Delay a bug when we see SelfCtor in ref pattern

compiler/rustc_resolve/src/late.rs

@@ -1870,6 +1870,15 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                 // These entities are explicitly allowed to be shadowed by fresh bindings.
                 None
             }
+            Res::SelfCtor(_) => {
+                // We resolve `Self` in pattern position as an ident sometimes during recovery,
+                // so delay a bug instead of ICEing.
+                self.r.session.delay_span_bug(
+                    ident.span,
+                    "unexpected `SelfCtor` in pattern, expected identifier"
+                );
+                None
+            }
             _ => span_bug!(
                 ident.span,
                 "unexpected resolution for an identifier in pattern: {:?}",

src/test/ui/pattern/issue-95878.rs

@@ -0,0 +1,12 @@
+struct Foo<'a>(&'a ());
+
+impl<'a> Foo<'a> {
+    fn spam(&mut self, baz: &mut Vec<u32>) {
+        match 15 {
+            ref Self => (),
+            //~^ ERROR expected identifier, found keyword `Self`
+        }
+    }
+}
+
+fn main() {}

src/test/ui/pattern/issue-95878.stderr

@@ -0,0 +1,8 @@
+error: expected identifier, found keyword `Self`
+  --> $DIR/issue-95878.rs:6:17
+   |
+LL |             ref Self => (),
+   |                 ^^^^ expected identifier, found keyword
+
+error: aborting due to previous error
+