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<style data-fill-with="stylesheet">/******************************************************************************
 *                   Style sheet for the W3C specifications                   *
 *
 * Special classes handled by this style sheet include:
 *
 * Indices
 *   - .toc for the Table of Contents (<ol class="toc">)
 *     + <span class="secno"> for the section numbers
 *   - #toc for the Table of Contents (<nav id="toc">)
 *   - ul.index for Indices (<a href="#ref">term</a><span>, in § N.M</span>)
 *   - table.index for Index Tables (e.g. for properties or elements)
 *
 * Structural Markup
 *   - table.data for general data tables
 *     -> use 'scope' attribute, <colgroup>, <thead>, and <tbody> for best results !
 *     -> use <table class='complex data'> for extra-complex tables
 *     -> use <td class='long'> for paragraph-length cell content
 *     -> use <td class='pre'> when manual line breaks/indentation would help readability
 *   - dl.switch for switch statements
 *   - ol.algorithm for algorithms (helps to visualize nesting)
 *   - .figure and .caption (HTML4) and figure and figcaption (HTML5)
 *     -> .sidefigure for right-floated figures
 *   - ins/del
 *     -> ins/del.c### for candidate and proposed changes (amendments)
 *
 * Code
 *   - pre and code
 *
 * Special Sections
 *   - .note       for informative notes             (div, p, span, aside, details)
 *   - .example    for informative examples          (div, p, pre, span)
 *   - .issue      for issues                        (div, p, span)
 *   - .advisement for loud normative statements     (div, p, strong)
 *   - .annoying-warning for spec obsoletion notices (div, aside, details)
 *   - .correction for "candidate corrections"       (div, aside, details, section)
 *   - .addition   for "candidate additions"         (div, aside, details, section)
 *   - .correction.proposed for "proposed corrections" (div, aside, details, section)
 *   - .addition.proposed   for "proposed additions"   (div, aside, details, section)
 *
 * Definition Boxes
 *   - pre.def   for WebIDL definitions
 *   - table.def for tables that define other entities (e.g. CSS properties)
 *   - dl.def    for definition lists that define other entitles (e.g. HTML elements)
 *
 * Numbering
 *   - .secno for section numbers in .toc and headings (<span class='secno'>3.2</span>)
 *   - .marker for source-inserted example/figure/issue numbers (<span class='marker'>Issue 4</span>)
 *   - ::before styled for CSS-generated issue/example/figure numbers:
 *     -> Documents wishing to use this only need to add
 *        figcaption::before,
 *        .caption::before { content: "Figure "  counter(figure) " ";  }
 *        .example::before { content: "Example " counter(example) " "; }
 *        .issue::before   { content: "Issue "   counter(issue) " ";   }
 *
 * Header Stuff (ignore, just don't conflict with these classes)
 *   - .head for the header
 *   - .copyright for the copyright
 *
 * Outdated warning for old specs
 *
 * Miscellaneous
 *   - .overlarge for things that should be as wide as possible, even if
 *     that overflows the body text area. This can be used on an item or
 *     on its container, depending on the effect desired.
 *     Note that this styling basically doesn't help at all when printing,
 *     since A4 paper isn't much wider than the max-width here.
 *     It's better to design things to fit into a narrower measure if possible.
 *
 *   - js-added ToC jump links (see fixup.js)
 *
 ******************************************************************************/

/* color variables included separately for reliability */

/******************************************************************************/
/*                                    Body                                    */
/******************************************************************************/

	html {
	}

	body {
		counter-reset: example figure issue;

		/* Layout */
		max-width: 50em;			  /* limit line length to 50em for readability   */
		margin: 0 auto;				/* center text within page                    */
		padding: 1.6em 1.5em 2em 50px; /* assume 16px font size for downlevel clients */
		padding: 1.6em 1.5em 2em calc(26px + 1.5em); /* leave space for status flag    */

		/* Typography */
		line-height: 1.5;
		font-family: sans-serif;
		widows: 2;
		orphans: 2;
		word-wrap: break-word;
		overflow-wrap: break-word;
		hyphens: auto;

		color: black;
		color: var(--text);
		background: white top left fixed no-repeat;
		background: var(--bg) top left fixed no-repeat;
		background-size: 25px auto;
	}


/******************************************************************************/
/*                         Front Matter & Navigation                          */
/******************************************************************************/

/** Header ********************************************************************/

	div.head { margin-bottom: 1em; }
	div.head hr { border-style: solid; }

	div.head h1 {
		font-weight: bold;
		margin: 0 0 .1em;
		font-size: 220%;
	}

	div.head h2 { margin-bottom: 1.5em;}

/** W3C Logo ******************************************************************/

	.head .logo {
		float: right;
		margin: 0.4rem 0 0.2rem .4rem;
	}

	.head img[src*="logos/W3C"] {
		display: block;
		border: solid #1a5e9a;
		border: solid var(--logo-bg);
		border-width: .65rem .7rem .6rem;
		border-radius: .4rem;
		background: #1a5e9a;
		background: var(--logo-bg);
		color: white;
		color: var(--logo-text);
		font-weight: bold;
	}

	.head a:hover > img[src*="logos/W3C"],
	.head a:focus > img[src*="logos/W3C"] {
		opacity: .8;
	}

	.head a:active > img[src*="logos/W3C"] {
		background: #c00;
		background: var(--logo-active-bg);
		border-color: #c00;
		border-color: var(--logo-active-bg);
	}

	/* see also additional rules in Link Styling section */

/** Copyright *****************************************************************/

	p.copyright,
	p.copyright small { font-size: small; }

/** Back to Top / ToC Toggle **************************************************/

	@media print {
		#toc-nav {
			display: none;
		}
	}
	@media not print {
		#toc-nav {
			position: fixed;
			z-index: 3;
			bottom: 0; left: 0;
			margin: 0;
			min-width: 1.33em;
			border-top-right-radius: 2rem;
			box-shadow: 0 0 2px;
			font-size: 1.5em;
		}
		#toc-nav > a {
			display: block;
			white-space: nowrap;

			height: 1.33em;
			padding: .1em 0.3em;
			margin: 0;

			box-shadow: 0 0 2px;
			border: none;
			border-top-right-radius: 1.33em;

			color: #707070;
			color: var(--tocnav-normal-text);
			background: white;
			background: var(--tocnav-normal-bg);
		}
		#toc-nav > a:hover,
		#toc-nav > a:focus {
			color: black;
			color: var(--tocnav-hover-text);
			background: #f8f8f8;
			background: var(--tocnav-hover-bg);
		}
		#toc-nav > a:active {
			color: #c00;
			color: var(--tocnav-active-text);
			background: white;
			background: var(--tocnav-active-bg);
		}

		#toc-nav > #toc-jump {
			padding-bottom: 2em;
			margin-bottom: -1.9em;
		}

		/* statusbar gets in the way on keyboard focus; remove once browsers fix */
		#toc-nav > a[href="#toc"]:not(:hover):focus:last-child {
			padding-bottom: 1.5rem;
		}

		#toc-nav:not(:hover) > a:not(:focus) > span + span {
			/* Ideally this uses :focus-within on #toc-nav */
			display: none;
		}
		#toc-nav > a > span + span {
			padding-right: 0.2em;
		}
	}

/** ToC Sidebar ***************************************************************/

	/* Floating sidebar */
	@media screen {
		body.toc-sidebar #toc {
			position: fixed;
			top: 0; bottom: 0;
			left: 0;
			width: 23.5em;
			max-width: 80%;
			max-width: calc(100% - 2em - 26px);
			overflow: auto;
			padding: 0 1em;
			padding-left: 42px;
			padding-left: calc(1em + 26px);
			color: black;
			color: var(--tocsidebar-text);
			background: inherit;
			background-color: #f7f8f9;
			background-color: var(--tocsidebar-bg);
			z-index: 1;
			box-shadow: -.1em 0 .25em rgba(0,0,0,.1) inset;
			box-shadow: -.1em 0 .25em var(--tocsidebar-shadow) inset;
		}
		body.toc-sidebar #toc h2 {
			margin-top: .8rem;
			font-variant: small-caps;
			font-variant: all-small-caps;
			text-transform: lowercase;
			font-weight: bold;
			color: gray;
			color: hsla(203,20%,40%,.7);
			color: var(--tocsidebar-heading-text);
		}
		body.toc-sidebar #toc-jump:not(:focus) {
			width: 0;
			height: 0;
			padding: 0;
			position: absolute;
			overflow: hidden;
		}
	}
	/* Hide main scroller when only the ToC is visible anyway */
	@media screen and (max-width: 28em) {
		body.toc-sidebar {
			overflow: hidden;
		}
	}

	/* Sidebar with its own space */
	@media screen and (min-width: 78em) {
		body:not(.toc-inline) #toc {
			position: fixed;
			top: 0; bottom: 0;
			left: 0;
			width: 23.5em;
			overflow: auto;
			padding: 0 1em;
			padding-left: 42px;
			padding-left: calc(1em + 26px);
			color: black;
			color: var(--tocsidebar-text);
			background: inherit;
			background-color: #f7f8f9;
			background-color: var(--tocsidebar-bg);
			z-index: 1;
			box-shadow: -.1em 0 .25em rgba(0,0,0,.1) inset;
			box-shadow: -.1em 0 .25em var(--tocsidebar-shadow) inset;
		}
		body:not(.toc-inline) #toc h2 {
			margin-top: .8rem;
			font-variant: small-caps;
			font-variant: all-small-caps;
			text-transform: lowercase;
			font-weight: bold;
			color: gray;
			color: hsla(203,20%,40%,.7);
			color: var(--tocsidebar-heading-text);
		}

		body:not(.toc-inline) {
			padding-left: 29em;
		}
		/* See also Overflow section at the bottom */

		body:not(.toc-inline) #toc-jump:not(:focus) {
			width: 0;
			height: 0;
			padding: 0;
			position: absolute;
			overflow: hidden;
		}
	}
	@media screen and (min-width: 90em) {
		body:not(.toc-inline) {
			margin: 0 4em;
		}
	}

/******************************************************************************/
/*                                Sectioning                                  */
/******************************************************************************/

/** Headings ******************************************************************/

	h1, h2, h3, h4, h5, h6, dt {
		page-break-after: avoid;
		page-break-inside: avoid;
		font: 100% sans-serif;   /* Reset all font styling to clear out UA styles */
		font-family: inherit;	/* Inherit the font family. */
		line-height: 1.2;		/* Keep wrapped headings compact */
		hyphens: manual;		/* Hyphenated headings look weird */
	}

	h2, h3, h4, h5, h6 {
		margin-top: 3rem;
	}

	h1, h2, h3 {
		color: #005A9C;
		color: var(--heading-text);
	}

	h1 { font-size: 170%; }
	h2 { font-size: 140%; }
	h3 { font-size: 120%; }
	h4 { font-weight: bold; }
	h5 { font-style: italic; }
	h6 { font-variant: small-caps; }
	dt { font-weight: bold; }

/** Subheadings ***************************************************************/

	h1 + h2,
	#profile-and-date {
		/* #profile-and-date is a subtitle in an H2 under the H1 */
		margin-top: 0;
	}
	h2 + h3,
	h3 + h4,
	h4 + h5,
	h5 + h6 {
		margin-top: 1.2em; /* = 1 x line-height */
	}

/** Section divider ***********************************************************/

	:not(.head) > :not(.head) + hr {
		font-size: 1.5em;
		text-align: center;
		margin: 1em auto;
		height: auto;
		color: black;
		color: var(--hr-text);
		border: transparent solid 0;
		background: transparent;
	}
	:not(.head) > hr::before {
		content: "\2727\2003\2003\2727\2003\2003\2727";
	}

/******************************************************************************/
/*                            Paragraphs and Lists                            */
/******************************************************************************/

	p {
		margin: 1em 0;
	}

	dd > p:first-child,
	li > p:first-child {
		margin-top: 0;
	}

	ul, ol {
		margin-left: 0;
		padding-left: 2em;
	}

	li {
		margin: 0.25em 0 0.5em;
		padding: 0;
	}

	dl dd {
		margin: 0 0 .5em 2em;
	}

	.head dd + dd { /* compact for header */
		margin-top: -.5em;
	}

	/* Style for algorithms */
	ol.algorithm ol:not(.algorithm),
	.algorithm > ol ol:not(.algorithm) {
	border-left: 0.5em solid #DEF;
	border-left: 0.5em solid var(--algo-border);
	}

	/* Put nice boxes around each algorithm. */
	[data-algorithm]:not(.heading) {
	 padding: .5em;
	 border: thin solid #ddd;
	 border: thin solid var(--algo-border);
	 border-radius: .5em;
	 margin: .5em calc(-0.5em - 1px);
	}
	[data-algorithm]:not(.heading) > :first-child {
	 margin-top: 0;
	}
	[data-algorithm]:not(.heading) > :last-child {
	 margin-bottom: 0;
	}

	/* Style for switch/case <dl>s */
	dl.switch > dd > ol.only,
	dl.switch > dd > .only > ol {
	margin-left: 0;
	}
	dl.switch > dd > ol.algorithm,
	dl.switch > dd > .algorithm > ol {
	margin-left: -2em;
	}
	dl.switch {
	padding-left: 2em;
	}
	dl.switch > dt {
	text-indent: -1.5em;
	margin-top: 1em;
	}
	dl.switch > dt + dt {
	margin-top: 0;
	}
	dl.switch > dt::before {
	content: '\21AA';
	padding: 0 0.5em 0 0;
	display: inline-block;
	width: 1em;
	text-align: right;
	line-height: 0.5em;
	}

/** Terminology Markup ********************************************************/


/******************************************************************************/
/*                                 Inline Markup                              */
/******************************************************************************/

/** Terminology Markup ********************************************************/
	dfn   { /* Defining instance */
		font-weight: bolder;
	}
	a > i { /* Instance of term */
		font-style: normal;
	}
	dt dfn code, code.idl {
		font-size: inherit;
	}
	dfn var {
		font-style: normal;
	}

/** Change Marking ************************************************************/

	del {
		color: #aa0000;
		color: var(--del-text);
		background: transparent;
		background: var(--del-bg);
		text-decoration: line-through;
	}
	ins {
		color: #006100;
		color: var(--ins-text);
		background: transparent;
		background: var(--ins-bg);
		text-decoration: underline;
	}

	/* for amendments (candidate/proposed changes) */

	.amendment ins, .correction ins, .addition ins,
	ins[class^=c] {
		text-decoration-style: dotted;
	}
	.amendment del, .correction del, .addition del,
	del[class^=c] {
		text-decoration-style: dotted;
	}
	.amendment.proposed ins, .correction.proposed ins, .addition.proposed ins,
	ins[class^=c].proposed {
		text-decoration-style: double;
	}
	.amendment.proposed del, .correction.proposed del, .addition.proposed del,
	del[class^=c].proposed {
		text-decoration-style: double;
	}

/** Miscellaneous improvements to inline formatting ***************************/

	sup {
		vertical-align: super;
		font-size: 80%
	}

/******************************************************************************/
/*                                    Code                                    */
/******************************************************************************/

/** General monospace/pre rules ***********************************************/

	pre, code, samp {
		font-family: Menlo, Consolas, "DejaVu Sans Mono", Monaco, monospace;
		font-size: .9em;
		hyphens: none;
		text-transform: none;
		text-align: left;
		text-align: start;
		font-variant: normal;
		orphans: 3;
		widows: 3;
		page-break-before: avoid;
	}
	pre code,
	code code {
		font-size: 100%;
	}

	pre {
		margin-top: 1em;
		margin-bottom: 1em;
		overflow: auto;
	}

/** Inline Code fragments *****************************************************/

	/* Do something nice. */

/******************************************************************************/
/*                                    Links                                   */
/******************************************************************************/

/** General Hyperlinks ********************************************************/

	/* We hyperlink a lot, so make it less intrusive */
	a[href] {
		color: #034575;
		color: var(--a-normal-text);
		text-decoration: underline #707070;
		text-decoration: underline var(--a-normal-underline);
		text-decoration-skip-ink: none;
	}
	a:visited {
		color: #034575;
		color: var(--a-visited-text);
		text-decoration-color: #bbb;
		text-decoration-color: var(--a-visited-underline);
	}

	/* Indicate interaction with the link */
	a[href]:focus,
	a[href]:hover {
		text-decoration-thickness: 2px;
	}
	a[href]:active {
		color: #c00;
		color: var(--a-active-text);
		text-decoration-color: #c00;
		text-decoration-color: var(--a-active-underline);
	}

	/* Backout above styling for W3C logo */
	.head .logo,
	.head .logo a {
		border: none;
		text-decoration: none;
		background: transparent;
	}

/******************************************************************************/
/*                                    Images                                  */
/******************************************************************************/

	img {
		border-style: none;
	}

	img, svg {
		/* Intentionally not color-scheme aware. */
		background: white;
	}

	/* For autogen numbers, add
	  .caption::before, figcaption::before { content: "Figure " counter(figure) ". "; }
	*/

	figure, .figure, .sidefigure {
		page-break-inside: avoid;
		text-align: center;
		margin: 2.5em 0;
	}
	.figure img,	.sidefigure img,	figure img,
	.figure object, .sidefigure object, figure object {
		max-width: 100%;
		margin: auto;
		height: auto;
	}
	.figure pre, .sidefigure pre, figure pre {
		text-align: left;
		display: table;
		margin: 1em auto;
	}
	.figure table, figure table {
		margin: auto;
	}
	@media screen and (min-width: 20em) {
		.sidefigure {
			float: right;
			width: 50%;
			margin: 0 0 0.5em 0.5em;
		}
	}
	.caption, figcaption, caption {
		font-style: italic;
		font-size: 90%;
	}
	.caption::before, figcaption::before, figcaption > .marker {
		font-weight: bold;
	}
	.caption, figcaption {
		counter-increment: figure;
	}

	/* DL list is indented 2em, but figure inside it is not */
	dd > .figure, dd > figure { margin-left: -2em; }

/******************************************************************************/
/*                             Colored Boxes                                  */
/******************************************************************************/

	.issue, .note, .example, .assertion, .advisement, blockquote,
	.amendment, .correction, .addition {
		margin: 1em auto;
		padding: .5em;
		border: .5em;
		border-left-style: solid;
		page-break-inside: avoid;
	}
	span.issue, span.note {
		padding: .1em .5em .15em;
		border-right-style: solid;
	}

	blockquote > :first-child,
	.note  > p:first-child,
	.issue > p:first-child,
	.amendment > p:first-child,
	.correction > p:first-child,
	.addition > p:first-child {
		margin-top: 0;
	}
	blockquote > :last-child,
	.note  > p:last-child,
	.issue > p:last-child,
	.amendment > p:last-child,
	.correction > p:last-child,
	.addition > p:last-child {
		margin-bottom: 0;
	}


	.issue::before, .issue > .marker,
	.example::before, .example > .marker,
	.note::before, .note > .marker,
	details.note > summary > .marker,
	.amendment::before, .amendment > .marker,
	details.amendment > summary > .marker,
	.addition::before, .addition > .marker,
	addition.amendment > summary > .marker,
	.correction::before, .correction > .marker,
	correction.amendment > summary > .marker
	{
		text-transform: uppercase;
		padding-right: 1em;
	}

	.example::before, .example > .marker {
		display: block;
		padding-right: 0em;
	}

/** Blockquotes ***************************************************************/

	blockquote {
		border-color: silver;
		border-color: var(--blockquote-border);
		background: transparent;
		background: var(--blockquote-bg);
		color: currentcolor;
		color: var(--blockquote-text);
	}

/** Open issue ****************************************************************/

	.issue {
		border-color: #e05252;
		border-color: var(--issue-border);
		background: #fbe9e9;
		background: var(--issue-bg);
		color: black;
		color: var(--issue-text);
		counter-increment: issue;
		overflow: auto;
	}
	.issue::before, .issue > .marker {
		color: #831616;
		color: var(--issueheading-text);
	}
	/* Add .issue::before { content: "Issue " counter(issue) " "; } for autogen numbers,
	  or use class="marker" to mark up the issue number in source. */

/** Example *******************************************************************/

	.example {
		border-color: #e0cb52;
		border-color: var(--example-border);
		background: #fcfaee;
		background: var(--example-bg);
		color: black;
		color: var(--example-text);
		counter-increment: example;
		overflow: auto;
		clear: both;
	}
	.example::before, .example > .marker {
		color: #574b0f;
		color: var(--exampleheading-text);
	}
	/* Add .example::before { content: "Example " counter(example) " "; } for autogen numbers,
	  or use class="marker" to mark up the example number in source. */

/** Non-normative Note ********************************************************/

	.note {
		border-color: #52e052;
		border-color: var(--note-border);
		background: #e9fbe9;
		background: var(--note-bg);
		color: black;
		color: var(--note-text);
		overflow: auto;
	}

	.note::before, .note > .marker,
	details.note > summary {
		color: hsl(120, 70%, 30%);
		color: var(--noteheading-text);
	}
	/* Add .note::before { content: "Note "; } for autogen label,
	  or use class="marker" to mark up the label in source. */

	details.note[open] > summary {
		border-bottom: 1px silver solid;
		border-bottom: 1px var(--notesummary-underline) solid;
	}

/** Assertion Box *************************************************************/
	/*  for assertions in algorithms */

	.assertion {
		border-color: #AAA;
		border-color: var(--assertion-border);
		background: #EEE;
		background: var(--assertion-bg);
		color: black;
		color: var(--assertion-text);
	}

/** Advisement Box ************************************************************/
	/*  for attention-grabbing normative statements */

	.advisement {
		border-color: orange;
		border-color: var(--advisement-border);
		border-style: none solid;
		background: #fec;
		background: var(--advisement-bg);
		color: black;
		color: var(--advisement-text);
	}
	strong.advisement {
		display: block;
		text-align: center;
	}
	.advisement::before, .advisement > .marker {
		color: #b35f00;
		color: var(--advisementheading-text);
	}

/** Amendment Box *************************************************************/

	.amendment, .correction, .addition {
		border-color: #330099;
		border-color: var(--amendment-border);
		background: #F5F0FF;
		background: var(--amendment-bg);
		color: black;
		color: var(--amendment-text);
	}
	.amendment.proposed, .correction.proposed, .addition.proposed {
		border-style: solid;
		border-block-width: 0.25em;
	}
	.amendment::before, .amendment > .marker,
	details.amendment > summary::before, details.amendment > summary > .marker,
	.correction::before, .correction > .marker,
	details.correction > summary::before, details.correction > summary > .marker,
	.addition::before, .addition > .marker,
	details.addition > summary::before, details.addition > summary > .marker {
		color: #220066;
		color: var(--amendmentheading-text);
	}
	.amendment.proposed::before, .amendment.proposed > .marker,
	details.amendment.proposed > summary::before, details.amendment.proposed > summary > .marker,
	.correction.proposed::before, .correction.proposed > .marker,
	details.correction.proposed > summary::before, details.correction.proposed > summary > .marker,
	.addition.proposed::before, .addition.proposed > .marker,
	details.addition.proposed > summary::before, details.addition.proposed > summary > .marker {
		font-weight: bold;
	}

/** Spec Obsoletion Notice ****************************************************/
	/* obnoxious obsoletion notice for older/abandoned specs. */

	details {
		display: block;
	}
	summary {
		font-weight: bolder;
	}

	.annoying-warning:not(details),
	details.annoying-warning:not([open]) > summary,
	details.annoying-warning[open] {
		background: hsla(40,100%,50%,0.95);
		background: var(--warning-bg);
		color: black;
		color: var(--warning-text);
		padding: .75em 1em;
		border: red;
		border: var(--warning-border);
		border-style: solid none;
		box-shadow: 0 2px 8px black;
		text-align: center;
	}
	.annoying-warning :last-child {
		margin-bottom: 0;
	}

@media not print {
	details.annoying-warning[open] {
		position: fixed;
		left: 0;
		right: 0;
		bottom: 2em;
		z-index: 1000;
	}
}

	details.annoying-warning:not([open]) > summary {
		text-align: center;
	}

/** Entity Definition Boxes ***************************************************/

	.def {
		padding: .5em 1em;
		background: #def;
		background: var(--def-bg);
		margin: 1.2em 0;
		border-left: 0.5em solid #8ccbf2;
		border-left: 0.5em solid var(--def-border);
		color: black;
		color: var(--def-text);
	}

/******************************************************************************/
/*                                    Tables                                  */
/******************************************************************************/

	th, td {
		text-align: left;
		text-align: start;
	}

/** Property/Descriptor Definition Tables *************************************/

	table.def {
		/* inherits .def box styling, see above */
		width: 100%;
		border-spacing: 0;
	}

	table.def td,
	table.def th {
		padding: 0.5em;
		vertical-align: baseline;
		border-bottom: 1px solid #bbd7e9;
		border-bottom: 1px solid var(--defrow-border);
	}

	table.def > tbody > tr:last-child th,
	table.def > tbody > tr:last-child td {
		border-bottom: 0;
	}

	table.def th {
		font-style: italic;
		font-weight: normal;
		padding-left: 1em;
		width: 3em;
	}

	/* For when values are extra-complex and need formatting for readability */
	table td.pre {
		white-space: pre-wrap;
	}

	/* A footnote at the bottom of a def table */
	table.def td.footnote {
		padding-top: 0.6em;
	}
	table.def td.footnote::before {
		content: " ";
		display: block;
		height: 0.6em;
		width: 4em;
		border-top: thin solid;
	}

/** Data tables (and properly marked-up index tables) *************************/
	/*
		<table class="data"> highlights structural relationships in a table
		when correct markup is used (e.g. thead/tbody, th vs. td, scope attribute)

		Use class="complex data" for particularly complicated tables --
		(This will draw more lines: busier, but clearer.)

		Use class="long" on table cells with paragraph-like contents
		(This will adjust text alignment accordingly.)
		Alternately use class="longlastcol" on tables, to have the last column assume "long".
	*/

	table {
		word-wrap: normal;
		overflow-wrap: normal;
		hyphens: manual;
	}

	table.data,
	table.index {
		margin: 1em auto;
		border-collapse: collapse;
		border: hidden;
		width: 100%;
	}
	table.data caption,
	table.index caption {
		max-width: 50em;
		margin: 0 auto 1em;
	}

	table.data td,  table.data th,
	table.index td, table.index th {
		padding: 0.5em 1em;
		border-width: 1px;
		border-color: silver;
		border-color: var(--datacell-border);
		border-top-style: solid;
	}

	table.data thead td:empty {
		padding: 0;
		border: 0;
	}

	table.data  thead,
	table.index thead,
	table.data  tbody,
	table.index tbody {
		border-bottom: 2px solid;
	}

	table.data colgroup,
	table.index colgroup {
		border-left: 2px solid;
	}

	table.data  tbody th:first-child,
	table.index tbody th:first-child  {
		border-right: 2px solid;
		border-top: 1px solid silver;
		border-top: 1px solid var(--datacell-border);
		padding-right: 1em;
	}

	table.data th[colspan],
	table.data td[colspan] {
		text-align: center;
	}

	table.complex.data th,
	table.complex.data td {
		border: 1px solid silver;
		border: 1px solid var(--datacell-border);
		text-align: center;
	}

	table.data.longlastcol td:last-child,
	table.data td.long {
		vertical-align: baseline;
		text-align: left;
	}

	table.data img {
		vertical-align: middle;
	}


/*
Alternate table alignment rules

	table.data,
	table.index {
		text-align: center;
	}

	table.data  thead th[scope="row"],
	table.index thead th[scope="row"] {
		text-align: right;
	}

	table.data  tbody th:first-child,
	table.index tbody th:first-child  {
		text-align: right;
	}

Possible extra rowspan handling

	table.data  tbody th[rowspan]:not([rowspan='1']),
	table.index tbody th[rowspan]:not([rowspan='1']),
	table.data  tbody td[rowspan]:not([rowspan='1']),
	table.index tbody td[rowspan]:not([rowspan='1']) {
		border-left: 1px solid silver;
	}

	table.data  tbody th[rowspan]:first-child,
	table.index tbody th[rowspan]:first-child,
	table.data  tbody td[rowspan]:first-child,
	table.index tbody td[rowspan]:first-child{
		border-left: 0;
		border-right: 1px solid silver;
	}
*/

/******************************************************************************/
/*                                  Indices                                   */
/******************************************************************************/


/** Table of Contents *********************************************************/

	.toc a {
		/* More spacing; use padding to make it part of the click target. */
		padding: 0.1rem 1px 0;
		/* Larger, more consistently-sized click target */
		display: block;
		/* Switch to using border-bottom for underlines */
		text-decoration: none;
		border-bottom: 1px solid;
		/* Reverse color scheme */
		color: black;
		color: var(--toclink-text);
		border-color: #3980b5;
		border-color: var(--toclink-underline);
	}
	.toc a:visited {
		color: black;
		color: var(--toclink-visited-text);
		border-color: #054572;
		border-color: var(--toclink-visited-underline);
	}
	.toc a:focus,
	.toc a:hover {
		background: rgba(75%, 75%, 75%, .25);
		background: var(--a-hover-bg);
		border-bottom-width: 3px;
		margin-bottom: -2px;
	}
	.toc a:not(:focus):not(:hover) {
		/* Allow colors to cascade through from link styling */
		border-bottom-color: transparent;
	}

	.toc, .toc ol, .toc ul, .toc li {
		list-style: none; /* Numbers must be inlined into source */
		/* because generated content isn't search/selectable and markers can't do multilevel yet */
		margin:  0;
		padding: 0;
	}
	.toc {
		line-height: 1.1em;
	}

	/* ToC not indented until third level, but font style & margins show hierarchy */
	.toc > li			{ font-weight: bold;   }
	.toc > li li		 { font-weight: normal; }
	.toc > li li li	  { font-size:   95%;	}
	.toc > li li li li	{ font-size:   90%;	}
	.toc > li li li li li { font-size:   85%;	}

	/* @supports not (display:grid) { */
		.toc > li			{ margin: 1.5rem 0;	}
		.toc > li li		 { margin: 0.3rem 0;	}
		.toc > li li li	  { margin-left: 2rem;   }

		/* Section numbers in a column of their own */
		.toc .secno {
			float: left;
			width: 4rem;
			white-space: nowrap;
		}
		.toc > li li li li .secno { font-size: 85%; }
		.toc > li li li li li .secno { font-size: 100%; }

		.toc li {
			clear: both;
		}

		:not(li) > .toc			 { margin-left:  5rem; }
		.toc .secno				 { margin-left: -5rem; }
		.toc > li li li .secno	  { margin-left: -7rem; }
		.toc > li li li li .secno	{ margin-left: -9rem; }
		.toc > li li li li li .secno { margin-left: -11rem; }

		/* Tighten up indentation in narrow ToCs */
		@media (max-width: 30em) {
			:not(li) > .toc			 { margin-left:  4rem; }
			.toc .secno				 { margin-left: -4rem; }
			.toc > li li li			 { margin-left:  1rem; }
			.toc > li li li .secno	  { margin-left: -5rem; }
			.toc > li li li li .secno	{ margin-left: -6rem; }
			.toc > li li li li li .secno { margin-left: -7rem; }
		}
		/* Loosen it on wide screens */
		@media screen and (min-width: 78em) {
			body:not(.toc-inline) :not(li) > .toc			 { margin-left:  4rem; }
			body:not(.toc-inline) .toc .secno				 { margin-left: -4rem; }
			body:not(.toc-inline) .toc > li li li			 { margin-left:  1rem; }
			body:not(.toc-inline) .toc > li li li .secno	  { margin-left: -5rem; }
			body:not(.toc-inline) .toc > li li li li .secno	{ margin-left: -6rem; }
			body:not(.toc-inline) .toc > li li li li li .secno { margin-left: -7rem; }
	}
	/* } */

	@supports (display:grid) and (display:contents) {
		/* Use #toc over .toc to override non-@supports rules. */
		#toc {
			display: grid;
			align-content: start;
			grid-template-columns: auto 1fr;
			grid-column-gap: 1rem;
			column-gap: 1rem;
			grid-row-gap: .6rem;
			row-gap: .6rem;
		}
		#toc h2 {
			grid-column: 1 / -1;
			margin-bottom: 0;
		}
		#toc ol,
		#toc li,
		#toc a {
			display: contents;
			/* Switch <a> to subgrid when supported */
		}
		#toc span {
			margin: 0;
		}
		#toc > .toc > li > a > span {
			/* The spans of the top-level list,
			  comprising the first items of each top-level section. */
			margin-top: 1.1rem;
		}
		#toc#toc .secno { /* Ugh, need more specificity to override base.css */
			grid-column: 1;
			width: auto;
			margin-left: 0;
		}
		#toc .content {
			grid-column: 2;
			width: auto;
			margin-right: 1rem;
			border-bottom: 3px solid transparent;
			margin-bottom: -3px;
		}
		#toc .content:hover,
		#toc .content:focus {
			background: rgba(75%, 75%, 75%, .25);
			background: var(--a-hover-bg);
			border-bottom-color: #054572;
			border-bottom-color: var(--toclink-underline);
		}
		#toc li li li .content {
			margin-left: 1rem;
		}
		#toc li li li li .content {
			margin-left: 2rem;
		}
	}


/** Index *********************************************************************/

	/* Index Lists: Layout */
	ul.index	  { margin-left: 0; columns: 15em; text-indent: 1em hanging; }
	ul.index li	{ margin-left: 0; list-style: none; break-inside: avoid; }
	ul.index li li { margin-left: 1em; }
	ul.index dl	{ margin-top: 0; }
	ul.index dt	{ margin: .2em 0 .2em 20px;}
	ul.index dd	{ margin: .2em 0 .2em 40px;}
	/* Index Lists: Typography */
	ul.index ul,
	ul.index dl { font-size: smaller; }
	@media not print {
		ul.index li a + span {
			white-space: nowrap;
			color: transparent; }
		ul.index li a:hover + span,
		ul.index li a:focus + span {
			color: #707070;
			color: var(--indexinfo-text);
		}
	}

/** Index Tables *****************************************************/
	/* See also the data table styling section, which this effectively subclasses */

	table.index {
		font-size: small;
		border-collapse: collapse;
		border-spacing: 0;
		text-align: left;
		margin: 1em 0;
	}

	table.index td,
	table.index th {
		padding: 0.4em;
	}

	table.index tr:hover td:not([rowspan]),
	table.index tr:hover th:not([rowspan]) {
		color: black;
		color: var(--indextable-hover-text);
		background: #f7f8f9;
		background: var(--indextable-hover-bg);
	}

	/* The link in the first column in the property table (formerly a TD) */
	table.index th:first-child a {
		font-weight: bold;
	}

/** Outdated warning **********************************************************/

.outdated-spec {
	color: black;
	color: var(--outdatedspec-text);
	background-color: rgba(0,0,0,0.5);
	background-color: var(--outdatedspec-bg);
}

.outdated-warning {
	position: fixed;
	bottom: 50%;
	left: 0;
	right: 0;
	margin: 0 auto;
	width: 50%;
	background: maroon;
	background: var(--outdated-bg);
	color: white;
	color: var(--outdated-text);
	border-radius: 1em;
	box-shadow: 0 0 1em red;
	box-shadow: 0 0 1em var(--outdated-shadow);
	padding: 2em;
	text-align: center;
	z-index: 2;
}

.outdated-warning a {
	color: currentcolor;
	background: transparent;
}

.edited-rec-warning {
	background: darkorange;
	background: var(--editedrec-bg);
	box-shadow: 0 0 1em;
}

.outdated-warning button {
	color: var(--outdated-text);
	border-radius: 1em;
	box-shadow: 0 0 1em red;
	box-shadow: 0 0 1em var(--outdated-shadow);
	padding: 2em;
	text-align: center;
	z-index: 2;
}

.outdated-warning a {
	color: currentcolor;
	background: transparent;
}

.edited-rec-warning {
	background: darkorange;
	background: var(--editedrec-bg);
	box-shadow: 0 0 1em;
}

.outdated-warning button {
	position: absolute;
	top: 0;
	right:0;
	margin: 0;
	border: 0;
	padding: 0.25em 0.5em;
	background: transparent;
	color: white;
	color: var(--outdated-text);
	font:1em sans-serif;
	text-align:center;
}

.outdated-warning span {
	display: block;
}

.outdated-collapsed {
	bottom: 0;
	border-radius: 0;
	width: 100%;
	padding: 0;
}

/******************************************************************************/
/*                                    Print                                   */
/******************************************************************************/

	@media print {
		/* Pages have their own margins. */
		html {
			margin: 0;
		}
		/* Serif for print. */
		body {
			font-family: serif;
		}

		.outdated-warning {
			position: absolute;
			border-style: solid;
			border-color: red;
		}

		.outdated-warning input {
			display: none;
		}
	}
	@page {
		margin: 1.5cm 1.1cm;
	}



/******************************************************************************/
/*                             Overflow Control                               */
/******************************************************************************/

	.figure .caption, .sidefigure .caption, figcaption {
		/* in case figure is overlarge, limit caption to 50em */
		max-width: 50rem;
		margin-left: auto;
		margin-right: auto;
	}
	.overlarge {
		/* Magic to create good item positioning:
		  "content column" is 50ems wide at max; less on smaller screens.
		  Extra space (after ToC + content) is empty on the right.

		  1. When item < content column, centers item in column.
		  2. When content < item < available, left-aligns.
		  3. When item > available, fills available + scroll bar.
		*/
		display: grid;
		grid-template-columns: minmax(0, 50em);
	}
	.overlarge > table {
		/* limit preferred width of table */
		max-width: 50em;
		margin-left: auto;
		margin-right: auto;
	}

	@media (min-width: 55em) {
		.overlarge {
			margin-right: calc(13px + 26.5rem - 50vw);
			max-width: none;
		}
	}
	@media screen and (min-width: 78em) {
		body:not(.toc-inline) .overlarge {
			/* 30.5em body padding 50em content area */
			margin-right: calc(40em - 50vw) !important;
		}
	}
	@media screen and (min-width: 90em) {
		body:not(.toc-inline) .overlarge {
			/* 4em html margin 30.5em body padding 50em content area */
			margin-right: calc(84.5em - 100vw) !important;
		}
	}

	@media not print {
		.overlarge {
			overflow-x: auto;
			/* See Lea Verou's explanation background-attachment:
			* http://lea.verou.me/2012/04/background-attachment-local/
			*
			background: top left  / 4em 100% linear-gradient(to right,  #ffffff, rgba(255, 255, 255, 0)) local,
						top right / 4em 100% linear-gradient(to left, #ffffff, rgba(255, 255, 255, 0)) local,
						top left  / 1em 100% linear-gradient(to right,  #c3c3c5, rgba(195, 195, 197, 0)) scroll,
						top right / 1em 100% linear-gradient(to left, #c3c3c5, rgba(195, 195, 197, 0)) scroll,
						white;
			background-repeat: no-repeat;
			*/
		}
	}
</style>
<style>
    table, th, td {
      border: 1px solid black;
      border-collapse: collapse;
      vertical-align: top;
    }
    th, td {
      border-left: none;
      border-right: none;
      padding: 0px 10px;
    }
    th {
      text-align: center;
    }

    del { background: #fcc; color: #000; text-decoration: line-through; }
    ins { background: #cfc; color: #000; }
    blockquote .highlight:not(.idl) { background: initial; margin: initial; padding: 0.5em }
    blockquote ul { background: inherit; }
    blockquote code.highlight:not(.idl) { padding: initial; }
    blockquote c-[a] { color: inherit; } /* Keyword.Declaration */
    blockquote c-[b] { color: inherit; } /* Keyword.Type */
    blockquote c-[c] { color: inherit; } /* Comment */
    blockquote c-[d] { color: inherit; } /* Comment.Multiline */
    blockquote c-[e] { color: inherit; } /* Name.Attribute */
    blockquote c-[f] { color: inherit; } /* Name.Tag */
    blockquote c-[g] { color: inherit; } /* Name.Variable */
    blockquote c-[k] { color: inherit; } /* Keyword */
    blockquote c-[l] { color: inherit; } /* Literal */
    blockquote c-[m] { color: inherit; } /* Literal.Number */
    blockquote c-[n] { color: inherit; } /* Name */
    blockquote c-[o] { color: inherit; } /* Operator */
    blockquote c-[p] { color: inherit; } /* Punctuation */
    blockquote c-[s] { color: inherit; } /* Literal.String */
    blockquote c-[t] { color: inherit; } /* Literal.String.Single */
    blockquote c-[u] { color: inherit; } /* Literal.String.Double */
    blockquote c-[cp] { color: inherit; } /* Comment.Preproc */
    blockquote c-[c1] { color: inherit; } /* Comment.Single */
    blockquote c-[cs] { color: inherit; } /* Comment.Special */
    blockquote c-[kc] { color: inherit; } /* Keyword.Constant */
    blockquote c-[kn] { color: inherit; } /* Keyword.Namespace */
    blockquote c-[kp] { color: inherit; } /* Keyword.Pseudo */
    blockquote c-[kr] { color: inherit; } /* Keyword.Reserved */
    blockquote c-[ld] { color: inherit; } /* Literal.Date */
    blockquote c-[nc] { color: inherit; } /* Name.Class */
    blockquote c-[no] { color: inherit; } /* Name.Constant */
    blockquote c-[nd] { color: inherit; } /* Name.Decorator */
    blockquote c-[ni] { color: inherit; } /* Name.Entity */
    blockquote c-[ne] { color: inherit; } /* Name.Exception */
    blockquote c-[nf] { color: inherit; } /* Name.Function */
    blockquote c-[nl] { color: inherit; } /* Name.Label */
    blockquote c-[nn] { color: inherit; } /* Name.Namespace */
    blockquote c-[py] { color: inherit; } /* Name.Property */
    blockquote c-[ow] { color: inherit; } /* Operator.Word */
    blockquote c-[mb] { color: inherit; } /* Literal.Number.Bin */
    blockquote c-[mf] { color: inherit; } /* Literal.Number.Float */
    blockquote c-[mh] { color: inherit; } /* Literal.Number.Hex */
    blockquote c-[mi] { color: inherit; } /* Literal.Number.Integer */
    blockquote c-[mo] { color: inherit; } /* Literal.Number.Oct */
    blockquote c-[sb] { color: inherit; } /* Literal.String.Backtick */
    blockquote c-[sc] { color: inherit; } /* Literal.String.Char */
    blockquote c-[sd] { color: inherit; } /* Literal.String.Doc */
    blockquote c-[se] { color: inherit; } /* Literal.String.Escape */
    blockquote c-[sh] { color: inherit; } /* Literal.String.Heredoc */
    blockquote c-[si] { color: inherit; } /* Literal.String.Interpol */
    blockquote c-[sx] { color: inherit; } /* Literal.String.Other */
    blockquote c-[sr] { color: inherit; } /* Literal.String.Regex */
    blockquote c-[ss] { color: inherit; } /* Literal.String.Symbol */
    blockquote c-[vc] { color: inherit; } /* Name.Variable.Class */
    blockquote c-[vg] { color: inherit; } /* Name.Variable.Global */
    blockquote c-[vi] { color: inherit; } /* Name.Variable.Instance */
    blockquote c-[il] { color: inherit; } /* Literal.Number.Integer.Long */
  </style>
  <meta content="Bikeshed version 97a1608be, updated Mon Feb 3 16:09:34 2025 -0800" name="generator">
  <link href="https://github.com/vasama/wg21" rel="canonical">
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 </head><body class="h-entry toc-sidebar"><p id="toc-nav"><a id="toc-jump" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#toc"><span aria-hidden="true">↑</span> <span>Jump to Table of Contents</span></a><a id="toc-toggle" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#toc"><span aria-hidden="true">←</span> <span>Collapse Sidebar</span></a></p>
  <div class="head">
   <p data-fill-with="logo"></p>
   <h1 class="p-name no-ref" id="title">P3492R2<br>Sized deallocation for placement new</h1>
   <h2 class="no-num no-toc no-ref heading settled" id="profile-and-date"><span class="content">Published Proposal, <time class="dt-updated" datetime="2025-02-13">2025-02-13</time></span></h2>
   <div data-fill-with="spec-metadata">
    <dl>
     <dt class="editor">Author:
     </dt><dd class="editor p-author h-card vcard"><a class="p-name fn u-email email" href="mailto:wg21@vasama.org">Lauri Vasama</a>
     </dd><dt>Audience:
     </dt><dd>EWG
     </dd><dt>Project:
     </dt><dd>ISO/IEC 14882 Programming Languages — C++, ISO/IEC JTC1/SC22/WG21
     </dd><dt>Current draft:
     </dt><dd><a href="https://vasama.github.io/wg21/D3492.html">vasama.github.io/wg21/D3492.html</a>
     </dd><dt>Current draft source:
     </dt><dd><a href="https://github.com/vasama/wg21/blob/main/D3492.bs">github.com/vasama/wg21/blob/main/D3492.bs</a>
    </dd></dl>
   </div>
   <div data-fill-with="warning"></div>
   <hr title="Separator for header">
  </div>
  <div class="p-summary" data-fill-with="abstract">
   <h2 class="no-num no-toc no-ref heading settled" id="abstract"><span class="content">Abstract</span></h2>
   <p>Permit the selection of a sized placement deallocation function in new expressions.</p>
  </div>
  <nav data-fill-with="table-of-contents" id="toc">
   <h2 class="no-num no-toc no-ref" id="contents">Table of Contents</h2>
   <ol class="toc" role="directory">
    <li>
     <a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#introduction"><span class="secno">1</span> <span class="content">Introduction</span></a>
     <ol class="toc">
      <li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#introduction_new_delete"><span class="secno">1.1</span> <span class="content">Usual new and delete expressions</span></a>
      </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#introduction_placement_new"><span class="secno">1.2</span> <span class="content">Placement new expressions</span></a>
      </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#introduction_allocators"><span class="secno">1.3</span> <span class="content">Usage with allocators</span></a>
     </li></ol>
    </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#divergence"><span class="secno">2</span> <span class="content">Implementation divergence</span></a>
    </li><li>
     <a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal"><span class="secno">3</span> <span class="content">Proposal</span></a>
     <ol class="toc">
      <li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal_deduced"><span class="secno">3.1</span> <span class="content">Deduced parameters</span></a>
      </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal_ambiguous"><span class="secno">3.2</span> <span class="content">Ambiguities</span></a>
      </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal_alignment"><span class="secno">3.3</span> <span class="content"><code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-></code></span></a>
      </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal_featuretest"><span class="secno">3.4</span> <span class="content">Feature-testing macro</span></a>
      </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal_cwg1628"><span class="secno">3.5</span> <span class="content">CWG1628</span></a>
      </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal_clarification"><span class="secno">3.6</span> <span class="content">Further clarification</span></a>
     </li></ol>
    </li><li>
     <a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#alternatives"><span class="secno">4</span> <span class="content">Alternatives</span></a>
     <ol class="toc">
      <li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#alternatives_function"><span class="secno">4.1</span> <span class="content">Library function</span></a>
     </li></ol>
    </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#implementation"><span class="secno">5</span> <span class="content">Implementation experience</span></a>
    </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#effect"><span class="secno">6</span> <span class="content">Effect on the standard</span></a>
    </li><li>
     <a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#wording"><span class="secno">7</span> <span class="content">Proposed wording</span></a>
     <ol class="toc">
      <li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#wording_newsyn"><span class="secno">7.1</span> <span class="content">[new.syn]</span></a>
      </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#wording_exprnew"><span class="secno">7.2</span> <span class="content">[expr.new]</span></a>
      </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#wording_cpppredefined"><span class="secno">7.3</span> <span class="content">[cpp.predefined]</span></a>
     </li></ol>
    </li><li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#acknowledgements"><span class="secno">8</span> <span class="content">Acknowledgements</span></a>
    </li><li>
     <a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#references"><span class="secno"></span> <span class="content">References</span></a>
     <ol class="toc">
      <li><a href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#informative"><span class="secno"></span> <span class="content">Informative References</span></a>
     </li></ol>
   </li></ol>
  </nav>
  <main>
   <h2 class="heading settled" data-level="1" id="introduction"><span class="secno">1. </span><span class="content">Introduction</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#introduction"></a></h2>
   <h3 class="heading settled" data-level="1.1" id="introduction_new_delete"><span class="secno">1.1. </span><span class="content">Usual new and delete expressions</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#introduction_new_delete"></a></h3>
   <p class="note" role="note"><span class="marker">Note:</span>For simplicity these examples ignore any class specific allocation or deallocation functions.</p>
   <p>Given the new expression <code class="highlight"><c- k="">new</c-> <c- n="">T</c-></code>, the compiler selects an allocation function matching one of the following calls:</p>
   <ul>
    <li data-md="">
     <p><code class="highlight"><c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- k="">sizeof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">))</c-></code></p>
    </li><li data-md="">
     <p><code class="highlight"><c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- k="">sizeof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">),</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-><c- p="">(</c-><c- k="">alignof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">)))</c-></code></p>
   </li></ul>
   <p>Given the delete expression <code class="highlight"><c- k="">delete</c-> <c- n="">t</c-></code>, the compiler selects a deallocation function overload matching one of the following calls:</p>
   <ul>
    <li data-md="">
     <p><code class="highlight"><c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><i><c- n="">storage</c-><c- o="">-</c-><c- n="">ptr</c-></i><c- p="">)</c-></code></p>
    </li><li data-md="">
     <p><code class="highlight"><c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><i><c- n="">storage</c-><c- o="">-</c-><c- n="">ptr</c-></i><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-><c- p="">(</c-><c- k="">alignof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">)))</c-></code></p>
    </li><li data-md="">
     <p><code class="highlight"><c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><i><c- n="">storage</c-><c- o="">-</c-><c- n="">ptr</c-></i><c- p="">,</c-> <c- k="">sizeof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">))</c-></code></p>
    </li><li data-md="">
     <p><code class="highlight"><c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><i><c- n="">storage</c-><c- o="">-</c-><c- n="">ptr</c-></i><c- p="">,</c-> <c- k="">sizeof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">),</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-><c- p="">(</c-><c- k="">alignof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">)))</c-></code></p>
   </li></ul>
   <p>When deallocation functions both with and without size parameters are present, it is unspecified which is selected.</p>
   <p class="note" role="note"><span class="marker">Note:</span>In both cases the preference for passing an alignment value depends on whether <code class="highlight"><c- n="">T</c-></code> has new-extended alignment.</p>
   <p>Going back to the case of <code class="highlight"><c- k="">new</c-> <c- n="">T</c-></code>; if the initialisation of the <code class="highlight"><c- n="">T</c-></code> object were to throw an exception, a <em>matching</em> deallocation function is used to deallocate the previously allocated storage. Currently the wording on this is not very clear, but it can be assumed that the intent is to use the deallocation function selected by <code class="highlight"><c- k="">delete</c-> <c- n="">T</c-></code>. That might mean selecting a deallocation function not exactly matching the parameters of the used allocation function. For example:</p>
   <ul>
    <li data-md="">
     <p><code class="highlight"><c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- k="">sizeof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">))</c-></code></p>
    </li><li data-md="">
     <p><code class="highlight"><c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><i><c- n="">storage</c-><c- o="">-</c-><c- n="">ptr</c-></i><c- p="">,</c-> <c- k="">sizeof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">))</c-></code><br> Here an additional size parameter is passed to the deallocation function.</p>
   </li></ul>
   <h3 class="heading settled" data-level="1.2" id="introduction_placement_new"><span class="secno">1.2. </span><span class="content">Placement new expressions</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#introduction_placement_new"></a></h3>
   <p>Given the placement new expression <code class="highlight"><c- k="">new</c-> <c- p="">(</c-><c- n="">args</c-><c- p="">...)</c-> <c- n="">T</c-></code>, the compiler selects an allocation function matching one of the following calls:</p>
   <ul>
    <li data-md="">
     <p><code class="highlight"><c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- k="">sizeof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">),</c-> <c- n="">args</c-><c- p="">...)</c-></code></p>
    </li><li data-md="">
     <p><code class="highlight"><c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- k="">sizeof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">),</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-><c- p="">(</c-><c- k="">alignof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">)),</c-> <c- n="">args</c-><c- p="">...)</c-></code></p>
   </li></ul>
   <p>If the initialisation of the <code class="highlight"><c- n="">T</c-></code> object were to throw an exception now, the storage may be deallocated <em>if</em> a matching placement deallocation function is found. In this case a deallocation function matches the allocation function if its parameters, after parameter transformations, are all identical to the parameters of the selected placement allocation function, except for the first parameter which is to be <code class="highlight"><c- b="">void</c-><c- o="">*</c-></code>. It is notable that in the case of failed placement new expressions, no deallocation function containing a size parameter will ever be selected. This is unfortunate for the same reasons explained in <a data-link-type="biblio" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#biblio-n3778" title="C++ Sized Deallocation">[N3778]</a> which introduced the global sized deallocation functions.</p>
   <p>Furthermore, unlike global deallocation functions, placement allocation functions are very intentionally provided context for the allocation. Since user allocation schemes are much less constrained than the global allocation and deallocation functions, it is conceivable that a user allocator providing a placement allocation function for ease use might be unable to deallocate the memory without being explicitly provided the size of the allocation. In fact this proposal was created after encountering just that scenario.</p>
   <p class="note" role="note"><span class="marker">Note:</span>The terms placement allocation function and placement deallocation function are not currently defined, but we take them to mean that set of allocation functions which are only ever selected by placement new expressions and not by usual new expressions, and the matching set of deallocation functions. See <a data-link-type="biblio" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#biblio-cwg2592" title="Missing definition for placement allocation/deallocation function">[CWG2592]</a>.</p>
   <h3 class="heading settled" data-level="1.3" id="introduction_allocators"><span class="secno">1.3. </span><span class="content">Usage with allocators</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#introduction_allocators"></a></h3>
   <p>The following pattern, using a custom placement allocation function is somewhat common:</p>
<pre class="highlight"><c- n="">T</c-><c- o="">*</c-> <c- n="">ptr</c-> <c- o="">=</c-> <c- k="">new</c-> <c- p="">(</c-><c- n="">alloc</c-><c- p="">)</c-> <c- n="">T</c-><c- p="">(</c-><c- n="">args</c-><c- p="">...);</c->
</pre>
   <p>If the construction throws an exception, and a matching placement deallocation function exists, it is invoked to free the allocated memory. That deallocation function does not have access to the size of the allocation. Therefore if <code class="highlight"><c- n="">alloc</c-></code> were to follow the standard allocator model, it would not be possible to deallocate the memory, because the standard allocator model requires providing the size of the allocation to its <code class="highlight"><c- n="">deallocate</c-></code> function.</p>
   <h2 class="heading settled" data-level="2" id="divergence"><span class="secno">2. </span><span class="content">Implementation divergence</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#divergence"></a></h2>
   <p>There are two cases of implementation divergence:</p>
   <ol>
    <li data-md="">
     <p>Whether function templates are considered valid candidates and argument deduction is performed. The current standard says no, however EDG alone conforms, and only in the case of global deallocation function templates.</p>
    </li><li data-md="">
     <p>The current wording specifies that if a deleted or inaccessible deallocation function is selected, the program is ill-formed. GCC and EDG are non-conforming in this case.</p>
   </li></ol>
<pre class="highlight"><c- k="">template</c-><c- o="">&lt;</c-><c- b="">int</c-><c- o="">&gt;</c->
<c- k="">struct</c-> <c- nc="">alloc</c-> <c- p="">{};</c->

<c- b="">void</c-><c- o="">*</c-> <c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- b="">size_t</c-><c- p="">,</c-> <c- n="">alloc</c-><c- o="">&lt;</c-><c- mi="">0</c-><c- o="">&gt;&amp;</c-> <c- n="">a</c-><c- p="">);</c->

<c- k="">template</c-><c- o="">&lt;</c-><c- b="">int</c-> <c- n="">I</c-><c- o="">&gt;</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-><c- p="">,</c-> <c- n="">alloc</c-><c- o="">&lt;</c-><c- n="">I</c-><c- o="">&gt;&amp;</c-> <c- n="">a</c-><c- p="">);</c-> <c- c1="">// 1</c->

<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-><c- p="">,</c-> <c- n="">alloc</c-><c- o="">&lt;</c-><c- mi="">0</c-><c- o="">&gt;&amp;</c-> <c- n="">a</c-><c- p="">)</c-> <c- o="">=</c-> <c- k="">delete</c-><c- p="">;</c-> <c- c1="">// 2</c->

<c- b="">int</c-> <c- nf="">main</c-><c- p="">()</c-> <c- p="">{</c->
    <c- n="">alloc</c-><c- o="">&lt;</c-><c- mi="">0</c-><c- o="">&gt;</c-> <c- n="">al</c-><c- p="">;</c->
    <c- k="">new</c-> <c- p="">(</c-><c- n="">al</c-><c- p="">)</c-> <c- n="">thrower</c-><c- p="">();</c->
<c- p="">}</c->
</pre>
   <p>Current implementation behaviour:</p>
   <table>
    <thead>
     <tr>
      <th>
      </th><th>As shown
      </th><th>With 1 removed
      </th><th>With 2 removed
    </th></tr></thead><tbody>
     <tr>
      <th>Clang
      </th><th>Warning: ambiguity
      </th><th>Error: 2 is deleted
      </th><th>Uses 1
     </th></tr><tr>
      <th>GCC
      </th><th>—
      </th><th>—
      </th><th>Uses 1
     </th></tr><tr>
      <th>MSVC
      </th><th>Error: 2 is deleted
      </th><th>Error: 2 is deleted
      </th><th>Uses 1
     </th></tr><tr>
      <th>EDG
      </th><th>—
      </th><th>—
      </th><th>—<sup>1</sup>
   </th></tr></tbody></table>
   <p><sup>1</sup> If the operators are class specific, EDG selects an unambiguous function template (i.e. with 1 removed) only if it is not deleted. If the selected function is deleted, no diagnostic is issued.</p>
   <p>This proposal provides a drive-by fix and a clarification for the two cases respectively:</p>
   <ol>
    <li data-md="">
     <p>The current behaviour of GCC, Clang and MSVC becomes conforming. Only EDG is affected.</p>
    </li><li data-md="">
     <p>The new example added by this proposal in <a href="https://eel.is/c++draft/new.syn">[new.syn]</a> clarifies this case. This change to the standard is non-normative. GCC, MSVC and EDG are non-conforming in different ways.</p>
   </li></ol>
   <h2 class="heading settled" data-level="3" id="proposal"><span class="secno">3. </span><span class="content">Proposal</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal"></a></h2>
   <p>We propose to permit placement new expressions to use two partially matching deallocation functions:</p>
   <ul>
    <li data-md="">
     <p><code class="highlight"><c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><i><c- n="">storage</c-><c- o="">-</c-><c- n="">ptr</c-></i><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-><c- p="">(</c-><c- n="">storage</c-><c- o="">-</c-><c- n="">size</c-><c- p="">),</c-> <c- n="">additional</c-><c- o="">-</c-><c- n="">args</c-><c- p="">...)</c-></code></p>
    </li><li data-md="">
     <p><code class="highlight"><c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><i><c- n="">storage</c-><c- o="">-</c-><c- n="">ptr</c-></i><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-><c- p="">(</c-><c- n="">storage</c-><c- o="">-</c-><c- n="">size</c-><c- p="">),</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-><c- p="">(</c-><c- n="">storage</c-><c- o="">-</c-><c- n="">alignment</c-><c- p="">),</c-> <c- n="">additional</c-><c- o="">-</c-><c- n="">args</c-><c- p="">...)</c-></code></p>
   </li></ul>
   <p>For the backwards compatibility reasons explained in <a data-link-type="biblio" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#biblio-p0035r4" title="Dynamic memory allocation for over-aligned data">[P0035R4]</a>, which introduced <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-></code>, we propose to use a similar type with the name <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-></code> for passing the size of the allocation. This in conjunction with ignoring overloads with deduced <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-></code> parameters prevents changing the meaning of any existing code.</p>
<pre class="highlight"><c- k="">namespace</c-> <c- nn="">std</c-> <c- p="">{</c->
    <c- k="">enum</c-> <c- k="">class</c-> <c- nc="">size_val_t</c-> <c- o="">:</c-> <c- b="">size_t</c-> <c- p="">{};</c->
<c- p="">}</c->
</pre>
   <p>Any matching overloads using <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-></code>, if available, are used in preference to those existing ones without <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-></code>. This is because a deallocation function with access to the size is no less efficient than one without, and thanks to the new <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-></code>, no existing code should have its meaning changed. In addition, the use of <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-></code> allows opting into new safer behaviour where ambiguities are no longer silently ignored.</p>
   <h3 class="heading settled" data-level="3.1" id="proposal_deduced"><span class="secno">3.1. </span><span class="content">Deduced parameters</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal_deduced"></a></h3>
   <p>In order to avoid matching existing placement allocation function <i>templates</i>, no otherwise matching overload is considered if the type of the <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-></code> parameter was deduced.</p>
   <p>Neither of these functions are valid candidates for sized placement deallocation:</p>
<pre class="highlight"><c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">s</c-><c- p="">,</c-> <c- k="">auto</c-><c- p="">...);</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">same_as</c-><c- o="">&lt;</c-><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-><c- o="">&gt;</c-> <c- k="">auto</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">my_allocator</c-><c- o="">&amp;</c-> <c- n="">a</c-><c- p="">)</c->
</pre>
   <h3 class="heading settled" data-level="3.2" id="proposal_ambiguous"><span class="secno">3.2. </span><span class="content">Ambiguities</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal_ambiguous"></a></h3>
   <p>In order to avoid accidental memory leaks, if more than one matching placement allocation function with a <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-></code> is found the program is ill-formed.</p>
<pre class="highlight"><c- k="">template</c-><c- o="">&lt;</c-><c- k="">typename</c-> <c- nc="">T</c-><c- o="">&gt;</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">my_allocator</c-><c- o="">&lt;</c-><c- n="">T</c-><c- o="">&gt;&amp;</c-> <c- n="">a</c-><c- p="">);</c->

<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">my_allocator</c-><c- o="">&lt;</c-><c- n="">U</c-><c- o="">&gt;&amp;</c-> <c- n="">a</c-><c- p="">);</c->

<c- n="">my_allocator</c-><c- o="">&lt;</c-><c- n="">U</c-><c- o="">&gt;</c-> <c- n="">alloc</c-><c- p="">;</c->
<c- k="">new</c-> <c- p="">(</c-><c- n="">alloc</c-><c- p="">)</c-> <c- n="">U</c-><c- p="">;</c-> <c- c1="">// Ill-formed</c->
</pre>
   <p>This is in contrast to existing placement new expressions, where ambiguous placement deallocation functions are simply ignored, as if no matching function was found at all.</p>
   <h3 class="heading settled" data-level="3.3" id="proposal_alignment"><span class="secno">3.3. </span><span class="content"><code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-></code></span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal_alignment"></a></h3>
   <p>If the selected placement allocation function contains an implicit <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-></code> parameter, as per the current rules, a matching placement deallocation function must also contain such a parameter. In this case the new <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-></code> parameter is placed directly after the <code class="highlight"><c- b="">void</c-><c- o="">*</c-></code> parameter and before the <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-></code> parameter if any.</p>
<pre class="highlight"><c- b="">void</c-><c- o="">*</c-> <c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- b="">size_t</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-> <c- n="">a</c-><c- p="">,</c-> <c- n="">my_allocator</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">);</c->

<c- c1="">// The only currently matching overload:</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-> <c- n="">a</c-><c- p="">,</c-> <c- n="">my_allocator</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">);</c->

<c- c1="">// This proposal allows this overload to be matched:</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-> <c- n="">a</c-><c- p="">,</c-> <c- n="">my_allocator</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">);</c->

<c- c1="">// This overload is never used:</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">align_val_t</c-> <c- n="">a</c-><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">my_allocator</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">);</c->
</pre>
   <h3 class="heading settled" data-level="3.4" id="proposal_featuretest"><span class="secno">3.4. </span><span class="content">Feature-testing macro</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal_featuretest"></a></h3>
   <p>Add the following feature test macro: <code class="highlight"><c- n="">__cpp_sized_placement_deallocation</c-></code></p>
   <h3 class="heading settled" data-level="3.5" id="proposal_cwg1628"><span class="secno">3.5. </span><span class="content">CWG1628</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal_cwg1628"></a></h3>
   <p>A partial drive-by fix for the core issue CWG1628 is provided by specifying that the selection of a deallocation function for placement new expressions performs function template argument deduction. This is already the case in GCC, Clang, and MSVC. EDG performs function template argument deduction only for class specific deallocation functions.</p>
   <h3 class="heading settled" data-level="3.6" id="proposal_clarification"><span class="secno">3.6. </span><span class="content">Further clarification</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#proposal_clarification"></a></h3>
   <p>The new wording provided in this proposal further clarifies two cases according to the existing behaviour of implementations:</p>
   <ol>
    <li data-md="">
     <p>This proposal contains new normative wording specifying that the variadicity of a placement deallocation function must match that of the allocation function in order to be selected. This exactly matches the behaviour of existing implementations:</p>
<pre class="highlight"><c- b="">void</c-><c- o="">*</c-> <c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- b="">size_t</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">alloc_1</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">,</c-> <c- p="">...);</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">alloc_1</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">);</c-> <c- c1="">// Never used</c->

<c- b="">void</c-><c- o="">*</c-> <c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- b="">size_t</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">alloc_2</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">);</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">alloc_2</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">,</c-> <c- p="">...);</c-> <c- c1="">// Never used</c->
</pre>
    </li><li data-md="">
     <p>This proposal contains a new non-normative note clarifying that additional trailing parameters with default arguments in a deallocation function declaration prevent an exact match. This exactly matches the behaviour of existing implementations:</p>
<pre class="highlight"><c- b="">void</c-><c- o="">*</c-> <c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- b="">size_t</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">alloc</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">);</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">alloc</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">,</c-> <c- b="">int</c-> <c- o="">=</c-> <c- mi="">0</c-><c- p="">);</c-> <c- c1="">// Never used</c->
</pre>
   </li></ol>
   <h2 class="heading settled" data-level="4" id="alternatives"><span class="secno">4. </span><span class="content">Alternatives</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#alternatives"></a></h2>
   <h3 class="heading settled" data-level="4.1" id="alternatives_function"><span class="secno">4.1. </span><span class="content">Library function</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#alternatives_function"></a></h3>
   <p>Any discussion of placement new and its deallocation behaviour raises the obvious question of placement deletion. Suppose one uses the placement new syntax to create objects of dynamic storage duration using some custom allocator: <code class="highlight"><c- k="">new</c-> <c- p="">(</c-><c- n="">alloc</c-><c- p="">)</c-> <c- n="">T</c-></code>. How does one then delete those objects? If explicit deletion is needed at all, most likely that is achieved using a function template taking the allocator and a pointer to the object to be deleted:</p>
<pre class="highlight"><c- k="">template</c-><c- o="">&lt;</c-><c- k="">typename</c-> <c- nc="">Allocator</c-><c- p="">,</c-> <c- k="">typename</c-> <c- nc="">T</c-><c- o="">&gt;</c->
<c- b="">void</c-> <c- n="">delete_via</c-><c- p="">(</c-><c- n="">Allocator</c-> <c- k="">const</c-><c- o="">&amp;</c-> <c- n="">allocator</c-><c- p="">,</c-> <c- n="">T</c-><c- o="">*</c-> <c- k="">const</c-> <c- n="">ptr</c-><c- p="">)</c->
<c- p="">{</c->
    <c- n="">std</c-><c- o="">::</c-><c- n="">destroy_at</c-><c- p="">(</c-><c- n="">ptr</c-><c- p="">);</c->
    <c- n="">allocator</c-><c- p="">.</c-><c- n="">deallocate</c-><c- p="">(</c-><c- n="">ptr</c-><c- p="">,</c-> <c- k="">sizeof</c-><c- p="">(</c-><c- n="">T</c-><c- p="">));</c->
<c- p="">}</c->

<c- n="">delete_via</c-><c- p="">(</c-><c- n="">alloc</c-><c- p="">,</c-> <c- k="">new</c-> <c- p="">(</c-><c- n="">alloc</c-><c- p="">)</c-> <c- n="">T</c-><c- p="">);</c->
</pre>
   <p>Or possibly by a more general function template implementing placement delete via calls to placement deallocation functions:</p>
<pre class="highlight"><c- n="">delete_via</c-><c- p="">(</c-><c- n="">alloc</c-><c- p="">)(</c-> <c- k="">new</c-> <c- p="">(</c-><c- n="">alloc</c-><c- p="">)</c-> <c- n="">T</c-> <c- p="">);</c->
</pre>
   <p><strong>Why then, should we not also use a function template for the object creation instead of placement new?</strong></p>
<pre class="highlight"><c- k="">template</c-><c- o="">&lt;</c-><c- k="">typename</c-> <c- nc="">T</c-><c- p="">,</c-> <c- k="">typename</c-> <c- nc="">Allocator</c-><c- p="">,</c-> <c- k="">typename</c-><c- p="">...</c-> <c- n="">Args</c-><c- o="">&gt;</c->
    <c- k="">requires</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">constructible_from</c-><c- o="">&lt;</c-><c- n="">T</c-><c- p="">,</c-> <c- n="">Args</c-><c- p="">...</c-><c- o="">&gt;</c->
<c- n="">T</c-><c- o="">*</c-> <c- n="">new_via</c-><c- p="">(</c-><c- n="">Allocator</c-> <c- k="">const</c-><c- o="">&amp;</c-> <c- n="">allocator</c-><c- p="">,</c-> <c- n="">Args</c-><c- o="">&amp;&amp;</c-><c- p="">...</c-> <c- n="">args</c-><c- p="">);</c->

<c- c1="">// new (alloc) T(a, b, c);</c->
<c- n="">new_via</c-><c- o="">&lt;</c-><c- n="">T</c-><c- o="">&gt;</c-><c- p="">(</c-><c- n="">alloc</c-><c- p="">,</c-> <c- n="">a</c-><c- p="">,</c-> <c- n="">b</c-><c- p="">,</c-> <c- n="">c</c-><c- p="">);</c->
</pre>
   <p>That is indeed possible and allows one to solve the problem in library, but there are some major drawbacks:</p>
   <ol>
    <li data-md="">
     <p><strong>Syntax</strong><br> The placement new syntax provides direct syntactic access to the object initialisation, which has real benefits:</p>
     <ul>
      <li data-md="">
       <p>An <code class="highlight"><c- n="">emplace</c-></code>-like function tends to lose IDE hints pertaining to the constructors of the type <code class="highlight"><c- n="">T</c-></code> being initialised.</p>
      </li><li data-md="">
       <p>Directly initialising the object allows for more expressive forms of initialisation, such as designated initialisation:</p>
<pre class="highlight"><c- k="">new</c-> <c- p="">(</c-><c- n="">alloc</c-><c- p="">)</c-> <c- n="">T</c-><c- p="">{</c-> <c- p="">.</c-><c- n="">a</c-> <c- o="">=</c-> <c- n="">x</c-><c- p="">,</c-> <c- p="">.</c-><c- n="">b</c-> <c- o="">=</c-> <c- n="">y</c-> <c- p="">}</c-></pre>
      </li><li data-md="">
       <p>The initialisation of <code class="highlight"><c- n="">T</c-></code> requires access to its constructors. If those constructors are not publicly accessible, <code class="highlight"><c- n="">new_via</c-></code> does not have access to them, unless befriended. Direct use of placement new has no such limitation.</p>
     </li></ul>
     <p>These things can still of course be achieved in library using a lambda, but this further degrades the user experience:</p>
<pre class="highlight"><c- n="">new_from_result_of</c-><c- p="">(</c-><c- n="">alloc</c-><c- p="">,</c-> <c- p="">[</c-><c- o="">&amp;</c-><c- p="">]()</c-> <c- p="">{</c-> <c- k="">return</c-> <c- n="">T</c-><c- p="">{</c-> <c- p="">.</c-><c- n="">a</c-> <c- o="">=</c-> <c- n="">x</c-><c- p="">,</c-> <c- p="">.</c-><c- n="">b</c-> <c- o="">=</c-> <c- n="">y</c-> <c- p="">};</c-> <c- p="">})</c-></pre>
     <p><br></p>
    </li><li data-md="">
     <p><strong>Existing usage</strong><br> The placement new syntax already exists and is widely used. Instead of inventing a new library alternative, we can improve the performance of code already out there and enable the same code to work correctly with new kinds of user-defined allocators.</p>
   </li></ol>
   <h2 class="heading settled" data-level="5" id="implementation"><span class="secno">5. </span><span class="content">Implementation experience</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#implementation"></a></h2>
   <p>This proposal was implemented in Clang at <a href="https://github.com/vasama/llvm/tree/P3492">github.com/vasama/llvm (branch P3492)</a>.</p>
   <p>This implementation was tested against large real world code bases that make extensive use of placement allocation functions and function templates, including function templates containing deduced parameter packs.</p>
   <h2 class="heading settled" data-level="6" id="effect"><span class="secno">6. </span><span class="content">Effect on the standard</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#effect"></a></h2>
   <ul>
    <li data-md="">
     <p>Adds one scoped enum in the standard library: <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-></code>.</p>
    </li><li data-md="">
     <p>Changes the selection of a deallocation function <u>only for placement</u> new expressions.</p>
    </li><li data-md="">
     <p>Adds a feature-testing macro: <code class="highlight"><c- n="">__cpp_sized_placement_deallocation</c-></code>.</p>
    </li><li data-md="">
     <p>Partially solves <a data-link-type="biblio" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#biblio-cwg1628" title="Deallocation function templates">[CWG1628]</a> by applying template argument deduction to placement deallocation function templates.</p>
   </li></ul>
   <h2 class="heading settled" data-level="7" id="wording"><span class="secno">7. </span><span class="content">Proposed wording</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#wording"></a></h2>
   <h3 class="heading settled" data-level="7.1" id="wording_newsyn"><span class="secno">7.1. </span><span class="content">[new.syn]</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#wording_newsyn"></a></h3>
   <p>Modify <a href="https://eel.is/c++draft/new.syn">[new.syn]</a> as follows:</p>
   <blockquote>
<pre class="highlight"><c- k="">namespace</c-> <c- nn="">std</c-> <c- p="">{</c->
<ins>    <c- c1="">// placement operator new control</c->
    <c- k="">enum</c-> <c- k="">class</c-> <c- nc="">size_val_t</c-> <c- o="">:</c-> <c- b="">size_t</c-> <c- p="">{};</c-></ins>
<c- p="">}</c->
</pre>
   </blockquote>
   <h3 class="heading settled" data-level="7.2" id="wording_exprnew"><span class="secno">7.2. </span><span class="content">[expr.new]</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#wording_exprnew"></a></h3>
   <p>Modify <a href="https://eel.is/c++draft/expr.new">[expr.new]</a> as follows:</p>
   <blockquote>
     If the <i>new-expression</i> does not begin with a unary ​<code class="highlight"><c- o="">::</c-></code>​ operator and the allocated type is a class type <code class="highlight"><c- n="">T</c-></code> or an array thereof, a search is performed for the deallocation function’s name in the scope of <code class="highlight"><c- n="">T</c-></code>. Otherwise, or if nothing is found, the deallocation function’s name is looked up by searching for it in the global scope. 
    <ins>The set of lookup results are the <i>candidates</i> used in the placement deallocation function selection process.</ins>
   </blockquote>
   <blockquote>
    <ins> For a placement allocation function, the selection of a placement deallocation function is first attempted using a prvalue argument of type <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-></code> immediately following the first argument. This is called the <i>size argument</i>. If the selection process terminates without having selected a deallocation function, the process is restarted without the size argument. The first argument together with the size argument (if any) are called the <i>implicit arguments</i>. <br> A placement deallocation function is selected as follows: </ins>
    <ul>
     <li data-md="">
      <ins>If a size argument is used, eliminate from further consideration any templated functions where the type of the second parameter is dependent.</ins>
     </li><li data-md="">
      <ins>In each case where a candidate is a function template, candidate function template specializations are generated using template argument deduction ([temp.over], [temp.deduct]). The arguments used for the deduction are the implicit arguments followed by the additional arguments.</ins>
     </li><li data-md="">
      <ins>Eliminate from further consideration any functions whose <i>parameter-declaration-clause</i> terminates with an ellipsis, but that of the allocation function does not.</ins>
     </li><li data-md="">
      <ins>Eliminate from further consideration any functions whose <i>parameter-declaration-clause</i> does not terminate with an ellipsis, but that of the allocation function does.</ins>
     </li><li data-md="">
      <ins>Eliminate from further consideration any functions where the number of parameters is not equal to the sum of the number of implicit arguments and the number of additional arguments.</ins>
     </li><li data-md="">
      <ins>Eliminate from further consideration any functions where, after parameter transformations ([dcl.fct]), the types of the function parameters are not identical to the types of the implicit arguments followed by the types of the parameters of the allocation function except its first parameter.</ins>
     </li><li data-md="">
      <ins>If exactly one function remains, that function is selected and the selection process terminates.</ins>
     </li><li data-md="">
      <ins>Otherwise, if an implicit size argument was used, the program is ill-formed.</ins>
     </li><li data-md="">
      <ins>Otherwise, the selection process terminates without having selected a deallocation function.</ins>
    </li></ul>
    <ins>[Note: A deallocation function with an additional trailing parameter compared to the allocation function is never matched, even if a default argument is provided. —end note]</ins>
   </blockquote>
   <blockquote>
    <del> A declaration of a placement deallocation function matches the declaration of a placement allocation function if it has the same number of parameters and, after parameter transformations ([dcl.fct]), all parameter types except the first are identical. If the lookup finds a single matching deallocation function, that function will be called; otherwise, no deallocation function will be called. If the lookup finds a usual deallocation function and that function, considered as a placement deallocation function, would have been selected as a match for the allocation function, the program is ill-formed.</del>
     For a non-placement allocation function, the normal deallocation function lookup is used to find the matching deallocation function ([expr.delete]). In any case, the matching deallocation function (if any) shall be non-deleted and accessible from the point where the <i>new-expression</i> appears. 
   </blockquote>
   <p>The following examples are entirely new, but are not highlighted in green in order to improve readability:</p>
   <ins>[Example:</ins>
<pre class="highlight"><c- k="">struct</c-> <c- nc="">A</c-> <c- p="">{};</c->
<c- k="">struct</c-> <c- nc="">T</c-> <c- p="">{};</c->

<c- b="">void</c-><c- o="">*</c-> <c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- n="">std</c-><c- o="">::</c-><c- b="">size_t</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">A</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">);</c-> <c- c1="">// #1</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">A</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">);</c-> <c- c1="">// #2</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-> <c- n="">x</c-><c- p="">,</c-> <c- n="">A</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">);</c-> <c- c1="">// #3</c->

<c- n="">A</c-> <c- n="">al</c-><c- p="">;</c->
<c- k="">new</c-> <c- p="">(</c-><c- n="">al</c-><c- p="">)</c-> <c- n="">T</c-><c- p="">();</c-> <c- c1="">// Uses #1 and #3.</c->
</pre>
   <ins>—end example]</ins>
   <br> 
   <ins>[Example:</ins>
<pre class="highlight"><c- k="">template</c-><c- o="">&lt;</c-><c- b="">int</c-> <c- n="">I</c-><c- o="">&gt;</c->
<c- k="">struct</c-> <c- nc="">A</c-> <c- p="">{};</c->
<c- k="">struct</c-> <c- nc="">T</c-> <c- p="">{};</c->

<c- b="">void</c-><c- o="">*</c-> <c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- n="">std</c-><c- o="">::</c-><c- b="">size_t</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">A</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">);</c->

<c- k="">template</c-><c- o="">&lt;</c-><c- b="">int</c-> <c- n="">I</c-><c- o="">&gt;</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-> <c- n="">x</c-><c- p="">,</c-> <c- n="">A</c-><c- o="">&lt;</c-><c- n="">I</c-><c- o="">&gt;&amp;</c-> <c- n="">al</c-><c- p="">);</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-> <c- n="">x</c-><c- p="">,</c-> <c- n="">A</c-><c- o="">&lt;</c-><c- mi="">0</c-><c- o="">&gt;&amp;</c-> <c- n="">al</c-><c- p="">);</c->

<c- n="">A</c-><c- o="">&lt;</c-><c- mi="">0</c-><c- o="">&gt;</c-> <c- n="">al</c-><c- p="">;</c->
<c- k="">new</c-> <c- p="">(</c-><c- n="">al</c-><c- p="">)</c-> <c- n="">T</c-><c- p="">();</c-> <c- c1="">// error: ambiguous deallocation function</c->
</pre>
   <ins>—end example]</ins>
   <br> 
   <ins>[Example:</ins>
<pre class="highlight"><c- k="">struct</c-> <c- nc="">A</c-> <c- p="">{};</c->
<c- k="">struct</c-> <c- nc="">T</c-> <c- p="">{};</c->

<c- b="">void</c-><c- o="">*</c-> <c- k="">operator</c-> <c- k="">new</c-><c- p="">(</c-><c- n="">std</c-><c- o="">::</c-><c- b="">size_t</c-> <c- n="">s</c-><c- p="">,</c-> <c- n="">A</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">);</c->
<c- b="">void</c-> <c- k="">operator</c-> <c- k="">delete</c-><c- p="">(</c-><c- b="">void</c-><c- o="">*</c-> <c- n="">p</c-><c- p="">,</c-> <c- n="">A</c-><c- o="">&amp;</c-> <c- n="">al</c-><c- p="">)</c-> <c- o="">=</c-> <c- k="">delete</c-><c- p="">;</c->

<c- n="">A</c-> <c- n="">al</c-><c- p="">;</c->
<c- k="">new</c-> <c- p="">(</c-><c- n="">al</c-><c- p="">)</c-> <c- n="">T</c-><c- p="">();</c-> <c- c1="">// error: attempted to use deleted function</c->
</pre>
   <ins>—end example]</ins>
   <p>
    If a <i>new-expression</i> calls a deallocation function, it passes the value returned from the allocation function call as the first argument of type <code class="highlight"><c- b="">void</c-><c- o="">*</c-></code>. 
    <ins>If a placement deallocation function with a parameter corresponding to an implicit size argument is called, it is passed the size argument used for the allocation function converted to <code class="highlight"><c- n="">std</c-><c- o="">::</c-><c- n="">size_val_t</c-></code>.</ins>
     If a placement deallocation function is called, it is passed the same additional arguments as were passed to the placement allocation function, that is, the same arguments as those specified with the <i>new-placement syntax</i>. If the implementation is allowed to introduce a temporary object or make a copy of any argument as part of the call to the allocation function, it is unspecified whether the same object is used in the call to both the allocation and deallocation functions.
   </p>
   <h3 class="heading settled" data-level="7.3" id="wording_cpppredefined"><span class="secno">7.3. </span><span class="content">[cpp.predefined]</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#wording_cpppredefined"></a></h3>
   <p>Add the following row to the table in <a href="https://eel.is/c++draft/cpp.predefined">[cpp.predefined]</a>:</p>
   <table class="def">
    <tbody>
     <tr>
      <th><code class="highlight"><c- n="">__cpp_sized_placement_deallocation</c-></code>
      </th><td><code class="highlight"><c- mf="">202502L</c-></code>
   </td></tr></tbody></table>
   <h2 class="heading settled" data-level="8" id="acknowledgements"><span class="secno">8. </span><span class="content">Acknowledgements</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#acknowledgements"></a></h2>
   <p>Big thanks to Oliver Hunt for the help.</p>
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  <h2 class="no-num no-ref heading settled" id="references"><span class="content">References</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#references"></a></h2>
  <h3 class="no-num no-ref heading settled" id="informative"><span class="content">Informative References</span><a class="self-link" href="https://wiki.edg.com/pub/Wg21hagenberg2025/EvolutionWorkingGroup/P3492R2.html#informative"></a></h3>
  <dl>
   <dt id="biblio-cwg1628">[CWG1628]
   </dt><dd>Richard Smith. <a href="https://wg21.link/cwg1628"><cite>Deallocation function templates</cite></a>. 22 February 2013. open. URL: <a href="https://wg21.link/cwg1628">https://wg21.link/cwg1628</a>
   </dd><dt id="biblio-cwg2592">[CWG2592]
   </dt><dd>Jim X. <a href="https://wg21.link/cwg2592"><cite>Missing definition for placement allocation/deallocation function</cite></a>. 14 April 2022. open. URL: <a href="https://wg21.link/cwg2592">https://wg21.link/cwg2592</a>
   </dd><dt id="biblio-n3778">[N3778]
   </dt><dd>Lawrence Crowl. <a href="https://wg21.link/n3778"><cite>C++ Sized Deallocation</cite></a>. 27 September 2013. URL: <a href="https://wg21.link/n3778">https://wg21.link/n3778</a>
   </dd><dt id="biblio-p0035r4">[P0035R4]
   </dt><dd>Clark Nelson. <a href="https://wg21.link/p0035r4"><cite>Dynamic memory allocation for over-aligned data</cite></a>. 21 June 2016. URL: <a href="https://wg21.link/p0035r4">https://wg21.link/p0035r4</a>
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