From 052651dd134c6016108c5fc50bfe4196012a6a8f Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Tue, 5 Jul 2022 16:53:48 -0400
Subject: [PATCH] fix cranelift and gcc backends

---
 compiler/rustc_codegen_cranelift/src/constant.rs | 1 +
 compiler/rustc_codegen_gcc/src/common.rs         | 9 ++++-----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/compiler/rustc_codegen_cranelift/src/constant.rs b/compiler/rustc_codegen_cranelift/src/constant.rs
index ef72e6efb94..f90ad534970 100644
--- a/compiler/rustc_codegen_cranelift/src/constant.rs
+++ b/compiler/rustc_codegen_cranelift/src/constant.rs
@@ -167,6 +167,7 @@ pub(crate) fn codegen_const_value<'tcx>(
     }
 
     match const_val {
+        ConstValue::ZST => unreachable!(), // we already handles ZST above
         ConstValue::Scalar(x) => match x {
             Scalar::Int(int) => {
                 if fx.clif_type(layout.ty).is_some() {
diff --git a/compiler/rustc_codegen_gcc/src/common.rs b/compiler/rustc_codegen_gcc/src/common.rs
index d156f874434..fc391f53f18 100644
--- a/compiler/rustc_codegen_gcc/src/common.rs
+++ b/compiler/rustc_codegen_gcc/src/common.rs
@@ -9,7 +9,6 @@
     StaticMethods,
 };
 use rustc_middle::mir::Mutability;
-use rustc_middle::ty::ScalarInt;
 use rustc_middle::ty::layout::{TyAndLayout, LayoutOf};
 use rustc_middle::mir::interpret::{ConstAllocation, GlobalAlloc, Scalar};
 use rustc_target::abi::{self, HasDataLayout, Pointer, Size};
@@ -159,13 +158,13 @@ fn const_to_opt_u128(&self, _v: RValue<'gcc>, _sign_ext: bool) -> Option<u128> {
         None
     }
 
+    fn zst_to_backend(&self, _ty: Type<'gcc>) -> RValue<'gcc> {
+        self.const_undef(self.type_ix(0))
+    }
+
     fn scalar_to_backend(&self, cv: Scalar, layout: abi::Scalar, ty: Type<'gcc>) -> RValue<'gcc> {
         let bitsize = if layout.is_bool() { 1 } else { layout.size(self).bits() };
         match cv {
-            Scalar::Int(ScalarInt::ZST) => {
-                assert_eq!(0, layout.size(self).bytes());
-                self.const_undef(self.type_ix(0))
-            }
             Scalar::Int(int) => {
                 let data = int.assert_bits(layout.size(self));