From 285b9d1cd4e170f6a6c98cbdf5f5059b52735d01 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Sun, 10 Apr 2022 20:55:10 -0700
Subject: [PATCH] Delay a bug when we see SelfCtor in ref pattern

---
 compiler/rustc_resolve/src/late.rs     |  9 +++++++++
 src/test/ui/pattern/issue-95878.rs     | 12 ++++++++++++
 src/test/ui/pattern/issue-95878.stderr |  8 ++++++++
 3 files changed, 29 insertions(+)
 create mode 100644 src/test/ui/pattern/issue-95878.rs
 create mode 100644 src/test/ui/pattern/issue-95878.stderr

diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index 6fedabc816c..0fdcc164f02 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/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: {:?}",
diff --git a/src/test/ui/pattern/issue-95878.rs b/src/test/ui/pattern/issue-95878.rs
new file mode 100644
index 00000000000..f59814468b2
--- /dev/null
+++ b/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() {}
diff --git a/src/test/ui/pattern/issue-95878.stderr b/src/test/ui/pattern/issue-95878.stderr
new file mode 100644
index 00000000000..e0eea06e0a3
--- /dev/null
+++ b/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
+