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Implement LWG-4398: enable_nonlocking_formatter_optimization should be disabled for container adaptors #5883

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Merged
StephanTLavavej merged 2 commits into from
Nov 27, 2025
+25 −0
Merged

Implement LWG-4398: enable_nonlocking_formatter_optimization should be disabled for container adaptors #5883

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96bcef5
Add partial template specializations from LWG-4398
JMazurkiewicz Nov 19, 2025
dd63f1d
Add tests
JMazurkiewicz Nov 19, 2025
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6 changes: 6 additions & 0 deletions stl/inc/queue
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Original file line number Diff line number Diff line change
Expand Up @@ -230,6 +230,9 @@ struct uses_allocator<queue<_Ty, _Container>, _Alloc> : uses_allocator<_Containe
template <_Format_supported_charT _CharT, class _Ty, formattable<_CharT> _Container>
struct formatter<queue<_Ty, _Container>, _CharT>
: _Adaptor_formatter_base<queue<_Ty, _Container>, _CharT, _RANGES ref_view> {};

template <class _Ty, class _Container>
constexpr bool enable_nonlocking_formatter_optimization<queue<_Ty, _Container>> = false;
#endif // _HAS_CXX23

_EXPORT_STD template <class _Ty, class _Container = vector<_Ty>, class _Pr = less<typename _Container::value_type>>
Expand Down Expand Up @@ -505,6 +508,9 @@ struct uses_allocator<priority_queue<_Ty, _Container, _Pr>, _Alloc> : uses_alloc
template <_Format_supported_charT _CharT, class _Ty, formattable<_CharT> _Container, class _Comp>
struct formatter<priority_queue<_Ty, _Container, _Comp>, _CharT>
: _Adaptor_formatter_base<priority_queue<_Ty, _Container, _Comp>, _CharT, _RANGES ref_view> {};

template <class _Ty, class _Container, class _Compare>
constexpr bool enable_nonlocking_formatter_optimization<priority_queue<_Ty, _Container, _Compare>> = false;
#endif // _HAS_CXX23
_STD_END

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3 changes: 3 additions & 0 deletions stl/inc/stack
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Expand Up @@ -217,6 +217,9 @@ struct uses_allocator<stack<_Ty, _Container>, _Alloc> : uses_allocator<_Containe
template <_Format_supported_charT _CharT, class _Ty, formattable<_CharT> _Container>
struct formatter<stack<_Ty, _Container>, _CharT>
: _Adaptor_formatter_base<stack<_Ty, _Container>, _CharT, _RANGES ref_view> {};

template <class _Ty, class _Container>
constexpr bool enable_nonlocking_formatter_optimization<stack<_Ty, _Container>> = false;
#endif // _HAS_CXX23
_STD_END

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16 changes: 16 additions & 0 deletions tests/std/tests/P3107R5_enabled_specializations/test.compile.pass.cpp
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Expand Up @@ -3,9 +3,13 @@

#include <chrono>
#include <cstddef>
#include <deque>
#include <format>
#include <functional>
#include <list>
#include <queue>
#include <ranges>
#include <stack>
#include <stacktrace>
#include <string>
#include <string_view>
Expand Down Expand Up @@ -142,6 +146,18 @@ static_assert(!enable_nonlocking_formatter_optimization<vector<unoptimized, myal
using R = decltype(vector<int>{} | views::take(3));
static_assert(!enable_nonlocking_formatter_optimization<R>);

// <queue> =====================================================================
static_assert(!enable_nonlocking_formatter_optimization<queue<int>>);
static_assert(!enable_nonlocking_formatter_optimization<queue<int, list<int>>>);
static_assert(!enable_nonlocking_formatter_optimization<priority_queue<int>>);
static_assert(!enable_nonlocking_formatter_optimization<priority_queue<int, deque<int>>>);
static_assert(!enable_nonlocking_formatter_optimization<priority_queue<int, vector<int>, greater<int>>>);
static_assert(!enable_nonlocking_formatter_optimization<priority_queue<int, deque<int>, greater<>>>);

// <stack> =====================================================================
static_assert(!enable_nonlocking_formatter_optimization<stack<int>>);
static_assert(!enable_nonlocking_formatter_optimization<stack<int, vector<int>>>);

// <stacktrace> ================================================================
static_assert(enable_nonlocking_formatter_optimization<stacktrace_entry>);
static_assert(enable_nonlocking_formatter_optimization<stacktrace>);
Expand Down