commit 04376c7d94d2331f1851ea4563c8920e1b6335a0
author David Tolnay <dtolnay@gmail.com> Fri Mar 26 17:08:48 2021 -0400
committer David Tolnay <dtolnay@gmail.com> Fri Mar 26 17:08:48 2021 -0400
tree 99825910d7f1709ebbfb238c1cd0b06d9b9ee597
parent 2dec4215e3bb959a03231de7019bfeaf60f799cf

Permit mut from ref in unsafe-to-call signatures

syntax/check.rs

diff --git a/syntax/check.rs b/syntax/check.rs
index 6ba6565..1e52c2e 100644
--- a/syntax/check.rs
+++ b/syntax/check.rs
@@ -508,6 +508,11 @@
 }
 
 fn check_mut_return_restriction(cx: &mut Check, efn: &ExternFn) {
+    if efn.sig.unsafety.is_some() {
+        // Unrestricted as long as the function is made unsafe-to-call.
+        return;
+    }
+
     match &efn.ret {
         Some(Type::Ref(ty)) if ty.mutable => {}
         _ => return,