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Expand Up @@ -137,13 +137,378 @@ <h3 id="4123"><a href="lwg-active.html#4123">4123</a>. Container effects use "th
This should talk about calls to <code class='backtick'>allocator_traits::destroy</code>.
</p>
<p>
23.3.5.4 <a href="https://wg21.link/deque.modifiers">[deque.modifiers]</a> is similar.
Look for similar problems elsewhere.
</p>

<p><i>[2024-12-06; Jonathan adds wording, incorporating Arthur's wording]</i></p>



<p id="res-4123"><b>Proposed resolution:</b></p>
<p>
This wording is relative to <a href="https://wg21.link/N4993" title=" Working Draft, Programming Languages — C++">N4993</a>.
</p>

<ol>
<li>
<p>Modify 23.3.5.3 <a href="https://wg21.link/deque.capacity">[deque.capacity]</a> as indicated:</p>
<blockquote>
<pre>void shrink_to_fit();</pre>
<p>
-5- <i>Preconditions</i>:
<code class='backtick'>T</code> is <i>CppMoveInsertable</i> into <code class='backtick'>deque</code>.
</p>
<p>
-6- <i>Effects</i>:
<code class='backtick'>shrink_to_fit</code> is a non-binding request to reduce memory use
but does not change the size of the sequence.
[<i>Note 1</i>:
The request is non-binding to allow latitude for
implementation-specific optimizations.
&mdash; <i>end note</i>]
If the size is equal to the old capacity, or
if an exception is thrown other than by the <del>move constructor</del>
<ins>move-construction of one object</ins>
of a non-<i>Cpp17CopyInsertable</i> <ins>type</ins> <code class='backtick'>T</code>
<ins>from another</ins>,
then there are no effects.
</p>
</blockquote>
</li>
<li>
<p>Modify 23.3.5.4 <a href="https://wg21.link/deque.modifiers">[deque.modifiers]</a> as indicated:</p>
<blockquote>
<pre>iterator insert(const_iterator position, const T&amp; x);
...
template&lt;<i>container-compatible-range</i>&lt;T&gt; R&gt;
void append_range(R&amp;&amp; rg);</pre>
<p>
-1- <i>Effects</i>: [...]
</p>
<p>
-2- <i>Complexity</i>:
The complexity is linear in the number of elements inserted plus
the lesser of the distances to the beginning and end of the deque.
Inserting a single element at either the beginning or end of a deque
always takes constant time and causes
<del>a single call to a constructor of T</del>
<ins>construction of a single object of type <code class='backtick'>T</code></ins>.
</p>
<p>
-3- <i>Remarks</i>:
If an exception is thrown other than by the
<del>copy constructor, move constructor,
assignment operator, or move assignment operator of <code class='backtick'>T</code>
</del>
<ins>
construction or assignment of one object of type <code class='backtick'>T</code> from another
</ins>,
there are no effects.
If an exception is thrown while inserting a single element at either end,
there are no effects.
Otherwise, if an exception is thrown by the
<del>move constructor of a</del>
<ins>move-construction of one object of</ins>
non-<i>Cpp17CopyInsertable</i>
<ins>type</ins>
<code class='backtick'>T</code> <ins>from another</ins>, the effects are unspecified.
<p>[...]</p>
-5- <i>Throws</i>:
Nothing unless an exception is thrown by
<del>the assignment operator of <code class='backtick'>T</code></del>
<ins>
the assignment of one object of type <code class='backtick'>T</code> from another
</ins>.
</p>
<pre>iterator erase(const_iterator position);
iterator erase(const_iterator first, const_iterator last);
void pop_front();
void pop_back();</pre>
<p>
-4- <i>Effects</i>:
An erase operation that erases the last element of a deque invalidates only
the past-the-end iterator
and all iterators and references to the erased elements.
An erase operation that erases the first element of a deque but not the last
element invalidates only iterators and references to the erased elements.
An erase operation that erases neither the first element nor the last element
of a deque invalidates the past-the-end iterator and all iterators and
references to all the elements of the deque.
</p>
<p>
[<i>Note 1</i>:
<code class='backtick'>pop_front</code> and <code class='backtick'>pop_back</code> are erase operations.
&mdash; <i>end note</i>]
</p>
<p>
-5- <i>Throws</i>:
Nothing unless an exception is thrown by <del>the</del><ins>an</ins>
assignment operator of <code class='backtick'>T</code>.
</p>
<p>
-6- <i>Complexity</i>:
The number of
<del>calls to the destructor of <code class='backtick'>T</code></del>
<ins>objects of type <code class='backtick'>T</code> destroyed</ins>
is the same as the number of
elements erased, but the number of calls to the assignment operator of <code class='backtick'>T</code>
is no more than the lesser of the number of elements before the erased
elements and the number of elements after the erased elements.
</p>
</blockquote>
</li>
<li>
<p>Modify 23.3.7.5 <a href="https://wg21.link/forward.list.modifiers">[forward.list.modifiers]</a> as indicated:</p>
<blockquote>
<p>
-1- [...]
Inserting <code class='backtick'>n</code> elements into a <code class='backtick'>forward_list</code> is linear in
<code class='backtick'>n</code>, and the number of <del>calls to the copy or move constructor of</del>
<ins>objects of type</ins> <code class='backtick'>T</code> <ins>constructed</ins> is
exactly equal to <code class='backtick'>n</code>. Erasing <code class='backtick'>n</code> elements from a <code class='backtick'>forward_list</code> is
linear in <code class='backtick'>n</code> and the number of <del>calls to the destructor of</del>
<ins>objects of</ins> type <code class='backtick'>T</code> <ins>destroyed</ins> is exactly equal to <code class='backtick'>n</code>.
</p>
</blockquote>
</li>
<li>
<p>Modify 23.3.9.4 <a href="https://wg21.link/list.modifiers">[list.modifiers]</a> as indicated:</p>
<blockquote>
<p>
-1- <i>Complexity</i>:
Insertion of a single element into a list takes constant time and exactly one
<del>call to a constructor of <code class='backtick'>T</code></del>
<ins>object of type <code class='backtick'>T</code> is constructed</ins>
Insertion of multiple elements into a list is linear in the number of
elements inserted and the number of
<del>calls to the copy constructor or move constructor of <code class='backtick'>T</code></del>
<ins>objects of type <code class='backtick'>T</code> constructed</ins>
is exactly equal to the number of elements inserted.
</p>
<p>
-2- <i>Remarks</i>:
Does not affect the validity of iterators and references.
If an exception is thrown, there are no effects.
</p>
<pre>iterator erase(const_iterator position);
iterator erase(const_iterator first, const_iterator last);
void pop_front();
void pop_back();
void clear() noexcept;</pre>
<p>
-3- <i>Effects</i>:
Invalidates only the iterators and references to the erased elements.
</p>
<p>
-4- <i>Throws</i>: Nothing.
</p>
<p>
-5- <i>Complexity</i>:
Erasing a single element is a constant time operation with a single
<del>call to the destructor of <code class='backtick'>T</code></del>
<ins>object of type <code class='backtick'>T</code> destroyed</ins>.
Erasing a range in a list is linear time in the
size of the range and the number of
<del>calls to the destructor of type <code class='backtick'>T</code></del>
<ins>objects of type <code class='backtick'>T</code> destroyed</ins>
is exactly equal to the size of the range.
</p>
</blockquote>
</li>
<li>
<p>Modify 23.3.11.2 <a href="https://wg21.link/vector.cons">[vector.cons]</a> as indicated:</p>
<blockquote>
<pre>template&lt;class InputIterator&gt;
constexpr vector(InputIterator first, InputIterator last,
const Allocator&amp; = Allocator());</pre>
<p>
-9- <i>Effects</i>:
Constructs a <code class='backtick'>vector</code> equal to the range [<code class='backtick'>first</code>, <code class='backtick'>last</code>),
using the specified allocator.
</p>
<p>
-10- <i>Complexity</i>:
<del>Makes only <i>N</i> calls to the copy constructor of</del>
<ins>Initializes exactly <i>N</i> objects of type</ins>
<code class='backtick'>T</code>
(where <i>N</i> is the distance between <code class='backtick'>first</code> and <code class='backtick'>last</code>)
and no reallocations if iterators <code class='backtick'>first</code> and <code class='backtick'>last</code> are of forward,
bidirectional, or random access categories.
It <del>makes</del> <ins>initializes</ins> order
<i>N</i>
<del>calls to the copy constructor of</del>
<ins>objects of type</ins>
<code class='backtick'>T</code> and <ins>performs</ins>
order log <i>N</i> reallocations if they are just input iterators.
</p>
<pre>template&lt;<i>container-compatible-range</i>&lt;T&gt; R&gt;
constexpr vector(from_range_t, R&amp;&amp; rg, const Allocator&amp; = Allocator());</pre>
<p>
-11- <i>Effects</i>:
Constructs a <code class='backtick'>vector</code> object with the elements of the range <code class='backtick'>rg</code>,
using the specified allocator.
</p>
<p>
-12- <i>Complexity</i>:
Initializes exactly <i>N</i> elements from the results of dereferencing
successive iterators of <code class='backtick'>rg</code>, where <i>N</i> is <code class='backtick'>ranges::distance(rg)</code>.
Performs no reallocations if <code class='backtick'>R</code> models <code class='backtick'>ranges::forward_range</code> or
<code class='backtick'>ranges::sized_range</code>; otherwise, performs order log <i>N</i> reallocations
and <ins>initializes</ins> order <i>N</i>
<del>calls to the copy or move constructor of</del>
<ins>objects of type</ins> <code class='backtick'>T</code>.
</p>
</blockquote>
</li>
<li>
<p>Modify 23.3.11.3 <a href="https://wg21.link/vector.capacity">[vector.capacity]</a> as indicated:</p>
<blockquote>
<pre>constexpr void reserve(size_type n);</pre>
<p>
-3- <i>Preconditions</i>:
<code class='backtick'>T</code> is <i>CppMoveInsertable</i> into <code class='backtick'>vector</code>.
</p>
<p>
-4- <i>Effects</i>:
A directive that informs a <code class='backtick'>vector</code> of a planned change in size,
so that it can manage the storage allocation accordingly.
After <code class='backtick'>reserve&lt;del&gt;()&lt;/del&gt;</code>, <code class='backtick'>capacity()</code> is greater or equal to
the argument of <code class='backtick'>reserve</code> if reallocation happens;
and equal to the previous value of <code class='backtick'>capacity()</code> otherwise.
Reallocation happens at this point if and only if
the current capacity is less than the argument of <code class='backtick'>reserve&lt;del&gt;()&lt;/del&gt;</code>.
If an exception is thrown other than by the
<del>move constructor of a</del>
<ins>move-construction of one object of</ins>
non-<i>Cpp17CopyInsertable</i>
<ins>type</ins> <code class='backtick'>T</code> <ins>from another</ins>, there are no effects.
</p>
<p>[...]</p>
<pre>constexpr shrink_to_fit();</pre>
<p>
-8- <i>Preconditions</i>:
<code class='backtick'>T</code> is <i>CppMoveInsertable</i> into <code class='backtick'>vector</code>.
</p>
<p>
-9- <i>Effects</i>:
<code class='backtick'>shrink_to_fit</code> is a non-binding request to reduce <code class='backtick'>capacity()</code> to <code class='backtick'>size()</code>.
[<i>Note 2</i>:
The request is non-binding to allow latitude for
implementation-specific optimizations.
&mdash; <i>end note</i>]
It does not increase <code class='backtick'>capacity()</code>, but may reduce <code class='backtick'>capacity()</code> by causing
reallocation.
If an exception is thrown other than by the <del>move constructor</del>
<ins>move-construction of one object</ins>
of a non-<i>Cpp17CopyInsertable</i> <ins>type</ins> <code class='backtick'>T</code>
<ins>from another</ins>,
there are no effects.
</p>
<p>[...]</p>
<pre>constexpr void resize(size_type sz);</pre>
<p>
-14- <i>Preconditions</i>:
<code class='backtick'>T</code> is <i>Cpp17MoveInsertable</i> and <i>Cpp17DefaultInsertable</i> into
<code class='backtick'>vector</code>.
</p>
<p>
-15- <i>Effects</i>: [...]
</p>
<p>
-16- <i>Remarks</i>:
If an exception is thrown other than by the <del>move constructor</del>
<ins>move-construction of one object</ins>
of a non-<i>Cpp17CopyInsertable</i> <ins>type</ins> <code class='backtick'>T</code>
<ins>from another</ins>,
there are no effects.
</p>
</blockquote>
</li>
<li>
<p>Modify 23.3.11.5 <a href="https://wg21.link/vector.modifiers">[vector.modifiers]</a> as indicated:</p>
<blockquote>
<pre>iterator insert(const_iterator position, const T&amp; x);
...
template&lt;<i>container-compatible-range</i>&lt;T&gt; R&gt;
void append_range(R&amp;&amp; rg);</pre>
<p>
-1- <i>Complexity</i>: [...]
</p>
<p>
-2- <i>Remarks</i>:
Causes reallocation if the new size is greater than the old capacity.
Reallocation invalidates all the references, pointers, and iterators
referring to the elements in the sequence, as well as the past-the-end iterator.
If no reallocation happens, then
references, pointers, and iterators
before the insertion point remain valid
but those at or after the insertion point,
including the past-the-end iterator,
are invalidated.
If an exception is thrown other than by the
<del>copy constructor, move constructor,
assignment operator, or move assignment operator of
<code class='backtick'>T</code> or by any \tcode{InputIterator} operation</del>
<ins>the construction or assignment of one object of type <code class='backtick'>T</code> from another,
or by any <code class='backtick'>InputIterator</code> operation</ins>,
there are no effects.
If an exception is thrown while inserting a single element at the end and
<code class='backtick'>T</code> is <i>Cpp17CopyInsertable</i> or
<code>is_nothrow_move_constructible_v&lt;T&gt;</code> is <code class='backtick'>true</code>,
there are no effects.
Otherwise, if an exception is thrown by the
<del>move constructor of a</del>
<ins>move-construction of one object of</ins>
non-<i>Cpp17CopyInsertable</i>
<ins>type</ins>
<code class='backtick'>T</code> <ins>from another</ins>, the effects are unspecified.
</p>
<pre>constexpr iterator erase(const_iterator position);
constexpr iterator erase(const_iterator first, const_iterator last);
constexpr void pop_back();</pre>
<p>
-3- <i>Effects</i>:
Invalidates iterators and references at or after the point of the erase.
</p>
<p>
-4- <i>Throws</i>:
Nothing unless an exception is thrown by the
<del>assignment operator or move assignment operator of <code class='backtick'>T</code></del>
<ins>construction or assignment of one object of type <code class='backtick'>T</code> from another</ins>.
</p>
<p>
-5- <i>Complexity</i>:
The
<del>destructor of <code class='backtick'>T</code> is called the number of times</del>
<ins>number of objects of type <code class='backtick'>T</code> destroyed is</ins>
equal to the number of the elements erased,
but <del>the</del><ins>an</ins>
assignment operator of <code class='backtick'>T</code> is called the number of times equal to
the number of elements in the vector after the erased elements.
</p>
</blockquote>
</li>
<li>
<p>Modify 23.3.14.5 <a href="https://wg21.link/inplace.vector.modifiers">[inplace.vector.modifiers]</a> as indicated:</p>
<blockquote>
<pre>constexpr iterator erase(const_iterator position);
constexpr iterator erase(const_iterator first, const_iterator last);
constexpr void pop_back();</pre>
<p>
-29- <i>Complexity</i>:
The
<del>destructor of <code class='backtick'>T</code> is called the number of times</del>
<ins>number of objects of type <code class='backtick'>T</code> destroyed is</ins>
equal to the number of the elements erased,
but <del>the</del><ins>an</ins>
assignment operator of <code class='backtick'>T</code> is called the number of times equal to
the number of elements after the erased elements.
</p>
</blockquote>
</li>

</ol>



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