Rollup merge of #111557 - cjgillot:revert-111020, r=petrochenkov

Revert "Validate resolution for SelfCtor too."

This reverts commit 83453408a0.

That PR introduced a breaking change.

Fixes https://github.com/rust-lang/rust/issues/111541
Reopens https://github.com/rust-lang/rust/issues/89868

r? `@petrochenkov`

compiler/rustc_resolve/src/diagnostics.rs

@@ -550,7 +550,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
 
                 let sm = self.tcx.sess.source_map();
                 let def_id = match outer_res {
-                    Res::SelfTyParam { .. } | Res::SelfCtor(_) => {
+                    Res::SelfTyParam { .. } => {
                         err.span_label(span, "can't use `Self` here");
                         return err;
                     }

compiler/rustc_resolve/src/ident.rs

@@ -1174,10 +1174,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> {
                     return Res::Err;
                 }
             }
-            Res::Def(DefKind::TyParam, _)
+            Res::Def(DefKind::TyParam, _) | Res::SelfTyParam { .. } | Res::SelfTyAlias { .. } => {
-            | Res::SelfTyParam { .. }
-            | Res::SelfTyAlias { .. }
-            | Res::SelfCtor(_) => {
                 for rib in ribs {
                     let has_generic_params: HasGenericParams = match rib.kind {
                         RibKind::Normal

tests/ui/self/self-ctor-inner-const.rs

@@ -1,17 +0,0 @@
-// Verify that we ban usage of `Self` as constructor from inner items.
-
-struct S0<T>(T);
-
-impl<T> S0<T> {
-    fn foo() {
-        const C: S0<u8> = Self(0);
-        //~^ ERROR can't use generic parameters from outer function
-        fn bar() -> Self {
-            //~^ ERROR can't use generic parameters from outer function
-            Self(0)
-            //~^ ERROR can't use generic parameters from outer function
-        }
-    }
-}
-
-fn main() {}

tests/ui/self/self-ctor-inner-const.stderr

@@ -1,33 +0,0 @@
-error[E0401]: can't use generic parameters from outer function
-  --> $DIR/self-ctor-inner-const.rs:7:27
-   |
-LL |         const C: S0<u8> = Self(0);
-   |                           ^^^^
-   |                           |
-   |                           use of generic parameter from outer function
-   |                           can't use `Self` here
-
-error[E0401]: can't use generic parameters from outer function
-  --> $DIR/self-ctor-inner-const.rs:9:21
-   |
-LL | impl<T> S0<T> {
-   | ---- `Self` type implicitly declared here, by this `impl`
-...
-LL |         fn bar() -> Self {
-   |                     ^^^^
-   |                     |
-   |                     use of generic parameter from outer function
-   |                     use a type here instead
-
-error[E0401]: can't use generic parameters from outer function
-  --> $DIR/self-ctor-inner-const.rs:11:13
-   |
-LL |             Self(0)
-   |             ^^^^
-   |             |
-   |             use of generic parameter from outer function
-   |             can't use `Self` here
-
-error: aborting due to 3 previous errors
-
-For more information about this error, try `rustc --explain E0401`.

tests/ui/self/self-ctor-nongeneric.rs

@@ -0,0 +1,15 @@
+// `Self` as a constructor is currently allowed when the outer item is not generic.
+// check-pass
+
+struct S0(usize);
+
+impl S0 {
+    fn foo() {
+        const C: S0 = Self(0);
+        fn bar() -> S0 {
+            Self(0)
+        }
+    }
+}
+
+fn main() {}