Account for self ty alias

compiler/rustc_hir_analysis/messages.ftl

@@ -384,7 +384,7 @@ hir_analysis_precise_capture_self_alias = `Self` can't be captured in `use<...>`
 
 hir_analysis_recursive_generic_parameter = {$param_def_kind} `{$param_name}` is only used recursively
     .label = {$param_def_kind} must be used non-recursively in the definition
-    .note = all type parameters must be used in a non-recursive way in order to constrain its variance
+    .note = all type parameters must be used in a non-recursive way in order to constrain their variance
 
 hir_analysis_redundant_lifetime_args = unnecessary lifetime parameter `{$victim}`
     .note = you can use the `{$candidate}` lifetime directly, in place of `{$victim}`

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1961,11 +1961,16 @@ impl<'tcx> Visitor<'tcx> for CollectUsageSpans<'_> {
     }
 
     fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx>) -> Self::Result {
-        if let hir::TyKind::Path(hir::QPath::Resolved(None, qpath)) = t.kind
+        if let hir::TyKind::Path(hir::QPath::Resolved(None, qpath)) = t.kind {
-            && let Res::Def(DefKind::TyParam, def_id) = qpath.res
+            if let Res::Def(DefKind::TyParam, def_id) = qpath.res
-            && def_id == self.param_def_id
+                && def_id == self.param_def_id
-        {
+            {
-            self.spans.push(t.span);
+                self.spans.push(t.span);
+                return;
+            } else if let Res::SelfTyAlias { .. } = qpath.res {
+                self.spans.push(t.span);
+                return;
+            }
         }
         intravisit::walk_ty(self, t);
     }

tests/ui/lazy-type-alias/inherent-impls-overflow.next.stderr

@@ -13,7 +13,7 @@ LL | type Poly0<T> = Poly1<(T,)>;
    |            type parameter must be used non-recursively in the definition
    |
    = help: consider removing `T` or referring to it in the body of the type alias
-   = note: all type parameters must be used in a non-recursive way in order to constrain its variance
+   = note: all type parameters must be used in a non-recursive way in order to constrain their variance
 
 error: type parameter `T` is only used recursively
   --> $DIR/inherent-impls-overflow.rs:17:24
@@ -24,7 +24,7 @@ LL | type Poly1<T> = Poly0<(T,)>;
    |            type parameter must be used non-recursively in the definition
    |
    = help: consider removing `T` or referring to it in the body of the type alias
-   = note: all type parameters must be used in a non-recursive way in order to constrain its variance
+   = note: all type parameters must be used in a non-recursive way in order to constrain their variance
 
 error[E0275]: overflow evaluating the requirement `Poly0<()> == _`
   --> $DIR/inherent-impls-overflow.rs:21:6

tests/ui/traits/issue-105231.stderr

@@ -24,7 +24,7 @@ LL | struct A<T>(B<T>);
    |          type parameter must be used non-recursively in the definition
    |
    = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
-   = note: all type parameters must be used in a non-recursive way in order to constrain its variance
+   = note: all type parameters must be used in a non-recursive way in order to constrain their variance
 
 error: type parameter `T` is only used recursively
   --> $DIR/issue-105231.rs:5:17
@@ -35,7 +35,7 @@ LL | struct B<T>(A<A<T>>);
    |          type parameter must be used non-recursively in the definition
    |
    = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
-   = note: all type parameters must be used in a non-recursive way in order to constrain its variance
+   = note: all type parameters must be used in a non-recursive way in order to constrain their variance
 
 error[E0275]: overflow evaluating the requirement `A<A<A<A<A<A<A<...>>>>>>>: Send`
    |

tests/ui/variance/variance-unused-type-param.rs

@@ -16,6 +16,9 @@ enum ListCell<T> {
     Nil
 }
 
+struct SelfTyAlias<T>(Box<Self>);
+//~^ ERROR parameter `T` is only used recursively
+
 struct WithBounds<T: Sized> {}
 //~^ ERROR parameter `T` is never used
 

tests/ui/variance/variance-unused-type-param.stderr

@@ -25,10 +25,21 @@ LL |     Cons(Box<ListCell<T>>),
    |                       ^
    |
    = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
-   = note: all type parameters must be used in a non-recursive way in order to constrain its variance
+   = note: all type parameters must be used in a non-recursive way in order to constrain their variance
+
+error: type parameter `T` is only used recursively
+  --> $DIR/variance-unused-type-param.rs:19:27
+   |
+LL | struct SelfTyAlias<T>(Box<Self>);
+   |                    -      ^^^^
+   |                    |
+   |                    type parameter must be used non-recursively in the definition
+   |
+   = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
+   = note: all type parameters must be used in a non-recursive way in order to constrain their variance
 
 error[E0392]: type parameter `T` is never used
-  --> $DIR/variance-unused-type-param.rs:19:19
+  --> $DIR/variance-unused-type-param.rs:22:19
    |
 LL | struct WithBounds<T: Sized> {}
    |                   ^ unused type parameter
@@ -36,7 +47,7 @@ LL | struct WithBounds<T: Sized> {}
    = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
 
 error[E0392]: type parameter `T` is never used
-  --> $DIR/variance-unused-type-param.rs:22:24
+  --> $DIR/variance-unused-type-param.rs:25:24
    |
 LL | struct WithWhereBounds<T> where T: Sized {}
    |                        ^ unused type parameter
@@ -44,13 +55,13 @@ LL | struct WithWhereBounds<T> where T: Sized {}
    = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
 
 error[E0392]: type parameter `T` is never used
-  --> $DIR/variance-unused-type-param.rs:25:27
+  --> $DIR/variance-unused-type-param.rs:28:27
    |
 LL | struct WithOutlivesBounds<T: 'static> {}
    |                           ^ unused type parameter
    |
    = help: consider removing `T`, referring to it in a field, or using a marker such as `PhantomData`
 
-error: aborting due to 6 previous errors
+error: aborting due to 7 previous errors
 
 For more information about this error, try `rustc --explain E0392`.