From 439048e074e1a4293e1839875e799329d92e4f81 Mon Sep 17 00:00:00 2001
From: Lieselotte <52315535+she3py@users.noreply.github.com>
Date: Sat, 29 Mar 2025 12:21:51 +0100
Subject: [PATCH] `BackendRepr::is_signed`: comment why this may panics

---
 compiler/rustc_abi/src/lib.rs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_abi/src/lib.rs b/compiler/rustc_abi/src/lib.rs
index 3f28dc7a1ef..843d5ca61dd 100644
--- a/compiler/rustc_abi/src/lib.rs
+++ b/compiler/rustc_abi/src/lib.rs
@@ -1462,7 +1462,8 @@ impl BackendRepr {
         !self.is_unsized()
     }
 
-    /// Returns `true` if this is a single signed integer scalar
+    /// Returns `true` if this is a single signed integer scalar.
+    /// Sanity check: panics if this is not a scalar type (see PR #70189).
     #[inline]
     pub fn is_signed(&self) -> bool {
         match self {