Merging upstream version 1.67.1+dfsg1.

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

9 files changed, 241 insertions, 52 deletions

diff --git a/compiler/rustc_macros/src/diagnostics/diagnostic.rs b/compiler/rustc_macros/src/diagnostics/diagnostic.rs
index ef1985b96..684835d8c 100644
--- a/compiler/rustc_macros/src/diagnostics/diagnostic.rs
+++ b/compiler/rustc_macros/src/diagnostics/diagnostic.rs
@@ -5,6 +5,7 @@ use crate::diagnostics::error::{span_err, DiagnosticDeriveError};
 use crate::diagnostics::utils::SetOnce;
 use proc_macro2::TokenStream;
 use quote::quote;
+use syn::spanned::Spanned;
 use synstructure::Structure;
 
 /// The central struct for constructing the `into_diagnostic` method from an annotated struct.
@@ -28,8 +29,8 @@ impl<'a> DiagnosticDerive<'a> {
         let DiagnosticDerive { mut structure, mut builder } = self;
 
         let implementation = builder.each_variant(&mut structure, |mut builder, variant| {
-            let preamble = builder.preamble(&variant);
-            let body = builder.body(&variant);
+            let preamble = builder.preamble(variant);
+            let body = builder.body(variant);
 
             let diag = &builder.parent.diag;
             let DiagnosticDeriveKind::Diagnostic { handler } = &builder.parent.kind else {
@@ -38,13 +39,24 @@ impl<'a> DiagnosticDerive<'a> {
             let init = match builder.slug.value_ref() {
                 None => {
                     span_err(builder.span, "diagnostic slug not specified")
-                        .help(&format!(
+                        .help(format!(
                             "specify the slug as the first argument to the `#[diag(...)]` \
                             attribute, such as `#[diag(hir_analysis_example_error)]`",
                         ))
                         .emit();
                     return DiagnosticDeriveError::ErrorHandled.to_compile_error();
                 }
+                Some(slug) if let Some( Mismatch { slug_name, crate_name, slug_prefix }) = Mismatch::check(slug) => {
+                    span_err(slug.span().unwrap(), "diagnostic slug and crate name do not match")
+                        .note(format!(
+                            "slug is `{slug_name}` but the crate name is `{crate_name}`"
+                        ))
+                        .help(format!(
+                            "expected a slug starting with `{slug_prefix}_...`"
+                        ))
+                        .emit();
+                    return DiagnosticDeriveError::ErrorHandled.to_compile_error();
+                }
                 Some(slug) => {
                     quote! {
                         let mut #diag = #handler.struct_diagnostic(rustc_errors::fluent::#slug);
@@ -69,6 +81,8 @@ impl<'a> DiagnosticDerive<'a> {
                     for @Self
                 where G: rustc_errors::EmissionGuarantee
             {
+
+                #[track_caller]
                 fn into_diagnostic(
                     self,
                     #handler: &'__diagnostic_handler_sess rustc_errors::Handler
@@ -99,8 +113,8 @@ impl<'a> LintDiagnosticDerive<'a> {
         let LintDiagnosticDerive { mut structure, mut builder } = self;
 
         let implementation = builder.each_variant(&mut structure, |mut builder, variant| {
-            let preamble = builder.preamble(&variant);
-            let body = builder.body(&variant);
+            let preamble = builder.preamble(variant);
+            let body = builder.body(variant);
 
             let diag = &builder.parent.diag;
             let formatting_init = &builder.formatting_init;
@@ -114,25 +128,41 @@ impl<'a> LintDiagnosticDerive<'a> {
 
         let msg = builder.each_variant(&mut structure, |mut builder, variant| {
             // Collect the slug by generating the preamble.
-            let _ = builder.preamble(&variant);
+            let _ = builder.preamble(variant);
 
             match builder.slug.value_ref() {
                 None => {
                     span_err(builder.span, "diagnostic slug not specified")
-                        .help(&format!(
+                        .help(format!(
                             "specify the slug as the first argument to the attribute, such as \
                             `#[diag(compiletest_example)]`",
                         ))
                         .emit();
-                    return DiagnosticDeriveError::ErrorHandled.to_compile_error();
+                    DiagnosticDeriveError::ErrorHandled.to_compile_error()
+                }
+                Some(slug) if let Some( Mismatch { slug_name, crate_name, slug_prefix }) = Mismatch::check(slug) => {
+                    span_err(slug.span().unwrap(), "diagnostic slug and crate name do not match")
+                        .note(format!(
+                            "slug is `{slug_name}` but the crate name is `{crate_name}`"
+                        ))
+                        .help(format!(
+                            "expected a slug starting with `{slug_prefix}_...`"
+                        ))
+                        .emit();
+                    DiagnosticDeriveError::ErrorHandled.to_compile_error()
+                }
+                Some(slug) => {
+                    quote! {
+                        rustc_errors::fluent::#slug.into()
+                    }
                 }
-                Some(slug) => quote! { rustc_errors::fluent::#slug.into() },
             }
         });
 
         let diag = &builder.diag;
         structure.gen_impl(quote! {
             gen impl<'__a> rustc_errors::DecorateLint<'__a, ()> for @Self {
+                #[track_caller]
                 fn decorate_lint<'__b>(
                     self,
                     #diag: &'__b mut rustc_errors::DiagnosticBuilder<'__a, ()>
@@ -148,3 +178,27 @@ impl<'a> LintDiagnosticDerive<'a> {
         })
     }
 }
+
+struct Mismatch {
+    slug_name: String,
+    crate_name: String,
+    slug_prefix: String,
+}
+
+impl Mismatch {
+    /// Checks whether the slug starts with the crate name it's in.
+    fn check(slug: &syn::Path) -> Option<Mismatch> {
+        // If this is missing we're probably in a test, so bail.
+        let crate_name = std::env::var("CARGO_CRATE_NAME").ok()?;
+
+        // If we're not in a "rustc_" crate, bail.
+        let Some(("rustc", slug_prefix)) = crate_name.split_once("_") else { return None };
+
+        let slug_name = slug.segments.first()?.ident.to_string();
+        if !slug_name.starts_with(slug_prefix) {
+            Some(Mismatch { slug_name, slug_prefix: slug_prefix.to_string(), crate_name })
+        } else {
+            None
+        }
+    }
+}
diff --git a/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs b/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs
index 3ea83fd09..9f2ac5112 100644
--- a/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs
+++ b/compiler/rustc_macros/src/diagnostics/diagnostic_builder.rs
@@ -100,7 +100,7 @@ impl DiagnosticDeriveBuilder {
                 _ => variant.ast().ident.span().unwrap(),
             };
             let builder = DiagnosticDeriveVariantBuilder {
-                parent: &self,
+                parent: self,
                 span,
                 field_map: build_field_mapping(variant),
                 formatting_init: TokenStream::new(),
@@ -211,7 +211,7 @@ impl<'a> DiagnosticDeriveVariantBuilder<'a> {
                     nested_iter.next();
                 }
                 Some(NestedMeta::Meta(Meta::NameValue { .. })) => {}
-                Some(nested_attr) => throw_invalid_nested_attr!(attr, &nested_attr, |diag| diag
+                Some(nested_attr) => throw_invalid_nested_attr!(attr, nested_attr, |diag| diag
                     .help("a diagnostic slug is required as the first argument")),
                 None => throw_invalid_attr!(attr, &meta, |diag| diag
                     .help("a diagnostic slug is required as the first argument")),
@@ -227,13 +227,13 @@ impl<'a> DiagnosticDeriveVariantBuilder<'a> {
                         ..
                     })) => (value, path),
                     NestedMeta::Meta(Meta::Path(_)) => {
-                        invalid_nested_attr(attr, &nested_attr)
+                        invalid_nested_attr(attr, nested_attr)
                             .help("diagnostic slug must be the first argument")
                             .emit();
                         continue;
                     }
                     _ => {
-                        invalid_nested_attr(attr, &nested_attr).emit();
+                        invalid_nested_attr(attr, nested_attr).emit();
                         continue;
                     }
                 };
@@ -251,7 +251,7 @@ impl<'a> DiagnosticDeriveVariantBuilder<'a> {
                             #diag.code(rustc_errors::DiagnosticId::Error(#code.to_string()));
                         });
                     }
-                    _ => invalid_nested_attr(attr, &nested_attr)
+                    _ => invalid_nested_attr(attr, nested_attr)
                         .help("only `code` is a valid nested attributes following the slug")
                         .emit(),
                 }
@@ -427,9 +427,9 @@ impl<'a> DiagnosticDeriveVariantBuilder<'a> {
                 Ok(self.add_spanned_subdiagnostic(binding, &fn_ident, slug))
             }
             SubdiagnosticKind::Note | SubdiagnosticKind::Help | SubdiagnosticKind::Warn => {
-                if type_matches_path(&info.ty, &["rustc_span", "Span"]) {
+                if type_matches_path(info.ty, &["rustc_span", "Span"]) {
                     Ok(self.add_spanned_subdiagnostic(binding, &fn_ident, slug))
-                } else if type_is_unit(&info.ty) {
+                } else if type_is_unit(info.ty) {
                     Ok(self.add_subdiagnostic(&fn_ident, slug))
                 } else {
                     report_type_error(attr, "`Span` or `()`")?
diff --git a/compiler/rustc_macros/src/diagnostics/error.rs b/compiler/rustc_macros/src/diagnostics/error.rs
index 0b1ededa7..4612f54e4 100644
--- a/compiler/rustc_macros/src/diagnostics/error.rs
+++ b/compiler/rustc_macros/src/diagnostics/error.rs
@@ -84,7 +84,7 @@ pub(crate) fn invalid_attr(attr: &Attribute, meta: &Meta) -> Diagnostic {
     }
 }
 
-/// Emit a error diagnostic for an invalid attribute (optionally performing additional decoration
+/// Emit an error diagnostic for an invalid attribute (optionally performing additional decoration
 /// using the `FnOnce` passed in `diag`) and return `Err(ErrorHandled)`.
 ///
 /// For methods that return a `Result<_, DiagnosticDeriveError>`:
@@ -126,7 +126,7 @@ pub(crate) fn invalid_nested_attr(attr: &Attribute, nested: &NestedMeta) -> Diag
     }
 }
 
-/// Emit a error diagnostic for an invalid nested attribute (optionally performing additional
+/// Emit an error diagnostic for an invalid nested attribute (optionally performing additional
 /// decoration using the `FnOnce` passed in `diag`) and return `Err(ErrorHandled)`.
 ///
 /// For methods that return a `Result<_, DiagnosticDeriveError>`:
diff --git a/compiler/rustc_macros/src/diagnostics/mod.rs b/compiler/rustc_macros/src/diagnostics/mod.rs
index 860340b43..78df0cd1d 100644
--- a/compiler/rustc_macros/src/diagnostics/mod.rs
+++ b/compiler/rustc_macros/src/diagnostics/mod.rs
@@ -129,7 +129,7 @@ pub fn lint_diagnostic_derive(s: Structure<'_>) -> TokenStream {
 /// }
 ///
 /// #[derive(Subdiagnostic)]
-/// #[suggestion_verbose(parser::raw_identifier)]
+/// #[suggestion(style = "verbose",parser::raw_identifier)]
 /// pub struct RawIdentifierSuggestion<'tcx> {
 ///     #[primary_span]
 ///     span: Span,
diff --git a/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs b/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs
index fa0ca5a52..446aebe4f 100644
--- a/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs
+++ b/compiler/rustc_macros/src/diagnostics/subdiagnostic.rs
@@ -409,7 +409,7 @@ impl<'parent, 'a> SubdiagnosticDeriveVariantBuilder<'parent, 'a> {
                 let mut code = None;
                 for nested_attr in list.nested.iter() {
                     let NestedMeta::Meta(ref meta) = nested_attr else {
-                        throw_invalid_nested_attr!(attr, &nested_attr);
+                        throw_invalid_nested_attr!(attr, nested_attr);
                     };
 
                     let span = meta.span().unwrap();
@@ -427,7 +427,7 @@ impl<'parent, 'a> SubdiagnosticDeriveVariantBuilder<'parent, 'a> {
                             );
                             code.set_once((code_field, formatting_init), span);
                         }
-                        _ => throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
+                        _ => throw_invalid_nested_attr!(attr, nested_attr, |diag| {
                             diag.help("`code` is the only valid nested attribute")
                         }),
                     }
diff --git a/compiler/rustc_macros/src/diagnostics/utils.rs b/compiler/rustc_macros/src/diagnostics/utils.rs
index 374c795d0..da9023352 100644
--- a/compiler/rustc_macros/src/diagnostics/utils.rs
+++ b/compiler/rustc_macros/src/diagnostics/utils.rs
@@ -12,7 +12,7 @@ use syn::{spanned::Spanned, Attribute, Field, Meta, Type, TypeTuple};
 use syn::{MetaList, MetaNameValue, NestedMeta, Path};
 use synstructure::{BindingInfo, VariantInfo};
 
-use super::error::invalid_nested_attr;
+use super::error::{invalid_attr, invalid_nested_attr};
 
 thread_local! {
     pub static CODE_IDENT_COUNT: RefCell<u32> = RefCell::new(0);
@@ -80,7 +80,7 @@ fn report_error_if_not_applied_to_ty(
     path: &[&str],
     ty_name: &str,
 ) -> Result<(), DiagnosticDeriveError> {
-    if !type_matches_path(&info.ty, path) {
+    if !type_matches_path(info.ty, path) {
         report_type_error(attr, ty_name)?;
     }
 
@@ -105,8 +105,8 @@ pub(crate) fn report_error_if_not_applied_to_span(
     attr: &Attribute,
     info: &FieldInfo<'_>,
 ) -> Result<(), DiagnosticDeriveError> {
-    if !type_matches_path(&info.ty, &["rustc_span", "Span"])
-        && !type_matches_path(&info.ty, &["rustc_errors", "MultiSpan"])
+    if !type_matches_path(info.ty, &["rustc_span", "Span"])
+        && !type_matches_path(info.ty, &["rustc_errors", "MultiSpan"])
     {
         report_type_error(attr, "`Span` or `MultiSpan`")?;
     }
@@ -472,16 +472,13 @@ pub(super) fn build_suggestion_code(
 }
 
 /// Possible styles for suggestion subdiagnostics.
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, PartialEq)]
 pub(super) enum SuggestionKind {
-    /// `#[suggestion]`
     Normal,
-    /// `#[suggestion_short]`
     Short,
-    /// `#[suggestion_hidden]`
     Hidden,
-    /// `#[suggestion_verbose]`
     Verbose,
+    ToolOnly,
 }
 
 impl FromStr for SuggestionKind {
@@ -489,15 +486,28 @@ impl FromStr for SuggestionKind {
 
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         match s {
-            "" => Ok(SuggestionKind::Normal),
-            "_short" => Ok(SuggestionKind::Short),
-            "_hidden" => Ok(SuggestionKind::Hidden),
-            "_verbose" => Ok(SuggestionKind::Verbose),
+            "normal" => Ok(SuggestionKind::Normal),
+            "short" => Ok(SuggestionKind::Short),
+            "hidden" => Ok(SuggestionKind::Hidden),
+            "verbose" => Ok(SuggestionKind::Verbose),
+            "tool-only" => Ok(SuggestionKind::ToolOnly),
             _ => Err(()),
         }
     }
 }
 
+impl fmt::Display for SuggestionKind {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            SuggestionKind::Normal => write!(f, "normal"),
+            SuggestionKind::Short => write!(f, "short"),
+            SuggestionKind::Hidden => write!(f, "hidden"),
+            SuggestionKind::Verbose => write!(f, "verbose"),
+            SuggestionKind::ToolOnly => write!(f, "tool-only"),
+        }
+    }
+}
+
 impl SuggestionKind {
     pub fn to_suggestion_style(&self) -> TokenStream {
         match self {
@@ -513,6 +523,19 @@ impl SuggestionKind {
             SuggestionKind::Verbose => {
                 quote! { rustc_errors::SuggestionStyle::ShowAlways }
             }
+            SuggestionKind::ToolOnly => {
+                quote! { rustc_errors::SuggestionStyle::CompletelyHidden }
+            }
+        }
+    }
+
+    fn from_suffix(s: &str) -> Option<Self> {
+        match s {
+            "" => Some(SuggestionKind::Normal),
+            "_short" => Some(SuggestionKind::Short),
+            "_hidden" => Some(SuggestionKind::Hidden),
+            "_verbose" => Some(SuggestionKind::Verbose),
+            _ => None,
         }
     }
 }
@@ -565,25 +588,49 @@ impl SubdiagnosticKind {
         let name = name.as_str();
 
         let meta = attr.parse_meta()?;
+
         let mut kind = match name {
             "label" => SubdiagnosticKind::Label,
             "note" => SubdiagnosticKind::Note,
             "help" => SubdiagnosticKind::Help,
             "warning" => SubdiagnosticKind::Warn,
             _ => {
+                // Recover old `#[(multipart_)suggestion_*]` syntaxes
+                // FIXME(#100717): remove
                 if let Some(suggestion_kind) =
-                    name.strip_prefix("suggestion").and_then(|s| s.parse().ok())
+                    name.strip_prefix("suggestion").and_then(SuggestionKind::from_suffix)
                 {
+                    if suggestion_kind != SuggestionKind::Normal {
+                        invalid_attr(attr, &meta)
+                            .help(format!(
+                                r#"Use `#[suggestion(..., style = "{}")]` instead"#,
+                                suggestion_kind
+                            ))
+                            .emit();
+                    }
+
                     SubdiagnosticKind::Suggestion {
-                        suggestion_kind,
+                        suggestion_kind: SuggestionKind::Normal,
                         applicability: None,
                         code_field: new_code_ident(),
                         code_init: TokenStream::new(),
                     }
                 } else if let Some(suggestion_kind) =
-                    name.strip_prefix("multipart_suggestion").and_then(|s| s.parse().ok())
+                    name.strip_prefix("multipart_suggestion").and_then(SuggestionKind::from_suffix)
                 {
-                    SubdiagnosticKind::MultipartSuggestion { suggestion_kind, applicability: None }
+                    if suggestion_kind != SuggestionKind::Normal {
+                        invalid_attr(attr, &meta)
+                            .help(format!(
+                                r#"Use `#[multipart_suggestion(..., style = "{}")]` instead"#,
+                                suggestion_kind
+                            ))
+                            .emit();
+                    }
+
+                    SubdiagnosticKind::MultipartSuggestion {
+                        suggestion_kind: SuggestionKind::Normal,
+                        applicability: None,
+                    }
                 } else {
                     throw_invalid_attr!(attr, &meta);
                 }
@@ -621,6 +668,7 @@ impl SubdiagnosticKind {
         };
 
         let mut code = None;
+        let mut suggestion_kind = None;
 
         let mut nested_iter = nested.into_iter().peekable();
 
@@ -638,7 +686,7 @@ impl SubdiagnosticKind {
             let meta = match nested_attr {
                 NestedMeta::Meta(ref meta) => meta,
                 NestedMeta::Lit(_) => {
-                    invalid_nested_attr(attr, &nested_attr).emit();
+                    invalid_nested_attr(attr, nested_attr).emit();
                     continue;
                 }
             };
@@ -650,7 +698,7 @@ impl SubdiagnosticKind {
             let string_value = match meta {
                 Meta::NameValue(MetaNameValue { lit: syn::Lit::Str(value), .. }) => Some(value),
 
-                Meta::Path(_) => throw_invalid_nested_attr!(attr, &nested_attr, |diag| {
+                Meta::Path(_) => throw_invalid_nested_attr!(attr, nested_attr, |diag| {
                     diag.help("a diagnostic slug must be the first argument to the attribute")
                 }),
                 _ => None,
@@ -672,7 +720,7 @@ impl SubdiagnosticKind {
                     | SubdiagnosticKind::MultipartSuggestion { ref mut applicability, .. },
                 ) => {
                     let Some(value) = string_value else {
-                        invalid_nested_attr(attr, &nested_attr).emit();
+                        invalid_nested_attr(attr, nested_attr).emit();
                         continue;
                     };
 
@@ -682,26 +730,56 @@ impl SubdiagnosticKind {
                     });
                     applicability.set_once(value, span);
                 }
+                (
+                    "style",
+                    SubdiagnosticKind::Suggestion { .. }
+                    | SubdiagnosticKind::MultipartSuggestion { .. },
+                ) => {
+                    let Some(value) = string_value else {
+                        invalid_nested_attr(attr, nested_attr).emit();
+                        continue;
+                    };
+
+                    let value = value.value().parse().unwrap_or_else(|()| {
+                        span_err(value.span().unwrap(), "invalid suggestion style")
+                            .help("valid styles are `normal`, `short`, `hidden`, `verbose` and `tool-only`")
+                            .emit();
+                        SuggestionKind::Normal
+                    });
+
+                    suggestion_kind.set_once(value, span);
+                }
 
                 // Invalid nested attribute
                 (_, SubdiagnosticKind::Suggestion { .. }) => {
-                    invalid_nested_attr(attr, &nested_attr)
-                        .help("only `code` and `applicability` are valid nested attributes")
+                    invalid_nested_attr(attr, nested_attr)
+                        .help(
+                            "only `style`, `code` and `applicability` are valid nested attributes",
+                        )
                         .emit();
                 }
                 (_, SubdiagnosticKind::MultipartSuggestion { .. }) => {
-                    invalid_nested_attr(attr, &nested_attr)
-                        .help("only `applicability` is a valid nested attributes")
+                    invalid_nested_attr(attr, nested_attr)
+                        .help("only `style` and `applicability` are valid nested attributes")
                         .emit()
                 }
                 _ => {
-                    invalid_nested_attr(attr, &nested_attr).emit();
+                    invalid_nested_attr(attr, nested_attr).emit();
                 }
             }
         }
 
         match kind {
-            SubdiagnosticKind::Suggestion { ref code_field, ref mut code_init, .. } => {
+            SubdiagnosticKind::Suggestion {
+                ref code_field,
+                ref mut code_init,
+                suggestion_kind: ref mut kind_field,
+                ..
+            } => {
+                if let Some(kind) = suggestion_kind.value() {
+                    *kind_field = kind;
+                }
+
                 *code_init = if let Some(init) = code.value() {
                     init
                 } else {
@@ -709,11 +787,17 @@ impl SubdiagnosticKind {
                     quote! { let #code_field = std::iter::empty(); }
                 };
             }
+            SubdiagnosticKind::MultipartSuggestion {
+                suggestion_kind: ref mut kind_field, ..
+            } => {
+                if let Some(kind) = suggestion_kind.value() {
+                    *kind_field = kind;
+                }
+            }
             SubdiagnosticKind::Label
             | SubdiagnosticKind::Note
             | SubdiagnosticKind::Help
-            | SubdiagnosticKind::Warn
-            | SubdiagnosticKind::MultipartSuggestion { .. } => {}
+            | SubdiagnosticKind::Warn => {}
         }
 
         Ok(Some((kind, slug)))
@@ -746,5 +830,5 @@ pub(super) fn should_generate_set_arg(field: &Field) -> bool {
 }
 
 pub(super) fn is_doc_comment(attr: &Attribute) -> bool {
-    attr.path.segments.last().unwrap().ident.to_string() == "doc"
+    attr.path.segments.last().unwrap().ident == "doc"
 }
diff --git a/compiler/rustc_macros/src/lib.rs b/compiler/rustc_macros/src/lib.rs
index 36bda3e0f..ac916bb60 100644
--- a/compiler/rustc_macros/src/lib.rs
+++ b/compiler/rustc_macros/src/lib.rs
@@ -1,4 +1,5 @@
 #![feature(allow_internal_unstable)]
+#![feature(if_let_guard)]
 #![feature(never_type)]
 #![feature(proc_macro_diagnostic)]
 #![feature(proc_macro_span)]
@@ -47,7 +48,7 @@ pub fn symbols(input: TokenStream) -> TokenStream {
 /// `u32::MAX`. You can also customize things like the `Debug` impl,
 /// what traits are derived, and so forth via the macro.
 #[proc_macro]
-#[allow_internal_unstable(step_trait, rustc_attrs, trusted_step)]
+#[allow_internal_unstable(step_trait, rustc_attrs, trusted_step, spec_option_partial_eq)]
 pub fn newtype_index(input: TokenStream) -> TokenStream {
     newtype::newtype(input)
 }
diff --git a/compiler/rustc_macros/src/newtype.rs b/compiler/rustc_macros/src/newtype.rs
index 0a77b734c..fd3f52251 100644
--- a/compiler/rustc_macros/src/newtype.rs
+++ b/compiler/rustc_macros/src/newtype.rs
@@ -192,6 +192,30 @@ impl Parse for Newtype {
                 }
             }
         };
+        let spec_partial_eq_impl = if let Lit::Int(max) = &max {
+            if let Ok(max_val) = max.base10_parse::<u32>() {
+                quote! {
+                    impl core::option::SpecOptionPartialEq for #name {
+                        #[inline]
+                        fn eq(l: &Option<Self>, r: &Option<Self>) -> bool {
+                            if #max_val < u32::MAX {
+                                l.map(|i| i.private).unwrap_or(#max_val+1) == r.map(|i| i.private).unwrap_or(#max_val+1)
+                            } else {
+                                match (l, r) {
+                                    (Some(l), Some(r)) => r == l,
+                                    (None, None) => true,
+                                    _ => false
+                                }
+                            }
+                        }
+                    }
+                }
+            } else {
+                quote! {}
+            }
+        } else {
+            quote! {}
+        };
 
         Ok(Self(quote! {
             #(#attrs)*
@@ -293,6 +317,8 @@ impl Parse for Newtype {
 
             #step
 
+            #spec_partial_eq_impl
+
             impl From<#name> for u32 {
                 #[inline]
                 fn from(v: #name) -> u32 {
diff --git a/compiler/rustc_macros/src/query.rs b/compiler/rustc_macros/src/query.rs
index 7cefafef9..789d83a0d 100644
--- a/compiler/rustc_macros/src/query.rs
+++ b/compiler/rustc_macros/src/query.rs
@@ -114,6 +114,9 @@ struct QueryModifiers {
 
     /// Always remap the ParamEnv's constness before hashing.
     remap_env_constness: Option<Ident>,
+
+    /// Generate a `feed` method to set the query's value from another query.
+    feedable: Option<Ident>,
 }
 
 fn parse_query_modifiers(input: ParseStream<'_>) -> Result<QueryModifiers> {
@@ -128,6 +131,7 @@ fn parse_query_modifiers(input: ParseStream<'_>) -> Result<QueryModifiers> {
     let mut depth_limit = None;
     let mut separate_provide_extern = None;
     let mut remap_env_constness = None;
+    let mut feedable = None;
 
     while !input.is_empty() {
         let modifier: Ident = input.parse()?;
@@ -187,6 +191,8 @@ fn parse_query_modifiers(input: ParseStream<'_>) -> Result<QueryModifiers> {
             try_insert!(separate_provide_extern = modifier);
         } else if modifier == "remap_env_constness" {
             try_insert!(remap_env_constness = modifier);
+        } else if modifier == "feedable" {
+            try_insert!(feedable = modifier);
         } else {
             return Err(Error::new(modifier.span(), "unknown query modifier"));
         }
@@ -206,6 +212,7 @@ fn parse_query_modifiers(input: ParseStream<'_>) -> Result<QueryModifiers> {
         depth_limit,
         separate_provide_extern,
         remap_env_constness,
+        feedable,
     })
 }
 
@@ -296,6 +303,7 @@ pub fn rustc_queries(input: TokenStream) -> TokenStream {
     let mut query_stream = quote! {};
     let mut query_description_stream = quote! {};
     let mut query_cached_stream = quote! {};
+    let mut feedable_queries = quote! {};
 
     for query in queries.0 {
         let Query { name, arg, modifiers, .. } = &query;
@@ -350,6 +358,18 @@ pub fn rustc_queries(input: TokenStream) -> TokenStream {
             [#attribute_stream] fn #name(#arg) #result,
         });
 
+        if modifiers.feedable.is_some() {
+            assert!(modifiers.anon.is_none(), "Query {name} cannot be both `feedable` and `anon`.");
+            assert!(
+                modifiers.eval_always.is_none(),
+                "Query {name} cannot be both `feedable` and `eval_always`."
+            );
+            feedable_queries.extend(quote! {
+                #(#doc_comments)*
+                [#attribute_stream] fn #name(#arg) #result,
+            });
+        }
+
         add_query_desc_cached_impl(&query, &mut query_description_stream, &mut query_cached_stream);
     }
 
@@ -363,7 +383,11 @@ pub fn rustc_queries(input: TokenStream) -> TokenStream {
                 }
             }
         }
-
+        macro_rules! rustc_feedable_queries {
+            ( $macro:ident! ) => {
+                $macro!(#feedable_queries);
+            }
+        }
         pub mod descs {
             use super::*;
             #query_description_stream