Specialize diagnostic for impl without Trait

compiler/rustc_lint/messages.ftl

@@ -446,7 +446,8 @@ lint_non_local_definitions_impl = non-local `impl` definition, `impl` blocks sho
             [one] `{$body_name}`
            *[other] `{$body_name}` and up {$depth} bodies
         }
-    .non_local = an `impl` definition is non-local if it is nested inside an item and may impact type checking outside of that item. This can be the case if neither the trait or the self type are at the same nesting level as the `impl`
+    .without_trait = methods and assoc const are still usable outside the current expression, only `impl Local` and `impl dyn Local` are local and only if the `Local` type is at the same nesting as the `impl` block
+    .with_trait = an `impl` definition is non-local if it is nested inside an item and may impact type checking outside of that item. This can be the case if neither the trait or the self type are at the same nesting level as the `impl`
     .bounds = `impl` may be usable in bounds, etc. from outside the expression, which might e.g. make something constructible that previously wasn't, because it's still on a publicly-visible type
     .exception = anon-const (`const _: () = {"{"} ... {"}"}`) at top-level module and anon-const at the same nesting as the trait or type are consider to be transparent regarding the nesting level
     .const_anon = use a const-anon item to suppress this lint

compiler/rustc_lint/src/lints.rs

@@ -1340,7 +1340,7 @@ pub enum NonLocalDefinitionsDiag {
         body_name: String,
         cargo_update: Option<NonLocalDefinitionsCargoUpdateNote>,
         const_anon: Option<Option<Span>>,
-        bounds: Option<()>,
+        has_trait: bool,
     },
     MacroRules {
         depth: u32,
@@ -1361,17 +1361,19 @@ impl<'a> LintDiagnostic<'a, ()> for NonLocalDefinitionsDiag {
                 body_name,
                 cargo_update,
                 const_anon,
-                bounds,
+                has_trait,
             } => {
                 diag.arg("depth", depth);
                 diag.arg("body_kind_descr", body_kind_descr);
                 diag.arg("body_name", body_name);
 
                 diag.help(fluent::lint_help);
-                if let Some(()) = bounds {
+                if has_trait {
                     diag.note(fluent::lint_bounds);
+                    diag.note(fluent::lint_with_trait);
+                } else {
+                    diag.note(fluent::lint_without_trait);
                 }
-                diag.note(fluent::lint_non_local);
 
                 if let Some(cargo_update) = cargo_update {
                     diag.subdiagnostic(&diag.dcx, cargo_update);

compiler/rustc_lint/src/non_local_def.rs

@@ -228,7 +228,7 @@ impl<'tcx> LateLintPass<'tcx> for NonLocalDefinitions {
                             .unwrap_or_else(|| "<unnameable>".to_string()),
                         cargo_update: cargo_update(),
                         const_anon,
-                        bounds: impl_.of_trait.map(|_| ()),
+                        has_trait: impl_.of_trait.is_some(),
                     },
                 )
             }

tests/ui/lint/non-local-defs/consts.stderr

@@ -48,7 +48,7 @@ LL | |     }
    | |_____^
    |
    = help: move this `impl` block outside the of the current function `main`
-   = note: an `impl` definition is non-local if it is nested inside an item and may impact type checking outside of that item. This can be the case if neither the trait or the self type are at the same nesting level as the `impl`
+   = note: methods and assoc const are still usable outside the current expression, only `impl Local` and `impl dyn Local` are local and only if the `Local` type is at the same nesting as the `impl` block
    = note: this lint may become deny-by-default in the edition 2024 and higher, see the tracking issue <https://github.com/rust-lang/rust/issues/120363>
 
 warning: non-local `impl` definition, `impl` blocks should be written at the same level as their item
@@ -61,7 +61,7 @@ LL | |         }
    | |_________^
    |
    = help: move this `impl` block outside the of the current inline constant `<unnameable>` and up 2 bodies
-   = note: an `impl` definition is non-local if it is nested inside an item and may impact type checking outside of that item. This can be the case if neither the trait or the self type are at the same nesting level as the `impl`
+   = note: methods and assoc const are still usable outside the current expression, only `impl Local` and `impl dyn Local` are local and only if the `Local` type is at the same nesting as the `impl` block
    = note: this lint may become deny-by-default in the edition 2024 and higher, see the tracking issue <https://github.com/rust-lang/rust/issues/120363>
 
 warning: non-local `impl` definition, `impl` blocks should be written at the same level as their item
@@ -74,7 +74,7 @@ LL | |         }
    | |_________^
    |
    = help: move this `impl` block outside the of the current constant `_` and up 2 bodies
-   = note: an `impl` definition is non-local if it is nested inside an item and may impact type checking outside of that item. This can be the case if neither the trait or the self type are at the same nesting level as the `impl`
+   = note: methods and assoc const are still usable outside the current expression, only `impl Local` and `impl dyn Local` are local and only if the `Local` type is at the same nesting as the `impl` block
    = note: anon-const (`const _: () = { ... }`) at top-level module and anon-const at the same nesting as the trait or type are consider to be transparent regarding the nesting level
    = note: this lint may become deny-by-default in the edition 2024 and higher, see the tracking issue <https://github.com/rust-lang/rust/issues/120363>
 

tests/ui/lint/non-local-defs/exhaustive.stderr

@@ -8,7 +8,7 @@ LL | |     }
    | |_____^
    |
    = help: move this `impl` block outside the of the current function `main`
-   = note: an `impl` definition is non-local if it is nested inside an item and may impact type checking outside of that item. This can be the case if neither the trait or the self type are at the same nesting level as the `impl`
+   = note: methods and assoc const are still usable outside the current expression, only `impl Local` and `impl dyn Local` are local and only if the `Local` type is at the same nesting as the `impl` block
    = note: this lint may become deny-by-default in the edition 2024 and higher, see the tracking issue <https://github.com/rust-lang/rust/issues/120363>
    = note: `#[warn(non_local_definitions)]` on by default
 
@@ -35,7 +35,7 @@ LL |     impl dyn Trait {}
    |     ^^^^^^^^^^^^^^^^^
    |
    = help: move this `impl` block outside the of the current function `main`
-   = note: an `impl` definition is non-local if it is nested inside an item and may impact type checking outside of that item. This can be the case if neither the trait or the self type are at the same nesting level as the `impl`
+   = note: methods and assoc const are still usable outside the current expression, only `impl Local` and `impl dyn Local` are local and only if the `Local` type is at the same nesting as the `impl` block
    = note: this lint may become deny-by-default in the edition 2024 and higher, see the tracking issue <https://github.com/rust-lang/rust/issues/120363>
 
 warning: non-local `impl` definition, `impl` blocks should be written at the same level as their item
@@ -229,7 +229,7 @@ LL | |         }
    | |_________^
    |
    = help: move this `impl` block outside the of the current function `inside_inside` and up 2 bodies
-   = note: an `impl` definition is non-local if it is nested inside an item and may impact type checking outside of that item. This can be the case if neither the trait or the self type are at the same nesting level as the `impl`
+   = note: methods and assoc const are still usable outside the current expression, only `impl Local` and `impl dyn Local` are local and only if the `Local` type is at the same nesting as the `impl` block
    = note: this lint may become deny-by-default in the edition 2024 and higher, see the tracking issue <https://github.com/rust-lang/rust/issues/120363>
 
 warning: 20 warnings emitted

tests/ui/lint/non-local-defs/weird-exprs.stderr

@@ -31,7 +31,7 @@ LL | |         }
    | |_________^
    |
    = help: move this `impl` block outside the of the current constant expression `<unnameable>` and up 2 bodies
-   = note: an `impl` definition is non-local if it is nested inside an item and may impact type checking outside of that item. This can be the case if neither the trait or the self type are at the same nesting level as the `impl`
+   = note: methods and assoc const are still usable outside the current expression, only `impl Local` and `impl dyn Local` are local and only if the `Local` type is at the same nesting as the `impl` block
    = note: this lint may become deny-by-default in the edition 2024 and higher, see the tracking issue <https://github.com/rust-lang/rust/issues/120363>
 
 warning: non-local `impl` definition, `impl` blocks should be written at the same level as their item