From fe9b522a7b2a6491ed31bc2b4d1896b70bed69a6 Mon Sep 17 00:00:00 2001
From: lcnr <rust@lcnr.de>
Date: Fri, 13 Feb 2026 12:52:05 +0000
Subject: [PATCH] ICE to delayed bug

(cherry picked from commit b3d9fbc17271a03bdd3ccbf95bb296b3505d4120)
---
 compiler/rustc_ty_utils/src/layout.rs                |  4 +++-
 .../ui/layout/rigid-alias-due-to-broken-impl.stderr  | 12 ++++++++++++
 2 files changed, 15 insertions(+), 1 deletion(-)
 create mode 100644 tests/ui/layout/rigid-alias-due-to-broken-impl.stderr

diff --git a/compiler/rustc_ty_utils/src/layout.rs b/compiler/rustc_ty_utils/src/layout.rs
index bebc0707e26..5a41e46f3a6 100644
--- a/compiler/rustc_ty_utils/src/layout.rs
+++ b/compiler/rustc_ty_utils/src/layout.rs
@@ -777,7 +777,9 @@ fn layout_of_uncached<'tcx>(
             let err = if ty.has_param() || !cx.typing_env.param_env.caller_bounds().is_empty() {
                 LayoutError::TooGeneric(ty)
             } else {
-                unreachable!("invalid rigid alias in layout_of after normalization: {ty:?}");
+                LayoutError::ReferencesError(cx.tcx().dcx().delayed_bug(format!(
+                    "unexpected rigid alias in layout_of after normalization: {ty:?}"
+                )))
             };
             return Err(error(cx, err));
         }
diff --git a/tests/ui/layout/rigid-alias-due-to-broken-impl.stderr b/tests/ui/layout/rigid-alias-due-to-broken-impl.stderr
new file mode 100644
index 00000000000..e9ba6df2fdc
--- /dev/null
+++ b/tests/ui/layout/rigid-alias-due-to-broken-impl.stderr
@@ -0,0 +1,12 @@
+error[E0046]: not all trait items implemented, missing: `Assoc`
+  --> $DIR/rigid-alias-due-to-broken-impl.rs:14:1
+   |
+LL |     type Assoc;
+   |     ---------- `Assoc` from trait
+...
+LL | impl Foo for str {}
+   | ^^^^^^^^^^^^^^^^ missing `Assoc` in implementation
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0046`.