Add note to E0401

compiler/rustc_resolve/messages.ftl

@@ -175,6 +175,7 @@ resolve_generic_params_from_outer_item =
     } from outer item
     .refer_to_type_directly = refer to the type directly here instead
     .suggestion = try introducing a local generic parameter here
+    .note = nested items are independent from their parent item for everything except for privacy and name resolution
 
 resolve_generic_params_from_outer_item_const = a `const` is a separate item from the item that contains it
 

compiler/rustc_resolve/src/errors.rs

@@ -11,6 +11,7 @@ use crate::{Res, fluent_generated as fluent};
 
 #[derive(Diagnostic)]
 #[diag(resolve_generic_params_from_outer_item, code = E0401)]
+#[note]
 pub(crate) struct GenericParamsFromOuterItem {
     #[primary_span]
     #[label]

tests/ui/const-generics/early/const-param-from-outer-fn.stderr

@@ -8,6 +8,7 @@ LL |     fn bar() -> u32 {
 LL |         X
    |         ^ use of generic parameter from outer item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |     fn bar<X>() -> u32 {

tests/ui/delegation/target-expr.stderr

@@ -8,6 +8,8 @@ LL |     reuse Trait::static_method {
 LL |
 LL |         let _ = T::Default();
    |                 ^ use of generic parameter from outer item
+   |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 
 error[E0434]: can't capture dynamic environment in a fn item
   --> $DIR/target-expr.rs:26:17

tests/ui/error-codes/E0401.stderr

@@ -8,6 +8,7 @@ LL |     fn bfnr<U, V: Baz<U>, W: Fn()>(y: T) {
    |        |
    |        generic parameter used in this inner function
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |     fn bfnr<T, U, V: Baz<U>, W: Fn()>(y: T) {
@@ -25,6 +26,7 @@ LL |     fn baz<U,
 LL |            (y: T) {
    |                ^ use of generic parameter from outer item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |     fn baz<T, U,
@@ -41,6 +43,7 @@ LL |         fn helper(sel: &Self) -> u8 {
    |            |
    |            `Self` used in this inner function
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: refer to the type directly here instead
    |
 LL -         fn helper(sel: &Self) -> u8 {

tests/ui/generics/enum-definition-with-outer-generic-parameter-5997.stderr

@@ -8,6 +8,7 @@ LL |     enum E { V(Z) }
    |          |
    |          generic parameter used in this inner enum
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |     enum E<Z> { V(Z) }

tests/ui/generics/generic-params-nested-fn-scope-error.stderr

@@ -8,6 +8,7 @@ LL |     fn bar(w: [U]) -> U {
    |        |
    |        generic parameter used in this inner function
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |     fn bar<U>(w: [U]) -> U {
@@ -23,6 +24,7 @@ LL |     fn bar(w: [U]) -> U {
    |        |
    |        generic parameter used in this inner function
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |     fn bar<U>(w: [U]) -> U {

tests/ui/generics/issue-98432.stderr

@@ -9,6 +9,7 @@ LL |         struct _Obligation where T:;
    |                |
    |                generic parameter used in this inner struct
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |         struct _Obligation<T> where T:;

tests/ui/resolve/bad-type-env-capture.stderr

@@ -8,6 +8,7 @@ LL |     fn bar(b: T) { }
    |        |
    |        generic parameter used in this inner function
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |     fn bar<T>(b: T) { }

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

@@ -8,6 +8,7 @@ LL |     const K: u32 = T::C;
    |           |
    |           generic parameter used in this inner constant item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = note: a `const` is a separate item from the item that contains it
 
 error[E0401]: can't use generic parameters from outer item
@@ -21,6 +22,7 @@ LL |         const I: u32 = T::C;
    |               |
    |               generic parameter used in this inner constant item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = note: a `const` is a separate item from the item that contains it
 
 error[E0401]: can't use generic parameters from outer item
@@ -33,6 +35,7 @@ LL |     const _: u32 = T::C;
    |           |
    |           generic parameter used in this inner constant item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = 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

@@ -8,6 +8,7 @@ LL |     const K: u32 = T::C;
    |           |
    |           generic parameter used in this inner constant item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = note: a `const` is a separate item from the item that contains it
 help: try introducing a local generic parameter here
    |
@@ -25,6 +26,7 @@ LL |         const I: u32 = T::C;
    |               |
    |               generic parameter used in this inner constant item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = note: a `const` is a separate item from the item that contains it
 help: try introducing a local generic parameter here
    |
@@ -41,6 +43,7 @@ LL |     const _: u32 = T::C;
    |           |
    |           generic parameter used in this inner constant item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = note: a `const` is a separate item from the item that contains it
 help: try introducing a local generic parameter here
    |

tests/ui/resolve/issue-12796.stderr

@@ -7,6 +7,8 @@ LL |         fn inner(_: &Self) {
    |            |         use of `Self` from outer item
    |            |         can't use `Self` here
    |            `Self` used in this inner function
+   |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 
 error: aborting due to 1 previous error
 

tests/ui/resolve/issue-3021-c.stderr

@@ -9,6 +9,7 @@ LL |     trait U {
 LL |         fn g(&self, x: T) -> T;
    |                        ^ use of generic parameter from outer item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |     trait U<T> {
@@ -25,6 +26,7 @@ LL |     trait U {
 LL |         fn g(&self, x: T) -> T;
    |                              ^ use of generic parameter from outer item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |     trait U<T> {

tests/ui/resolve/issue-3214.stderr

@@ -8,6 +8,7 @@ LL |     struct Foo {
 LL |         x: T,
    |            ^ use of generic parameter from outer item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |     struct Foo<T> {

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

@@ -10,6 +10,7 @@ LL | |
 LL | |     }
    | |_____- generic parameter used in this inner extern block
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = note: a `static` is a separate item from the item that contains it
 
 error: aborting due to 1 previous error

tests/ui/resolve/issue-65035-static-with-parent-generics.stderr

@@ -10,6 +10,7 @@ LL | |
 LL | |     }
    | |_____- generic parameter used in this inner extern block
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = note: a `static` is a separate item from the item that contains it
 
 error[E0401]: can't use generic parameters from outer item
@@ -22,6 +23,7 @@ LL |     static a: *const T = Default::default();
    |            |
    |            generic parameter used in this inner static item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = note: a `static` is a separate item from the item that contains it
 
 error[E0401]: can't use generic parameters from outer item
@@ -36,6 +38,7 @@ LL | |
 LL | |     }
    | |_____- generic parameter used in this inner extern block
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = note: a `static` is a separate item from the item that contains it
 
 error[E0401]: can't use generic parameters from outer item
@@ -48,6 +51,7 @@ LL |     static a: [u8; N] = [0; N];
    |            |
    |            generic parameter used in this inner static item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = note: a `static` is a separate item from the item that contains it
 
 error[E0401]: can't use generic parameters from outer item
@@ -60,6 +64,7 @@ LL |     static a: [u8; N] = [0; N];
    |            |
    |            generic parameter used in this inner static item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = note: a `static` is a separate item from the item that contains it
 
 error: aborting due to 5 previous errors

tests/ui/resolve/resolve-type-param-in-item-in-trait.stderr

@@ -9,6 +9,7 @@ LL |         enum Foo<B> {
 LL |             Variance(A)
    |                      ^ use of generic parameter from outer item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |         enum Foo<A, B> {
@@ -25,6 +26,7 @@ LL |         struct Foo<B>(A);
    |                |
    |                generic parameter used in this inner struct
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |         struct Foo<A, B>(A);
@@ -41,6 +43,7 @@ LL |         struct Foo<B> { a: A }
    |                |
    |                generic parameter used in this inner struct
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |         struct Foo<A, B> { a: A }
@@ -57,6 +60,7 @@ LL |         fn foo<B>(a: A) { }
    |            |
    |            generic parameter used in this inner function
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |         fn foo<A, B>(a: A) { }

tests/ui/resolve/use-self-in-inner-fn.rs

@@ -8,6 +8,7 @@ impl A {
         //~| NOTE use of `Self` from outer item
         //~| NOTE `Self` used in this inner function
         //~| HELP refer to the type directly here instead
+        //~| NOTE nested items are independent from their
         }
     }
 }
@@ -27,6 +28,7 @@ impl MyEnum {
             //~^ ERROR can't use `Self` from outer item
             //~| NOTE use of `Self` from outer item
             //~| HELP refer to the type directly here instead
+            //~| NOTE nested items are independent from their
             MyEnum::do_something(move || {});
         }
         inner();

tests/ui/resolve/use-self-in-inner-fn.stderr

@@ -9,6 +9,7 @@ LL |         fn peach(this: &Self) {
    |            |
    |            `Self` used in this inner function
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: refer to the type directly here instead
    |
 LL -         fn peach(this: &Self) {
@@ -16,7 +17,7 @@ LL +         fn peach(this: &A) {
    |
 
 error[E0401]: can't use `Self` from outer item
-  --> $DIR/use-self-in-inner-fn.rs:26:13
+  --> $DIR/use-self-in-inner-fn.rs:27:13
    |
 LL | impl MyEnum {
    | ---- `Self` type implicitly declared here, by this `impl`
@@ -27,6 +28,7 @@ LL |
 LL |             Self::do_something(move || {});
    |             ^^^^ use of `Self` from outer item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: refer to the type directly here instead
    |
 LL -             Self::do_something(move || {});

tests/ui/statics/static-generic-param-soundness.stderr

@@ -8,6 +8,7 @@ LL |     static a: Bar<T> = Bar::What;
    |            |
    |            generic parameter used in this inner static item
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
    = note: a `static` is a separate item from the item that contains it
 
 error[E0392]: type parameter `T` is never used

tests/ui/type/type-arg-out-of-scope.stderr

@@ -8,6 +8,7 @@ LL |     fn bar(f: Box<dyn FnMut(T) -> T>) { }
    |        |
    |        generic parameter used in this inner function
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |     fn bar<T>(f: Box<dyn FnMut(T) -> T>) { }
@@ -23,6 +24,7 @@ LL |     fn bar(f: Box<dyn FnMut(T) -> T>) { }
    |        |
    |        generic parameter used in this inner function
    |
+   = note: nested items are independent from their parent item for everything except for privacy and name resolution
 help: try introducing a local generic parameter here
    |
 LL |     fn bar<T>(f: Box<dyn FnMut(T) -> T>) { }