From 292cafe62401c9d4d8aa5e95238fb43129e2c9ee Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jakub=20Ber=C3=A1nek?= <berykubik@gmail.com>
Date: Fri, 7 Jul 2023 11:49:45 +0200
Subject: [PATCH] Disable building `rustc` with (Thin)LTO on Windows

---
 src/bootstrap/compile.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/bootstrap/compile.rs b/src/bootstrap/compile.rs
index 14c3ef79a78f2..59b87baa9df33 100644
--- a/src/bootstrap/compile.rs
+++ b/src/bootstrap/compile.rs
@@ -817,6 +817,13 @@ impl Step for Rustc {
         if compiler.stage != 0 {
             match builder.config.rust_lto {
                 RustcLto::Thin | RustcLto::Fat => {
+                    if target == "x86_64-pc-windows-msvc" {
+                        panic!(
+                            "(Thin)LTO is currently known to produce miscompilations on `x86_64-pc-windows-msvc`. \
+See https://github.com/rust-lang/rust/issues/109067."
+                        );
+                    }
+
                     // Since using LTO for optimizing dylibs is currently experimental,
                     // we need to pass -Zdylib-lto.
                     cargo.rustflag("-Zdylib-lto");