Rollup merge of #115744 - fmease:fix-e0401, r=compiler-errors

Improve diagnostic for generic params from outer items (E0401)

Generalize the wording of E0401 to talk about *outer items* instead of *outer functions* since the current phrasing is outdated. The outer item can be a function, constant, trait, ADT or impl block (see the new UI test for the more exotic examples).

Further, don't suggest introducing generic parameters to constant items unless the feature `generic_const_items` is enabled.

Lastly, make E0401 translatable while we're at it.

Fixes #115720.

Author: matthiaskrgr

compiler/rustc_error_codes/src/error_codes/E0401.md

@@ -1,4 +1,4 @@
-Inner items do not inherit type or const parameters from the functions
+Inner items do not inherit the generic parameters from the items
 they are embedded in.
 
 Erroneous code example:
@@ -32,8 +32,8 @@ fn foo<T>(x: T) {
 }
 ```
 
-Items inside functions are basically just like top-level items, except
-that they can only be used from the function they are in.
+Items nested inside other items are basically just like top-level items, except
+that they can only be used from the item they are in.
 
 There are a couple of solutions for this.
 

compiler/rustc_resolve/messages.ftl

@@ -68,9 +68,6 @@ resolve_cannot_find_ident_in_this_scope =
 resolve_cannot_glob_import_possible_crates =
     cannot glob-import all possible crates
 
-resolve_cannot_use_self_type_here =
-    can't use `Self` here
-
 resolve_change_import_binding =
     you can use `as` to change the binding name of the import
 
@@ -90,9 +87,6 @@ resolve_const_not_member_of_trait =
     const `{$const_}` is not a member of trait `{$trait_}`
     .label = not a member of trait `{$trait_}`
 
-resolve_const_param_from_outer_fn =
-    const parameter from outer function
-
 resolve_const_param_in_enum_discriminant =
     const parameters may not be used in enum discriminant values
 
@@ -119,10 +113,19 @@ resolve_forward_declared_generic_param =
     generic parameters with a default cannot use forward declared identifiers
     .label = defaulted generic parameters cannot be forward declared
 
-resolve_generic_params_from_outer_function =
-    can't use generic parameters from outer function
-    .label = use of generic parameter from outer function
-    .suggestion = try using a local generic parameter instead
+resolve_generic_params_from_outer_item =
+    can't use generic parameters from outer item
+    .label = use of generic parameter 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_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_ty_param = type parameter from outer item
 
 resolve_glob_import_doesnt_reexport =
     glob import doesn't reexport anything because no candidate is public enough
@@ -277,9 +280,6 @@ resolve_type_not_member_of_trait =
     type `{$type_}` is not a member of trait `{$trait_}`
     .label = not a member of trait `{$trait_}`
 
-resolve_type_param_from_outer_fn =
-    type parameter from outer function
-
 resolve_type_param_in_enum_discriminant =
     type parameters may not be used in enum discriminant values
 
@@ -315,9 +315,6 @@ resolve_unreachable_label_suggestion_use_similarly_named =
 resolve_unreachable_label_with_similar_name_exists =
     a label with a similar name exists but is unreachable
 
-resolve_use_a_type_here_instead =
-    use a type here instead
-
 resolve_variable_bound_with_different_mode =
     variable `{$variable_name}` is bound inconsistently across alternatives separated by `|`
     .label = bound in different ways