Special case 'generic param from outer item' message for `Self`

8 files changed, 20 insertions, 11 deletions

diff --git a/compiler/rustc_resolve/messages.ftl b/compiler/rustc_resolve/messages.ftl
index 1947107235b..69675b57e31 100644
--- a/compiler/rustc_resolve/messages.ftl
+++ b/compiler/rustc_resolve/messages.ftl
@@ -114,8 +114,14 @@ resolve_forward_declared_generic_param =
     .label = defaulted generic parameters cannot be forward declared
 
 resolve_generic_params_from_outer_item =
-    can't use generic parameters from outer item
-    .label = use of generic parameter from outer item
+    can't use {$is_self ->
+        [true] `Self`
+        *[false] generic parameters
+    } from outer item
+    .label = use of {$is_self ->
+        [true] `Self`
+        *[false] generic parameter
+    } from outer item
     .refer_to_type_directly = refer to the type directly here instead
     .suggestion = try introducing a local generic parameter here
 
diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs
index 46da5b9d2e4..da31382112a 100644
--- a/compiler/rustc_resolve/src/diagnostics.rs
+++ b/compiler/rustc_resolve/src/diagnostics.rs
@@ -568,12 +568,14 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                     DefKind::Const => Some(errs::GenericParamsFromOuterItemStaticOrConst::Const),
                     _ => None,
                 };
+                let is_self = matches!(outer_res, Res::SelfTyParam { .. } | Res::SelfTyAlias { .. });
                 let mut err = errs::GenericParamsFromOuterItem {
                     span,
                     label: None,
                     refer_to_type_directly: None,
                     sugg: None,
                     static_or_const,
+                    is_self,
                 };
 
                 let sm = self.tcx.sess.source_map();
diff --git a/compiler/rustc_resolve/src/errors.rs b/compiler/rustc_resolve/src/errors.rs
index bd00cab66b0..da89df84c8a 100644
--- a/compiler/rustc_resolve/src/errors.rs
+++ b/compiler/rustc_resolve/src/errors.rs
@@ -46,6 +46,7 @@ pub(crate) struct GenericParamsFromOuterItem {
     pub(crate) sugg: Option<GenericParamsFromOuterItemSugg>,
     #[subdiagnostic]
     pub(crate) static_or_const: Option<GenericParamsFromOuterItemStaticOrConst>,
+    pub(crate) is_self: bool,
 }
 
 #[derive(Subdiagnostic)]
diff --git a/tests/ui/error-codes/E0401.stderr b/tests/ui/error-codes/E0401.stderr
index d27fade487f..754867061c7 100644
--- a/tests/ui/error-codes/E0401.stderr
+++ b/tests/ui/error-codes/E0401.stderr
@@ -20,7 +20,7 @@ LL |     fn baz<U,
 LL |            (y: T) {
    |                ^ use of generic parameter from outer item
 
-error[E0401]: can't use generic parameters from outer item
+error[E0401]: can't use `Self` from outer item
   --> $DIR/E0401.rs:24:25
    |
 LL | impl<T> Iterator for A<T> {
@@ -29,7 +29,7 @@ LL | impl<T> Iterator for A<T> {
 LL |         fn helper(sel: &Self) -> u8 {
    |                         ^^^^
    |                         |
-   |                         use of generic parameter from outer item
+   |                         use of `Self` from outer item
    |                         refer to the type directly here instead
 
 error[E0283]: type annotations needed
diff --git a/tests/ui/resolve/issue-12796.rs b/tests/ui/resolve/issue-12796.rs
index de3e73437f0..e5dcf964345 100644
--- a/tests/ui/resolve/issue-12796.rs
+++ b/tests/ui/resolve/issue-12796.rs
@@ -1,7 +1,7 @@
 trait Trait {
     fn outer(&self) {
         fn inner(_: &Self) {
-            //~^ ERROR can't use generic parameters from outer item
+            //~^ ERROR can't use `Self` from outer item
         }
     }
 }
diff --git a/tests/ui/resolve/issue-12796.stderr b/tests/ui/resolve/issue-12796.stderr
index 6809fd50f74..2305971303a 100644
--- a/tests/ui/resolve/issue-12796.stderr
+++ b/tests/ui/resolve/issue-12796.stderr
@@ -1,10 +1,10 @@
-error[E0401]: can't use generic parameters from outer item
+error[E0401]: can't use `Self` from outer item
   --> $DIR/issue-12796.rs:3:22
    |
 LL |         fn inner(_: &Self) {
    |                      ^^^^
    |                      |
-   |                      use of generic parameter from outer item
+   |                      use of `Self` from outer item
    |                      can't use `Self` here
 
 error: aborting due to 1 previous error
diff --git a/tests/ui/resolve/use-self-in-inner-fn.rs b/tests/ui/resolve/use-self-in-inner-fn.rs
index f4dfa4c40ab..62f9dc5664f 100644
--- a/tests/ui/resolve/use-self-in-inner-fn.rs
+++ b/tests/ui/resolve/use-self-in-inner-fn.rs
@@ -4,8 +4,8 @@ impl A {
 //~^ NOTE `Self` type implicitly declared here, by this `impl`
     fn banana(&mut self) {
         fn peach(this: &Self) {
-        //~^ ERROR can't use generic parameters from outer item
-        //~| NOTE use of generic parameter from outer item
+        //~^ ERROR can't use `Self` from outer item
+        //~| NOTE use of `Self` from outer item
         //~| NOTE refer to the type directly here instead
         }
     }
diff --git a/tests/ui/resolve/use-self-in-inner-fn.stderr b/tests/ui/resolve/use-self-in-inner-fn.stderr
index 165e100bf2f..9c388df8bc2 100644
--- a/tests/ui/resolve/use-self-in-inner-fn.stderr
+++ b/tests/ui/resolve/use-self-in-inner-fn.stderr
@@ -1,4 +1,4 @@
-error[E0401]: can't use generic parameters from outer item
+error[E0401]: can't use `Self` from outer item
   --> $DIR/use-self-in-inner-fn.rs:6:25
    |
 LL | impl A {
@@ -7,7 +7,7 @@ LL | impl A {
 LL |         fn peach(this: &Self) {
    |                         ^^^^
    |                         |
-   |                         use of generic parameter from outer item
+   |                         use of `Self` from outer item
    |                         refer to the type directly here instead
 
 error: aborting due to 1 previous error