From 5b6e747f37bd75c611674781b7035b2e47bb2d4c Mon Sep 17 00:00:00 2001
From: Jules Bertholet <julesbertholet@quoi.xyz>
Date: Wed, 26 Apr 2023 19:46:10 -0400
Subject: [PATCH] Nicer ICE for #67981

---
 compiler/rustc_codegen_ssa/src/mir/mod.rs | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_codegen_ssa/src/mir/mod.rs b/compiler/rustc_codegen_ssa/src/mir/mod.rs
index e4f04b83d58..6bade5714be 100644
--- a/compiler/rustc_codegen_ssa/src/mir/mod.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/mod.rs
@@ -304,7 +304,17 @@ fn arg_local_refs<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
                     bug!("spread argument isn't a tuple?!");
                 };
 
-                let place = PlaceRef::alloca(bx, bx.layout_of(arg_ty));
+                let layout = bx.layout_of(arg_ty);
+
+                // FIXME: support unsized params in "rust-call" ABI
+                if layout.is_unsized() {
+                    span_bug!(
+                        arg_decl.source_info.span,
+                        "\"rust-call\" ABI does not support unsized params",
+                    );
+                }
+
+                let place = PlaceRef::alloca(bx, layout);
                 for i in 0..tupled_arg_tys.len() {
                     let arg = &fx.fn_abi.args[idx];
                     idx += 1;