[libcxx-commits] [libcxx] [libcxx] implement LWG4148: unique_ptr::operator* should not allow dangling references (PR #128213)

[A. Jiang via libcxx-commits]

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@@ -0,0 +1,26 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++11
+
+// <memory>
+
+#include <memory>
+
+struct deleter {
+  using pointer = long*;
+  void operator()(pointer) const {}
+};
+
+void test() {
+  long l = 0;
+  std::unique_ptr<const int, deleter> p(&l);
+  // expected-error-re@*:* {{static assertion failed{{.*}}'!__reference_converts_from_temporary(const int &, long &)': Reference type _Tp must not convert from a temporary object}}
+  // expected-error@*:*{{returning reference to local temporary object}}
+  std::ignore = *p; // expected-note {{requested here}}
----------------
frederick-vs-ja wrote:

Hmm, `<memory>` isn't required to provide `std::ignore`, and we can use a simpler discarding style.
```suggestion
  (void)*p; // expected-note {{requested here}}
```

https://github.com/llvm/llvm-project/pull/128213