deserializing" => {
-                        skip_deserializing.set_true();
+                        skip_deserializing.set_true(word);
                     }
 
                     // Parse `#[serde(skip)]`
                     Meta(Word(ref word)) if word == "skip" => {
-                        skip_serializing.set_true();
+                        skip_serializing.set_true(word);
-                        skip_deserializing.set_true();
+                        skip_deserializing.set_true(word);
                     }
 
                     // Parse `#[serde(skip_serializing_if = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "skip_serializing_if" => {
                         if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
-                            skip_serializing_if.set(path);
+                            skip_serializing_if.set(&m.ident, path);
                         }
                     }
 
                     // Parse `#[serde(serialize_with = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "serialize_with" => {
                         if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
-                            serialize_with.set(path);
+                            serialize_with.set(&m.ident, path);
                         }
                     }
 
                     // Parse `#[serde(deserialize_with = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "deserialize_with" => {
                         if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
-                            deserialize_with.set(path);
+                            deserialize_with.set(&m.ident, path);
                         }
                     }
 
@@ -907,13 +1030,13 @@ impl Field {
                                 .path
                                 .segments
                                 .push(Ident::new("serialize", Span::call_site()).into());
-                            serialize_with.set(ser_path);
+                            serialize_with.set(&m.ident, ser_path);
                             let mut de_path = path;
                             de_path
                                 .path
                                 .segments
                                 .push(Ident::new("deserialize", Span::call_site()).into());
-                            deserialize_with.set(de_path);
+                            deserialize_with.set(&m.ident, de_path);
                         }
                     }
 
@@ -922,39 +1045,39 @@ impl Field {
                         if let Ok(where_predicates) =
                             parse_lit_into_where(cx, &m.ident, &m.ident, &m.lit)
                         {
-                            ser_bound.set(where_predicates.clone());
+                            ser_bound.set(&m.ident, where_predicates.clone());
-                            de_bound.set(where_predicates);
+                            de_bound.set(&m.ident, where_predicates);
                         }
                     }
 
                     // Parse `#[serde(bound(serialize = "...", deserialize = "..."))]`
                     Meta(List(ref m)) if m.ident == "bound" => {
                         if let Ok((ser, de)) = get_where_predicates(cx, &m.nested) {
-                            ser_bound.set_opt(ser);
+                            ser_bound.set_opt(&m.ident, ser);
-                            de_bound.set_opt(de);
+                            de_bound.set_opt(&m.ident, de);
                         }
                     }
 
                     // Parse `#[serde(borrow)]`
                     Meta(Word(ref word)) if word == "borrow" => {
-                        if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, &field.ty) {
+                        if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, field) {
-                            borrowed_lifetimes.set(borrowable);
+                            borrowed_lifetimes.set(word, borrowable);
                         }
                     }
 
                     // Parse `#[serde(borrow = "'a + 'b")]`
                     Meta(NameValue(ref m)) if m.ident == "borrow" => {
                         if let Ok(lifetimes) = parse_lit_into_lifetimes(cx, &m.ident, &m.lit) {
-                            if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, &field.ty) {
+                            if let Ok(borrowable) = borrowable_lifetimes(cx, &ident, field) {
                                 for lifetime in &lifetimes {
                                     if !borrowable.contains(lifetime) {
-                                        cx.error(format!(
+                                        cx.error_spanned_by(field, format!(
                                             "field `{}` does not have lifetime {}",
                                             ident, lifetime
                                         ));
                                     }
                                 }
-                                borrowed_lifetimes.set(lifetimes);
+                                borrowed_lifetimes.set(&m.ident, lifetimes);
                             }
                         }
                     }
@@ -962,24 +1085,27 @@ impl Field {
                     // Parse `#[serde(getter = "...")]`
                     Meta(NameValue(ref m)) if m.ident == "getter" => {
                         if let Ok(path) = parse_lit_into_expr_path(cx, &m.ident, &m.lit) {
-                            getter.set(path);
+                            getter.set(&m.ident, path);
                         }
                     }
 
                     // Parse `#[serde(flatten)]`
                     Meta(Word(ref word)) if word == "flatten" => {
-                        flatten.set_true();
+                        flatten.set_true(word);
                     }
 
                     Meta(ref meta_item) => {
-                        cx.error(format!(
+                        cx.error_spanned_by(meta_item.name(), format!(
                             "unknown serde field attribute `{}`",
                             meta_item.name()
                         ));
                     }
 
-                    Literal(_) => {
+                    Literal(ref lit) => {
-                        cx.error("unexpected literal in serde field attribute");
+                        cx.error_spanned_by(
+                            lit,
+                            "unexpected literal in serde field attribute",
+                        );
                     }
                 }
             }
@@ -1162,18 +1288,18 @@ where
         match *meta {
             Meta(NameValue(ref meta)) if meta.ident == "serialize" => {
                 if let Ok(v) = f(cx, &attr_name, &meta.ident, &meta.lit) {
-                    ser_meta.set(v);
+                    ser_meta.set(&meta.ident, v);
                 }
             }
 
             Meta(NameValue(ref meta)) if meta.ident == "deserialize" => {
                 if let Ok(v) = f(cx, &attr_name, &meta.ident, &meta.lit) {
-                    de_meta.set(v);
+                    de_meta.set(&meta.ident, v);
                 }
             }
 
             _ => {
-                cx.error(format!(
+                cx.error_spanned_by(meta, format!(
                     "malformed {0} attribute, expected `{0}(serialize = ..., \
                      deserialize = ...)`",
                     attr_name
@@ -1223,7 +1349,7 @@ fn get_lit_str<'a>(
     if let syn::Lit::Str(ref lit) = *lit {
         Ok(lit)
     } else {
-        cx.error(format!(
+        cx.error_spanned_by(lit, format!(
             "expected serde {} attribute to be a string: `{} = \"...\"`",
             attr_name, meta_item_name
         ));
@@ -1234,7 +1360,10 @@ fn get_lit_str<'a>(
 fn parse_lit_into_path(cx: &Ctxt, attr_name: &Ident, lit: &syn::Lit) -> Result<syn::Path, ()> {
     let string = try!(get_lit_str(cx, attr_name, attr_name, lit));
     parse_lit_str(string)
-        .map_err(|_| cx.error(format!("failed to parse path: {:?}", string.value())))
+        .map_err(|_| cx.error_spanned_by(
+            lit,
+            format!("failed to parse path: {:?}", string.value()),
+        ))
 }
 
 fn parse_lit_into_expr_path(
@@ -1244,7 +1373,10 @@ fn parse_lit_into_expr_path(
 ) -> Result<syn::ExprPath, ()> {
     let string = try!(get_lit_str(cx, attr_name, attr_name, lit));
     parse_lit_str(string)
-        .map_err(|_| cx.error(format!("failed to parse path: {:?}", string.value())))
+        .map_err(|_| cx.error_spanned_by(
+            lit,
+            format!("failed to parse path: {:?}", string.value()),
+        ))
 }
 
 fn parse_lit_into_where(
@@ -1262,14 +1394,14 @@ fn parse_lit_into_where(
 
     parse_lit_str::<syn::WhereClause>(&where_string)
         .map(|wh| wh.predicates.into_iter().collect())
-        .map_err(|err| cx.error(err))
+        .map_err(|err| cx.error_spanned_by(lit, err))
 }
 
 fn parse_lit_into_ty(cx: &Ctxt, attr_name: &Ident, lit: &syn::Lit) -> Result<syn::Type, ()> {
     let string = try!(get_lit_str(cx, attr_name, attr_name, lit));
 
     parse_lit_str(string).map_err(|_| {
-        cx.error(format!(
+        cx.error_spanned_by(lit, format!(
             "failed to parse type: {} = {:?}",
             attr_name,
             string.value()
@@ -1286,7 +1418,7 @@ fn parse_lit_into_lifetimes(
 ) -> Result<BTreeSet<syn::Lifetime>, ()> {
     let string = try!(get_lit_str(cx, attr_name, attr_name, lit));
     if string.value().is_empty() {
-        cx.error("at least one lifetime must be borrowed");
+        cx.error_spanned_by(lit, "at least one lifetime must be borrowed");
         return Err(());
     }
 
@@ -1302,13 +1434,16 @@ fn parse_lit_into_lifetimes(
         let mut set = BTreeSet::new();
         for lifetime in lifetimes {
             if !set.insert(lifetime.clone()) {
-                cx.error(format!("duplicate borrowed lifetime `{}`", lifetime));
+                cx.error_spanned_by(
+                    lit,
+                    format!("duplicate borrowed lifetime `{}`", lifetime),
+                );
             }
         }
         return Ok(set);
     }
 
-    cx.error(format!(
+    cx.error_spanned_by(lit, format!(
         "failed to parse borrowed lifetimes: {:?}",
         string.value()
     ));
@@ -1461,12 +1596,15 @@ fn is_primitive_path(path: &syn::Path, primitive: &str) -> bool {
 fn borrowable_lifetimes(
     cx: &Ctxt,
     name: &str,
-    ty: &syn::Type,
+    field: &syn::Field,
 ) -> Result<BTreeSet<syn::Lifetime>, ()> {
     let mut lifetimes = BTreeSet::new();
-    collect_lifetimes(ty, &mut lifetimes);
+    collect_lifetimes(&field.ty, &mut lifetimes);
     if lifetimes.is_empty() {
-        cx.error(format!("field `{}` has no lifetimes to borrow", name));
+        cx.error_spanned_by(
+            field,
+            format!("field `{}` has no lifetimes to borrow", name),
+        );
         Err(())
     } else {
         Ok(lifetimes)

serde_derive/src/internals/check.rs

@@ -21,12 +21,16 @@ fn check_getter(cx: &Ctxt, cont: &Container) {
     match cont.data {
         Data::Enum(_) => {
             if cont.data.has_getter() {
-                cx.error("#[serde(getter = \"...\")] is not allowed in an enum");
+                cx.error_spanned_by(
+                    cont.original,
+                    "#[serde(getter = \"...\")] is not allowed in an enum",
+                );
             }
         }
         Data::Struct(_, _) => {
             if cont.data.has_getter() && cont.attrs.remote().is_none() {
-                cx.error(
+                cx.error_spanned_by(
+                    cont.original,
                     "#[serde(getter = \"...\")] can only be used in structs \
                      that have #[serde(remote = \"...\")]",
                 );
@@ -59,26 +63,35 @@ fn check_flatten_field(cx: &Ctxt, style: Style, field: &Field) {
     }
     match style {
         Style::Tuple => {
-            cx.error("#[serde(flatten)] cannot be used on tuple structs");
+            cx.error_spanned_by(
+                field.original,
+                "#[serde(flatten)] cannot be used on tuple structs",
+            );
         }
         Style::Newtype => {
-            cx.error("#[serde(flatten)] cannot be used on newtype structs");
+            cx.error_spanned_by(
+                field.original,
+                "#[serde(flatten)] cannot be used on newtype structs",
+            );
         }
         _ => {}
     }
     if field.attrs.skip_serializing() {
-        cx.error(
+        cx.error_spanned_by(
-            "#[serde(flatten] can not be combined with \
+            field.original,
+            "#[serde(flatten)] can not be combined with \
              #[serde(skip_serializing)]",
         );
     } else if field.attrs.skip_serializing_if().is_some() {
-        cx.error(
+        cx.error_spanned_by(
-            "#[serde(flatten] can not be combined with \
+            field.original,
+            "#[serde(flatten)] can not be combined with \
              #[serde(skip_serializing_if = \"...\")]",
         );
     } else if field.attrs.skip_deserializing() {
-        cx.error(
+        cx.error_spanned_by(
-            "#[serde(flatten] can not be combined with \
+            field.original,
+            "#[serde(flatten)] can not be combined with \
              #[serde(skip_deserializing)]",
         );
     }
@@ -107,24 +120,36 @@ fn check_identifier(cx: &Ctxt, cont: &Container) {
         ) {
             // The `other` attribute may not be used in a variant_identifier.
             (_, Identifier::Variant, true, _) => {
-                cx.error("#[serde(other)] may not be used on a variant_identifier");
+                cx.error_spanned_by(
+                    variant.original,
+                    "#[serde(other)] may not be used on a variant identifier",
+                );
             }
 
             // Variant with `other` attribute cannot appear in untagged enum
             (_, Identifier::No, true, &EnumTag::None) => {
-                cx.error("#[serde(other)] cannot appear on untagged enum");
+                cx.error_spanned_by(
+                    variant.original,
+                    "#[serde(other)] cannot appear on untagged enum",
+                );
             }
 
             // Variant with `other` attribute must be the last one.
             (Style::Unit, Identifier::Field, true, _) | (Style::Unit, Identifier::No, true, _) => {
                 if i < variants.len() - 1 {
-                    cx.error("#[serde(other)] must be the last variant");
+                    cx.error_spanned_by(
+                        variant.original,
+                        "#[serde(other)] must be on the last variant",
+                    );
                 }
             }
 
             // Variant with `other` attribute must be a unit variant.
             (_, Identifier::Field, true, _) | (_, Identifier::No, true, _) => {
-                cx.error("#[serde(other)] must be on a unit variant");
+                cx.error_spanned_by(
+                    variant.original,
+                    "#[serde(other)] must be on a unit variant",
+                );
             }
 
             // Any sort of variant is allowed if this is not an identifier.
@@ -136,16 +161,25 @@ fn check_identifier(cx: &Ctxt, cont: &Container) {
             // The last field is allowed to be a newtype catch-all.
             (Style::Newtype, Identifier::Field, false, _) => {
                 if i < variants.len() - 1 {
-                    cx.error(format!("`{}` must be the last variant", variant.ident));
+                    cx.error_spanned_by(
+                        variant.original,
+                        format!("`{}` must be the last variant", variant.ident),
+                    );
                 }
             }
 
             (_, Identifier::Field, false, _) => {
-                cx.error("field_identifier may only contain unit variants");
+                cx.error_spanned_by(
+                    variant.original,
+                    "#[serde(field_identifier)] may only contain unit variants",
+                );
             }
 
             (_, Identifier::Variant, false, _) => {
-                cx.error("variant_identifier may only contain unit variants");
+                cx.error_spanned_by(
+                    variant.original,
+                    "#[serde(variant_identifier)] may only contain unit variants",
+                );
             }
         }
     }
@@ -164,7 +198,7 @@ fn check_variant_skip_attrs(cx: &Ctxt, cont: &Container) {
     for variant in variants.iter() {
         if variant.attrs.serialize_with().is_some() {
             if variant.attrs.skip_serializing() {
-                cx.error(format!(
+                cx.error_spanned_by(variant.original, format!(
                     "variant `{}` cannot have both #[serde(serialize_with)] and \
                      #[serde(skip_serializing)]",
                     variant.ident
@@ -175,7 +209,7 @@ fn check_variant_skip_attrs(cx: &Ctxt, cont: &Container) {
                 let member = member_message(&field.member);
 
                 if field.attrs.skip_serializing() {
-                    cx.error(format!(
+                    cx.error_spanned_by(variant.original, format!(
                         "variant `{}` cannot have both #[serde(serialize_with)] and \
                          a field {} marked with #[serde(skip_serializing)]",
                         variant.ident, member
@@ -183,7 +217,7 @@ fn check_variant_skip_attrs(cx: &Ctxt, cont: &Container) {
                 }
 
                 if field.attrs.skip_serializing_if().is_some() {
-                    cx.error(format!(
+                    cx.error_spanned_by(variant.original, format!(
                         "variant `{}` cannot have both #[serde(serialize_with)] and \
                          a field {} marked with #[serde(skip_serializing_if)]",
                         variant.ident, member
@@ -194,7 +228,7 @@ fn check_variant_skip_attrs(cx: &Ctxt, cont: &Container) {
 
         if variant.attrs.deserialize_with().is_some() {
             if variant.attrs.skip_deserializing() {
-                cx.error(format!(
+                cx.error_spanned_by(variant.original, format!(
                     "variant `{}` cannot have both #[serde(deserialize_with)] and \
                      #[serde(skip_deserializing)]",
                     variant.ident
@@ -205,7 +239,7 @@ fn check_variant_skip_attrs(cx: &Ctxt, cont: &Container) {
                 if field.attrs.skip_deserializing() {
                     let member = member_message(&field.member);
 
-                    cx.error(format!(
+                    cx.error_spanned_by(variant.original, format!(
                         "variant `{}` cannot have both #[serde(deserialize_with)] \
                          and a field {} marked with #[serde(skip_deserializing)]",
                         variant.ident, member
@@ -231,10 +265,10 @@ fn check_internal_tag_field_name_conflict(cx: &Ctxt, cont: &Container) {
         EnumTag::External | EnumTag::Adjacent { .. } | EnumTag::None => return,
     };
 
-    let diagnose_conflict = || {
+    let diagnose_conflict = || cx.error_spanned_by(
-        let message = format!("variant field name `{}` conflicts with internal tag", tag);
+        cont.original,
-        cx.error(message);
+        format!("variant field name `{}` conflicts with internal tag", tag),
-    };
+    );
 
     for variant in variants {
         match variant.style {
@@ -269,11 +303,10 @@ fn check_adjacent_tag_conflict(cx: &Ctxt, cont: &Container) {
     };
 
     if type_tag == content_tag {
-        let message = format!(
+        cx.error_spanned_by(cont.original, format!(
             "enum tags `{}` for type and content conflict with each other",
             type_tag
-        );
+        ));
-        cx.error(message);
     }
 }
 
@@ -284,20 +317,32 @@ fn check_transparent(cx: &Ctxt, cont: &mut Container, derive: Derive) {
     }
 
     if cont.attrs.type_from().is_some() {
-        cx.error("#[serde(transparent)] is not allowed with #[serde(from = \"...\")]");
+        cx.error_spanned_by(
+            cont.original,
+            "#[serde(transparent)] is not allowed with #[serde(from = \"...\")]",
+        );
     }
 
     if cont.attrs.type_into().is_some() {
-        cx.error("#[serde(transparent)] is not allowed with #[serde(into = \"...\")]");
+        cx.error_spanned_by(
+            cont.original,
+            "#[serde(transparent)] is not allowed with #[serde(into = \"...\")]",
+        );
     }
 
     let fields = match cont.data {
         Data::Enum(_) => {
-            cx.error("#[serde(transparent)] is not allowed on an enum");
+            cx.error_spanned_by(
+                cont.original,
+                "#[serde(transparent)] is not allowed on an enum",
+            );
             return;
         }
         Data::Struct(Style::Unit, _) => {
-            cx.error("#[serde(transparent)] is not allowed on a unit struct");
+            cx.error_spanned_by(
+                cont.original,
+                "#[serde(transparent)] is not allowed on a unit struct",
+            );
             return;
         }
         Data::Struct(_, ref mut fields) => fields,
@@ -308,7 +353,8 @@ fn check_transparent(cx: &Ctxt, cont: &mut Container, derive: Derive) {
     for field in fields {
         if allow_transparent(field, derive) {
             if transparent_field.is_some() {
-                cx.error(
+                cx.error_spanned_by(
+                    cont.original,
                     "#[serde(transparent)] requires struct to have at most one transparent field",
                 );
                 return;
@@ -321,10 +367,16 @@ fn check_transparent(cx: &Ctxt, cont: &mut Container, derive: Derive) {
         Some(transparent_field) => transparent_field.attrs.mark_transparent(),
         None => match derive {
             Derive::Serialize => {
-                cx.error("#[serde(transparent)] requires at least one field that is not skipped");
+                cx.error_spanned_by(
+                    cont.original,
+                    "#[serde(transparent)] requires at least one field that is not skipped",
+                );
             }
             Derive::Deserialize => {
-                cx.error("#[serde(transparent)] requires at least one field that is neither skipped nor has a default");
+                cx.error_spanned_by(
+                    cont.original,
+                    "#[serde(transparent)] requires at least one field that is neither skipped nor has a default",
+                );
             }
         },
     }
@@ -333,7 +385,7 @@ fn check_transparent(cx: &Ctxt, cont: &mut Container, derive: Derive) {
 fn member_message(member: &Member) -> String {
     match *member {
         Member::Named(ref ident) => format!("`{}`", ident),
-        Member::Unnamed(ref i) => i.index.to_string(),
+        Member::Unnamed(ref i) => format!("#{}", i.index),
     }
 }
 

serde_derive/src/internals/ctxt.rs

@@ -1,6 +1,8 @@
+use quote::ToTokens;
 use std::cell::RefCell;
 use std::fmt::Display;
 use std::thread;
+use syn;
 
 /// A type to collect errors together and format them.
 ///
@@ -11,7 +13,7 @@ use std::thread;
 pub struct Ctxt {
     // The contents will be set to `None` during checking. This is so that checking can be
     // enforced.
-    errors: RefCell<Option<Vec<String>>>,
+    errors: RefCell<Option<Vec<syn::Error>>>,
 }
 
 impl Ctxt {
@@ -24,29 +26,24 @@ impl Ctxt {
         }
     }
 
-    /// Add an error to the context object.
+    /// Add an error to the context object with a tokenenizable object.
-    pub fn error<T: Display>(&self, msg: T) {
+    ///
+    /// The object is used for spanning in error messages.
+    pub fn error_spanned_by<A: ToTokens, T: Display>(&self, obj: A, msg: T) {
         self.errors
             .borrow_mut()
             .as_mut()
             .unwrap()
-            .push(msg.to_string());
+            // Curb monomorphization from generating too many identical methods.
+            .push(syn::Error::new_spanned(obj.into_token_stream(), msg));
     }
 
     /// Consume this object, producing a formatted error string if there are errors.
-    pub fn check(self) -> Result<(), String> {
+    pub fn check(self) -> Result<(), Vec<syn::Error>> {
-        let mut errors = self.errors.borrow_mut().take().unwrap();
+        let errors = self.errors.borrow_mut().take().unwrap();
         match errors.len() {
             0 => Ok(()),
-            1 => Err(errors.pop().unwrap()),
+            _ => Err(errors),
-            n => {
-                let mut msg = format!("{} errors:", n);
-                for err in errors {
-                    msg.push_str("\n\t# ");
-                    msg.push_str(&err);
-                }
-                Err(msg)
-            }
         }
     }
 }

serde_derive/src/lib.rs

@@ -62,7 +62,6 @@ mod internals;
 
 use proc_macro::TokenStream;
 use syn::DeriveInput;
-use syn::spanned::Spanned;
 
 #[macro_use]
 mod bound;
@@ -78,7 +77,7 @@ mod try;
 pub fn derive_serialize(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
     ser::expand_derive_serialize(&input)
-        .unwrap_or_else(|message| compile_error(input.span(), message))
+        .unwrap_or_else(to_compile_errors)
         .into()
 }
 
@@ -86,12 +85,11 @@ pub fn derive_serialize(input: TokenStream) -> TokenStream {
 pub fn derive_deserialize(input: TokenStream) -> TokenStream {
     let input = parse_macro_input!(input as DeriveInput);
     de::expand_derive_deserialize(&input)
-        .unwrap_or_else(|message| compile_error(input.span(), message))
+        .unwrap_or_else(to_compile_errors)
         .into()
 }
 
-fn compile_error(span: proc_macro2::Span, message: String) -> proc_macro2::TokenStream {
+fn to_compile_errors(errors: Vec<syn::Error>) -> proc_macro2::TokenStream {
-    quote_spanned! {span=>
+    let compile_errors = errors.iter().map(syn::Error::to_compile_error);
-        compile_error!(#message);
+    quote!(#(#compile_errors)*)
-    }
 }

serde_derive/src/ser.rs

@@ -9,9 +9,12 @@ use internals::{attr, Ctxt, Derive};
 use pretend;
 use try;
 
-pub fn expand_derive_serialize(input: &syn::DeriveInput) -> Result<TokenStream, String> {
+pub fn expand_derive_serialize(input: &syn::DeriveInput) -> Result<TokenStream, Vec<syn::Error>> {
     let ctxt = Ctxt::new();
-    let cont = Container::from_ast(&ctxt, input, Derive::Serialize);
+    let cont = match Container::from_ast(&ctxt, input, Derive::Serialize) {
+        Some(cont) => cont,
+        None => return Err(ctxt.check().unwrap_err()),
+    };
     precondition(&ctxt, &cont);
     try!(ctxt.check());
 
@@ -72,10 +75,10 @@ fn precondition(cx: &Ctxt, cont: &Container) {
     match cont.attrs.identifier() {
         attr::Identifier::No => {}
         attr::Identifier::Field => {
-            cx.error("field identifiers cannot be serialized");
+            cx.error_spanned_by(cont.original, "field identifiers cannot be serialized");
         }
         attr::Identifier::Variant => {
-            cx.error("variant identifiers cannot be serialized");
+            cx.error_spanned_by(cont.original, "variant identifiers cannot be serialized");
         }
     }
 }

test_suite/tests/ui/borrow/bad_lifetimes.stderr

@@ -1,8 +1,8 @@
 error: failed to parse borrowed lifetimes: "zzz"
- --> $DIR/bad_lifetimes.rs:4:10
+ --> $DIR/bad_lifetimes.rs:6:22
   |
-4 | #[derive(Deserialize)]
+6 |     #[serde(borrow = "zzz")]
-  |          ^^^^^^^^^^^
+  |                      ^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/borrow/duplicate_lifetime.stderr

@@ -1,8 +1,8 @@
 error: duplicate borrowed lifetime `'a`
- --> $DIR/duplicate_lifetime.rs:4:10
+ --> $DIR/duplicate_lifetime.rs:6:22
   |
-4 | #[derive(Deserialize)]
+6 |     #[serde(borrow = "'a + 'a")]
-  |          ^^^^^^^^^^^
+  |                      ^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/borrow/duplicate_variant.stderr

@@ -1,8 +1,8 @@
 error: duplicate serde attribute `borrow`
- --> $DIR/duplicate_variant.rs:7:10
+ --> $DIR/duplicate_variant.rs:9:13
   |
-7 | #[derive(Deserialize)]
+9 |     #[serde(borrow)]
-  |          ^^^^^^^^^^^
+  |             ^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/borrow/empty_lifetimes.stderr

@@ -1,8 +1,8 @@
 error: at least one lifetime must be borrowed
- --> $DIR/empty_lifetimes.rs:4:10
+ --> $DIR/empty_lifetimes.rs:6:22
   |
-4 | #[derive(Deserialize)]
+6 |     #[serde(borrow = "")]
-  |          ^^^^^^^^^^^
+  |                      ^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/borrow/no_lifetimes.stderr

@@ -1,8 +1,9 @@
 error: field `s` has no lifetimes to borrow
- --> $DIR/no_lifetimes.rs:4:10
+ --> $DIR/no_lifetimes.rs:6:5
   |
-4 | #[derive(Deserialize)]
+6 | /     #[serde(borrow)]
-  |          ^^^^^^^^^^^
+7 | |     s: String,
+  | |_____________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/borrow/struct_variant.stderr

@@ -1,8 +1,9 @@
 error: #[serde(borrow)] may only be used on newtype variants
- --> $DIR/struct_variant.rs:7:10
+  --> $DIR/struct_variant.rs:9:5
-  |
+   |
-7 | #[derive(Deserialize)]
+9  | /     #[serde(borrow)]
-  |          ^^^^^^^^^^^
+10 | |     S { s: Str<'a> },
+   | |____________________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/borrow/wrong_lifetime.stderr

@@ -1,8 +1,9 @@
 error: field `s` does not have lifetime 'b
- --> $DIR/wrong_lifetime.rs:4:10
+ --> $DIR/wrong_lifetime.rs:6:5
   |
-4 | #[derive(Deserialize)]
+6 | /     #[serde(borrow = "'b")]
-  |          ^^^^^^^^^^^
+7 | |     s: &'a str,
+  | |______________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/conflict/adjacent-tag.stderr

@@ -1,8 +1,12 @@
 error: enum tags `conflict` for type and content conflict with each other
- --> $DIR/adjacent-tag.rs:4:10
+ --> $DIR/adjacent-tag.rs:5:1
   |
-4 | #[derive(Serialize)]
+5 | / #[serde(tag = "conflict", content = "conflict")]
-  |          ^^^^^^^^^
+6 | | enum E {
+7 | |     A,
+8 | |     B,
+9 | | }
+  | |_^
 
 error: aborting due to previous error
 

test_suite/tests/ui/conflict/flatten-newtype-struct.stderr

@@ -1,8 +1,8 @@
 error: #[serde(flatten)] cannot be used on newtype structs
- --> $DIR/flatten-newtype-struct.rs:4:10
+ --> $DIR/flatten-newtype-struct.rs:5:12
   |
-4 | #[derive(Serialize)]
+5 | struct Foo(#[serde(flatten)] HashMap<String, String>);
-  |          ^^^^^^^^^
+  |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/conflict/flatten-skip-deserializing.stderr

@@ -1,8 +1,9 @@
-error: #[serde(flatten] can not be combined with #[serde(skip_deserializing)]
+error: #[serde(flatten)] can not be combined with #[serde(skip_deserializing)]
- --> $DIR/flatten-skip-deserializing.rs:4:10
+ --> $DIR/flatten-skip-deserializing.rs:6:5
   |
-4 | #[derive(Deserialize)]
+6 | /     #[serde(flatten, skip_deserializing)]
-  |          ^^^^^^^^^^^
+7 | |     other: Other,
+  | |________________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/conflict/flatten-skip-serializing-if.stderr

@@ -1,8 +1,9 @@
-error: #[serde(flatten] can not be combined with #[serde(skip_serializing_if = "...")]
+error: #[serde(flatten)] can not be combined with #[serde(skip_serializing_if = "...")]
- --> $DIR/flatten-skip-serializing-if.rs:4:10
+ --> $DIR/flatten-skip-serializing-if.rs:6:5
   |
-4 | #[derive(Serialize)]
+6 | /     #[serde(flatten, skip_serializing_if = "Option::is_none")]
-  |          ^^^^^^^^^
+7 | |     other: Option<Other>,
+  | |________________________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/conflict/flatten-skip-serializing.stderr

@@ -1,8 +1,9 @@
-error: #[serde(flatten] can not be combined with #[serde(skip_serializing)]
+error: #[serde(flatten)] can not be combined with #[serde(skip_serializing)]
- --> $DIR/flatten-skip-serializing.rs:4:10
+ --> $DIR/flatten-skip-serializing.rs:6:5
   |
-4 | #[derive(Serialize)]
+6 | /     #[serde(flatten, skip_serializing)]
-  |          ^^^^^^^^^
+7 | |     other: Other,
+  | |________________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/conflict/flatten-tuple-struct.stderr

@@ -1,8 +1,8 @@
 error: #[serde(flatten)] cannot be used on tuple structs
- --> $DIR/flatten-tuple-struct.rs:4:10
+ --> $DIR/flatten-tuple-struct.rs:5:17
   |
-4 | #[derive(Serialize)]
+5 | struct Foo(u32, #[serde(flatten)] HashMap<String, String>);
-  |          ^^^^^^^^^
+  |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/conflict/internal-tag.stderr

@@ -1,8 +1,14 @@
 error: variant field name `conflict` conflicts with internal tag
- --> $DIR/internal-tag.rs:4:10
+  --> $DIR/internal-tag.rs:5:1
-  |
+   |
-4 | #[derive(Serialize)]
+5  | / #[serde(tag = "conflict")]
-  |          ^^^^^^^^^
+6  | | enum E {
+7  | |     A {
+8  | |         #[serde(rename = "conflict")]
+9  | |         x: (),
+10 | |     },
+11 | | }
+   | |_^
 
 error: aborting due to previous error
 

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

@@ -1,8 +1,8 @@
 error: #[serde(default)] can only be used on structs with named fields
- --> $DIR/enum.rs:4:10
+ --> $DIR/enum.rs:6:1
   |
-4 | #[derive(Deserialize)]
+6 | enum E {
-  |          ^^^^^^^^^^^
+  | ^^^^
 
 error: aborting due to previous error
 

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

@@ -1,8 +1,8 @@
 error: #[serde(default)] can only be used on structs with named fields
- --> $DIR/nameless_struct_fields.rs:4:10
+ --> $DIR/nameless_struct_fields.rs:6:9
   |
-4 | #[derive(Deserialize)]
+6 | struct T(u8, u8);
-  |          ^^^^^^^^^^^
+  |         ^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/duplicate-attribute/rename-and-ser.stderr

@@ -1,8 +1,8 @@
 error: unknown serde field attribute `serialize`
- --> $DIR/rename-and-ser.rs:4:10
+ --> $DIR/rename-and-ser.rs:6:27
   |
-4 | #[derive(Serialize)]
+6 |     #[serde(rename = "x", serialize = "y")]
-  |          ^^^^^^^^^
+  |                           ^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/duplicate-attribute/rename-rename-de.stderr

@@ -1,8 +1,8 @@
 error: duplicate serde attribute `rename`
- --> $DIR/rename-rename-de.rs:4:10
+ --> $DIR/rename-rename-de.rs:7:13
   |
-4 | #[derive(Serialize)]
+7 |     #[serde(rename(deserialize = "y"))]
-  |          ^^^^^^^^^
+  |             ^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/duplicate-attribute/rename-ser-rename-ser.stderr

@@ -1,8 +1,8 @@
 error: duplicate serde attribute `rename`
- --> $DIR/rename-ser-rename-ser.rs:4:10
+ --> $DIR/rename-ser-rename-ser.rs:6:38
   |
-4 | #[derive(Serialize)]
+6 |     #[serde(rename(serialize = "x"), rename(serialize = "y"))]
-  |          ^^^^^^^^^
+  |                                      ^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/duplicate-attribute/rename-ser-rename.stderr

@@ -1,8 +1,8 @@
 error: duplicate serde attribute `rename`
- --> $DIR/rename-ser-rename.rs:4:10
+ --> $DIR/rename-ser-rename.rs:7:13
   |
-4 | #[derive(Serialize)]
+7 |     #[serde(rename = "y")]
-  |          ^^^^^^^^^
+  |             ^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/duplicate-attribute/rename-ser-ser.stderr

@@ -1,8 +1,8 @@
 error: duplicate serde attribute `rename`
- --> $DIR/rename-ser-ser.rs:4:10
+ --> $DIR/rename-ser-ser.rs:6:37
   |
-4 | #[derive(Serialize)]
+6 |     #[serde(rename(serialize = "x", serialize = "y"))]
-  |          ^^^^^^^^^
+  |                                     ^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/duplicate-attribute/two-rename-ser.stderr

@@ -1,8 +1,8 @@
 error: duplicate serde attribute `rename`
- --> $DIR/two-rename-ser.rs:4:10
+ --> $DIR/two-rename-ser.rs:7:13
   |
-4 | #[derive(Serialize)]
+7 |     #[serde(rename(serialize = "y"))]
-  |          ^^^^^^^^^
+  |             ^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/duplicate-attribute/with-and-serialize-with.stderr

@@ -1,8 +1,8 @@
 error: duplicate serde attribute `serialize_with`
- --> $DIR/with-and-serialize-with.rs:4:10
+ --> $DIR/with-and-serialize-with.rs:6:25
   |
-4 | #[derive(Serialize)]
+6 |     #[serde(with = "w", serialize_with = "s")]
-  |          ^^^^^^^^^
+  |                         ^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/enum-representation/internal-tuple-variant.stderr

@@ -1,8 +1,8 @@
 error: #[serde(tag = "...")] cannot be used with tuple variants
- --> $DIR/internal-tuple-variant.rs:4:10
+ --> $DIR/internal-tuple-variant.rs:7:5
   |
-4 | #[derive(Serialize)]
+7 |     Tuple(u8, u8),
-  |          ^^^^^^^^^
+  |     ^^^^^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/enum-representation/internally-tagged-struct.stderr

@@ -1,8 +1,8 @@
 error: #[serde(tag = "...")] can only be used on enums
- --> $DIR/internally-tagged-struct.rs:4:10
+ --> $DIR/internally-tagged-struct.rs:6:1
   |
-4 | #[derive(Serialize)]
+6 | struct S;
-  |          ^^^^^^^^^
+  | ^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/enum-representation/untagged-and-internal.stderr

@@ -1,8 +1,14 @@
 error: enum cannot be both untagged and internally tagged
- --> $DIR/untagged-and-internal.rs:4:10
+ --> $DIR/untagged-and-internal.rs:5:9
   |
-4 | #[derive(Serialize)]
+5 | #[serde(untagged)]
-  |          ^^^^^^^^^
+  |         ^^^^^^^^
 
-error: aborting due to previous error
+error: enum cannot be both untagged and internally tagged
+ --> $DIR/untagged-and-internal.rs:6:9
+  |
+6 | #[serde(tag = "type")]
+  |         ^^^
+
+error: aborting due to 2 previous errors
 

test_suite/tests/ui/enum-representation/untagged-struct.stderr

@@ -1,8 +1,8 @@
 error: #[serde(untagged)] can only be used on enums
- --> $DIR/untagged-struct.rs:4:10
+ --> $DIR/untagged-struct.rs:6:1
   |
-4 | #[derive(Serialize)]
+6 | struct S;
-  |          ^^^^^^^^^
+  | ^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/identifier/both.stderr

@@ -1,8 +1,14 @@
-error: `field_identifier` and `variant_identifier` cannot both be set
+error: #[serde(field_identifier)] and #[serde(variant_identifier)] cannot both be set
- --> $DIR/both.rs:4:10
+ --> $DIR/both.rs:5:9
   |
-4 | #[derive(Deserialize)]
+5 | #[serde(field_identifier, variant_identifier)]
-  |          ^^^^^^^^^^^
+  |         ^^^^^^^^^^^^^^^^
 
-error: aborting due to previous error
+error: #[serde(field_identifier)] and #[serde(variant_identifier)] cannot both be set
+ --> $DIR/both.rs:5:27
+  |
+5 | #[serde(field_identifier, variant_identifier)]
+  |                           ^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 2 previous errors
 

test_suite/tests/ui/identifier/field_struct.stderr

@@ -1,8 +1,8 @@
-error: `field_identifier` can only be used on an enum
+error: #[serde(field_identifier)] can only be used on an enum
- --> $DIR/field_struct.rs:4:10
+ --> $DIR/field_struct.rs:6:1
   |
-4 | #[derive(Deserialize)]
+6 | struct S;
-  |          ^^^^^^^^^^^
+  | ^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/identifier/field_tuple.stderr

@@ -1,8 +1,8 @@
-error: field_identifier may only contain unit variants
+error: #[serde(field_identifier)] may only contain unit variants
- --> $DIR/field_tuple.rs:4:10
+ --> $DIR/field_tuple.rs:8:5
   |
-4 | #[derive(Deserialize)]
+8 |     B(u8, u8),
-  |          ^^^^^^^^^^^
+  |     ^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/identifier/newtype_not_last.stderr

@@ -1,8 +1,8 @@
 error: `Other` must be the last variant
- --> $DIR/newtype_not_last.rs:4:10
+ --> $DIR/newtype_not_last.rs:8:5
   |
-4 | #[derive(Deserialize)]
+8 |     Other(String),
-  |          ^^^^^^^^^^^
+  |     ^^^^^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/identifier/not_unit.stderr

@@ -1,8 +1,9 @@
 error: #[serde(other)] must be on a unit variant
- --> $DIR/not_unit.rs:4:10
+ --> $DIR/not_unit.rs:8:5
   |
-4 | #[derive(Deserialize)]
+8 | /     #[serde(other)]
-  |          ^^^^^^^^^^^
+9 | |     Other(u8, u8),
+  | |_________________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/identifier/other_not_last.stderr

@@ -1,8 +1,9 @@
-error: #[serde(other)] must be the last variant
+error: #[serde(other)] must be on the last variant
- --> $DIR/other_not_last.rs:4:10
+ --> $DIR/other_not_last.rs:8:5
   |
-4 | #[derive(Deserialize)]
+8 | /     #[serde(other)]
-  |          ^^^^^^^^^^^
+9 | |     Other,
+  | |_________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/identifier/serialize.stderr

@@ -1,8 +1,12 @@
 error: field identifiers cannot be serialized
- --> $DIR/serialize.rs:4:10
+ --> $DIR/serialize.rs:5:1
   |
-4 | #[derive(Serialize)]
+5 | / #[serde(field_identifier)]
-  |          ^^^^^^^^^
+6 | | enum F {
+7 | |     A,
+8 | |     B,
+9 | | }
+  | |_^
 
 error: aborting due to previous error
 

test_suite/tests/ui/identifier/variant_struct.stderr

@@ -1,8 +1,8 @@
-error: `variant_identifier` can only be used on an enum
+error: #[serde(variant_identifier)] can only be used on an enum
- --> $DIR/variant_struct.rs:4:10
+ --> $DIR/variant_struct.rs:6:1
   |
-4 | #[derive(Deserialize)]
+6 | struct S;
-  |          ^^^^^^^^^^^
+  | ^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/identifier/variant_tuple.stderr

@@ -1,8 +1,8 @@
-error: variant_identifier may only contain unit variants
+error: #[serde(variant_identifier)] may only contain unit variants
- --> $DIR/variant_tuple.rs:4:10
+ --> $DIR/variant_tuple.rs:8:5
   |
-4 | #[derive(Deserialize)]
+8 |     B(u8, u8),
-  |          ^^^^^^^^^^^
+  |     ^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/precondition/deserialize_de_lifetime.stderr

@@ -1,8 +1,8 @@
 error: cannot deserialize when there is a lifetime parameter called 'de
- --> $DIR/deserialize_de_lifetime.rs:4:10
+ --> $DIR/deserialize_de_lifetime.rs:5:10
   |
-4 | #[derive(Deserialize)]
+5 | struct S<'de> {
-  |          ^^^^^^^^^^^
+  |          ^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/precondition/deserialize_dst.stderr

@@ -1,8 +1,11 @@
 error: cannot deserialize a dynamically sized struct
- --> $DIR/deserialize_dst.rs:4:10
+ --> $DIR/deserialize_dst.rs:5:1
   |
-4 | #[derive(Deserialize)]
+5 | / struct S {
-  |          ^^^^^^^^^^^
+6 | |     string: String,
+7 | |     slice: [u8],
+8 | | }
+  | |_^
 
 error: aborting due to previous error
 

test_suite/tests/ui/remote/bad_getter.stderr

@@ -1,8 +1,8 @@
 error: failed to parse path: "~~~"
-  --> $DIR/bad_getter.rs:10:10
+  --> $DIR/bad_getter.rs:13:22
    |
-10 | #[derive(Serialize)]
+13 |     #[serde(getter = "~~~")]
-   |          ^^^^^^^^^
+   |                      ^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/remote/bad_remote.stderr

@@ -1,8 +1,8 @@
 error: failed to parse path: "~~~"
-  --> $DIR/bad_remote.rs:10:10
+  --> $DIR/bad_remote.rs:11:18
    |
-10 | #[derive(Serialize)]
+11 | #[serde(remote = "~~~")]
-   |          ^^^^^^^^^
+   |                  ^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/remote/enum_getter.stderr

@@ -1,8 +1,14 @@
 error: #[serde(getter = "...")] is not allowed in an enum
-  --> $DIR/enum_getter.rs:10:10
+  --> $DIR/enum_getter.rs:11:1
    |
-10 | #[derive(Serialize)]
+11 | / #[serde(remote = "remote::E")]
-   |          ^^^^^^^^^
+12 | | pub enum E {
+13 | |     A {
+14 | |         #[serde(getter = "get_a")]
+15 | |         a: u8,
+16 | |     },
+17 | | }
+   | |_^
 
 error: aborting due to previous error
 

test_suite/tests/ui/remote/nonremote_getter.stderr

@@ -1,8 +1,11 @@
 error: #[serde(getter = "...")] can only be used in structs that have #[serde(remote = "...")]
- --> $DIR/nonremote_getter.rs:4:10
+ --> $DIR/nonremote_getter.rs:5:1
   |
-4 | #[derive(Serialize)]
+5 | / struct S {
-  |          ^^^^^^^^^
+6 | |     #[serde(getter = "S::get")]
+7 | |     a: u8,
+8 | | }
+  | |_^
 
 error: aborting due to previous error
 

test_suite/tests/ui/transparent/at_most_one.stderr

@@ -1,8 +1,12 @@
 error: #[serde(transparent)] requires struct to have at most one transparent field
- --> $DIR/at_most_one.rs:4:10
+ --> $DIR/at_most_one.rs:5:1
   |
-4 | #[derive(Serialize)]
+5 | / #[serde(transparent)]
-  |          ^^^^^^^^^
+6 | | struct S {
+7 | |     a: u8,
+8 | |     b: u8,
+9 | | }
+  | |_^
 
 error: aborting due to previous error
 

test_suite/tests/ui/transparent/de_at_least_one.stderr

@@ -1,8 +1,14 @@
 error: #[serde(transparent)] requires at least one field that is neither skipped nor has a default
- --> $DIR/de_at_least_one.rs:4:10
+  --> $DIR/de_at_least_one.rs:5:1
-  |
+   |
-4 | #[derive(Deserialize)]
+5  | / #[serde(transparent)]
-  |          ^^^^^^^^^^^
+6  | | struct S {
+7  | |     #[serde(skip)]
+8  | |     a: u8,
+9  | |     #[serde(default)]
+10 | |     b: u8,
+11 | | }
+   | |_^
 
 error: aborting due to previous error
 

test_suite/tests/ui/transparent/ser_at_least_one.stderr

@@ -1,8 +1,12 @@
 error: #[serde(transparent)] requires at least one field that is not skipped
- --> $DIR/ser_at_least_one.rs:4:10
+ --> $DIR/ser_at_least_one.rs:5:1
   |
-4 | #[derive(Serialize)]
+5 | / #[serde(transparent)]
-  |          ^^^^^^^^^
+6 | | struct S {
+7 | |     #[serde(skip)]
+8 | |     a: u8,
+9 | | }
+  | |_^
 
 error: aborting due to previous error
 

test_suite/tests/ui/type-attribute/from.stderr

@@ -1,8 +1,8 @@
 error: failed to parse type: from = "Option<T"
- --> $DIR/from.rs:4:10
+ --> $DIR/from.rs:5:16
   |
-4 | #[derive(Deserialize)]
+5 | #[serde(from = "Option<T")]
-  |          ^^^^^^^^^^^
+  |                ^^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/type-attribute/into.stderr

@@ -1,8 +1,8 @@
 error: failed to parse type: into = "Option<T"
- --> $DIR/into.rs:4:10
+ --> $DIR/into.rs:5:16
   |
-4 | #[derive(Serialize)]
+5 | #[serde(into = "Option<T")]
-  |          ^^^^^^^^^
+  |                ^^^^^^^^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/unknown-attribute/container.stderr

@@ -1,8 +1,8 @@
 error: unknown serde container attribute `abc`
- --> $DIR/container.rs:4:10
+ --> $DIR/container.rs:5:9
   |
-4 | #[derive(Serialize)]
+5 | #[serde(abc = "xyz")]
-  |          ^^^^^^^^^
+  |         ^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/unknown-attribute/field.stderr

@@ -1,8 +1,8 @@
 error: unknown serde field attribute `abc`
- --> $DIR/field.rs:4:10
+ --> $DIR/field.rs:6:13
   |
-4 | #[derive(Serialize)]
+6 |     #[serde(abc = "xyz")]
-  |          ^^^^^^^^^
+  |             ^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/unknown-attribute/variant.stderr

@@ -1,8 +1,8 @@
 error: unknown serde variant attribute `abc`
- --> $DIR/variant.rs:4:10
+ --> $DIR/variant.rs:6:13
   |
-4 | #[derive(Serialize)]
+6 |     #[serde(abc = "xyz")]
-  |          ^^^^^^^^^
+  |             ^^^
 
 error: aborting due to previous error
 

test_suite/tests/ui/with-variant/skip_de_newtype_field.stderr

@@ -1,8 +1,9 @@
-error: variant `Newtype` cannot have both #[serde(deserialize_with)] and a field 0 marked with #[serde(skip_deserializing)]
+error: variant `Newtype` cannot have both #[serde(deserialize_with)] and a field #0 marked with #[serde(skip_deserializing)]
- --> $DIR/skip_de_newtype_field.rs:4:10
+ --> $DIR/skip_de_newtype_field.rs:6:5
   |
-4 | #[derive(Deserialize)]
+6 | /     #[serde(deserialize_with = "deserialize_some_newtype_variant")]
-  |          ^^^^^^^^^^^
+7 | |     Newtype(#[serde(skip_deserializing)] String),
+  | |________________________________________________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/with-variant/skip_de_struct_field.stderr

@@ -1,8 +1,13 @@
 error: variant `Struct` cannot have both #[serde(deserialize_with)] and a field `f1` marked with #[serde(skip_deserializing)]
- --> $DIR/skip_de_struct_field.rs:4:10
+  --> $DIR/skip_de_struct_field.rs:6:5
-  |
+   |
-4 | #[derive(Deserialize)]
+6  | /     #[serde(deserialize_with = "deserialize_some_other_variant")]
-  |          ^^^^^^^^^^^
+7  | |     Struct {
+8  | |         #[serde(skip_deserializing)]
+9  | |         f1: String,
+10 | |         f2: u8,
+11 | |     },
+   | |_____^
 
 error: aborting due to previous error
 

test_suite/tests/ui/with-variant/skip_de_tuple_field.stderr

@@ -1,8 +1,9 @@
-error: variant `Tuple` cannot have both #[serde(deserialize_with)] and a field 0 marked with #[serde(skip_deserializing)]
+error: variant `Tuple` cannot have both #[serde(deserialize_with)] and a field #0 marked with #[serde(skip_deserializing)]
- --> $DIR/skip_de_tuple_field.rs:4:10
+ --> $DIR/skip_de_tuple_field.rs:6:5
   |
-4 | #[derive(Deserialize)]
+6 | /     #[serde(deserialize_with = "deserialize_some_other_variant")]
-  |          ^^^^^^^^^^^
+7 | |     Tuple(#[serde(skip_deserializing)] String, u8),
+  | |__________________________________________________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/with-variant/skip_de_whole_variant.stderr

@@ -1,8 +1,10 @@
 error: variant `Unit` cannot have both #[serde(deserialize_with)] and #[serde(skip_deserializing)]
- --> $DIR/skip_de_whole_variant.rs:4:10
+ --> $DIR/skip_de_whole_variant.rs:6:5
   |
-4 | #[derive(Deserialize)]
+6 | /     #[serde(deserialize_with = "deserialize_some_unit_variant")]
-  |          ^^^^^^^^^^^
+7 | |     #[serde(skip_deserializing)]
+8 | |     Unit,
+  | |________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/with-variant/skip_ser_newtype_field.stderr

@@ -1,8 +1,9 @@
-error: variant `Newtype` cannot have both #[serde(serialize_with)] and a field 0 marked with #[serde(skip_serializing)]
+error: variant `Newtype` cannot have both #[serde(serialize_with)] and a field #0 marked with #[serde(skip_serializing)]
- --> $DIR/skip_ser_newtype_field.rs:4:10
+ --> $DIR/skip_ser_newtype_field.rs:6:5
   |
-4 | #[derive(Serialize)]
+6 | /     #[serde(serialize_with = "serialize_some_newtype_variant")]
-  |          ^^^^^^^^^
+7 | |     Newtype(#[serde(skip_serializing)] String),
+  | |______________________________________________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/with-variant/skip_ser_newtype_field_if.stderr

@@ -1,8 +1,9 @@
-error: variant `Newtype` cannot have both #[serde(serialize_with)] and a field 0 marked with #[serde(skip_serializing_if)]
+error: variant `Newtype` cannot have both #[serde(serialize_with)] and a field #0 marked with #[serde(skip_serializing_if)]
- --> $DIR/skip_ser_newtype_field_if.rs:4:10
+ --> $DIR/skip_ser_newtype_field_if.rs:6:5
   |
-4 | #[derive(Serialize)]
+6 | /     #[serde(serialize_with = "serialize_some_newtype_variant")]
-  |          ^^^^^^^^^
+7 | |     Newtype(#[serde(skip_serializing_if = "always")] String),
+  | |____________________________________________________________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/with-variant/skip_ser_struct_field.stderr

@@ -1,8 +1,13 @@
 error: variant `Struct` cannot have both #[serde(serialize_with)] and a field `f1` marked with #[serde(skip_serializing)]
- --> $DIR/skip_ser_struct_field.rs:4:10
+  --> $DIR/skip_ser_struct_field.rs:6:5
-  |
+   |
-4 | #[derive(Serialize)]
+6  | /     #[serde(serialize_with = "serialize_some_other_variant")]
-  |          ^^^^^^^^^
+7  | |     Struct {
+8  | |         #[serde(skip_serializing)]
+9  | |         f1: String,
+10 | |         f2: u8,
+11 | |     },
+   | |_____^
 
 error: aborting due to previous error
 

test_suite/tests/ui/with-variant/skip_ser_struct_field_if.stderr

@@ -1,8 +1,13 @@
 error: variant `Struct` cannot have both #[serde(serialize_with)] and a field `f1` marked with #[serde(skip_serializing_if)]
- --> $DIR/skip_ser_struct_field_if.rs:4:10
+  --> $DIR/skip_ser_struct_field_if.rs:6:5
-  |
+   |
-4 | #[derive(Serialize)]
+6  | /     #[serde(serialize_with = "serialize_some_newtype_variant")]
-  |          ^^^^^^^^^
+7  | |     Struct {
+8  | |         #[serde(skip_serializing_if = "always")]
+9  | |         f1: String,
+10 | |         f2: u8,
+11 | |     },
+   | |_____^
 
 error: aborting due to previous error
 

test_suite/tests/ui/with-variant/skip_ser_tuple_field.stderr

@@ -1,8 +1,9 @@
-error: variant `Tuple` cannot have both #[serde(serialize_with)] and a field 0 marked with #[serde(skip_serializing)]
+error: variant `Tuple` cannot have both #[serde(serialize_with)] and a field #0 marked with #[serde(skip_serializing)]
- --> $DIR/skip_ser_tuple_field.rs:4:10
+ --> $DIR/skip_ser_tuple_field.rs:6:5
   |
-4 | #[derive(Serialize)]
+6 | /     #[serde(serialize_with = "serialize_some_other_variant")]
-  |          ^^^^^^^^^
+7 | |     Tuple(#[serde(skip_serializing)] String, u8),
+  | |________________________________________________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/with-variant/skip_ser_tuple_field_if.stderr

@@ -1,8 +1,9 @@
-error: variant `Tuple` cannot have both #[serde(serialize_with)] and a field 0 marked with #[serde(skip_serializing_if)]
+error: variant `Tuple` cannot have both #[serde(serialize_with)] and a field #0 marked with #[serde(skip_serializing_if)]
- --> $DIR/skip_ser_tuple_field_if.rs:4:10
+ --> $DIR/skip_ser_tuple_field_if.rs:6:5
   |
-4 | #[derive(Serialize)]
+6 | /     #[serde(serialize_with = "serialize_some_other_variant")]
-  |          ^^^^^^^^^
+7 | |     Tuple(#[serde(skip_serializing_if = "always")] String, u8),
+  | |______________________________________________________________^
 
 error: aborting due to previous error
 

test_suite/tests/ui/with-variant/skip_ser_whole_variant.stderr

@@ -1,8 +1,10 @@
 error: variant `Unit` cannot have both #[serde(serialize_with)] and #[serde(skip_serializing)]
- --> $DIR/skip_ser_whole_variant.rs:4:10
+ --> $DIR/skip_ser_whole_variant.rs:6:5
   |
-4 | #[derive(Serialize)]
+6 | /     #[serde(serialize_with = "serialize_some_unit_variant")]
-  |          ^^^^^^^^^
+7 | |     #[serde(skip_serializing)]
+8 | |     Unit,
+  | |________^
 
 error: aborting due to previous error