macros: use typed identifiers in diag derive

Using typed identifiers instead of strings with the Fluent identifier
enables the diagnostic derive to benefit from the compile-time
validation that comes with typed identifiers - use of a non-existent
Fluent identifier will not compile.

Signed-off-by: David Wood <david.wood@huawei.com>

compiler/rustc_builtin_macros/src/cfg.rs

@@ -36,7 +36,7 @@ pub fn expand_cfg(
 }
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "builtin-macros-requires-cfg-pattern")]
+#[error(builtin_macros::requires_cfg_pattern)]
 struct RequiresCfgPattern {
     #[primary_span]
     #[label]
@@ -44,7 +44,7 @@ struct RequiresCfgPattern {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "builtin-macros-expected-one-cfg-pattern")]
+#[error(builtin_macros::expected_one_cfg_pattern)]
 struct OneCfgPattern {
     #[primary_span]
     span: Span,

compiler/rustc_error_messages/locales/en-US/builtin_macros.ftl

@@ -1,5 +1,5 @@
-builtin-macros-requires-cfg-pattern =
+builtin_macros-requires-cfg-pattern =
     macro requires a cfg-pattern as an argument
     .label = cfg-pattern required
 
-builtin-macros-expected-one-cfg-pattern = expected 1 cfg-pattern
+builtin_macros-expected-one-cfg-pattern = expected 1 cfg-pattern

compiler/rustc_macros/src/diagnostics/diagnostic.rs

@@ -12,7 +12,9 @@ use proc_macro2::{Ident, TokenStream};
 use quote::{format_ident, quote};
 use std::collections::HashMap;
 use std::str::FromStr;
-use syn::{spanned::Spanned, Attribute, Meta, MetaList, MetaNameValue, Type};
+use syn::{
+    parse_quote, spanned::Spanned, Attribute, Meta, MetaList, MetaNameValue, NestedMeta, Path, Type,
+};
 use synstructure::{BindingInfo, Structure};
 
 /// The central struct for constructing the `into_diagnostic` method from an annotated struct.
@@ -118,23 +120,23 @@ impl<'a> SessionDiagnosticDerive<'a> {
                         return SessionDiagnosticDeriveError::ErrorHandled.to_compile_error();
                     }
                     (Some((kind, _)), None) => {
-                        span_err(span, "`slug` not specified")
+                        span_err(span, "diagnostic slug not specified")
-                            .help(&format!("use the `#[{}(slug = \"...\")]` attribute to set this diagnostic's slug", kind.descr()))
+                            .help(&format!(
+                                "specify the slug as the first argument to the attribute, such as \
+                                 `#[{}(typeck::example_error)]`",
+                                kind.descr()
+                            ))
                             .emit();
                         return SessionDiagnosticDeriveError::ErrorHandled.to_compile_error();
                     }
                     (Some((SessionDiagnosticKind::Error, _)), Some((slug, _))) => {
                         quote! {
-                            let mut #diag = #sess.struct_err(
+                            let mut #diag = #sess.struct_err(rustc_errors::fluent::#slug);
-                                rustc_errors::DiagnosticMessage::new(#slug),
-                            );
                         }
                     }
                     (Some((SessionDiagnosticKind::Warn, _)), Some((slug, _))) => {
                         quote! {
-                            let mut #diag = #sess.struct_warn(
+                            let mut #diag = #sess.struct_warn(rustc_errors::fluent::#slug);
-                                rustc_errors::DiagnosticMessage::new(#slug),
-                            );
                         }
                     }
                 };
@@ -226,7 +228,7 @@ struct SessionDiagnosticDeriveBuilder {
     kind: Option<(SessionDiagnosticKind, proc_macro::Span)>,
     /// Slug is a mandatory part of the struct attribute as corresponds to the Fluent message that
     /// has the actual diagnostic message.
-    slug: Option<(String, proc_macro::Span)>,
+    slug: Option<(Path, proc_macro::Span)>,
     /// Error codes are a optional part of the struct attribute - this is only set to detect
     /// multiple specifications.
     code: Option<(String, proc_macro::Span)>,
@@ -240,50 +242,79 @@ impl HasFieldMap for SessionDiagnosticDeriveBuilder {
 
 impl SessionDiagnosticDeriveBuilder {
     /// Establishes state in the `SessionDiagnosticDeriveBuilder` resulting from the struct
-    /// attributes like `#[error(..)#`, such as the diagnostic kind and slug. Generates
+    /// attributes like `#[error(..)`, such as the diagnostic kind and slug. Generates
     /// diagnostic builder calls for setting error code and creating note/help messages.
     fn generate_structure_code(
         &mut self,
         attr: &Attribute,
     ) -> Result<TokenStream, SessionDiagnosticDeriveError> {
+        let diag = &self.diag;
         let span = attr.span().unwrap();
 
         let name = attr.path.segments.last().unwrap().ident.to_string();
         let name = name.as_str();
         let meta = attr.parse_meta()?;
 
-        if matches!(name, "help" | "note") && matches!(meta, Meta::Path(_) | Meta::NameValue(_)) {
+        let is_help_or_note = matches!(name, "help" | "note");
-            let diag = &self.diag;
-            let id = match meta {
-                Meta::Path(..) => quote! { #name },
-                Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(s), .. }) => {
-                    quote! { #s }
-                }
-                _ => unreachable!(),
-            };
-            let fn_name = proc_macro2::Ident::new(name, attr.span());
-
-            return Ok(quote! {
-                #diag.#fn_name(rustc_errors::SubdiagnosticMessage::attr(#id));
-            });
-        }
 
         let nested = match meta {
+            // Most attributes are lists, like `#[error(..)]`/`#[warning(..)]` for most cases or
+            // `#[help(..)]`/`#[note(..)]` when the user is specifying a alternative slug.
             Meta::List(MetaList { ref nested, .. }) => nested,
+            // Subdiagnostics without spans can be applied to the type too, and these are just
+            // paths: `#[help]` and `#[note]`
+            Meta::Path(_) if is_help_or_note => {
+                let fn_name = proc_macro2::Ident::new(name, attr.span());
+                return Ok(quote! { #diag.#fn_name(rustc_errors::fluent::_subdiag::#fn_name); });
+            }
             _ => throw_invalid_attr!(attr, &meta),
         };
 
-        let kind = match name {
+        // Check the kind before doing any further processing so that there aren't misleading
-            "error" => SessionDiagnosticKind::Error,
+        // "no kind specified" errors if there are failures later.
-            "warning" => SessionDiagnosticKind::Warn,
+        match name {
+            "error" => self.kind.set_once((SessionDiagnosticKind::Error, span)),
+            "warning" => self.kind.set_once((SessionDiagnosticKind::Warn, span)),
+            "help" | "note" => (),
             _ => throw_invalid_attr!(attr, &meta, |diag| {
-                diag.help("only `error` and `warning` are valid attributes")
+                diag.help("only `error`, `warning`, `help` and `note` are valid attributes")
             }),
-        };
+        }
-        self.kind.set_once((kind, span));
 
+        // First nested element should always be the path, e.g. `#[error(typeck::invalid)]` or
+        // `#[help(typeck::another_help)]`.
+        let mut nested_iter = nested.into_iter();
+        if let Some(nested_attr) = nested_iter.next() {
+            // Report an error if there are any other list items after the path.
+            if is_help_or_note && nested_iter.next().is_some() {
+                throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
+                    diag.help("`help` and `note` struct attributes can only have one argument")
+                });
+            }
+
+            match nested_attr {
+                NestedMeta::Meta(Meta::Path(path)) if is_help_or_note => {
+                    let fn_name = proc_macro2::Ident::new(name, attr.span());
+                    return Ok(quote! { #diag.#fn_name(rustc_errors::fluent::#path); });
+                }
+                NestedMeta::Meta(Meta::Path(path)) => {
+                    self.slug.set_once((path.clone(), span));
+                }
+                NestedMeta::Meta(meta @ Meta::NameValue(_))
+                    if !is_help_or_note
+                        && meta.path().segments.last().unwrap().ident.to_string() == "code" =>
+                {
+                    // don't error for valid follow-up attributes
+                }
+                nested_attr => throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
+                    diag.help("first argument of the attribute should be the diagnostic slug")
+                }),
+            };
+        }
+
+        // Remaining attributes are optional, only `code = ".."` at the moment.
         let mut tokens = Vec::new();
-        for nested_attr in nested {
+        for nested_attr in nested_iter {
             let meta = match nested_attr {
                 syn::NestedMeta::Meta(meta) => meta,
                 _ => throw_invalid_nested_attr!(attr, &nested_attr),
@@ -291,28 +322,24 @@ impl SessionDiagnosticDeriveBuilder {
 
             let path = meta.path();
             let nested_name = path.segments.last().unwrap().ident.to_string();
-            match &meta {
+            // Struct attributes are only allowed to be applied once, and the diagnostic
-                // Struct attributes are only allowed to be applied once, and the diagnostic
+            // changes will be set in the initialisation code.
-                // changes will be set in the initialisation code.
+            if let Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(s), .. }) = &meta {
-                Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(s), .. }) => {
+                let span = s.span().unwrap();
-                    let span = s.span().unwrap();
+                match nested_name.as_str() {
-                    match nested_name.as_str() {
+                    "code" => {
-                        "slug" => {
+                        self.code.set_once((s.value(), span));
-                            self.slug.set_once((s.value(), span));
+                        let code = &self.code.as_ref().map(|(v, _)| v);
-                        }
+                        tokens.push(quote! {
-                        "code" => {
+                            #diag.code(rustc_errors::DiagnosticId::Error(#code.to_string()));
-                            self.code.set_once((s.value(), span));
+                        });
-                            let (diag, code) = (&self.diag, &self.code.as_ref().map(|(v, _)| v));
-                            tokens.push(quote! {
-                                #diag.code(rustc_errors::DiagnosticId::Error(#code.to_string()));
-                            });
-                        }
-                        _ => invalid_nested_attr(attr, &nested_attr)
-                            .help("only `slug` and `code` are valid nested attributes")
-                            .emit(),
                     }
+                    _ => invalid_nested_attr(attr, &nested_attr)
+                        .help("only `code` is a valid nested attributes following the slug")
+                        .emit(),
                 }
-                _ => invalid_nested_attr(attr, &nested_attr).emit(),
+            } else {
+                invalid_nested_attr(attr, &nested_attr).emit()
             }
         }
 
@@ -382,142 +409,215 @@ impl SessionDiagnosticDeriveBuilder {
         info: FieldInfo<'_>,
         binding: TokenStream,
     ) -> Result<TokenStream, SessionDiagnosticDeriveError> {
+        let meta = attr.parse_meta()?;
+        match meta {
+            Meta::Path(_) => self.generate_inner_field_code_path(attr, info, binding),
+            Meta::List(MetaList { .. }) => self.generate_inner_field_code_list(attr, info, binding),
+            _ => throw_invalid_attr!(attr, &meta),
+        }
+    }
+
+    fn generate_inner_field_code_path(
+        &mut self,
+        attr: &Attribute,
+        info: FieldInfo<'_>,
+        binding: TokenStream,
+    ) -> Result<TokenStream, SessionDiagnosticDeriveError> {
+        assert!(matches!(attr.parse_meta()?, Meta::Path(_)));
         let diag = &self.diag;
 
+        let meta = attr.parse_meta()?;
+
         let ident = &attr.path.segments.last().unwrap().ident;
         let name = ident.to_string();
         let name = name.as_str();
-
+        match name {
-        let meta = attr.parse_meta()?;
+            "skip_arg" => {
-        match meta {
+                // Don't need to do anything - by virtue of the attribute existing, the
-            Meta::Path(_) => match name {
+                // `set_arg` call will not be generated.
-                "skip_arg" => {
+                Ok(quote! {})
-                    // Don't need to do anything - by virtue of the attribute existing, the
+            }
-                    // `set_arg` call will not be generated.
+            "primary_span" => {
-                    Ok(quote! {})
+                report_error_if_not_applied_to_span(attr, &info)?;
-                }
+                Ok(quote! {
-                "primary_span" => {
+                    #diag.set_span(#binding);
-                    report_error_if_not_applied_to_span(attr, &info)?;
+                })
-                    Ok(quote! {
+            }
-                        #diag.set_span(#binding);
+            "label" => {
-                    })
+                report_error_if_not_applied_to_span(attr, &info)?;
-                }
+                Ok(self.add_spanned_subdiagnostic(binding, ident, parse_quote! { _subdiag::label }))
-                "label" => {
+            }
-                    report_error_if_not_applied_to_span(attr, &info)?;
+            "note" | "help" => {
-                    Ok(self.add_spanned_subdiagnostic(binding, ident, name))
+                let path = match name {
-                }
+                    "note" => parse_quote! { _subdiag::note },
-                "note" | "help" => {
+                    "help" => parse_quote! { _subdiag::help },
-                    if type_matches_path(&info.ty, &["rustc_span", "Span"]) {
+                    _ => unreachable!(),
-                        Ok(self.add_spanned_subdiagnostic(binding, ident, name))
-                    } else if type_is_unit(&info.ty) {
-                        Ok(self.add_subdiagnostic(ident, name))
-                    } else {
-                        report_type_error(attr, "`Span` or `()`")?;
-                    }
-                }
-                "subdiagnostic" => Ok(quote! { #diag.subdiagnostic(#binding); }),
-                _ => throw_invalid_attr!(attr, &meta, |diag| {
-                    diag
-                        .help("only `skip_arg`, `primary_span`, `label`, `note`, `help` and `subdiagnostic` are valid field attributes")
-                }),
-            },
-            Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(ref s), .. }) => match name {
-                "label" => {
-                    report_error_if_not_applied_to_span(attr, &info)?;
-                    Ok(self.add_spanned_subdiagnostic(binding, ident, &s.value()))
-                }
-                "note" | "help" => {
-                    if type_matches_path(&info.ty, &["rustc_span", "Span"]) {
-                        Ok(self.add_spanned_subdiagnostic(binding, ident, &s.value()))
-                    } else if type_is_unit(&info.ty) {
-                        Ok(self.add_subdiagnostic(ident, &s.value()))
-                    } else {
-                        report_type_error(attr, "`Span` or `()`")?;
-                    }
-                }
-                _ => throw_invalid_attr!(attr, &meta, |diag| {
-                    diag.help("only `label`, `note` and `help` are valid field attributes")
-                }),
-            },
-            Meta::List(MetaList { ref path, ref nested, .. }) => {
-                let name = path.segments.last().unwrap().ident.to_string();
-                let name = name.as_ref();
-
-                match name {
-                    "suggestion" | "suggestion_short" | "suggestion_hidden"
-                    | "suggestion_verbose" => (),
-                    _ => throw_invalid_attr!(attr, &meta, |diag| {
-                        diag
-                            .help("only `suggestion{,_short,_hidden,_verbose}` are valid field attributes")
-                    }),
                 };
+                if type_matches_path(&info.ty, &["rustc_span", "Span"]) {
+                    Ok(self.add_spanned_subdiagnostic(binding, ident, path))
+                } else if type_is_unit(&info.ty) {
+                    Ok(self.add_subdiagnostic(ident, path))
+                } else {
+                    report_type_error(attr, "`Span` or `()`")?;
+                }
+            }
+            "subdiagnostic" => Ok(quote! { #diag.subdiagnostic(#binding); }),
+            _ => throw_invalid_attr!(attr, &meta, |diag| {
+                diag.help(
+                    "only `skip_arg`, `primary_span`, `label`, `note`, `help` and `subdiagnostic` \
+                     are valid field attributes",
+                )
+            }),
+        }
+    }
 
-                let (span_field, mut applicability) = self.span_and_applicability_of_ty(info)?;
+    fn generate_inner_field_code_list(
+        &mut self,
+        attr: &Attribute,
+        info: FieldInfo<'_>,
+        binding: TokenStream,
+    ) -> Result<TokenStream, SessionDiagnosticDeriveError> {
+        let meta = attr.parse_meta()?;
+        let Meta::List(MetaList { ref path, ref nested, .. }) = meta  else { unreachable!() };
 
-                let mut msg = None;
+        let ident = &attr.path.segments.last().unwrap().ident;
-                let mut code = None;
+        let name = path.segments.last().unwrap().ident.to_string();
+        let name = name.as_ref();
+        match name {
+            "suggestion" | "suggestion_short" | "suggestion_hidden" | "suggestion_verbose" => {
+                return self.generate_inner_field_code_suggestion(attr, info);
+            }
+            "label" | "help" | "note" => (),
+            _ => throw_invalid_attr!(attr, &meta, |diag| {
+                diag.help(
+                    "only `label`, `note`, `help` or `suggestion{,_short,_hidden,_verbose}` are \
+                     valid field attributes",
+                )
+            }),
+        }
 
-                for nested_attr in nested {
+        // For `#[label(..)]`, `#[note(..)]` and `#[help(..)]`, the first nested element must be a
-                    let meta = match nested_attr {
+        // path, e.g. `#[label(typeck::label)]`.
-                        syn::NestedMeta::Meta(ref meta) => meta,
+        let mut nested_iter = nested.into_iter();
-                        syn::NestedMeta::Lit(_) => throw_invalid_nested_attr!(attr, &nested_attr),
+        let msg = match nested_iter.next() {
-                    };
+            Some(NestedMeta::Meta(Meta::Path(path))) => path.clone(),
+            Some(nested_attr) => throw_invalid_nested_attr!(attr, &nested_attr),
+            None => throw_invalid_attr!(attr, &meta),
+        };
 
-                    let nested_name = meta.path().segments.last().unwrap().ident.to_string();
+        // None of these attributes should have anything following the slug.
-                    let nested_name = nested_name.as_str();
+        if nested_iter.next().is_some() {
-                    match meta {
+            throw_invalid_attr!(attr, &meta);
-                        Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(s), .. }) => {
+        }
-                            let span = meta.span().unwrap();
+
-                            match nested_name {
+        match name {
-                                "message" => {
+            "label" => {
-                                    msg = Some(s.value());
+                report_error_if_not_applied_to_span(attr, &info)?;
-                                }
+                Ok(self.add_spanned_subdiagnostic(binding, ident, msg))
-                                "code" => {
+            }
-                                    let formatted_str = self.build_format(&s.value(), s.span());
+            "note" | "help" if type_matches_path(&info.ty, &["rustc_span", "Span"]) => {
-                                    code = Some(formatted_str);
+                Ok(self.add_spanned_subdiagnostic(binding, ident, msg))
-                                }
+            }
-                                "applicability" => {
+            "note" | "help" if type_is_unit(&info.ty) => Ok(self.add_subdiagnostic(ident, msg)),
-                                    applicability = match applicability {
+            "note" | "help" => {
-                                        Some(v) => {
+                report_type_error(attr, "`Span` or `()`")?;
-                                            span_err(
+            }
-                                                span,
+            _ => unreachable!(),
-                                                "applicability cannot be set in both the field and attribute"
+        }
-                                            ).emit();
+    }
-                                            Some(v)
+
-                                        }
+    fn generate_inner_field_code_suggestion(
-                                        None => match Applicability::from_str(&s.value()) {
+        &mut self,
-                                            Ok(v) => Some(quote! { #v }),
+        attr: &Attribute,
-                                            Err(()) => {
+        info: FieldInfo<'_>,
-                                                span_err(span, "invalid applicability").emit();
+    ) -> Result<TokenStream, SessionDiagnosticDeriveError> {
-                                                None
+        let diag = &self.diag;
-                                            }
+
-                                        },
+        let mut meta = attr.parse_meta()?;
-                                    }
+        let Meta::List(MetaList { ref path, ref mut nested, .. }) = meta  else { unreachable!() };
-                                }
+
-                                _ => throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
+        let (span_field, mut applicability) = self.span_and_applicability_of_ty(info)?;
-                                    diag.help(
+
-                                        "only `message`, `code` and `applicability` are valid field attributes",
+        let mut msg = None;
+        let mut code = None;
+
+        let mut nested_iter = nested.into_iter().peekable();
+        if let Some(nested_attr) = nested_iter.peek() {
+            if let NestedMeta::Meta(Meta::Path(path)) = nested_attr {
+                msg = Some(path.clone());
+            }
+        };
+        // Move the iterator forward if a path was found (don't otherwise so that
+        // code/applicability can be found or an error emitted).
+        if msg.is_some() {
+            let _ = nested_iter.next();
+        }
+
+        for nested_attr in nested_iter {
+            let meta = match nested_attr {
+                syn::NestedMeta::Meta(ref meta) => meta,
+                syn::NestedMeta::Lit(_) => throw_invalid_nested_attr!(attr, &nested_attr),
+            };
+
+            let nested_name = meta.path().segments.last().unwrap().ident.to_string();
+            let nested_name = nested_name.as_str();
+            match meta {
+                Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(s), .. }) => {
+                    let span = meta.span().unwrap();
+                    match nested_name {
+                        "code" => {
+                            let formatted_str = self.build_format(&s.value(), s.span());
+                            code = Some(formatted_str);
+                        }
+                        "applicability" => {
+                            applicability = match applicability {
+                                Some(v) => {
+                                    span_err(
+                                        span,
+                                        "applicability cannot be set in both the field and \
+                                         attribute",
                                     )
-                                }),
+                                    .emit();
+                                    Some(v)
+                                }
+                                None => match Applicability::from_str(&s.value()) {
+                                    Ok(v) => Some(quote! { #v }),
+                                    Err(()) => {
+                                        span_err(span, "invalid applicability").emit();
+                                        None
+                                    }
+                                },
                             }
                         }
-                        _ => throw_invalid_nested_attr!(attr, &nested_attr),
+                        _ => throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
+                            diag.help(
+                                "only `message`, `code` and `applicability` are valid field \
+                                 attributes",
+                            )
+                        }),
                     }
                 }
-
+                _ => throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
-                let applicability = applicability
+                    if matches!(meta, Meta::Path(_)) {
-                    .unwrap_or_else(|| quote!(rustc_errors::Applicability::Unspecified));
+                        diag.help("a diagnostic slug must be the first argument to the attribute")
-
+                    } else {
-                let method = format_ident!("span_{}", name);
+                        diag
-
+                    }
-                let msg = msg.as_deref().unwrap_or("suggestion");
+                }),
-                let msg = quote! { rustc_errors::SubdiagnosticMessage::attr(#msg) };
-                let code = code.unwrap_or_else(|| quote! { String::new() });
-
-                Ok(quote! { #diag.#method(#span_field, #msg, #code, #applicability); })
             }
-            _ => throw_invalid_attr!(attr, &meta),
         }
+
+        let applicability =
+            applicability.unwrap_or_else(|| quote!(rustc_errors::Applicability::Unspecified));
+
+        let name = path.segments.last().unwrap().ident.to_string();
+        let method = format_ident!("span_{}", name);
+
+        let msg = msg.unwrap_or_else(|| parse_quote! { _subdiag::suggestion });
+        let msg = quote! { rustc_errors::fluent::#msg };
+        let code = code.unwrap_or_else(|| quote! { String::new() });
+
+        Ok(quote! { #diag.#method(#span_field, #msg, #code, #applicability); })
     }
 
     /// Adds a spanned subdiagnostic by generating a `diag.span_$kind` call with the current slug
@@ -526,24 +626,24 @@ impl SessionDiagnosticDeriveBuilder {
         &self,
         field_binding: TokenStream,
         kind: &Ident,
-        fluent_attr_identifier: &str,
+        fluent_attr_identifier: Path,
     ) -> TokenStream {
         let diag = &self.diag;
         let fn_name = format_ident!("span_{}", kind);
         quote! {
             #diag.#fn_name(
                 #field_binding,
-                rustc_errors::SubdiagnosticMessage::attr(#fluent_attr_identifier)
+                rustc_errors::fluent::#fluent_attr_identifier
             );
         }
     }
 
     /// Adds a subdiagnostic by generating a `diag.span_$kind` call with the current slug
     /// and `fluent_attr_identifier`.
-    fn add_subdiagnostic(&self, kind: &Ident, fluent_attr_identifier: &str) -> TokenStream {
+    fn add_subdiagnostic(&self, kind: &Ident, fluent_attr_identifier: Path) -> TokenStream {
         let diag = &self.diag;
         quote! {
-            #diag.#kind(rustc_errors::SubdiagnosticMessage::attr(#fluent_attr_identifier));
+            #diag.#kind(rustc_errors::fluent::#fluent_attr_identifier);
         }
     }
 
@@ -569,7 +669,8 @@ impl SessionDiagnosticDeriveBuilder {
                         } else {
                             throw_span_err!(
                                 info.span.unwrap(),
-                                "type of field annotated with `#[suggestion(...)]` contains more than one `Span`"
+                                "type of field annotated with `#[suggestion(...)]` contains more \
+                                 than one `Span`"
                             );
                         }
                     } else if type_matches_path(elem, &["rustc_errors", "Applicability"]) {
@@ -578,7 +679,8 @@ impl SessionDiagnosticDeriveBuilder {
                         } else {
                             throw_span_err!(
                                 info.span.unwrap(),
-                                "type of field annotated with `#[suggestion(...)]` contains more than one Applicability"
+                                "type of field annotated with `#[suggestion(...)]` contains more \
+                                 than one Applicability"
                             );
                         }
                     }
@@ -595,12 +697,18 @@ impl SessionDiagnosticDeriveBuilder {
                 }
 
                 throw_span_err!(info.span.unwrap(), "wrong types for suggestion", |diag| {
-                    diag.help("`#[suggestion(...)]` on a tuple field must be applied to fields of type `(Span, Applicability)`")
+                    diag.help(
+                        "`#[suggestion(...)]` on a tuple field must be applied to fields of type \
+                         `(Span, Applicability)`",
+                    )
                 });
             }
             // If `ty` isn't a `Span` or `(Span, Applicability)` then emit an error.
             _ => throw_span_err!(info.span.unwrap(), "wrong field type for suggestion", |diag| {
-                diag.help("`#[suggestion(...)]` should be applied to fields of type `Span` or `(Span, Applicability)`")
+                diag.help(
+                    "`#[suggestion(...)]` should be applied to fields of type `Span` or \
+                     `(Span, Applicability)`",
+                )
             }),
         }
     }

compiler/rustc_macros/src/diagnostics/error.rs

@@ -39,6 +39,19 @@ pub(crate) fn _throw_err(
     SessionDiagnosticDeriveError::ErrorHandled
 }
 
+/// Helper function for printing `syn::Path` - doesn't handle arguments in paths and these are
+/// unlikely to come up much in use of the macro.
+fn path_to_string(path: &syn::Path) -> String {
+    let mut out = String::new();
+    for (i, segment) in path.segments.iter().enumerate() {
+        if i > 0 || path.leading_colon.is_some() {
+            out.push_str("::");
+        }
+        out.push_str(&segment.ident.to_string());
+    }
+    out
+}
+
 /// Returns an error diagnostic on span `span` with msg `msg`.
 pub(crate) fn span_err(span: impl MultiSpan, msg: &str) -> Diagnostic {
     Diagnostic::spanned(span, Level::Error, msg)
@@ -61,15 +74,13 @@ pub(crate) use throw_span_err;
 /// Returns an error diagnostic for an invalid attribute.
 pub(crate) fn invalid_attr(attr: &Attribute, meta: &Meta) -> Diagnostic {
     let span = attr.span().unwrap();
-    let name = attr.path.segments.last().unwrap().ident.to_string();
+    let path = path_to_string(&attr.path);
-    let name = name.as_str();
-
     match meta {
-        Meta::Path(_) => span_err(span, &format!("`#[{}]` is not a valid attribute", name)),
+        Meta::Path(_) => span_err(span, &format!("`#[{}]` is not a valid attribute", path)),
         Meta::NameValue(_) => {
-            span_err(span, &format!("`#[{} = ...]` is not a valid attribute", name))
+            span_err(span, &format!("`#[{} = ...]` is not a valid attribute", path))
         }
-        Meta::List(_) => span_err(span, &format!("`#[{}(...)]` is not a valid attribute", name)),
+        Meta::List(_) => span_err(span, &format!("`#[{}(...)]` is not a valid attribute", path)),
     }
 }
 
@@ -101,18 +112,16 @@ pub(crate) fn invalid_nested_attr(attr: &Attribute, nested: &NestedMeta) -> Diag
     };
 
     let span = meta.span().unwrap();
-    let nested_name = meta.path().segments.last().unwrap().ident.to_string();
+    let path = path_to_string(meta.path());
-    let nested_name = nested_name.as_str();
     match meta {
-        Meta::NameValue(..) => span_err(
+        Meta::NameValue(..) => {
-            span,
+            span_err(span, &format!("`#[{}({} = ...)]` is not a valid attribute", name, path))
-            &format!("`#[{}({} = ...)]` is not a valid attribute", name, nested_name),
+        }
-        ),
         Meta::Path(..) => {
-            span_err(span, &format!("`#[{}({})]` is not a valid attribute", name, nested_name))
+            span_err(span, &format!("`#[{}({})]` is not a valid attribute", name, path))
         }
         Meta::List(..) => {
-            span_err(span, &format!("`#[{}({}(...))]` is not a valid attribute", name, nested_name))
+            span_err(span, &format!("`#[{}({}(...))]` is not a valid attribute", name, path))
         }
     }
 }

compiler/rustc_macros/src/diagnostics/fluent.rs

@@ -254,6 +254,17 @@ pub(crate) fn fluent_messages(input: proc_macro::TokenStream) -> proc_macro::Tok
             ];
 
             #generated
+
+            pub mod _subdiag {
+                pub const note: crate::SubdiagnosticMessage =
+                    crate::SubdiagnosticMessage::FluentAttr(std::borrow::Cow::Borrowed("note"));
+                pub const help: crate::SubdiagnosticMessage =
+                    crate::SubdiagnosticMessage::FluentAttr(std::borrow::Cow::Borrowed("help"));
+                pub const label: crate::SubdiagnosticMessage =
+                    crate::SubdiagnosticMessage::FluentAttr(std::borrow::Cow::Borrowed("label"));
+                pub const suggestion: crate::SubdiagnosticMessage =
+                    crate::SubdiagnosticMessage::FluentAttr(std::borrow::Cow::Borrowed("suggestion"));
+            }
         }
     }
     .into()

compiler/rustc_macros/src/diagnostics/mod.rs

@@ -22,14 +22,14 @@ use synstructure::Structure;
 /// # extern crate rust_middle;
 /// # use rustc_middle::ty::Ty;
 /// #[derive(SessionDiagnostic)]
-/// #[error(code = "E0505", slug = "borrowck-move-out-of-borrow")]
+/// #[error(borrowck::move_out_of_borrow, code = "E0505")]
 /// pub struct MoveOutOfBorrowError<'tcx> {
 ///     pub name: Ident,
 ///     pub ty: Ty<'tcx>,
 ///     #[primary_span]
 ///     #[label]
 ///     pub span: Span,
-///     #[label = "first-borrow-label"]
+///     #[label(borrowck::first_borrow_label)]
 ///     pub first_borrow_span: Span,
 ///     #[suggestion(code = "{name}.clone()")]
 ///     pub clone_sugg: Option<(Span, Applicability)>

compiler/rustc_parse/src/parser/diagnostics.rs

@@ -244,7 +244,7 @@ impl MultiSugg {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "parser-maybe-report-ambiguous-plus")]
+#[error(parser::maybe_report_ambiguous_plus)]
 struct AmbiguousPlus {
     pub sum_ty: String,
     #[primary_span]
@@ -253,7 +253,7 @@ struct AmbiguousPlus {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0178", slug = "parser-maybe-recover-from-bad-type-plus")]
+#[error(parser::maybe_recover_from_bad_type_plus, code = "E0178")]
 struct BadTypePlus {
     pub ty: String,
     #[primary_span]
@@ -287,7 +287,7 @@ pub enum BadTypePlusSub {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "parser-maybe-recover-from-bad-qpath-stage-2")]
+#[error(parser::maybe_recover_from_bad_qpath_stage_2)]
 struct BadQPathStage2 {
     #[primary_span]
     #[suggestion(applicability = "maybe-incorrect")]
@@ -296,7 +296,7 @@ struct BadQPathStage2 {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "parser-incorrect-semicolon")]
+#[error(parser::incorrect_semicolon)]
 struct IncorrectSemicolon<'a> {
     #[primary_span]
     #[suggestion_short(applicability = "machine-applicable")]
@@ -307,26 +307,26 @@ struct IncorrectSemicolon<'a> {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "parser-incorrect-use-of-await")]
+#[error(parser::incorrect_use_of_await)]
 struct IncorrectUseOfAwait {
     #[primary_span]
-    #[suggestion(message = "parentheses-suggestion", applicability = "machine-applicable")]
+    #[suggestion(parser::parentheses_suggestion, applicability = "machine-applicable")]
     span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "parser-incorrect-use-of-await")]
+#[error(parser::incorrect_use_of_await)]
 struct IncorrectAwait {
     #[primary_span]
     span: Span,
-    #[suggestion(message = "postfix-suggestion", code = "{expr}.await{question_mark}")]
+    #[suggestion(parser::postfix_suggestion, code = "{expr}.await{question_mark}")]
     sugg_span: (Span, Applicability),
     expr: String,
     question_mark: &'static str,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "parser-in-in-typo")]
+#[error(parser::in_in_typo)]
 struct InInTypo {
     #[primary_span]
     span: Span,

compiler/rustc_typeck/src/errors.rs

@@ -6,18 +6,18 @@ use rustc_session::{parse::ParseSess, SessionDiagnostic};
 use rustc_span::{symbol::Ident, Span, Symbol};
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0062", slug = "typeck-field-multiply-specified-in-initializer")]
+#[error(typeck::field_multiply_specified_in_initializer, code = "E0062")]
 pub struct FieldMultiplySpecifiedInInitializer {
     #[primary_span]
     #[label]
     pub span: Span,
-    #[label = "previous-use-label"]
+    #[label(typeck::previous_use_label)]
     pub prev_span: Span,
     pub ident: Ident,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0092", slug = "typeck-unrecognized-atomic-operation")]
+#[error(typeck::unrecognized_atomic_operation, code = "E0092")]
 pub struct UnrecognizedAtomicOperation<'a> {
     #[primary_span]
     #[label]
@@ -26,7 +26,7 @@ pub struct UnrecognizedAtomicOperation<'a> {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0094", slug = "typeck-wrong-number-of-generic-arguments-to-intrinsic")]
+#[error(typeck::wrong_number_of_generic_arguments_to_intrinsic, code = "E0094")]
 pub struct WrongNumberOfGenericArgumentsToIntrinsic<'a> {
     #[primary_span]
     #[label]
@@ -37,7 +37,7 @@ pub struct WrongNumberOfGenericArgumentsToIntrinsic<'a> {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0093", slug = "typeck-unrecognized-intrinsic-function")]
+#[error(typeck::unrecognized_intrinsic_function, code = "E0093")]
 pub struct UnrecognizedIntrinsicFunction {
     #[primary_span]
     #[label]
@@ -46,19 +46,19 @@ pub struct UnrecognizedIntrinsicFunction {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0195", slug = "typeck-lifetimes-or-bounds-mismatch-on-trait")]
+#[error(typeck::lifetimes_or_bounds_mismatch_on_trait, code = "E0195")]
 pub struct LifetimesOrBoundsMismatchOnTrait {
     #[primary_span]
     #[label]
     pub span: Span,
-    #[label = "generics-label"]
+    #[label(typeck::generics_label)]
     pub generics_span: Option<Span>,
     pub item_kind: &'static str,
     pub ident: Ident,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0120", slug = "typeck-drop-impl-on-wrong-item")]
+#[error(typeck::drop_impl_on_wrong_item, code = "E0120")]
 pub struct DropImplOnWrongItem {
     #[primary_span]
     #[label]
@@ -66,18 +66,18 @@ pub struct DropImplOnWrongItem {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0124", slug = "typeck-field-already-declared")]
+#[error(typeck::field_already_declared, code = "E0124")]
 pub struct FieldAlreadyDeclared {
     pub field_name: Ident,
     #[primary_span]
     #[label]
     pub span: Span,
-    #[label = "previous-decl-label"]
+    #[label(typeck::previous_decl_label)]
     pub prev_span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0184", slug = "typeck-copy-impl-on-type-with-dtor")]
+#[error(typeck::copy_impl_on_type_with_dtor, code = "E0184")]
 pub struct CopyImplOnTypeWithDtor {
     #[primary_span]
     #[label]
@@ -85,14 +85,14 @@ pub struct CopyImplOnTypeWithDtor {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0203", slug = "typeck-multiple-relaxed-default-bounds")]
+#[error(typeck::multiple_relaxed_default_bounds, code = "E0203")]
 pub struct MultipleRelaxedDefaultBounds {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0206", slug = "typeck-copy-impl-on-non-adt")]
+#[error(typeck::copy_impl_on_non_adt, code = "E0206")]
 pub struct CopyImplOnNonAdt {
     #[primary_span]
     #[label]
@@ -100,23 +100,23 @@ pub struct CopyImplOnNonAdt {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0224", slug = "typeck-trait-object-declared-with-no-traits")]
+#[error(typeck::trait_object_declared_with_no_traits, code = "E0224")]
 pub struct TraitObjectDeclaredWithNoTraits {
     #[primary_span]
     pub span: Span,
-    #[label = "alias-span"]
+    #[label(typeck::alias_span)]
     pub trait_alias_span: Option<Span>,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0227", slug = "typeck-ambiguous-lifetime-bound")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0227")]
 pub struct AmbiguousLifetimeBound {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0229", slug = "typeck-assoc-type-binding-not-allowed")]
+#[error(typeck::assoc_type_binding_not_allowed, code = "E0229")]
 pub struct AssocTypeBindingNotAllowed {
     #[primary_span]
     #[label]
@@ -124,14 +124,14 @@ pub struct AssocTypeBindingNotAllowed {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0436", slug = "typeck-functional-record-update-on-non-struct")]
+#[error(typeck::functional_record_update_on_non_struct, code = "E0436")]
 pub struct FunctionalRecordUpdateOnNonStruct {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0516", slug = "typeck-typeof-reserved-keyword-used")]
+#[error(typeck::typeof_reserved_keyword_used, code = "E0516")]
 pub struct TypeofReservedKeywordUsed<'tcx> {
     pub ty: Ty<'tcx>,
     #[primary_span]
@@ -142,25 +142,25 @@ pub struct TypeofReservedKeywordUsed<'tcx> {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0572", slug = "typeck-return-stmt-outside-of-fn-body")]
+#[error(typeck::return_stmt_outside_of_fn_body, code = "E0572")]
 pub struct ReturnStmtOutsideOfFnBody {
     #[primary_span]
     pub span: Span,
-    #[label = "encl-body-label"]
+    #[label(typeck::encl_body_label)]
     pub encl_body_span: Option<Span>,
-    #[label = "encl-fn-label"]
+    #[label(typeck::encl_fn_label)]
     pub encl_fn_span: Option<Span>,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0627", slug = "typeck-yield-expr-outside-of-generator")]
+#[error(typeck::yield_expr_outside_of_generator, code = "E0627")]
 pub struct YieldExprOutsideOfGenerator {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0639", slug = "typeck-struct-expr-non-exhaustive")]
+#[error(typeck::struct_expr_non_exhaustive, code = "E0639")]
 pub struct StructExprNonExhaustive {
     #[primary_span]
     pub span: Span,
@@ -168,26 +168,26 @@ pub struct StructExprNonExhaustive {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0699", slug = "typeck-method-call-on-unknown-type")]
+#[error(typeck::method_call_on_unknown_type, code = "E0699")]
 pub struct MethodCallOnUnknownType {
     #[primary_span]
     pub span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0719", slug = "typeck-value-of-associated-struct-already-specified")]
+#[error(typeck::value_of_associated_struct_already_specified, code = "E0719")]
 pub struct ValueOfAssociatedStructAlreadySpecified {
     #[primary_span]
     #[label]
     pub span: Span,
-    #[label = "previous-bound-label"]
+    #[label(typeck::previous_bound_label)]
     pub prev_span: Span,
     pub item_name: Ident,
     pub def_path: String,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0745", slug = "typeck-address-of-temporary-taken")]
+#[error(typeck::address_of_temporary_taken, code = "E0745")]
 pub struct AddressOfTemporaryTaken {
     #[primary_span]
     #[label]
@@ -233,7 +233,7 @@ pub enum ExpectedReturnTypeLabel<'tcx> {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "typeck-unconstrained-opaque-type")]
+#[error(typeck::unconstrained_opaque_type)]
 #[note]
 pub struct UnconstrainedOpaqueType {
     #[primary_span]
@@ -301,7 +301,7 @@ impl<'a> SessionDiagnostic<'a> for MissingTypeParams {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0183", slug = "typeck-manual-implementation")]
+#[error(typeck::manual_implementation, code = "E0183")]
 #[help]
 pub struct ManualImplementation {
     #[primary_span]
@@ -311,7 +311,7 @@ pub struct ManualImplementation {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "typeck-substs-on-overridden-impl")]
+#[error(typeck::substs_on_overridden_impl)]
 pub struct SubstsOnOverriddenImpl {
     #[primary_span]
     pub span: Span,

src/test/ui-fulldeps/internal-lints/diagnostics.rs

@@ -16,7 +16,7 @@ use rustc_session::{parse::ParseSess, SessionDiagnostic};
 use rustc_span::Span;
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "parser-expect-path")]
+#[error(parser::expect_path)]
 struct DeriveSessionDiagnostic {
     #[primary_span]
     span: Span,

src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.rs

@@ -26,15 +26,15 @@ use rustc_errors::Applicability;
 extern crate rustc_session;
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "hello-world")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct Hello {}
 
 #[derive(SessionDiagnostic)]
-#[warning(code = "E0123", slug = "hello-world")]
+#[warning(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct HelloWarn {}
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 //~^ ERROR `#[derive(SessionDiagnostic)]` can only be used on structs
 enum SessionDiagnosticOnEnum {
     Foo,
@@ -42,13 +42,13 @@ enum SessionDiagnosticOnEnum {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 #[error = "E0123"]
 //~^ ERROR `#[error = ...]` is not a valid attribute
 struct WrongStructAttrStyle {}
 
 #[derive(SessionDiagnostic)]
-#[nonsense(code = "E0123", slug = "foo")]
+#[nonsense(typeck::ambiguous_lifetime_bound, code = "E0123")]
 //~^ ERROR `#[nonsense(...)]` is not a valid attribute
 //~^^ ERROR diagnostic kind not specified
 //~^^^ ERROR cannot find attribute `nonsense` in this scope
@@ -57,31 +57,39 @@ struct InvalidStructAttr {}
 #[derive(SessionDiagnostic)]
 #[error("E0123")]
 //~^ ERROR `#[error("...")]` is not a valid attribute
-//~^^ ERROR `slug` not specified
+//~^^ ERROR diagnostic slug not specified
 struct InvalidLitNestedAttr {}
 
 #[derive(SessionDiagnostic)]
-#[error(nonsense, code = "E0123", slug = "foo")]
+#[error(nonsense, code = "E0123")]
-//~^ ERROR `#[error(nonsense)]` is not a valid attribute
+//~^ ERROR cannot find value `nonsense` in module `rustc_errors::fluent`
 struct InvalidNestedStructAttr {}
 
 #[derive(SessionDiagnostic)]
 #[error(nonsense("foo"), code = "E0123", slug = "foo")]
 //~^ ERROR `#[error(nonsense(...))]` is not a valid attribute
+//~^^ ERROR diagnostic slug not specified
 struct InvalidNestedStructAttr1 {}
 
 #[derive(SessionDiagnostic)]
 #[error(nonsense = "...", code = "E0123", slug = "foo")]
 //~^ ERROR `#[error(nonsense = ...)]` is not a valid attribute
+//~^^ ERROR diagnostic slug not specified
 struct InvalidNestedStructAttr2 {}
 
 #[derive(SessionDiagnostic)]
 #[error(nonsense = 4, code = "E0123", slug = "foo")]
 //~^ ERROR `#[error(nonsense = ...)]` is not a valid attribute
+//~^^ ERROR diagnostic slug not specified
 struct InvalidNestedStructAttr3 {}
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123", slug = "foo")]
+//~^ ERROR `#[error(slug = ...)]` is not a valid attribute
+struct InvalidNestedStructAttr4 {}
+
+#[derive(SessionDiagnostic)]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct WrongPlaceField {
     #[suggestion = "bar"]
     //~^ ERROR `#[suggestion = ...]` is not a valid attribute
@@ -89,44 +97,45 @@ struct WrongPlaceField {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
-#[error(code = "E0456", slug = "bar")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0456")]
 //~^ ERROR specified multiple times
 //~^^ ERROR specified multiple times
 //~^^^ ERROR specified multiple times
 struct ErrorSpecifiedTwice {}
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
-#[warning(code = "E0293", slug = "bar")]
+#[warning(typeck::ambiguous_lifetime_bound, code = "E0293")]
 //~^ ERROR specified multiple times
 //~^^ ERROR specified multiple times
 //~^^^ ERROR specified multiple times
 struct WarnSpecifiedAfterError {}
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0456", code = "E0457", slug = "bar")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0456", code = "E0457")]
 //~^ ERROR specified multiple times
 struct CodeSpecifiedTwice {}
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0456", slug = "foo", slug = "bar")]
+#[error(typeck::ambiguous_lifetime_bound, typeck::ambiguous_lifetime_bound, code = "E0456")]
-//~^ ERROR specified multiple times
+//~^ ERROR `#[error(typeck::ambiguous_lifetime_bound)]` is not a valid attribute
 struct SlugSpecifiedTwice {}
 
 #[derive(SessionDiagnostic)]
 struct KindNotProvided {} //~ ERROR diagnostic kind not specified
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0456")] //~ ERROR `slug` not specified
+#[error(code = "E0456")]
+//~^ ERROR diagnostic slug not specified
 struct SlugNotProvided {}
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound)]
 struct CodeNotProvided {}
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct MessageWrongType {
     #[primary_span]
     //~^ ERROR `#[primary_span]` attribute can only be applied to fields of type `Span`
@@ -134,7 +143,7 @@ struct MessageWrongType {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct InvalidPathFieldAttr {
     #[nonsense]
     //~^ ERROR `#[nonsense]` is not a valid attribute
@@ -143,34 +152,34 @@ struct InvalidPathFieldAttr {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithField {
     name: String,
-    #[label = "bar"]
+    #[label(typeck::label)]
     span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithMessageAppliedToField {
-    #[label = "bar"]
+    #[label(typeck::label)]
-    //~^ ERROR the `#[label = ...]` attribute can only be applied to fields of type `Span`
+    //~^ ERROR the `#[label(...)]` attribute can only be applied to fields of type `Span`
     name: String,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithNonexistentField {
-    #[suggestion(message = "bar", code = "{name}")]
+    #[suggestion(typeck::suggestion, code = "{name}")]
     //~^ ERROR `name` doesn't refer to a field on this type
     suggestion: (Span, Applicability),
 }
 
 #[derive(SessionDiagnostic)]
 //~^ ERROR invalid format string: expected `'}'`
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorMissingClosingBrace {
-    #[suggestion(message = "bar", code = "{name")]
+    #[suggestion(typeck::suggestion, code = "{name")]
     suggestion: (Span, Applicability),
     name: String,
     val: usize,
@@ -178,48 +187,48 @@ struct ErrorMissingClosingBrace {
 
 #[derive(SessionDiagnostic)]
 //~^ ERROR invalid format string: unmatched `}`
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorMissingOpeningBrace {
-    #[suggestion(message = "bar", code = "name}")]
+    #[suggestion(typeck::suggestion, code = "name}")]
     suggestion: (Span, Applicability),
     name: String,
     val: usize,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct LabelOnSpan {
-    #[label = "bar"]
+    #[label(typeck::label)]
     sp: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct LabelOnNonSpan {
-    #[label = "bar"]
+    #[label(typeck::label)]
-    //~^ ERROR the `#[label = ...]` attribute can only be applied to fields of type `Span`
+    //~^ ERROR the `#[label(...)]` attribute can only be applied to fields of type `Span`
     id: u32,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct Suggest {
-    #[suggestion(message = "bar", code = "This is the suggested code")]
+    #[suggestion(typeck::suggestion, code = "This is the suggested code")]
-    #[suggestion_short(message = "qux", code = "This is the suggested code")]
+    #[suggestion_short(typeck::suggestion, code = "This is the suggested code")]
-    #[suggestion_hidden(message = "foobar", code = "This is the suggested code")]
+    #[suggestion_hidden(typeck::suggestion, code = "This is the suggested code")]
-    #[suggestion_verbose(message = "fooqux", code = "This is the suggested code")]
+    #[suggestion_verbose(typeck::suggestion, code = "This is the suggested code")]
     suggestion: (Span, Applicability),
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct SuggestWithoutCode {
-    #[suggestion(message = "bar")]
+    #[suggestion(typeck::suggestion)]
     suggestion: (Span, Applicability),
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct SuggestWithBadKey {
     #[suggestion(nonsense = "bar")]
     //~^ ERROR `#[suggestion(nonsense = ...)]` is not a valid attribute
@@ -227,7 +236,7 @@ struct SuggestWithBadKey {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct SuggestWithShorthandMsg {
     #[suggestion(msg = "bar")]
     //~^ ERROR `#[suggestion(msg = ...)]` is not a valid attribute
@@ -235,91 +244,91 @@ struct SuggestWithShorthandMsg {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct SuggestWithoutMsg {
     #[suggestion(code = "bar")]
     suggestion: (Span, Applicability),
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct SuggestWithTypesSwapped {
-    #[suggestion(message = "bar", code = "This is suggested code")]
+    #[suggestion(typeck::suggestion, code = "This is suggested code")]
     suggestion: (Applicability, Span),
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct SuggestWithWrongTypeApplicabilityOnly {
-    #[suggestion(message = "bar", code = "This is suggested code")]
+    #[suggestion(typeck::suggestion, code = "This is suggested code")]
     //~^ ERROR wrong field type for suggestion
     suggestion: Applicability,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct SuggestWithSpanOnly {
-    #[suggestion(message = "bar", code = "This is suggested code")]
+    #[suggestion(typeck::suggestion, code = "This is suggested code")]
     suggestion: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct SuggestWithDuplicateSpanAndApplicability {
-    #[suggestion(message = "bar", code = "This is suggested code")]
+    #[suggestion(typeck::suggestion, code = "This is suggested code")]
     //~^ ERROR type of field annotated with `#[suggestion(...)]` contains more than one `Span`
     suggestion: (Span, Span, Applicability),
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct SuggestWithDuplicateApplicabilityAndSpan {
-    #[suggestion(message = "bar", code = "This is suggested code")]
+    #[suggestion(typeck::suggestion, code = "This is suggested code")]
     //~^ ERROR type of field annotated with `#[suggestion(...)]` contains more than one
     suggestion: (Applicability, Applicability, Span),
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct WrongKindOfAnnotation {
-    #[label("bar")]
+    #[label = "bar"]
-    //~^ ERROR `#[label(...)]` is not a valid attribute
+    //~^ ERROR `#[label = ...]` is not a valid attribute
     z: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct OptionsInErrors {
-    #[label = "bar"]
+    #[label(typeck::label)]
     label: Option<Span>,
-    #[suggestion(message = "bar")]
+    #[suggestion(typeck::suggestion)]
     opt_sugg: Option<(Span, Applicability)>,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0456", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0456")]
 struct MoveOutOfBorrowError<'tcx> {
     name: Ident,
     ty: Ty<'tcx>,
     #[primary_span]
-    #[label = "bar"]
+    #[label(typeck::label)]
     span: Span,
-    #[label = "qux"]
+    #[label(typeck::label)]
     other_span: Span,
-    #[suggestion(message = "bar", code = "{name}.clone()")]
+    #[suggestion(typeck::suggestion, code = "{name}.clone()")]
     opt_sugg: Option<(Span, Applicability)>,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithLifetime<'a> {
-    #[label = "bar"]
+    #[label(typeck::label)]
     span: Span,
     name: &'a str,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithDefaultLabelAttr<'a> {
     #[label]
     span: Span,
@@ -328,7 +337,7 @@ struct ErrorWithDefaultLabelAttr<'a> {
 
 #[derive(SessionDiagnostic)]
 //~^ ERROR the trait bound `Hello: IntoDiagnosticArg` is not satisfied
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ArgFieldWithoutSkip {
     #[primary_span]
     span: Span,
@@ -336,7 +345,7 @@ struct ArgFieldWithoutSkip {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ArgFieldWithSkip {
     #[primary_span]
     span: Span,
@@ -347,116 +356,116 @@ struct ArgFieldWithSkip {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithSpannedNote {
     #[note]
     span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithSpannedNoteCustom {
-    #[note = "bar"]
+    #[note(typeck::note)]
     span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 #[note]
 struct ErrorWithNote {
     val: String,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
-#[note = "bar"]
+#[note(typeck::note)]
 struct ErrorWithNoteCustom {
     val: String,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithSpannedHelp {
     #[help]
     span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithSpannedHelpCustom {
-    #[help = "bar"]
+    #[help(typeck::help)]
     span: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 #[help]
 struct ErrorWithHelp {
     val: String,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
-#[help = "bar"]
+#[help(typeck::help)]
 struct ErrorWithHelpCustom {
     val: String,
 }
 
 #[derive(SessionDiagnostic)]
 #[help]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithHelpWrongOrder {
     val: String,
 }
 
 #[derive(SessionDiagnostic)]
-#[help = "bar"]
+#[help(typeck::help)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithHelpCustomWrongOrder {
     val: String,
 }
 
 #[derive(SessionDiagnostic)]
 #[note]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithNoteWrongOrder {
     val: String,
 }
 
 #[derive(SessionDiagnostic)]
-#[note = "bar"]
+#[note(typeck::note)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ErrorWithNoteCustomWrongOrder {
     val: String,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ApplicabilityInBoth {
-    #[suggestion(message = "bar", code = "...", applicability = "maybe-incorrect")]
+    #[suggestion(typeck::suggestion, code = "...", applicability = "maybe-incorrect")]
     //~^ ERROR applicability cannot be set in both the field and attribute
     suggestion: (Span, Applicability),
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct InvalidApplicability {
-    #[suggestion(message = "bar", code = "...", applicability = "batman")]
+    #[suggestion(typeck::suggestion, code = "...", applicability = "batman")]
     //~^ ERROR invalid applicability
     suggestion: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct ValidApplicability {
-    #[suggestion(message = "bar", code = "...", applicability = "maybe-incorrect")]
+    #[suggestion(typeck::suggestion, code = "...", applicability = "maybe-incorrect")]
     suggestion: Span,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct NoApplicability {
-    #[suggestion(message = "bar", code = "...")]
+    #[suggestion(typeck::suggestion, code = "...")]
     suggestion: Span,
 }
 
@@ -465,14 +474,14 @@ struct NoApplicability {
 struct Note;
 
 #[derive(SessionDiagnostic)]
-#[error(slug = "subdiagnostic")]
+#[error(typeck::ambiguous_lifetime_bound)]
 struct Subdiagnostic {
     #[subdiagnostic]
     note: Note,
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct VecField {
     #[primary_span]
     #[label]
@@ -480,23 +489,47 @@ struct VecField {
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct UnitField {
     #[primary_span]
     spans: Span,
     #[help]
     foo: (),
-    #[help = "a"]
+    #[help(typeck::help)]
     bar: (),
 }
 
 #[derive(SessionDiagnostic)]
-#[error(code = "E0123", slug = "foo")]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 struct OptUnitField {
     #[primary_span]
     spans: Span,
     #[help]
     foo: Option<()>,
-    #[help = "a"]
+    #[help(typeck::help)]
     bar: Option<()>,
 }
+
+#[derive(SessionDiagnostic)]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
+struct LabelWithTrailingPath {
+    #[label(typeck::label, foo)]
+    //~^ ERROR `#[label(...)]` is not a valid attribute
+    span: Span,
+}
+
+#[derive(SessionDiagnostic)]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
+struct LabelWithTrailingNameValue {
+    #[label(typeck::label, foo = "...")]
+    //~^ ERROR `#[label(...)]` is not a valid attribute
+    span: Span,
+}
+
+#[derive(SessionDiagnostic)]
+#[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
+struct LabelWithTrailingList {
+    #[label(typeck::label, foo("..."))]
+    //~^ ERROR `#[label(...)]` is not a valid attribute
+    span: Span,
+}

src/test/ui-fulldeps/session-diagnostic/diagnostic-derive.stderr

@@ -1,7 +1,7 @@
 error: `#[derive(SessionDiagnostic)]` can only be used on structs
   --> $DIR/diagnostic-derive.rs:37:1
    |
-LL | / #[error(code = "E0123", slug = "foo")]
+LL | / #[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
 LL | |
 LL | | enum SessionDiagnosticOnEnum {
 LL | |     Foo,
@@ -18,15 +18,15 @@ LL | #[error = "E0123"]
 error: `#[nonsense(...)]` is not a valid attribute
   --> $DIR/diagnostic-derive.rs:51:1
    |
-LL | #[nonsense(code = "E0123", slug = "foo")]
+LL | #[nonsense(typeck::ambiguous_lifetime_bound, code = "E0123")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = help: only `error` and `warning` are valid attributes
+   = help: only `error`, `warning`, `help` and `note` are valid attributes
 
 error: diagnostic kind not specified
   --> $DIR/diagnostic-derive.rs:51:1
    |
-LL | / #[nonsense(code = "E0123", slug = "foo")]
+LL | / #[nonsense(typeck::ambiguous_lifetime_bound, code = "E0123")]
 LL | |
 LL | |
 LL | |
@@ -40,8 +40,10 @@ error: `#[error("...")]` is not a valid attribute
    |
 LL | #[error("E0123")]
    |         ^^^^^^^
+   |
+   = help: first argument of the attribute should be the diagnostic slug
 
-error: `slug` not specified
+error: diagnostic slug not specified
   --> $DIR/diagnostic-derive.rs:58:1
    |
 LL | / #[error("E0123")]
@@ -50,183 +52,215 @@ LL | |
 LL | | struct InvalidLitNestedAttr {}
    | |______________________________^
    |
-   = help: use the `#[error(slug = "...")]` attribute to set this diagnostic's slug
+   = help: specify the slug as the first argument to the attribute, such as `#[error(typeck::example_error)]`
-
-error: `#[error(nonsense)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:64:9
-   |
-LL | #[error(nonsense, code = "E0123", slug = "foo")]
-   |         ^^^^^^^^
 
 error: `#[error(nonsense(...))]` is not a valid attribute
   --> $DIR/diagnostic-derive.rs:69:9
    |
 LL | #[error(nonsense("foo"), code = "E0123", slug = "foo")]
    |         ^^^^^^^^^^^^^^^
+   |
+   = help: first argument of the attribute should be the diagnostic slug
+
+error: diagnostic slug not specified
+  --> $DIR/diagnostic-derive.rs:69:1
+   |
+LL | / #[error(nonsense("foo"), code = "E0123", slug = "foo")]
+LL | |
+LL | |
+LL | | struct InvalidNestedStructAttr1 {}
+   | |__________________________________^
+   |
+   = help: specify the slug as the first argument to the attribute, such as `#[error(typeck::example_error)]`
 
 error: `#[error(nonsense = ...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:74:9
+  --> $DIR/diagnostic-derive.rs:75:9
    |
 LL | #[error(nonsense = "...", code = "E0123", slug = "foo")]
    |         ^^^^^^^^^^^^^^^^
    |
-   = help: only `slug` and `code` are valid nested attributes
+   = help: first argument of the attribute should be the diagnostic slug
+
+error: diagnostic slug not specified
+  --> $DIR/diagnostic-derive.rs:75:1
+   |
+LL | / #[error(nonsense = "...", code = "E0123", slug = "foo")]
+LL | |
+LL | |
+LL | | struct InvalidNestedStructAttr2 {}
+   | |__________________________________^
+   |
+   = help: specify the slug as the first argument to the attribute, such as `#[error(typeck::example_error)]`
 
 error: `#[error(nonsense = ...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:79:9
+  --> $DIR/diagnostic-derive.rs:81:9
    |
 LL | #[error(nonsense = 4, code = "E0123", slug = "foo")]
    |         ^^^^^^^^^^^^
+   |
+   = help: first argument of the attribute should be the diagnostic slug
+
+error: diagnostic slug not specified
+  --> $DIR/diagnostic-derive.rs:81:1
+   |
+LL | / #[error(nonsense = 4, code = "E0123", slug = "foo")]
+LL | |
+LL | |
+LL | | struct InvalidNestedStructAttr3 {}
+   | |__________________________________^
+   |
+   = help: specify the slug as the first argument to the attribute, such as `#[error(typeck::example_error)]`
+
+error: `#[error(slug = ...)]` is not a valid attribute
+  --> $DIR/diagnostic-derive.rs:87:59
+   |
+LL | #[error(typeck::ambiguous_lifetime_bound, code = "E0123", slug = "foo")]
+   |                                                           ^^^^^^^^^^^^
+   |
+   = help: only `code` is a valid nested attributes following the slug
 
 error: `#[suggestion = ...]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:86:5
+  --> $DIR/diagnostic-derive.rs:94:5
    |
 LL |     #[suggestion = "bar"]
    |     ^^^^^^^^^^^^^^^^^^^^^
-   |
-   = help: only `label`, `note` and `help` are valid field attributes
-
-error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:93:1
-   |
-LL | #[error(code = "E0456", slug = "bar")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-note: previously specified here
-  --> $DIR/diagnostic-derive.rs:92:1
-   |
-LL | #[error(code = "E0123", slug = "foo")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:93:16
-   |
-LL | #[error(code = "E0456", slug = "bar")]
-   |                ^^^^^^^
-   |
-note: previously specified here
-  --> $DIR/diagnostic-derive.rs:92:16
-   |
-LL | #[error(code = "E0123", slug = "foo")]
-   |                ^^^^^^^
-
-error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:93:32
-   |
-LL | #[error(code = "E0456", slug = "bar")]
-   |                                ^^^^^
-   |
-note: previously specified here
-  --> $DIR/diagnostic-derive.rs:92:32
-   |
-LL | #[error(code = "E0123", slug = "foo")]
-   |                                ^^^^^
 
 error: specified multiple times
   --> $DIR/diagnostic-derive.rs:101:1
    |
-LL | #[warning(code = "E0293", slug = "bar")]
+LL | #[error(typeck::ambiguous_lifetime_bound, code = "E0456")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: previously specified here
   --> $DIR/diagnostic-derive.rs:100:1
    |
-LL | #[error(code = "E0123", slug = "foo")]
+LL | #[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:101:18
+  --> $DIR/diagnostic-derive.rs:101:1
    |
-LL | #[warning(code = "E0293", slug = "bar")]
+LL | #[error(typeck::ambiguous_lifetime_bound, code = "E0456")]
-   |                  ^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/diagnostic-derive.rs:100:16
+  --> $DIR/diagnostic-derive.rs:100:1
    |
-LL | #[error(code = "E0123", slug = "foo")]
+LL | #[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
-   |                ^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:101:34
+  --> $DIR/diagnostic-derive.rs:101:50
    |
-LL | #[warning(code = "E0293", slug = "bar")]
+LL | #[error(typeck::ambiguous_lifetime_bound, code = "E0456")]
-   |                                  ^^^^^
+   |                                                  ^^^^^^^
    |
 note: previously specified here
-  --> $DIR/diagnostic-derive.rs:100:32
+  --> $DIR/diagnostic-derive.rs:100:50
    |
-LL | #[error(code = "E0123", slug = "foo")]
+LL | #[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
-   |                                ^^^^^
+   |                                                  ^^^^^^^
 
 error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:108:32
+  --> $DIR/diagnostic-derive.rs:109:1
    |
-LL | #[error(code = "E0456", code = "E0457", slug = "bar")]
+LL | #[warning(typeck::ambiguous_lifetime_bound, code = "E0293")]
-   |                                ^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/diagnostic-derive.rs:108:16
+  --> $DIR/diagnostic-derive.rs:108:1
    |
-LL | #[error(code = "E0456", code = "E0457", slug = "bar")]
+LL | #[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
-   |                ^^^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: specified multiple times
-  --> $DIR/diagnostic-derive.rs:113:46
+  --> $DIR/diagnostic-derive.rs:109:1
    |
-LL | #[error(code = "E0456", slug = "foo", slug = "bar")]
+LL | #[warning(typeck::ambiguous_lifetime_bound, code = "E0293")]
-   |                                              ^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
 note: previously specified here
-  --> $DIR/diagnostic-derive.rs:113:32
+  --> $DIR/diagnostic-derive.rs:108:1
    |
-LL | #[error(code = "E0456", slug = "foo", slug = "bar")]
+LL | #[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
-   |                                ^^^^^
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: specified multiple times
+  --> $DIR/diagnostic-derive.rs:109:52
+   |
+LL | #[warning(typeck::ambiguous_lifetime_bound, code = "E0293")]
+   |                                                    ^^^^^^^
+   |
+note: previously specified here
+  --> $DIR/diagnostic-derive.rs:108:50
+   |
+LL | #[error(typeck::ambiguous_lifetime_bound, code = "E0123")]
+   |                                                  ^^^^^^^
+
+error: specified multiple times
+  --> $DIR/diagnostic-derive.rs:116:66
+   |
+LL | #[error(typeck::ambiguous_lifetime_bound, code = "E0456", code = "E0457")]
+   |                                                                  ^^^^^^^
+   |
+note: previously specified here
+  --> $DIR/diagnostic-derive.rs:116:50
+   |
+LL | #[error(typeck::ambiguous_lifetime_bound, code = "E0456", code = "E0457")]
+   |                                                  ^^^^^^^
+
+error: `#[error(typeck::ambiguous_lifetime_bound)]` is not a valid attribute
+  --> $DIR/diagnostic-derive.rs:121:43
+   |
+LL | #[error(typeck::ambiguous_lifetime_bound, typeck::ambiguous_lifetime_bound, code = "E0456")]
+   |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: diagnostic kind not specified
-  --> $DIR/diagnostic-derive.rs:118:1
+  --> $DIR/diagnostic-derive.rs:126:1
    |
 LL | struct KindNotProvided {}
    | ^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: use the `#[error(...)]` attribute to create an error
 
-error: `slug` not specified
+error: diagnostic slug not specified
-  --> $DIR/diagnostic-derive.rs:121:1
+  --> $DIR/diagnostic-derive.rs:129:1
    |
 LL | / #[error(code = "E0456")]
+LL | |
 LL | | struct SlugNotProvided {}
    | |_________________________^
    |
-   = help: use the `#[error(slug = "...")]` attribute to set this diagnostic's slug
+   = help: specify the slug as the first argument to the attribute, such as `#[error(typeck::example_error)]`
 
 error: the `#[primary_span]` attribute can only be applied to fields of type `Span`
-  --> $DIR/diagnostic-derive.rs:131:5
+  --> $DIR/diagnostic-derive.rs:140:5
    |
 LL |     #[primary_span]
    |     ^^^^^^^^^^^^^^^
 
 error: `#[nonsense]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:139:5
+  --> $DIR/diagnostic-derive.rs:148:5
    |
 LL |     #[nonsense]
    |     ^^^^^^^^^^^
    |
    = help: only `skip_arg`, `primary_span`, `label`, `note`, `help` and `subdiagnostic` are valid field attributes
 
-error: the `#[label = ...]` attribute can only be applied to fields of type `Span`
+error: the `#[label(...)]` attribute can only be applied to fields of type `Span`
-  --> $DIR/diagnostic-derive.rs:156:5
+  --> $DIR/diagnostic-derive.rs:165:5
    |
-LL |     #[label = "bar"]
+LL |     #[label(typeck::label)]
-   |     ^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `name` doesn't refer to a field on this type
-  --> $DIR/diagnostic-derive.rs:164:42
+  --> $DIR/diagnostic-derive.rs:173:45
    |
-LL |     #[suggestion(message = "bar", code = "{name}")]
+LL |     #[suggestion(typeck::suggestion, code = "{name}")]
-   |                                          ^^^^^^^^
+   |                                             ^^^^^^^^
 
 error: invalid format string: expected `'}'` but string was terminated
-  --> $DIR/diagnostic-derive.rs:169:16
+  --> $DIR/diagnostic-derive.rs:178:16
    |
 LL | #[derive(SessionDiagnostic)]
    |           -    ^ expected `'}'` in format string
@@ -237,7 +271,7 @@ LL | #[derive(SessionDiagnostic)]
    = note: this error originates in the derive macro `SessionDiagnostic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: invalid format string: unmatched `}` found
-  --> $DIR/diagnostic-derive.rs:179:15
+  --> $DIR/diagnostic-derive.rs:188:15
    |
 LL | #[derive(SessionDiagnostic)]
    |               ^ unmatched `}` in format string
@@ -245,14 +279,14 @@ LL | #[derive(SessionDiagnostic)]
    = note: if you intended to print `}`, you can escape it using `}}`
    = note: this error originates in the derive macro `SessionDiagnostic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: the `#[label = ...]` attribute can only be applied to fields of type `Span`
+error: the `#[label(...)]` attribute can only be applied to fields of type `Span`
-  --> $DIR/diagnostic-derive.rs:199:5
+  --> $DIR/diagnostic-derive.rs:208:5
    |
-LL |     #[label = "bar"]
+LL |     #[label(typeck::label)]
-   |     ^^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `#[suggestion(nonsense = ...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:224:18
+  --> $DIR/diagnostic-derive.rs:233:18
    |
 LL |     #[suggestion(nonsense = "bar")]
    |                  ^^^^^^^^^^^^^^^^
@@ -260,7 +294,7 @@ LL |     #[suggestion(nonsense = "bar")]
    = help: only `message`, `code` and `applicability` are valid field attributes
 
 error: `#[suggestion(msg = ...)]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:232:18
+  --> $DIR/diagnostic-derive.rs:241:18
    |
 LL |     #[suggestion(msg = "bar")]
    |                  ^^^^^^^^^^^
@@ -268,9 +302,9 @@ LL |     #[suggestion(msg = "bar")]
    = help: only `message`, `code` and `applicability` are valid field attributes
 
 error: wrong field type for suggestion
-  --> $DIR/diagnostic-derive.rs:254:5
+  --> $DIR/diagnostic-derive.rs:263:5
    |
-LL | /     #[suggestion(message = "bar", code = "This is suggested code")]
+LL | /     #[suggestion(typeck::suggestion, code = "This is suggested code")]
 LL | |
 LL | |     suggestion: Applicability,
    | |_____________________________^
@@ -278,55 +312,77 @@ LL | |     suggestion: Applicability,
    = help: `#[suggestion(...)]` should be applied to fields of type `Span` or `(Span, Applicability)`
 
 error: type of field annotated with `#[suggestion(...)]` contains more than one `Span`
-  --> $DIR/diagnostic-derive.rs:269:5
+  --> $DIR/diagnostic-derive.rs:278:5
    |
-LL | /     #[suggestion(message = "bar", code = "This is suggested code")]
+LL | /     #[suggestion(typeck::suggestion, code = "This is suggested code")]
 LL | |
 LL | |     suggestion: (Span, Span, Applicability),
    | |___________________________________________^
 
 error: type of field annotated with `#[suggestion(...)]` contains more than one Applicability
-  --> $DIR/diagnostic-derive.rs:277:5
+  --> $DIR/diagnostic-derive.rs:286:5
    |
-LL | /     #[suggestion(message = "bar", code = "This is suggested code")]
+LL | /     #[suggestion(typeck::suggestion, code = "This is suggested code")]
 LL | |
 LL | |     suggestion: (Applicability, Applicability, Span),
    | |____________________________________________________^
 
-error: `#[label(...)]` is not a valid attribute
+error: `#[label = ...]` is not a valid attribute
-  --> $DIR/diagnostic-derive.rs:285:5
+  --> $DIR/diagnostic-derive.rs:294:5
    |
-LL |     #[label("bar")]
+LL |     #[label = "bar"]
-   |     ^^^^^^^^^^^^^^^
+   |     ^^^^^^^^^^^^^^^^
-   |
-   = help: only `suggestion{,_short,_hidden,_verbose}` are valid field attributes
 
 error: applicability cannot be set in both the field and attribute
-  --> $DIR/diagnostic-derive.rs:436:49
+  --> $DIR/diagnostic-derive.rs:445:52
    |
-LL |     #[suggestion(message = "bar", code = "...", applicability = "maybe-incorrect")]
+LL |     #[suggestion(typeck::suggestion, code = "...", applicability = "maybe-incorrect")]
-   |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: invalid applicability
-  --> $DIR/diagnostic-derive.rs:444:49
+  --> $DIR/diagnostic-derive.rs:453:52
    |
-LL |     #[suggestion(message = "bar", code = "...", applicability = "batman")]
+LL |     #[suggestion(typeck::suggestion, code = "...", applicability = "batman")]
-   |                                                 ^^^^^^^^^^^^^^^^^^^^^^^^
+   |                                                    ^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: `#[label(...)]` is not a valid attribute
+  --> $DIR/diagnostic-derive.rs:516:5
+   |
+LL |     #[label(typeck::label, foo)]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: `#[label(...)]` is not a valid attribute
+  --> $DIR/diagnostic-derive.rs:524:5
+   |
+LL |     #[label(typeck::label, foo = "...")]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: `#[label(...)]` is not a valid attribute
+  --> $DIR/diagnostic-derive.rs:532:5
+   |
+LL |     #[label(typeck::label, foo("..."))]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: cannot find attribute `nonsense` in this scope
   --> $DIR/diagnostic-derive.rs:51:3
    |
-LL | #[nonsense(code = "E0123", slug = "foo")]
+LL | #[nonsense(typeck::ambiguous_lifetime_bound, code = "E0123")]
    |   ^^^^^^^^
 
 error: cannot find attribute `nonsense` in this scope
-  --> $DIR/diagnostic-derive.rs:139:7
+  --> $DIR/diagnostic-derive.rs:148:7
    |
 LL |     #[nonsense]
    |       ^^^^^^^^
 
+error[E0425]: cannot find value `nonsense` in module `rustc_errors::fluent`
+  --> $DIR/diagnostic-derive.rs:64:9
+   |
+LL | #[error(nonsense, code = "E0123")]
+   |         ^^^^^^^^ not found in `rustc_errors::fluent`
+
 error[E0277]: the trait bound `Hello: IntoDiagnosticArg` is not satisfied
-  --> $DIR/diagnostic-derive.rs:329:10
+  --> $DIR/diagnostic-derive.rs:338:10
    |
 LL | #[derive(SessionDiagnostic)]
    |          ^^^^^^^^^^^^^^^^^ the trait `IntoDiagnosticArg` is not implemented for `Hello`
@@ -345,6 +401,7 @@ LL |         arg: impl IntoDiagnosticArg,
    |                   ^^^^^^^^^^^^^^^^^ required by this bound in `DiagnosticBuilder::<'a, G>::set_arg`
    = note: this error originates in the derive macro `SessionDiagnostic` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error: aborting due to 39 previous errors
+error: aborting due to 46 previous errors
 
-For more information about this error, try `rustc --explain E0277`.
+Some errors have detailed explanations: E0277, E0425.
+For more information about an error, try `rustc --explain E0277`.