From 48ae9e6f73e1f790c91f96348aa36bdd3cff6b7c Mon Sep 17 00:00:00 2001
From: Gurinder Singh <frederick.the.fool@gmail.com>
Date: Tue, 16 Jul 2024 14:20:59 +0530
Subject: [PATCH] Do not ICE when trying to get layout of an infer type

or other types whose layout cannot be computed such
as bound, coroutine witness etc.
---
 compiler/rustc_ty_utils/src/layout.rs         |  3 ++-
 tests/crashes/126942.rs                       | 11 ----------
 .../ice-layout-of-invalid-type-126942.rs      | 22 +++++++++++++++++++
 .../ice-layout-of-invalid-type-126942.stderr  | 19 ++++++++++++++++
 4 files changed, 43 insertions(+), 12 deletions(-)
 delete mode 100644 tests/crashes/126942.rs
 create mode 100644 tests/ui/layout/ice-layout-of-invalid-type-126942.rs
 create mode 100644 tests/ui/layout/ice-layout-of-invalid-type-126942.stderr

diff --git a/compiler/rustc_ty_utils/src/layout.rs b/compiler/rustc_ty_utils/src/layout.rs
index 6045abc50a9da..254341e8305be 100644
--- a/compiler/rustc_ty_utils/src/layout.rs
+++ b/compiler/rustc_ty_utils/src/layout.rs
@@ -671,7 +671,8 @@ fn layout_of_uncached<'tcx>(
         }
 
         ty::Bound(..) | ty::CoroutineWitness(..) | ty::Infer(_) | ty::Error(_) => {
-            bug!("Layout::compute: unexpected type `{}`", ty)
+            tcx.dcx().delayed_bug(format!("Layout::compute: unexpected type `{}`", ty));
+            return Err(error(cx, LayoutError::Unknown(ty)));
         }
 
         ty::Placeholder(..) | ty::Param(_) => {
diff --git a/tests/crashes/126942.rs b/tests/crashes/126942.rs
deleted file mode 100644
index e4adc8fab287e..0000000000000
--- a/tests/crashes/126942.rs
+++ /dev/null
@@ -1,11 +0,0 @@
-//@ known-bug: rust-lang/rust#126942
-struct Thing;
-
-pub trait Every {
-    type Assoc;
-}
-impl<T: ?Sized> Every for Thing {
-    type Assoc = T;
-}
-
-static I: <Thing as Every>::Assoc = 3;
diff --git a/tests/ui/layout/ice-layout-of-invalid-type-126942.rs b/tests/ui/layout/ice-layout-of-invalid-type-126942.rs
new file mode 100644
index 0000000000000..c59ed156747a0
--- /dev/null
+++ b/tests/ui/layout/ice-layout-of-invalid-type-126942.rs
@@ -0,0 +1,22 @@
+// Regression test for #126942
+
+// Tests that we do not ICE when an attempt
+// is made to compute the layout of a type
+// that normalizes to an infer type
+
+struct Thing;
+
+pub trait Every {
+    type Assoc;
+}
+impl<T: ?Sized> Every for Thing {
+//~^ ERROR the type parameter `T` is not constrained by the impl trait, self type, or predicates
+    type Assoc = T;
+}
+
+ // The type of this static normalizes to `Infer`
+ // thanks to the `?Sized` constraint in the impl above
+static I: <Thing as Every>::Assoc = 3;
+//~^ ERROR type annotations needed
+
+fn main() {}
diff --git a/tests/ui/layout/ice-layout-of-invalid-type-126942.stderr b/tests/ui/layout/ice-layout-of-invalid-type-126942.stderr
new file mode 100644
index 0000000000000..75dfe0883518c
--- /dev/null
+++ b/tests/ui/layout/ice-layout-of-invalid-type-126942.stderr
@@ -0,0 +1,19 @@
+error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predicates
+  --> $DIR/ice-layout-of-invalid-type-126942.rs:12:6
+   |
+LL | impl<T: ?Sized> Every for Thing {
+   |      ^ unconstrained type parameter
+
+error[E0283]: type annotations needed
+  --> $DIR/ice-layout-of-invalid-type-126942.rs:19:11
+   |
+LL | static I: <Thing as Every>::Assoc = 3;
+   |           ^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type for type parameter `T`
+   |
+   = note: cannot satisfy `_: Sync`
+   = note: shared static variables must have a type that implements `Sync`
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0207, E0283.
+For more information about an error, try `rustc --explain E0207`.