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P3567R2 flat_meow fixes #8524

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ea393ab
P3567R2 flat_meow fixes
eisenwave Nov 15, 2025
b6d9c10
[flat.{map,set,multimap,multiset}] Add constexpr to new member functions
eisenwave Nov 21, 2025
7c5ad9d
Fixup: Ooops, swap() changes are still missing
eisenwave Nov 29, 2025
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173 changes: 150 additions & 23 deletions source/containers.tex
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -17033,7 +17033,9 @@

\pnum
If any member function in \ref{flat.map.defn} exits via an exception
the invariants are restored.
the invariants of the object argument are restored.
For the move constructor and move assignment operator,
the invariants of both arguments are restored.
\begin{note}
This can result in the \tcode{flat_map} being emptied.
\end{note}
Expand Down Expand Up @@ -17118,6 +17120,11 @@
// \ref{flat.map.cons}, constructors
constexpr flat_map() : flat_map(key_compare()) { }

constexpr flat_map(const flat_map&);
constexpr flat_map(flat_map&&);
constexpr flat_map& operator=(const flat_map&);
constexpr flat_map& operator=(flat_map&&);

constexpr explicit flat_map(const key_compare& comp)
: @\exposid{c}@(), @\exposid{compare}@(comp) { }

Expand Down Expand Up @@ -17258,6 +17265,8 @@
constexpr void insert(sorted_unique_t, InputIterator first, InputIterator last);
template<@\exposconcept{container-compatible-range}@<value_type> R>
constexpr void insert_range(R&& rg);
template<@\exposconcept{container-compatible-range}@<value_type> R>
constexpr void insert_range(sorted_unique_t, R&& rg);

constexpr void insert(initializer_list<value_type> il)
{ insert(il.begin(), il.end()); }
Expand Down Expand Up @@ -17298,7 +17307,7 @@
template<class K> constexpr size_type erase(K&& x);
constexpr iterator erase(const_iterator first, const_iterator last);

constexpr void swap(flat_map& y) noexcept;
constexpr void swap(flat_map& y) noexcept(@\seebelow@);
constexpr void clear() noexcept;

// observers
Expand Down Expand Up @@ -17341,7 +17350,7 @@
friend constexpr @\exposid{synth-three-way-result}@<value_type>
operator<=>(const flat_map& x, const flat_map& y);

friend constexpr void swap(flat_map& x, flat_map& y) noexcept
friend constexpr void swap(flat_map& x, flat_map& y) noexcept(noexcept(x.swap(y)))
{ x.swap(y); }

private:
Expand Down Expand Up @@ -17816,10 +17825,10 @@
\effects
Adds elements to \exposid{c} as if by:
\begin{codeblock}
for (const auto& e : rg) {
@\exposid{c}@.keys.insert(@\exposid{c}@.keys.end(), e.first);
@\exposid{c}@.values.insert(@\exposid{c}@.values.end(), e.second);
}
ranges::for_each(rg, [&](value_type e) {
@\exposid{c}@.keys.insert(@\exposid{c}@.keys.end(), std::move(e.first));
@\exposid{c}@.values.insert(@\exposid{c}@.values.end(), std::move(e.second));
});
\end{codeblock}
Then, sorts the range of newly inserted elements
with respect to \tcode{value_comp()};
Expand All @@ -17845,6 +17854,22 @@
Since this operation performs an in-place merge, it may allocate memory.
\end{itemdescr}

\indexlibrarymember{insert_range}{flat_map}%
\begin{itemdecl}
template<@\exposconcept{container-compatible-range}@<value_type> R>
constexpr void insert_range(sorted_unique_t, R&& rg);
\end{itemdecl}

\begin{itemdescr}
\pnum
\effects
Equivalent to \tcode{insert_range(rg)}.

\pnum
\complexity
Linear in $N$, where $N$ is \tcode{size()} after the operation.
\end{itemdescr}

\indexlibrarymember{try_emplace}{flat_map}%
\begin{itemdecl}
template<class... Args>
Expand Down Expand Up @@ -18047,7 +18072,10 @@

\indexlibrarymember{swap}{flat_map}%
\begin{itemdecl}
constexpr void swap(flat_map& y) noexcept;
constexpr void swap(flat_map& y)
noexcept(is_nothrow_swappable_v<key_container_type> &&
is_nothrow_swappable_v<mapped_container_type> &&
is_nothrow_swappable_v<key_compare>);
\end{itemdecl}

\begin{itemdescr}
Expand Down Expand Up @@ -18209,7 +18237,9 @@

\pnum
If any member function in \ref{flat.multimap.defn} exits via an exception,
the invariants are restored.
the invariants of the object argument are restored.
For the move constructor and move assignment operator,
the invariants of both arguments are restored.
\begin{note}
This can result in the \tcode{flat_multimap} being emptied.
\end{note}
Expand Down Expand Up @@ -18292,6 +18322,11 @@
// \ref{flat.multimap.cons}, constructors
constexpr flat_multimap() : flat_multimap(key_compare()) { }

constexpr flat_multimap(const flat_multimap&);
constexpr flat_multimap(flat_multimap&&);
constexpr flat_multimap& operator=(const flat_multimap&);
constexpr flat_multimap& operator=(flat_multimap&&);

constexpr explicit flat_multimap(const key_compare& comp)
: @\exposid{c}@(), @\exposid{compare}@(comp) { }

Expand Down Expand Up @@ -18425,6 +18460,8 @@
constexpr void insert(sorted_equivalent_t, InputIterator first, InputIterator last);
template<@\exposconcept{container-compatible-range}@<value_type> R>
constexpr void insert_range(R&& rg);
template<@\exposconcept{container-compatible-range}@<value_type> R>
constexpr void insert_range(sorted_equivalent_t, R&& rg);

constexpr void insert(initializer_list<value_type> il)
{ insert(il.begin(), il.end()); }
Expand All @@ -18440,7 +18477,10 @@
template<class K> constexpr size_type erase(K&& x);
constexpr iterator erase(const_iterator first, const_iterator last);

constexpr void swap(flat_multimap&) noexcept;
constexpr void swap(flat_multimap&)
noexcept(is_nothrow_swappable_v<key_container_type> &&
is_nothrow_swappable_v<mapped_container_type> &&
is_nothrow_swappable_v<key_compare>);
constexpr void clear() noexcept;

// observers
Expand Down Expand Up @@ -18484,7 +18524,8 @@
friend constexpr @\exposid{synth-three-way-result}@<value_type>
operator<=>(const flat_multimap& x, const flat_multimap& y);

friend constexpr void swap(flat_multimap& x, flat_multimap& y) noexcept
friend constexpr void swap(flat_multimap& x, flat_multimap& y)
noexcept(noexcept(x.swap(y)))
{ x.swap(y); }

private:
Expand Down Expand Up @@ -18852,7 +18893,9 @@

\pnum
If any member function in \ref{flat.set.defn} exits via an exception,
the invariant is restored.
the invariant of the object argument is restored.
For the move constructor and move assignment operator,
the invariants of both arguments are restored.
\begin{note}
This can result in the \tcode{flat_set}'s being emptied.
\end{note}
Expand Down Expand Up @@ -18906,6 +18949,11 @@
// \ref{flat.set.cons}, constructors
constexpr flat_set() : flat_set(key_compare()) { }

constexpr flat_set(const flat_set&);
constexpr flat_set(flat_set&&);
constexpr flat_set& operator=(const flat_set&);
constexpr flat_set& operator=(flat_set&&);

constexpr explicit flat_set(const key_compare& comp)
: @\exposid{c}@(), @\exposid{compare}@(comp) { }

Expand Down Expand Up @@ -19031,6 +19079,8 @@
constexpr void insert(sorted_unique_t, InputIterator first, InputIterator last);
template<@\exposconcept{container-compatible-range}@<value_type> R>
constexpr void insert_range(R&& rg);
template<@\exposconcept{container-compatible-range}@<value_type> R>
constexpr void insert_range(sorted_unique_t, R&& rg);

constexpr void insert(initializer_list<value_type> il)
{ insert(il.begin(), il.end()); }
Expand All @@ -19046,7 +19096,7 @@
template<class K> constexpr size_type erase(K&& x);
constexpr iterator erase(const_iterator first, const_iterator last);

constexpr void swap(flat_set& y) noexcept;
constexpr void swap(flat_set& y) noexcept(@\seebelow@);
constexpr void clear() noexcept;

// observers
Expand Down Expand Up @@ -19087,7 +19137,8 @@
friend constexpr @\exposid{synth-three-way-result}@<value_type>
operator<=>(const flat_set& x, const flat_set& y);

friend constexpr void swap(flat_set& x, flat_set& y) noexcept { x.swap(y); }
friend constexpr void swap(flat_set& x, flat_set& y) noexcept(noexcept(x.swap(y)))
{ x.swap(y); }

private:
container_type @\exposidnc{c}@; // \expos
Expand Down Expand Up @@ -19359,9 +19410,9 @@
\effects
Adds elements to \exposid{c} as if by:
\begin{codeblock}
for (const auto& e : rg) {
@\exposid{c}@.insert(@\exposid{c}@.end(), e);
}
ranges::for_each(rg, [&](auto&& e) {
@\exposid{c}@.insert(@\exposid{c}@.end(), std::forward<decltype(e)>(e));
});
\end{codeblock}
Then,
sorts the range of newly inserted elements with respect to \exposid{compare};
Expand All @@ -19380,9 +19431,27 @@
Since this operation performs an in-place merge, it may allocate memory.
\end{itemdescr}

\indexlibrarymember{insert_range}{flat_set}%
\begin{itemdecl}
template<@\exposconcept{container-compatible-range}@<value_type> R>
constexpr void insert_range(sorted_unique_t, R&& rg);
\end{itemdecl}

\begin{itemdescr}
\pnum
\effects
Equivalent to \tcode{insert_range(rg)}.

\pnum
\complexity
Linear in $N$, where $N$ is \tcode{size()} after the operation.
\end{itemdescr}

\indexlibrarymember{swap}{flat_set}%
\begin{itemdecl}
constexpr void swap(flat_set& y) noexcept;
constexpr void swap(flat_set& y)
noexcept(is_nothrow_swappable_v<container_type> &&
is_nothrow_swappable_v<key_compare>);
\end{itemdecl}

\begin{itemdescr}
Expand Down Expand Up @@ -19522,7 +19591,9 @@

\pnum
If any member function in \ref{flat.multiset.defn} exits via an exception,
the invariant is restored.
the invariant of the object argument is restored.
For the move constructor and move assignment operator,
the invariants of both arguments are restored.
\begin{note}
This can result in the \tcode{flat_multiset}'s being emptied.
\end{note}
Expand Down Expand Up @@ -19575,6 +19646,11 @@
// \ref{flat.multiset.cons}, constructors
constexpr flat_multiset() : flat_multiset(key_compare()) { }

constexpr flat_multiset(const flat_multiset&);
constexpr flat_multiset(flat_multiset&&);
constexpr flat_multiset& operator=(const flat_multiset&);
constexpr flat_multiset& operator=(flat_multiset&&);

constexpr explicit flat_multiset(const key_compare& comp)
: @\exposid{c}@(), @\exposid{compare}@(comp) { }

Expand Down Expand Up @@ -19702,6 +19778,8 @@
constexpr void insert(sorted_equivalent_t, InputIterator first, InputIterator last);
template<@\exposconcept{container-compatible-range}@<value_type> R>
constexpr void insert_range(R&& rg);
template<@\exposconcept{container-compatible-range}@<value_type> R>
constexpr void insert_range(sorted_equivalent_t, R&& rg);

constexpr void insert(initializer_list<value_type> il)
{ insert(il.begin(), il.end()); }
Expand All @@ -19717,7 +19795,7 @@
template<class K> constexpr size_type erase(K&& x);
constexpr iterator erase(const_iterator first, const_iterator last);

constexpr void swap(flat_multiset& y) noexcept;
constexpr void swap(flat_multiset& y) noexcept(@\seebelow@);
constexpr void clear() noexcept;

// observers
Expand Down Expand Up @@ -19758,7 +19836,8 @@
friend constexpr @\exposid{synth-three-way-result}@<value_type>
operator<=>(const flat_multiset& x, const flat_multiset& y);

friend constexpr void swap(flat_multiset& x, flat_multiset& y) noexcept
friend constexpr void swap(flat_multiset& x, flat_multiset& y)
noexcept(noexcept(x.swap(y)))
{ x.swap(y); }

private:
Expand Down Expand Up @@ -20005,12 +20084,60 @@

\pnum
\complexity
Linear.
Linear in $N$, where $N$ is \tcode{size()} after the operation.
\end{itemdescr}

\indexlibrarymember{insert_range}{flat_multiset}%
\begin{itemdecl}
template<@\exposconcept{container-compatible-range}@<value_type> R>
void insert_range(R&& rg);
\end{itemdecl}

\begin{itemdescr}
\pnum
\effects
Adds elements to \exposid{c} as if by:
\begin{codeblock}
ranges::for_each(rg, [&](auto&& e) {
@\exposid{c}@.insert(@\exposid{c}@.end(), std::forward<decltype(e)>(e));
});
\end{codeblock}
Then, sorts the range of newly inserted elements with respect to \exposid{compare},
and merges the resulting sorted range and
the sorted range of pre-existing elements into a single sorted range.

\pnum
\complexity
$N$ + $M \log M$, where $N$ is \tcode{size()} before the operation and $M$
is \tcode{ranges::distance(rg)}.
Comment on lines +20111 to +20112
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@jwakely jwakely Nov 27, 2025

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Suggested change
$N$ + $M \log M$, where $N$ is \tcode{size()} before the operation and $M$
is \tcode{ranges::distance(rg)}.
$N$ + $M \log M$, where $N$ is \tcode{size()} before the operation
and $M$ is \tcode{ranges::distance(rg)}.

(semantic break)

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@eisenwave eisenwave Nov 29, 2025

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The chosen line break is consistent with what we have further up for flat_map::insert and further below for flat_set::insert.

The and here is also a conjunction in a list, so it seems more appropriate to put it at the end of the line.


\pnum
\remarks
Since this operation performs an in-place merge,
it may allocate memory.
\end{itemdescr}

\indexlibrarymember{insert_range}{flat_multiset}%
\begin{itemdecl}
template<@\exposconcept{container-compatible-range}@<value_type> R>
constexpr void insert_range(sorted_equivalent_t, R&& rg);
\end{itemdecl}

\begin{itemdescr}
\pnum
\effects
Equivalent to \tcode{insert_range(rg)}.

\pnum
\complexity
Linear in $N$, where $N$ is \tcode{size()} after the operation.
\end{itemdescr}

\indexlibrarymember{swap}{flat_multiset}%
\begin{itemdecl}
constexpr void swap(flat_multiset& y) noexcept;
constexpr void swap(flat_multiset& y)
noexcept(is_nothrow_swappable_v<container_type> &&
is_nothrow_swappable_v<key_compare>);
\end{itemdecl}

\begin{itemdescr}
Expand Down
4 changes: 2 additions & 2 deletions source/support.tex
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -673,8 +673,8 @@
#define @\defnlibxname{cpp_lib_execution}@ 201902L // also in \libheader{execution}
#define @\defnlibxname{cpp_lib_expected}@ 202211L // also in \libheader{expected}
#define @\defnlibxname{cpp_lib_filesystem}@ 201703L // also in \libheader{filesystem}
#define @\defnlibxname{cpp_lib_flat_map}@ 202207L // also in \libheader{flat_map}
#define @\defnlibxname{cpp_lib_flat_set}@ 202207L // also in \libheader{flat_set}
#define @\defnlibxname{cpp_lib_flat_map}@ 202511L // also in \libheader{flat_map}
#define @\defnlibxname{cpp_lib_flat_set}@ 202511L // also in \libheader{flat_set}
#define @\defnlibxname{cpp_lib_format}@ 202311L // also in \libheader{format}
#define @\defnlibxname{cpp_lib_format_path}@ 202506L // also in \libheader{filesystem}
#define @\defnlibxname{cpp_lib_format_ranges}@ 202207L // also in \libheader{format}
Expand Down