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[libc++] Prohibits initializer_list specializations. #128042

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Merged
merged 1 commit into from
Mar 1, 2025
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[libc++] Prohibits initializer_list specializations. #128042

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2 changes: 1 addition & 1 deletion libcxx/docs/Status/Cxx17Issues.csv
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@
"`LWG2404 <https://wg21.link/LWG2404>`__","``mismatch()``\ 's complexity needs to be updated","2014-11 (Urbana)","|Complete|","",""
"`LWG2408 <https://wg21.link/LWG2408>`__","SFINAE-friendly ``common_type``\ / ``iterator_traits``\ is missing in C++14","2014-11 (Urbana)","|Complete|","",""
"`LWG2106 <https://wg21.link/LWG2106>`__","``move_iterator``\ wrapping iterators returning prvalues","2014-11 (Urbana)","|Complete|","",""
"`LWG2129 <https://wg21.link/LWG2129>`__","User specializations of ``std::initializer_list``\ ","2014-11 (Urbana)","|Complete|","",""
"`LWG2129 <https://wg21.link/LWG2129>`__","User specializations of ``std::initializer_list``\ ","2014-11 (Urbana)","|Complete|","21",""
"`LWG2212 <https://wg21.link/LWG2212>`__","``tuple_size``\ for ``const pair``\ request <tuple> header","2014-11 (Urbana)","|Complete|","",""
"`LWG2217 <https://wg21.link/LWG2217>`__","``operator==(sub_match, string)``\ slices on embedded '\0's","2014-11 (Urbana)","|Complete|","",""
"`LWG2230 <https://wg21.link/LWG2230>`__","""see below"" for ``initializer_list``\ constructors of unordered containers","2014-11 (Urbana)","|Complete|","",""
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2 changes: 1 addition & 1 deletion libcxx/include/initializer_list
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Expand Up @@ -59,7 +59,7 @@ namespace std // purposefully not versioned
# ifndef _LIBCPP_CXX03_LANG

template <class _Ep>
class _LIBCPP_TEMPLATE_VIS initializer_list {
class _LIBCPP_TEMPLATE_VIS _LIBCPP_NO_SPECIALIZATIONS initializer_list {
const _Ep* __begin_;
size_t __size_;

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31 changes: 31 additions & 0 deletions ...test/std/language.support/support.initlist/support.initlist.syn/specialization.verify.cpp
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@@ -0,0 +1,31 @@
//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: c++03

// template<class E> class initializer_list;
//
// If an explicit specialization or partial specialization of initializer_list
// is declared, the program is ill-formed.

#include <initializer_list>

#if !__has_warning("-Winvalid-specializations")
// expected-no-diagnostics
#else

// expected-error@+2 {{'initializer_list' cannot be specialized: Users are not allowed to specialize this standard library entity}}
template <>
class std::initializer_list<int> {
}; //expected-error 0-1 {{explicit specialization of 'std::initializer_list<int>' after instantiation}}

// expected-error@+2 {{'initializer_list' cannot be specialized: Users are not allowed to specialize this standard library entity}}
template <typename T>
class std::initializer_list<T*> {};

#endif