From 21bcd2ee9c9e8d4453afc28a7f736ee754241457 Mon Sep 17 00:00:00 2001
From: clubby789 <jamie@hill-daniel.co.uk>
Date: Fri, 17 Feb 2023 16:19:13 +0000
Subject: [PATCH] Fix ICE on type alias in recursion

---
 compiler/rustc_middle/src/values.rs     |  5 +++--
 tests/ui/infinite/auxiliary/alias.rs    |  2 ++
 tests/ui/infinite/infinite-alias.rs     |  9 +++++++++
 tests/ui/infinite/infinite-alias.stderr | 14 ++++++++++++++
 4 files changed, 28 insertions(+), 2 deletions(-)
 create mode 100644 tests/ui/infinite/auxiliary/alias.rs
 create mode 100644 tests/ui/infinite/infinite-alias.rs
 create mode 100644 tests/ui/infinite/infinite-alias.stderr

diff --git a/compiler/rustc_middle/src/values.rs b/compiler/rustc_middle/src/values.rs
index 34e8a559784e6..21f3ef9267ff3 100644
--- a/compiler/rustc_middle/src/values.rs
+++ b/compiler/rustc_middle/src/values.rs
@@ -2,7 +2,7 @@ use crate::dep_graph::DepKind;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{pluralize, struct_span_err, Applicability, MultiSpan};
 use rustc_hir as hir;
-use rustc_hir::def::DefKind;
+use rustc_hir::def::{DefKind, Res};
 use rustc_middle::ty::Representability;
 use rustc_middle::ty::{self, DefIdTree, Ty, TyCtxt};
 use rustc_query_system::query::QueryInfo;
@@ -199,7 +199,8 @@ fn find_item_ty_spans(
 ) {
     match ty.kind {
         hir::TyKind::Path(hir::QPath::Resolved(_, path)) => {
-            if let Some(def_id) = path.res.opt_def_id() {
+            if let Res::Def(kind, def_id) = path.res
+                && kind != DefKind::TyAlias {
                 let check_params = def_id.as_local().map_or(true, |def_id| {
                     if def_id == needle {
                         spans.push(ty.span);
diff --git a/tests/ui/infinite/auxiliary/alias.rs b/tests/ui/infinite/auxiliary/alias.rs
new file mode 100644
index 0000000000000..59add7eb18bdb
--- /dev/null
+++ b/tests/ui/infinite/auxiliary/alias.rs
@@ -0,0 +1,2 @@
+pub struct W<T>(T);
+pub type Wrapper<T> = W<T>;
diff --git a/tests/ui/infinite/infinite-alias.rs b/tests/ui/infinite/infinite-alias.rs
new file mode 100644
index 0000000000000..45356f359cede
--- /dev/null
+++ b/tests/ui/infinite/infinite-alias.rs
@@ -0,0 +1,9 @@
+// aux-build: alias.rs
+// regression test for 108160
+
+extern crate alias;
+
+use alias::Wrapper;
+struct Rec(Wrapper<Rec>); //~ ERROR recursive type `Rec` has infinite
+
+fn main() {}
diff --git a/tests/ui/infinite/infinite-alias.stderr b/tests/ui/infinite/infinite-alias.stderr
new file mode 100644
index 0000000000000..9d9265f8c367c
--- /dev/null
+++ b/tests/ui/infinite/infinite-alias.stderr
@@ -0,0 +1,14 @@
+error[E0072]: recursive type `Rec` has infinite size
+  --> $DIR/infinite-alias.rs:7:1
+   |
+LL | struct Rec(Wrapper<Rec>);
+   | ^^^^^^^^^^ ------------ recursive without indirection
+   |
+help: insert some indirection (e.g., a `Box`, `Rc`, or `&`) to break the cycle
+   |
+LL | struct Rec(Box<Wrapper<Rec>>);
+   |            ++++            +
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0072`.