Add note to resolve error about generics from inside static/const

Author: clubby789

compiler/rustc_resolve/messages.ftl

@@ -119,12 +119,16 @@ resolve_generic_params_from_outer_item =
     .refer_to_type_directly = refer to the type directly here instead
     .suggestion = try introducing a local generic parameter here
 
+resolve_generic_params_from_outer_item_const = a `const` is a separate item from the item that contains it
+
 resolve_generic_params_from_outer_item_const_param = const parameter from outer item
 
 resolve_generic_params_from_outer_item_self_ty_alias = `Self` type implicitly declared here, by this `impl`
 
 resolve_generic_params_from_outer_item_self_ty_param = can't use `Self` here
 
+resolve_generic_params_from_outer_item_static = a `static` is a separate item from the item that contains it
+
 resolve_generic_params_from_outer_item_ty_param = type parameter from outer item
 
 

compiler/rustc_resolve/src/diagnostics.rs

@@ -561,13 +561,19 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
         resolution_error: ResolutionError<'a>,
     ) -> DiagnosticBuilder<'_> {
         match resolution_error {
-            ResolutionError::GenericParamsFromOuterItem(outer_res, has_generic_params) => {
+            ResolutionError::GenericParamsFromOuterItem(outer_res, has_generic_params, defkind) => {
                 use errs::GenericParamsFromOuterItemLabel as Label;
+                let static_or_const = match defkind {
+                    DefKind::Static(_) => Some(errs::GenericParamsFromOuterItemStaticOrConst::Static),
+                    DefKind::Const => Some(errs::GenericParamsFromOuterItemStaticOrConst::Const),
+                    _ => None,
+                };
                 let mut err = errs::GenericParamsFromOuterItem {
                     span,
                     label: None,
                     refer_to_type_directly: None,
                     sugg: None,
+                    static_or_const,
                 };
 
                 let sm = self.tcx.sess.source_map();

compiler/rustc_resolve/src/errors.rs

@@ -44,6 +44,16 @@ pub(crate) struct GenericParamsFromOuterItem {
     pub(crate) refer_to_type_directly: Option<Span>,
     #[subdiagnostic]
     pub(crate) sugg: Option<GenericParamsFromOuterItemSugg>,
+    #[subdiagnostic]
+    pub(crate) static_or_const: Option<GenericParamsFromOuterItemStaticOrConst>,
+}
+
+#[derive(Subdiagnostic)]
+pub(crate) enum GenericParamsFromOuterItemStaticOrConst {
+    #[note(resolve_generic_params_from_outer_item_static)]
+    Static,
+    #[note(resolve_generic_params_from_outer_item_const)]
+    Const,
 }
 
 #[derive(Subdiagnostic)]

compiler/rustc_resolve/src/ident.rs

@@ -10,9 +10,7 @@ use rustc_span::symbol::{kw, Ident};
 use rustc_span::Span;
 
 use crate::errors::{ParamKindInEnumDiscriminant, ParamKindInNonTrivialAnonConst};
-use crate::late::{
-    ConstantHasGenerics, HasGenericParams, NoConstantGenericsReason, PathSource, Rib, RibKind,
-};
+use crate::late::{ConstantHasGenerics, NoConstantGenericsReason, PathSource, Rib, RibKind};
 use crate::macros::{sub_namespace_match, MacroRulesScope};
 use crate::BindingKey;
 use crate::{errors, AmbiguityError, AmbiguityErrorMisc, AmbiguityKind, Determinacy, Finalize};
@@ -1090,7 +1088,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                         | RibKind::ForwardGenericParamBan => {
                             // Nothing to do. Continue.
                         }
-                        RibKind::Item(_) | RibKind::AssocItem => {
+                        RibKind::Item(..) | RibKind::AssocItem => {
                             // This was an attempt to access an upvar inside a
                             // named function item. This is not allowed, so we
                             // report an error.
@@ -1155,7 +1153,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
             }
             Res::Def(DefKind::TyParam, _) | Res::SelfTyParam { .. } | Res::SelfTyAlias { .. } => {
                 for rib in ribs {
-                    let has_generic_params: HasGenericParams = match rib.kind {
+                    let (has_generic_params, defkind) = match rib.kind {
                         RibKind::Normal
                         | RibKind::FnOrCoroutine
                         | RibKind::Module(..)
@@ -1213,7 +1211,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                         }
 
                         // This was an attempt to use a type parameter outside its scope.
-                        RibKind::Item(has_generic_params) => has_generic_params,
+                        RibKind::Item(has_generic_params, defkind) => (has_generic_params, defkind),
                         RibKind::ConstParamTy => {
                             if let Some(span) = finalize {
                                 self.report_error(
@@ -1231,15 +1229,19 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                     if let Some(span) = finalize {
                         self.report_error(
                             span,
-                            ResolutionError::GenericParamsFromOuterItem(res, has_generic_params),
+                            ResolutionError::GenericParamsFromOuterItem(
+                                res,
+                                has_generic_params,
+                                defkind,
+                            ),
                         );
                     }
                     return Res::Err;
                 }
             }
             Res::Def(DefKind::ConstParam, _) => {
                 for rib in ribs {
-                    let has_generic_params = match rib.kind {
+                    let (has_generic_params, defkind) = match rib.kind {
                         RibKind::Normal
                         | RibKind::FnOrCoroutine
                         | RibKind::Module(..)
@@ -1276,7 +1278,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                             continue;
                         }
 
-                        RibKind::Item(has_generic_params) => has_generic_params,
+                        RibKind::Item(has_generic_params, defkind) => (has_generic_params, defkind),
                         RibKind::ConstParamTy => {
                             if let Some(span) = finalize {
                                 self.report_error(
@@ -1295,7 +1297,11 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                     if let Some(span) = finalize {
                         self.report_error(
                             span,
-                            ResolutionError::GenericParamsFromOuterItem(res, has_generic_params),
+                            ResolutionError::GenericParamsFromOuterItem(
+                                res,
+                                has_generic_params,
+                                defkind,
+                            ),
                         );
                     }
                     return Res::Err;

compiler/rustc_resolve/src/late.rs

@@ -181,7 +181,8 @@ pub(crate) enum RibKind<'a> {
     FnOrCoroutine,
 
     /// We passed through an item scope. Disallow upvars.
-    Item(HasGenericParams),
+    /// Note if this is a static/const to help with some confusing diagnostics
+    Item(HasGenericParams, DefKind),
 
     /// We're in a constant item. Can't refer to dynamic stuff.
     ///
@@ -221,7 +222,7 @@ impl RibKind<'_> {
             | RibKind::MacroDefinition(_)
             | RibKind::ConstParamTy
             | RibKind::InlineAsmSym => false,
-            RibKind::AssocItem | RibKind::Item(_) | RibKind::ForwardGenericParamBan => true,
+            RibKind::AssocItem | RibKind::Item(..) | RibKind::ForwardGenericParamBan => true,
         }
     }
 
@@ -870,7 +871,7 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
             ForeignItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
                 self.with_generic_param_rib(
                     &generics.params,
-                    RibKind::Item(HasGenericParams::Yes(generics.span)),
+                    RibKind::Item(HasGenericParams::Yes(generics.span), DefKind::ForeignTy),
                     LifetimeRibKind::Generics {
                         binder: foreign_item.id,
                         kind: LifetimeBinderKind::Item,
@@ -882,7 +883,7 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
             ForeignItemKind::Fn(box Fn { ref generics, .. }) => {
                 self.with_generic_param_rib(
                     &generics.params,
-                    RibKind::Item(HasGenericParams::Yes(generics.span)),
+                    RibKind::Item(HasGenericParams::Yes(generics.span), DefKind::Fn),
                     LifetimeRibKind::Generics {
                         binder: foreign_item.id,
                         kind: LifetimeBinderKind::Function,
@@ -891,8 +892,8 @@ impl<'a: 'ast, 'ast, 'tcx> Visitor<'ast> for LateResolutionVisitor<'a, '_, 'ast,
                     |this| visit::walk_foreign_item(this, foreign_item),
                 );
             }
-            ForeignItemKind::Static(..) => {
-                self.with_static_rib(|this| {
+            ForeignItemKind::Static(_, mutability, _) => {
+                self.with_static_rib(mutability, |this| {
                     visit::walk_foreign_item(this, foreign_item);
                 });
             }
@@ -2268,10 +2269,17 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
 
     fn resolve_adt(&mut self, item: &'ast Item, generics: &'ast Generics) {
         debug!("resolve_adt");
+        let kind = match item.kind {
+            ItemKind::Enum(_, _) => DefKind::Enum,
+            ItemKind::Struct(_, _) => DefKind::Struct,
+            ItemKind::Union(_, _) => DefKind::Union,
+            // only called if `item` is one of the above
+            _ => unreachable!(),
+        };
         self.with_current_self_item(item, |this| {
             this.with_generic_param_rib(
                 &generics.params,
-                RibKind::Item(HasGenericParams::Yes(generics.span)),
+                RibKind::Item(HasGenericParams::Yes(generics.span), kind),
                 LifetimeRibKind::Generics {
                     binder: item.id,
                     kind: LifetimeBinderKind::Item,
@@ -2349,7 +2357,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
             ItemKind::TyAlias(box TyAlias { ref generics, .. }) => {
                 self.with_generic_param_rib(
                     &generics.params,
-                    RibKind::Item(HasGenericParams::Yes(generics.span)),
+                    RibKind::Item(HasGenericParams::Yes(generics.span), DefKind::TyAlias),
                     LifetimeRibKind::Generics {
                         binder: item.id,
                         kind: LifetimeBinderKind::Item,
@@ -2362,7 +2370,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
             ItemKind::Fn(box Fn { ref generics, .. }) => {
                 self.with_generic_param_rib(
                     &generics.params,
-                    RibKind::Item(HasGenericParams::Yes(generics.span)),
+                    RibKind::Item(HasGenericParams::Yes(generics.span), DefKind::Fn),
                     LifetimeRibKind::Generics {
                         binder: item.id,
                         kind: LifetimeBinderKind::Function,
@@ -2401,7 +2409,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                 // Create a new rib for the trait-wide type parameters.
                 self.with_generic_param_rib(
                     &generics.params,
-                    RibKind::Item(HasGenericParams::Yes(generics.span)),
+                    RibKind::Item(HasGenericParams::Yes(generics.span), DefKind::Trait),
                     LifetimeRibKind::Generics {
                         binder: item.id,
                         kind: LifetimeBinderKind::Item,
@@ -2422,7 +2430,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                 // Create a new rib for the trait-wide type parameters.
                 self.with_generic_param_rib(
                     &generics.params,
-                    RibKind::Item(HasGenericParams::Yes(generics.span)),
+                    RibKind::Item(HasGenericParams::Yes(generics.span), DefKind::TraitAlias),
                     LifetimeRibKind::Generics {
                         binder: item.id,
                         kind: LifetimeBinderKind::Item,
@@ -2455,8 +2463,8 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
                 });
             }
 
-            ItemKind::Static(box ast::StaticItem { ref ty, ref expr, .. }) => {
-                self.with_static_rib(|this| {
+            ItemKind::Static(box ast::StaticItem { ref ty, ref expr, mutability }) => {
+                self.with_static_rib(mutability, |this| {
                     this.with_lifetime_rib(LifetimeRibKind::Elided(LifetimeRes::Static), |this| {
                         this.visit_ty(ty);
                     });
@@ -2471,11 +2479,14 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
             ItemKind::Const(box ast::ConstItem { ref generics, ref ty, ref expr, .. }) => {
                 self.with_generic_param_rib(
                     &generics.params,
-                    RibKind::Item(if self.r.tcx.features().generic_const_items {
-                        HasGenericParams::Yes(generics.span)
-                    } else {
-                        HasGenericParams::No
-                    }),
+                    RibKind::Item(
+                        if self.r.tcx.features().generic_const_items {
+                            HasGenericParams::Yes(generics.span)
+                        } else {
+                            HasGenericParams::No
+                        },
+                        DefKind::Const,
+                    ),
                     LifetimeRibKind::Generics {
                         binder: item.id,
                         kind: LifetimeBinderKind::ConstItem,
@@ -2560,7 +2571,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
             let mut add_bindings_for_ns = |ns| {
                 let parent_rib = self.ribs[ns]
                     .iter()
-                    .rfind(|r| matches!(r.kind, RibKind::Item(_)))
+                    .rfind(|r| matches!(r.kind, RibKind::Item(..)))
                     .expect("associated item outside of an item");
                 seen_bindings.extend(parent_rib.bindings.keys().map(|ident| (*ident, ident.span)));
             };
@@ -2695,8 +2706,8 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
         self.label_ribs.pop();
     }
 
-    fn with_static_rib(&mut self, f: impl FnOnce(&mut Self)) {
-        let kind = RibKind::Item(HasGenericParams::No);
+    fn with_static_rib(&mut self, mutability: Mutability, f: impl FnOnce(&mut Self)) {
+        let kind = RibKind::Item(HasGenericParams::No, DefKind::Static(mutability));
         self.with_rib(ValueNS, kind, |this| this.with_rib(TypeNS, kind, f))
     }
 
@@ -2877,7 +2888,7 @@ impl<'a: 'ast, 'b, 'ast, 'tcx> LateResolutionVisitor<'a, 'b, 'ast, 'tcx> {
         // If applicable, create a rib for the type parameters.
         self.with_generic_param_rib(
             &generics.params,
-            RibKind::Item(HasGenericParams::Yes(generics.span)),
+            RibKind::Item(HasGenericParams::Yes(generics.span), DefKind::Impl { of_trait: opt_trait_reference.is_some() }),
             LifetimeRibKind::Generics {
                 span: generics.span,
                 binder: item_id,

compiler/rustc_resolve/src/lib.rs

@@ -185,7 +185,7 @@ struct BindingError {
 #[derive(Debug)]
 enum ResolutionError<'a> {
     /// Error E0401: can't use type or const parameters from outer item.
-    GenericParamsFromOuterItem(Res, HasGenericParams),
+    GenericParamsFromOuterItem(Res, HasGenericParams, DefKind),
     /// Error E0403: the name is already used for a type or const parameter in this generic
     /// parameter list.
     NameAlreadyUsedInParameterList(Symbol, Span),

tests/ui/inner-static-type-parameter.stderr

@@ -5,6 +5,8 @@ LL | fn foo<T>() {
    |        - type parameter from outer item
 LL |     static a: Bar<T> = Bar::What;
    |                   ^ use of generic parameter from outer item
+   |
+   = note: a `static` is a separate item from the item that contains it
 
 error[E0392]: parameter `T` is never used
   --> $DIR/inner-static-type-parameter.rs:3:10

tests/ui/resolve/generic-params-from-outer-item-in-const-item.default.stderr

@@ -5,6 +5,8 @@ LL | fn outer<T: Tr>() { // outer function
    |          - type parameter from outer item
 LL |     const K: u32 = T::C;
    |                    ^^^^ use of generic parameter from outer item
+   |
+   = note: a `const` is a separate item from the item that contains it
 
 error[E0401]: can't use generic parameters from outer item
   --> $DIR/generic-params-from-outer-item-in-const-item.rs:19:24
@@ -14,6 +16,8 @@ LL | impl<T> Tr for T { // outer impl block
 LL |     const C: u32 = {
 LL |         const I: u32 = T::C;
    |                        ^^^^ use of generic parameter from outer item
+   |
+   = note: a `const` is a separate item from the item that contains it
 
 error[E0401]: can't use generic parameters from outer item
   --> $DIR/generic-params-from-outer-item-in-const-item.rs:27:20
@@ -22,6 +26,8 @@ LL | struct S<T: Tr>(U32<{ // outer struct
    |          - type parameter from outer item
 LL |     const _: u32 = T::C;
    |                    ^^^^ use of generic parameter from outer item
+   |
+   = note: a `const` is a separate item from the item that contains it
 
 error: aborting due to 3 previous errors
 

tests/ui/resolve/generic-params-from-outer-item-in-const-item.generic_const_items.stderr

@@ -7,6 +7,8 @@ LL |     const K: u32 = T::C;
    |            -       ^^^^ use of generic parameter from outer item
    |            |
    |            help: try introducing a local generic parameter here: `<T>`
+   |
+   = note: a `const` is a separate item from the item that contains it
 
 error[E0401]: can't use generic parameters from outer item
   --> $DIR/generic-params-from-outer-item-in-const-item.rs:19:24
@@ -18,6 +20,8 @@ LL |         const I: u32 = T::C;
    |                -       ^^^^ use of generic parameter from outer item
    |                |
    |                help: try introducing a local generic parameter here: `<T>`
+   |
+   = note: a `const` is a separate item from the item that contains it
 
 error[E0401]: can't use generic parameters from outer item
   --> $DIR/generic-params-from-outer-item-in-const-item.rs:27:20
@@ -28,6 +32,8 @@ LL |     const _: u32 = T::C;
    |            -       ^^^^ use of generic parameter from outer item
    |            |
    |            help: try introducing a local generic parameter here: `<T>`
+   |
+   = note: a `const` is a separate item from the item that contains it
 
 error: aborting due to 3 previous errors
 

tests/ui/resolve/issue-65025-extern-static-parent-generics.stderr

@@ -6,6 +6,8 @@ LL | unsafe fn foo<A>() {
 LL |     extern "C" {
 LL |         static baz: *const A;
    |                            ^ use of generic parameter from outer item
+   |
+   = note: a `static` is a separate item from the item that contains it
 
 error: aborting due to 1 previous error