From 0b2716415f1bd26e80887c2d8459fd436fc8e9b3 Mon Sep 17 00:00:00 2001
From: Takayuki Maeda <takoyaki0316@gmail.com>
Date: Wed, 19 Oct 2022 11:17:46 +0900
Subject: [PATCH] fix `SelfVisitor::is_self_ty` ICE

---
 compiler/rustc_resolve/src/late.rs      | 6 +++---
 src/test/ui/resolve/issue-103202.rs     | 7 +++++++
 src/test/ui/resolve/issue-103202.stderr | 9 +++++++++
 3 files changed, 19 insertions(+), 3 deletions(-)
 create mode 100644 src/test/ui/resolve/issue-103202.rs
 create mode 100644 src/test/ui/resolve/issue-103202.stderr

diff --git a/compiler/rustc_resolve/src/late.rs b/compiler/rustc_resolve/src/late.rs
index cc877e2fd30..5b99cd1e264 100644
--- a/compiler/rustc_resolve/src/late.rs
+++ b/compiler/rustc_resolve/src/late.rs
@@ -1928,11 +1928,11 @@ fn is_self_ty(&self, ty: &Ty) -> bool {
                 match ty.kind {
                     TyKind::ImplicitSelf => true,
                     TyKind::Path(None, _) => {
-                        let path_res = self.r.partial_res_map[&ty.id].expect_full_res();
-                        if let Res::SelfTyParam { .. } | Res::SelfTyAlias { .. } = path_res {
+                        let path_res = self.r.partial_res_map[&ty.id].full_res();
+                        if let Some(Res::SelfTyParam { .. } | Res::SelfTyAlias { .. }) = path_res {
                             return true;
                         }
-                        Some(path_res) == self.impl_self
+                        path_res == self.impl_self
                     }
                     _ => false,
                 }
diff --git a/src/test/ui/resolve/issue-103202.rs b/src/test/ui/resolve/issue-103202.rs
new file mode 100644
index 00000000000..469d9d7c860
--- /dev/null
+++ b/src/test/ui/resolve/issue-103202.rs
@@ -0,0 +1,7 @@
+struct S {}
+
+impl S {
+    fn f(self: &S::x) {} //~ ERROR ambiguous associated type
+}
+
+fn main() {}
diff --git a/src/test/ui/resolve/issue-103202.stderr b/src/test/ui/resolve/issue-103202.stderr
new file mode 100644
index 00000000000..880389371ef
--- /dev/null
+++ b/src/test/ui/resolve/issue-103202.stderr
@@ -0,0 +1,9 @@
+error[E0223]: ambiguous associated type
+  --> $DIR/issue-103202.rs:4:17
+   |
+LL |     fn f(self: &S::x) {}
+   |                 ^^^^ help: use fully-qualified syntax: `<S as Trait>::x`
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0223`.