mGCA: Make trait object types with type-level associated consts dyn compatible if all of the latter are specified via bindings

Cargo.lock

@@ -3352,9 +3352,9 @@ dependencies = [
 
 [[package]]
 name = "rustc-demangle"
-version = "0.1.26"
+version = "0.1.27"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "56f7d92ca342cea22a06f2121d944b4fd82af56988c270852495420f961d4ace"
+checksum = "b50b8869d9fc858ce7266cce0194bd74df58b9d0e3f6df3a9fc8eb470d95c09d"
 
 [[package]]
 name = "rustc-hash"

compiler/rustc_hir_analysis/messages.ftl

@@ -165,6 +165,11 @@ hir_analysis_drop_impl_reservation = reservation `Drop` impls are not supported
 hir_analysis_duplicate_precise_capture = cannot capture parameter `{$name}` twice
     .label = parameter captured again here
 
+hir_analysis_dyn_trait_assoc_item_binding_mentions_self =
+    {$kind} binding in trait object type mentions `Self`
+    .label = contains a mention of `Self`
+    .binding_label = this binding mentions `Self`
+
 hir_analysis_eii_with_generics =
     #[{$eii_name}] cannot have generic parameters other than lifetimes
     .label = required by this attribute
@@ -329,37 +334,18 @@ hir_analysis_manual_implementation =
 hir_analysis_method_should_return_future = method should be `async` or return a future, but it is synchronous
     .note = this method is `async` so it expects a future to be returned
 
-hir_analysis_missing_one_of_trait_item = not all trait items implemented, missing one of: `{$missing_items_msg}`
-    .label = missing one of `{$missing_items_msg}` in implementation
-    .note = required because of this annotation
-
-hir_analysis_missing_trait_item = not all trait items implemented, missing: `{$missing_items_msg}`
-    .label = missing `{$missing_items_msg}` in implementation
-
-hir_analysis_missing_trait_item_label = `{$item}` from trait
-
-hir_analysis_missing_trait_item_suggestion = implement the missing item: `{$snippet}`
-
-hir_analysis_missing_trait_item_unstable = not all trait items implemented, missing: `{$missing_item_name}`
-    .note = default implementation of `{$missing_item_name}` is unstable
-    .some_note = use of unstable library feature `{$feature}`: {$reason}
-    .none_note = use of unstable library feature `{$feature}`
-
-hir_analysis_missing_type_params =
-    the type {$parameterCount ->
+hir_analysis_missing_generic_params =
+    the {$descr} {$parameterCount ->
         [one] parameter
         *[other] parameters
     } {$parameters} must be explicitly specified
-    .label = type {$parameterCount ->
+    .label = {$descr} {$parameterCount ->
         [one] parameter
         *[other] parameters
     } {$parameters} must be specified for this
-    .suggestion = set the type {$parameterCount ->
+    .suggestion = explicitly specify the {$descr} {$parameterCount ->
         [one] parameter
         *[other] parameters
-    } to the desired {$parameterCount ->
-        [one] type
-        *[other] types
     }
     .no_suggestion_label = missing {$parameterCount ->
         [one] reference
@@ -371,7 +357,23 @@ hir_analysis_missing_type_params =
     } `Self`, the {$parameterCount ->
         [one] parameter
         *[other] parameters
-    } must be specified on the object type
+    } must be specified on the trait object type
+
+hir_analysis_missing_one_of_trait_item = not all trait items implemented, missing one of: `{$missing_items_msg}`
+    .label = missing one of `{$missing_items_msg}` in implementation
+    .note = required because of this annotation
+
+hir_analysis_missing_trait_item = not all trait items implemented, missing: `{$missing_items_msg}`
+    .label = missing `{$missing_items_msg}` in implementation
+
+hir_analysis_missing_trait_item_label = `{$item}` from trait
+
+hir_analysis_missing_trait_item_suggestion = implement the missing item: `{$snippet}`
+
+hir_analysis_missing_trait_item_unstable = not all trait items implemented, missing: `{$missing_item_name}`
+    .note = default implementation of `{$missing_item_name}` is unstable
+    .some_note = use of unstable library feature `{$feature}`: {$reason}
+    .none_note = use of unstable library feature `{$feature}`
 
 hir_analysis_no_variant_named = no variant named `{$ident}` found for enum `{$ty}`
 
@@ -480,9 +482,6 @@ hir_analysis_self_in_impl_self =
     `Self` is not valid in the self type of an impl block
     .note = replace `Self` with a different type
 
-hir_analysis_self_in_type_alias = `Self` is not allowed in type aliases
-    .label = `Self` is only available in impls, traits, and concrete type definitions
-
 hir_analysis_self_ty_not_captured = `impl Trait` must mention the `Self` type of the trait in `use<...>`
     .label = `Self` type parameter is implicitly captured by this `impl Trait`
     .note = currently, all type parameters are required to be mentioned in the precise captures list

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -1960,7 +1960,7 @@ fn compare_generic_param_kinds<'tcx>(
     trait_item: ty::AssocItem,
     delay: bool,
 ) -> Result<(), ErrorGuaranteed> {
-    assert_eq!(impl_item.as_tag(), trait_item.as_tag());
+    assert_eq!(impl_item.tag(), trait_item.tag());
 
     let ty_const_params_of = |def_id| {
         tcx.generics_of(def_id).own_params.iter().filter(|param| {

compiler/rustc_hir_analysis/src/errors.rs

@@ -4,11 +4,11 @@ use rustc_abi::ExternAbi;
 use rustc_errors::codes::*;
 use rustc_errors::{
     Applicability, Diag, DiagCtxtHandle, DiagSymbolList, Diagnostic, EmissionGuarantee, Level,
-    MultiSpan,
+    MultiSpan, listify,
 };
 use rustc_hir::limit::Limit;
 use rustc_macros::{Diagnostic, LintDiagnostic, Subdiagnostic};
-use rustc_middle::ty::Ty;
+use rustc_middle::ty::{self, Ty};
 use rustc_span::{Ident, Span, Symbol};
 
 use crate::fluent_generated as fluent;
@@ -400,35 +400,58 @@ pub(crate) struct UnconstrainedOpaqueType {
     pub what: &'static str,
 }
 
-pub(crate) struct MissingTypeParams {
+pub(crate) struct MissingGenericParams {
     pub span: Span,
     pub def_span: Span,
     pub span_snippet: Option<String>,
-    pub missing_type_params: Vec<Symbol>,
+    pub missing_generic_params: Vec<(Symbol, ty::GenericParamDefKind)>,
     pub empty_generic_args: bool,
 }
 
-// Manual implementation of `Diagnostic` to be able to call `span_to_snippet`.
-impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for MissingTypeParams {
+// FIXME: This doesn't need to be a manual impl!
+impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for MissingGenericParams {
     #[track_caller]
     fn into_diag(self, dcx: DiagCtxtHandle<'a>, level: Level) -> Diag<'a, G> {
-        let mut err = Diag::new(dcx, level, fluent::hir_analysis_missing_type_params);
+        let mut err = Diag::new(dcx, level, fluent::hir_analysis_missing_generic_params);
         err.span(self.span);
         err.code(E0393);
-        err.arg("parameterCount", self.missing_type_params.len());
+        err.span_label(self.def_span, fluent::hir_analysis_label);
+
+        enum Descr {
+            Generic,
+            Type,
+            Const,
+        }
+
+        let mut descr = None;
+        for (_, kind) in &self.missing_generic_params {
+            descr = match (&descr, kind) {
+                (None, ty::GenericParamDefKind::Type { .. }) => Some(Descr::Type),
+                (None, ty::GenericParamDefKind::Const { .. }) => Some(Descr::Const),
+                (Some(Descr::Type), ty::GenericParamDefKind::Const { .. })
+                | (Some(Descr::Const), ty::GenericParamDefKind::Type { .. }) => {
+                    Some(Descr::Generic)
+                }
+                _ => continue,
+            }
+        }
+
+        err.arg(
+            "descr",
+            match descr.unwrap() {
+                Descr::Generic => "generic",
+                Descr::Type => "type",
+                Descr::Const => "const",
+            },
+        );
+        err.arg("parameterCount", self.missing_generic_params.len());
         err.arg(
             "parameters",
-            self.missing_type_params
-                .iter()
-                .map(|n| format!("`{n}`"))
-                .collect::<Vec<_>>()
-                .join(", "),
+            listify(&self.missing_generic_params, |(n, _)| format!("`{n}`")).unwrap(),
         );
 
-        err.span_label(self.def_span, fluent::hir_analysis_label);
-
         let mut suggested = false;
-        // Don't suggest setting the type params if there are some already: the order is
+        // Don't suggest setting the generic params if there are some already: The order is
         // tricky to get right and the user will already know what the syntax is.
         if let Some(snippet) = self.span_snippet
             && self.empty_generic_args
@@ -438,16 +461,16 @@ impl<'a, G: EmissionGuarantee> Diagnostic<'a, G> for MissingTypeParams {
                 // we would have to preserve the right order. For now, as clearly the user is
                 // aware of the syntax, we do nothing.
             } else {
-                // The user wrote `Iterator`, so we don't have a type we can suggest, but at
-                // least we can clue them to the correct syntax `Iterator<Type>`.
+                // The user wrote `Trait`, so we don't have a type we can suggest, but at
+                // least we can clue them to the correct syntax `Trait</* Term */>`.
                 err.span_suggestion_verbose(
                     self.span.shrink_to_hi(),
                     fluent::hir_analysis_suggestion,
                     format!(
                         "<{}>",
-                        self.missing_type_params
+                        self.missing_generic_params
                             .iter()
-                            .map(|n| n.to_string())
+                            .map(|(n, _)| format!("/* {n} */"))
                             .collect::<Vec<_>>()
                             .join(", ")
                     ),
@@ -1609,11 +1632,14 @@ pub(crate) enum SupertraitItemShadowee {
 }
 
 #[derive(Diagnostic)]
-#[diag(hir_analysis_self_in_type_alias, code = E0411)]
-pub(crate) struct SelfInTypeAlias {
+#[diag(hir_analysis_dyn_trait_assoc_item_binding_mentions_self)]
+pub(crate) struct DynTraitAssocItemBindingMentionsSelf {
     #[primary_span]
     #[label]
     pub span: Span,
+    pub kind: &'static str,
+    #[label(hir_analysis_binding_label)]
+    pub binding: Span,
 }
 
 #[derive(Diagnostic)]