[libcxx-commits] [libcxx] [libc++] Fix ambiguity when using std::scoped_allocator constructor (PR #80261)

[Rajveer Singh Bharadwaj via libcxx-commits]

https://github.com/Rajveer100 updated https://github.com/llvm/llvm-project/pull/80261

>From d01c6f0ca1add939530be2ef8c9f3598c2c4c5be Mon Sep 17 00:00:00 2001
From: Rajveer <rajveer.developer at icloud.com>
Date: Thu, 1 Feb 2024 14:58:18 +0530
Subject: [PATCH] [libc++] Fix ambiguity when using std::scoped_allocator
 constructor

Resolves Issue #78754
---
 libcxx/include/scoped_allocator                 |  4 ++--
 .../allocator.adaptor.cnstr/allocs.pass.cpp     | 17 ++++++++++++-----
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/libcxx/include/scoped_allocator b/libcxx/include/scoped_allocator
index 6078906e92248..cfa2efe41456a 100644
--- a/libcxx/include/scoped_allocator
+++ b/libcxx/include/scoped_allocator
@@ -477,8 +477,8 @@ public:
 
 private:
   template <class _OuterA2, __enable_if_t<is_constructible<outer_allocator_type, _OuterA2>::value, int> = 0>
-  _LIBCPP_HIDE_FROM_ABI scoped_allocator_adaptor(_OuterA2&& __o, const inner_allocator_type& __i) _NOEXCEPT
-      : base(std::forward<_OuterA2>(__o), __i) {}
+  _LIBCPP_HIDE_FROM_ABI explicit scoped_allocator_adaptor(outer_allocator_type&& __o, inner_allocator_type&& __i) _NOEXCEPT
+      : base(std::move(__o), std::move(__i)) {}
 
   template <class _Tp, class... _Args>
   _LIBCPP_HIDE_FROM_ABI void __construct(integral_constant<int, 0>, _Tp* __p, _Args&&... __args) {
diff --git a/libcxx/test/std/utilities/allocator.adaptor/allocator.adaptor.cnstr/allocs.pass.cpp b/libcxx/test/std/utilities/allocator.adaptor/allocator.adaptor.cnstr/allocs.pass.cpp
index 2a9d7052eb655..526da0338acea 100644
--- a/libcxx/test/std/utilities/allocator.adaptor/allocator.adaptor.cnstr/allocs.pass.cpp
+++ b/libcxx/test/std/utilities/allocator.adaptor/allocator.adaptor.cnstr/allocs.pass.cpp
@@ -107,12 +107,19 @@ int main(int, char**)
         assert((a.inner_allocator() ==
             std::scoped_allocator_adaptor<A2<int>, A3<int>>(A2<int>(5), A3<int>(6))));
     }
-//  Test for LWG2782
     {
-        static_assert(!std::is_convertible<A1<int>, A2<int>>::value, "");
-        static_assert(!std::is_convertible<
-             std::scoped_allocator_adaptor<A1<int>>,
-             std::scoped_allocator_adaptor<A2<int>>>::value, "");
+      //  Test for LWG2782
+      static_assert(!std::is_convertible<A1<int>, A2<int>>::value, "");
+      static_assert(
+          !std::is_convertible< std::scoped_allocator_adaptor<A1<int>>, std::scoped_allocator_adaptor<A2<int>>>::value,
+          "");
+    }
+    {
+      // Test construction from convertible-to-allocator types
+      typedef std::scoped_allocator_adaptor<A1<int>, A1<int>> A;
+      A a(A1<char>(4), A1<char>(5));
+      assert(a.outer_allocator() == A1<int>(4));
+      assert(a.inner_allocator() == A1<int>(5));
     }
 
   return 0;