From 8ab480373668d010c2609bf90742424228705ec8 Mon Sep 17 00:00:00 2001
From: Ralf Jung <post@ralfj.de>
Date: Fri, 5 May 2023 09:23:15 +0200
Subject: [PATCH] ensure that the proc_macro crate exists in the sysroot

---
 src/tools/miri/test-cargo-miri/subcrate/src/lib.rs | 13 ++++++++++++-
 src/tools/miri/tests/pass/sysroot.rs               |  9 +++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 src/tools/miri/tests/pass/sysroot.rs

diff --git a/src/tools/miri/test-cargo-miri/subcrate/src/lib.rs b/src/tools/miri/test-cargo-miri/subcrate/src/lib.rs
index 2ccb6704b05e..98c22fef0766 100644
--- a/src/tools/miri/test-cargo-miri/subcrate/src/lib.rs
+++ b/src/tools/miri/test-cargo-miri/subcrate/src/lib.rs
@@ -1,5 +1,16 @@
+// This is a proc-macro crate.
+
+extern crate proc_macro; // make sure proc_macro is in the sysroot
+
 #[cfg(doctest)]
 compile_error!("rustdoc should not touch me");
 
-#[cfg(test)]
+#[cfg(miri)]
 compile_error!("Miri should not touch me");
+
+use proc_macro::TokenStream;
+
+#[proc_macro]
+pub fn make_answer(_item: TokenStream) -> TokenStream {
+    "fn answer() -> u32 { 42 }".parse().unwrap()
+}
diff --git a/src/tools/miri/tests/pass/sysroot.rs b/src/tools/miri/tests/pass/sysroot.rs
new file mode 100644
index 000000000000..2c80e5bbd841
--- /dev/null
+++ b/src/tools/miri/tests/pass/sysroot.rs
@@ -0,0 +1,9 @@
+//! Just check that some things are available in the sysroot.
+#![feature(test)]
+#![allow(unused)]
+
+extern crate proc_macro;
+extern crate std;
+extern crate test;
+
+fn main() {}