<!doctype html><html lang="en">
 <head>
  <meta content="text/html; charset=utf-8" http-equiv="Content-Type">
  <meta content="width=device-width, initial-scale=1, shrink-to-fit=no" name="viewport">
  <title>P2077R1: Heterogeneous erasure overloads for associative containers</title>
<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
 *
 * 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)
 *   - .assertion  for assertions                    (div, p, span)
 *   - .advisement for loud normative statements     (div, p, strong)
 *   - .annoying-warning for spec obsoletion notices (div, aside, details)
 *
 * 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
 *
 * 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)
 *
 ******************************************************************************/

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

	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;

		/* Colors */
		color: black;
		background: white 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-width: .65rem .7rem .6rem;
		border-radius: .4rem;
		background: #1a5e9a;
		color: white;
		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;
		border-color: #c00;
	}

	/* 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: 2;
			bottom: 0; left: 0;
			margin: 0;
			min-width: 1.33em;
			border-top-right-radius: 2rem;
			box-shadow: 0 0 2px;
			font-size: 1.5em;
			color: black;
		}
		#toc-nav > a {
			display: block;
			white-space: nowrap;

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

			background: white;
			box-shadow: 0 0 2px;
			border: none;
			border-top-right-radius: 1.33em;
			background: white;
		}
		#toc-nav > #toc-jump {
			padding-bottom: 2em;
			margin-bottom: -1.9em;
		}

		#toc-nav > a:hover,
		#toc-nav > a:focus {
			background: #f8f8f8;
		}
		#toc-nav > a:not(:hover):not(:focus) {
			color: #707070;
		}

		/* 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-toggle-inline {
			vertical-align: 0.05em;
			font-size: 80%;
			color: gray;
			color: hsla(203,20%,40%,.7);
			border-style: none;
			background: transparent;
			position: relative;
		}
		#toc-toggle-inline:hover:not(:active),
		#toc-toggle-inline:focus:not(:active) {
			text-shadow: 1px 1px silver;
			top: -1px;
			left: -1px;
		}

		#toc-nav :active {
			color: #C00;
		}
	}

/** 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);
			background: inherit;
			background-color: #f7f8f9;
			z-index: 1;
			box-shadow: -.1em 0 .25em rgba(0,0,0,.1) 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);
		}
		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);
			background: inherit;
			background-color: #f7f8f9;
			z-index: 1;
			box-shadow: -.1em 0 .25em rgba(0,0,0,.1) 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);
		}

		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;
		background: transparent;
	}

	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,
	#subtitle {
		/* #subtitle 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) > hr {
		font-size: 1.5em;
		text-align: center;
		margin: 1em auto;
		height: auto;
		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;
	}

	/* Put nice boxes around each algorithm. */
	[data-algorithm]:not(.heading) {
	  padding: .5em;
	  border: thin solid #ddd; 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: medium;
	}
	dfn var {
		font-style: normal;
	}

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

	del { color: red;  text-decoration: line-through; }
	ins { color: #080; text-decoration: underline;    }

/** 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;
		page-break-inside: avoid;
		hyphens: none;
		text-transform: none;
	}
	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;
		text-decoration: none;
		border-bottom: 1px solid #707070;
		/* Need a bit of extending for it to look okay */
		padding: 0 1px 0;
		margin: 0 -1px 0;
	}
	a:visited {
		border-bottom-color: #BBB;
	}

	/* Use distinguishing colors when user is interacting with the link */
	a[href]:focus,
	a[href]:hover {
		background: #f8f8f8;
		background: rgba(75%, 75%, 75%, .25);
		border-bottom-width: 3px;
		margin-bottom: -2px;
	}
	a[href]:active {
		color: #C00;
		border-color: #C00;
	}

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

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

	img {
		border-style: none;
	}

	/* 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;
	}
	.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 {
		padding: .5em;
		border: .5em;
		border-left-style: solid;
		page-break-inside: avoid;
	}
	span.issue, span.note {
		padding: .1em .5em .15em;
		border-right-style: solid;
	}

	.issue,
	.note,
	.example,
	.advisement,
	.assertion,
	blockquote {
		margin: 1em auto;
	}
	.note  > p:first-child,
	.issue > p:first-child,
	blockquote > :first-child {
		margin-top: 0;
	}
	blockquote > :last-child {
		margin-bottom: 0;
	}

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

	blockquote {
		border-color: silver;
	}

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

	.issue {
		border-color: #E05252;
		background: #FBE9E9;
		counter-increment: issue;
		overflow: auto;
	}
	.issue::before, .issue > .marker {
		text-transform: uppercase;
		color: #AE1E1E;
		padding-right: 1em;
		text-transform: uppercase;
	}
	/* 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;
		background: #FCFAEE;
		counter-increment: example;
		overflow: auto;
		clear: both;
	}
	.example::before, .example > .marker {
		text-transform: uppercase;
		color: #827017;
		min-width: 7.5em;
		display: block;
	}
	/* 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;
		background: #E9FBE9;
		overflow: auto;
	}

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

	details.note > summary {
		display: block;
		color: hsl(120, 70%, 30%);
	}
	details.note[open] > summary {
		border-bottom: 1px silver solid;
	}

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

	.assertion {
		border-color: #AAA;
		background: #EEE;
	}

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

	.advisement {
		border-color: orange;
		border-style: none solid;
		background: #FFEECC;
	}
	strong.advisement {
		display: block;
		text-align: center;
	}
	.advisement > .marker {
		color: #B35F00;
	}

/** 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: #fdd;
		color: red;
		font-weight: bold;
		padding: .75em 1em;
		border: thick red;
		border-style: solid;
		border-radius: 1em;
	}
	.annoying-warning :last-child {
		margin-bottom: 0;
	}

@media not print {
	details.annoying-warning[open] {
		position: fixed;
		left: 1em;
		right: 1em;
		bottom: 1em;
		z-index: 1000;
	}
}

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

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

	.def {
		padding: .5em 1em;
		background: #DEF;
		margin: 1.2em 0;
		border-left: 0.5em solid #8CCBF2;
	}

/******************************************************************************/
/*                                    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;
	}

	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-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;
		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;
		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-top: 0.1rem;
		/* Larger, more consistently-sized click target */
		display: block;
		/* Reverse color scheme */
		color: black;
		border-color: #3980B5;
		border-bottom-width: 3px !important;
		margin-bottom: 0px !important;
	}
	.toc a:visited {
		border-color: #054572;
	}
	.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;
		line-height: 1.1rem; /* consistent spacing */
	}

	/* 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 .secno { font-size: 85%; }
	.toc > li li li li li { font-size:   85%;    }
	.toc > li li li li li .secno { font-size: 100%; }

	/* @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 {
			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; }
		}
	/* } */

	@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;
		}
		#toc .content:hover {
			background: rgba(75%, 75%, 75%, .25);
			border-bottom: 3px solid #054572;
			margin-bottom: -3px;
		}
		#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 span {
			white-space: nowrap;
			color: transparent; }
		ul.index li a:hover + span,
		ul.index li a:focus + span {
			color: #707070;
		}
	}

/** 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]) {
		background: #f7f8f9;
	}

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

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

	@media print {
		/* Pages have their own margins. */
		html {
			margin: 0;
		}
		/* Serif for print. */
		body {
			font-family: serif;
		}
	}
	@page {
		margin: 1.5cm 1.1cm;
	}

/******************************************************************************/
/*                                    Legacy                                  */
/******************************************************************************/

	/* This rule is inherited from past style sheets. No idea what it's for. */
	.hide { display: none }



/******************************************************************************/
/*                             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 table positioning:
		   "content column" is 50ems wide at max; less on smaller screens.
		   Extra space (after ToC + content) is empty on the right.

		   1. When table < content column, centers table in column.
		   2. When content < table < available, left-aligns.
		   3. When table > 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 type="text/css">
    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 5f7b0e20, updated Tue Aug 18 15:46:28 2020 -0700" name="generator">
  <link href="http://wg21.link/P2077R1" rel="canonical">
  <link href="https://isocpp.org/favicon.ico" rel="icon">
  <meta content="356ec2226285c88ffd4df5ab7688e8f7281d146f" name="document-revision">
<style>
img.resize {
  max-width:75%;
  max-height:75%;
}
</style>
<style>/* style-autolinks */

.css.css, .property.property, .descriptor.descriptor {
    color: #005a9c;
    font-size: inherit;
    font-family: inherit;
}
.css::before, .property::before, .descriptor::before {
    content: "‘";
}
.css::after, .property::after, .descriptor::after {
    content: "’";
}
.property, .descriptor {
    /* Don't wrap property and descriptor names */
    white-space: nowrap;
}
.type { /* CSS value <type> */
    font-style: italic;
}
pre .property::before, pre .property::after {
    content: "";
}
[data-link-type="property"]::before,
[data-link-type="propdesc"]::before,
[data-link-type="descriptor"]::before,
[data-link-type="value"]::before,
[data-link-type="function"]::before,
[data-link-type="at-rule"]::before,
[data-link-type="selector"]::before,
[data-link-type="maybe"]::before {
    content: "‘";
}
[data-link-type="property"]::after,
[data-link-type="propdesc"]::after,
[data-link-type="descriptor"]::after,
[data-link-type="value"]::after,
[data-link-type="function"]::after,
[data-link-type="at-rule"]::after,
[data-link-type="selector"]::after,
[data-link-type="maybe"]::after {
    content: "’";
}

[data-link-type].production::before,
[data-link-type].production::after,
.prod [data-link-type]::before,
.prod [data-link-type]::after {
    content: "";
}

[data-link-type=element],
[data-link-type=element-attr] {
    font-family: Menlo, Consolas, "DejaVu Sans Mono", monospace;
    font-size: .9em;
}
[data-link-type=element]::before { content: "<" }
[data-link-type=element]::after  { content: ">" }

[data-link-type=biblio] {
    white-space: pre;
}</style>
<style>/* style-counters */

body {
    counter-reset: example figure issue;
}
.issue {
    counter-increment: issue;
}
.issue:not(.no-marker)::before {
    content: "Issue " counter(issue);
}

.example {
    counter-increment: example;
}
.example:not(.no-marker)::before {
    content: "Example " counter(example);
}
.invalid.example:not(.no-marker)::before,
.illegal.example:not(.no-marker)::before {
    content: "Invalid Example" counter(example);
}

figcaption {
    counter-increment: figure;
}
figcaption:not(.no-marker)::before {
    content: "Figure " counter(figure) " ";
}</style>
<style>/* style-md-lists */

/* This is a weird hack for me not yet following the commonmark spec
   regarding paragraph and lists. */
[data-md] > :first-child {
    margin-top: 0;
}
[data-md] > :last-child {
    margin-bottom: 0;
}</style>
<style>/* style-selflinks */

.heading, .issue, .note, .example, li, dt {
    position: relative;
}
a.self-link {
    position: absolute;
    top: 0;
    left: calc(-1 * (3.5rem - 26px));
    width: calc(3.5rem - 26px);
    height: 2em;
    text-align: center;
    border: none;
    transition: opacity .2s;
    opacity: .5;
}
a.self-link:hover {
    opacity: 1;
}
.heading > a.self-link {
    font-size: 83%;
}
li > a.self-link {
    left: calc(-1 * (3.5rem - 26px) - 2em);
}
dfn > a.self-link {
    top: auto;
    left: auto;
    opacity: 0;
    width: 1.5em;
    height: 1.5em;
    background: gray;
    color: white;
    font-style: normal;
    transition: opacity .2s, background-color .2s, color .2s;
}
dfn:hover > a.self-link {
    opacity: 1;
}
dfn > a.self-link:hover {
    color: black;
}

a.self-link::before            { content: "¶"; }
.heading > a.self-link::before { content: "§"; }
dfn > a.self-link::before      { content: "#"; }</style>
<style>/* style-syntax-highlighting */

.highlight:not(.idl) { background: hsl(24, 20%, 95%); }
code.highlight { padding: .1em; border-radius: .3em; }
pre.highlight, pre > code.highlight { display: block; padding: 1em; margin: .5em 0; overflow: auto; border-radius: 0; }
c-[a] { color: #990055 } /* Keyword.Declaration */
c-[b] { color: #990055 } /* Keyword.Type */
c-[c] { color: #708090 } /* Comment */
c-[d] { color: #708090 } /* Comment.Multiline */
c-[e] { color: #0077aa } /* Name.Attribute */
c-[f] { color: #669900 } /* Name.Tag */
c-[g] { color: #222222 } /* Name.Variable */
c-[k] { color: #990055 } /* Keyword */
c-[l] { color: #000000 } /* Literal */
c-[m] { color: #000000 } /* Literal.Number */
c-[n] { color: #0077aa } /* Name */
c-[o] { color: #999999 } /* Operator */
c-[p] { color: #999999 } /* Punctuation */
c-[s] { color: #a67f59 } /* Literal.String */
c-[t] { color: #a67f59 } /* Literal.String.Single */
c-[u] { color: #a67f59 } /* Literal.String.Double */
c-[cp] { color: #708090 } /* Comment.Preproc */
c-[c1] { color: #708090 } /* Comment.Single */
c-[cs] { color: #708090 } /* Comment.Special */
c-[kc] { color: #990055 } /* Keyword.Constant */
c-[kn] { color: #990055 } /* Keyword.Namespace */
c-[kp] { color: #990055 } /* Keyword.Pseudo */
c-[kr] { color: #990055 } /* Keyword.Reserved */
c-[ld] { color: #000000 } /* Literal.Date */
c-[nc] { color: #0077aa } /* Name.Class */
c-[no] { color: #0077aa } /* Name.Constant */
c-[nd] { color: #0077aa } /* Name.Decorator */
c-[ni] { color: #0077aa } /* Name.Entity */
c-[ne] { color: #0077aa } /* Name.Exception */
c-[nf] { color: #0077aa } /* Name.Function */
c-[nl] { color: #0077aa } /* Name.Label */
c-[nn] { color: #0077aa } /* Name.Namespace */
c-[py] { color: #0077aa } /* Name.Property */
c-[ow] { color: #999999 } /* Operator.Word */
c-[mb] { color: #000000 } /* Literal.Number.Bin */
c-[mf] { color: #000000 } /* Literal.Number.Float */
c-[mh] { color: #000000 } /* Literal.Number.Hex */
c-[mi] { color: #000000 } /* Literal.Number.Integer */
c-[mo] { color: #000000 } /* Literal.Number.Oct */
c-[sb] { color: #a67f59 } /* Literal.String.Backtick */
c-[sc] { color: #a67f59 } /* Literal.String.Char */
c-[sd] { color: #a67f59 } /* Literal.String.Doc */
c-[se] { color: #a67f59 } /* Literal.String.Escape */
c-[sh] { color: #a67f59 } /* Literal.String.Heredoc */
c-[si] { color: #a67f59 } /* Literal.String.Interpol */
c-[sx] { color: #a67f59 } /* Literal.String.Other */
c-[sr] { color: #a67f59 } /* Literal.String.Regex */
c-[ss] { color: #a67f59 } /* Literal.String.Symbol */
c-[vc] { color: #0077aa } /* Name.Variable.Class */
c-[vg] { color: #0077aa } /* Name.Variable.Global */
c-[vi] { color: #0077aa } /* Name.Variable.Instance */
c-[il] { color: #000000 } /* Literal.Number.Integer.Long */
</style>
 <body class="h-entry">
  <div class="head">
   <p data-fill-with="logo"></p>
   <h1 class="p-name no-ref" id="title">P2077R1<br>Heterogeneous erasure overloads for associative containers</h1>
   <h2 class="no-num no-toc no-ref heading settled" id="subtitle"><span class="content">Published Proposal, <time class="dt-updated" datetime="2020-09-15">2020-09-15</time></span></h2>
   <div data-fill-with="spec-metadata">
    <dl>
     <dt>This version:
     <dd><a class="u-url" href="http://wg21.link/P2077R1">http://wg21.link/P2077R1</a>
     <dt>Authors:
     <dd>
      <dd class="editor p-author h-card vcard"><a class="p-name fn u-email email" href="mailto:konstantin.boyarinov@intel.com">Konstantin Boyarinov</a> (<span class="p-org org">Intel</span>)
     <dd>
      <dd class="editor p-author h-card vcard"><a class="p-name fn u-email email" href="mailto:sergey.vinogradov@intel.com">Sergey Vinogradov</a> (<span class="p-org org">Intel</span>)
     <dd>
      <dd class="editor p-author h-card vcard"><a class="p-name fn u-email email" href="mailto:ruslan.arutyunyan@intel.com">Ruslan Arutyunyan</a> (<span class="p-org org">Intel</span>)
     <dt>Audience:
     <dd>LEWG
     <dt>Project:
     <dd>ISO/IEC JTC1/SC22/WG21 14882: Programming Language — C++
    </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>The authors propose heterogeneous erasure overloads for ordered and unordered associative

          containers, which add an ability to erase values or extract nodes without creating a
          temporary <i>key_type</i> object.<br></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="#intro"><span class="secno">1</span> <span class="content">Motivation</span></a>
    <li><a href="#prior"><span class="secno">2</span> <span class="content">Prior Work</span></a>
    <li><a href="#over"><span class="secno">3</span> <span class="content">Proposal overview</span></a>
    <li><a href="#perf"><span class="secno">4</span> <span class="content">Performance evaluation</span></a>
    <li><a href="#word"><span class="secno">5</span> <span class="content">Formal wording</span></a>
    <li>
     <a href="#changes"><span class="secno">6</span> <span class="content">Revision history</span></a>
     <ol class="toc">
      <li><a href="#r0r1"><span class="secno">6.1</span> <span class="content">R0 ➡ R1</span></a>
     </ol>
    <li>
     <a href="#references"><span class="secno"></span> <span class="content">References</span></a>
     <ol class="toc">
      <li><a href="#informative"><span class="secno"></span> <span class="content">Informative References</span></a>
     </ol>
   </ol>
  </nav>
  <main>
   <h2 class="heading settled" data-level="1" id="intro"><span class="secno">1. </span><span class="content">Motivation</span><a class="self-link" href="#intro"></a></h2>
   <p><a data-link-type="biblio" href="#biblio-n3657">[N3657]</a> and <a data-link-type="biblio" href="#biblio-p0919r0">[P0919R0]</a> introduced heterogeneous lookup support for ordered and unordered
associative containers in C++ Standard Library. As a result, a temporary key object is not
created when a different (but comparable) type is provided as a key to the member function.
But there are no heterogeneous <code class="highlight"><c- n>erase</c-></code> and <code class="highlight"><c- n>extract</c-></code> overloads.</p>
   <p>Consider the following example:</p>
<pre class="language-cpp highlight"><c- b>void</c-> <c- nf>foo</c-><c- p>(</c-> <c- n>std</c-><c- o>::</c-><c- n>map</c-><c- o>&lt;</c-><c- n>std</c-><c- o>::</c-><c- n>string</c-><c- p>,</c-> <c- b>int</c-><c- p>,</c-> <c- n>std</c-><c- o>::</c-><c- n>less</c-><c- o>&lt;</c-><c- b>void</c-><c- o>>>&amp;</c-> <c- n>m</c-> <c- p>)</c-> <c- p>{</c->
    <c- k>const</c-> <c- b>char</c-><c- o>*</c-> <c- n>lookup_str</c-> <c- o>=</c-> <c- s>"Lookup_str"</c-><c- p>;</c->
    <c- k>auto</c-> <c- n>it</c-> <c- o>=</c-> <c- n>m</c-><c- p>.</c-><c- n>find</c-><c- p>(</c-><c- n>lookup_str</c-><c- p>);</c-> <c- c1>// matches to template overload</c->
    <c- c1>// some other actions with iterator</c->
    <c- n>m</c-><c- p>.</c-><c- n>erase</c-><c- p>(</c-><c- n>lookup_str</c-><c- p>);</c-> <c- c1>// causes implicit conversion</c->
<c- p>}</c->
</pre>
   <p>Function <code class="highlight"><c- n>foo</c-></code> accepts a reference to the <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>map</c-><c- o>&lt;</c-><c- n>std</c-><c- o>::</c-><c- n>string</c-><c- p>,</c-> <c- b>int</c-><c- o>></c-></code> object. A
comparator for the map is <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>less</c-><c- o>&lt;</c-><c- b>void</c-><c- o>></c-></code>, which provides <code class="highlight"><c- n>is_transparent</c-></code> valid
qualified-id, so the <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>map</c-></code> allows using heterogeneous overloads with <code class="highlight"><c- n>Key</c-></code> template
parameter for lookup functions, such as <code class="highlight"><c- n>find</c-></code>, <code class="highlight"><c- n>upped_bound</c-></code>, <code class="highlight"><c- n>equal_range</c-></code>, etc.</p>
   <p>In the example above, the <code class="highlight"><c- n>m</c-><c- p>.</c-><c- n>find</c-><c- p>(</c-><c- n>lookup_str</c-><c- p>)</c-></code> call does not create a temporary object of
the <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-></code> to perform a lookup. But, the <code class="highlight"><c- n>m</c-><c- p>.</c-><c- n>erase</c-><c- p>(</c-><c- n>lookup_str</c-><c- p>)</c-></code> call causes implicit
conversion from <code class="highlight"><c- k>const</c-> <c- b>char</c-><c- o>*</c-></code> to <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-></code>. The allocation and construction (as well as
subsequent destruction and deallocation) of the temporary object of <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-></code> <i>or any custom object</i> can be quite expensive and reduce the program performance.</p>
   <p>Erasure from the STL associative containers with the <code class="highlight"><c- n>key</c-></code> instance of the type that is different
from <code class="highlight"><c- n>key_type</c-></code> is possible with the following code snippet:</p>
<pre class="language-cpp highlight"><c- k>auto</c-> <c- n>eq_range</c-> <c- o>=</c-> <c- n>container</c-><c- p>.</c-><c- n>equal_range</c-><c- p>(</c-><c- n>key</c-><c- p>);</c->
<c- k>auto</c-> <c- n>previous_size</c-> <c- o>=</c-> <c- n>container</c-><c- p>.</c-><c- n>size</c-><c- p>();</c->
<c- n>container</c-><c- p>.</c-><c- n>erase</c-><c- p>(</c-><c- n>eq_range</c-><c- p>.</c-><c- n>first</c-><c- p>,</c-> <c- n>eq_range</c-><c- p>.</c-><c- n>second</c-><c- p>);</c->
<c- k>auto</c-> <c- n>erased_count</c-> <c- o>=</c-> <c- n>container</c-><c- p>.</c-><c- n>size</c-><c- p>()</c-> <c- o>-</c-> <c- n>previous_size</c-><c- p>;</c->
</pre>
   <p>where <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>is_same_v</c-><c- o>&lt;</c-><c- k>decltype</c-><c- p>(</c-><c- n>key</c-><c- p>),</c-> <c- n>key_type</c-><c- o>></c-></code> is <code class="highlight">false</code>.</p>
   <p><code class="highlight"><c- n>erased_count</c-></code> determines the count of erased items and <code class="highlight"><c- n>container</c-></code> is either:</p>
   <ul>
    <li data-md>
     <p>An ordered associative container in which <code class="highlight"><c- n>key_compare</c-><c- o>::</c-><c- n>is_transparent</c-></code> is a valid qualified-id.</p>
    <li data-md>
     <p>An unordered associative container in which <code class="highlight"><c- n>hasher</c-><c- o>::</c-><c- n>is_transparent</c-></code> and <code class="highlight"><c- n>key_equal</c-><c- o>::</c-><c- n>is_transparent</c-></code> are valid qualified-ids.</p>
   </ul>
   <p>The code above is a valid alternative for the heterogeneous <code class="highlight"><c- n>erase</c-></code> overload. But
heterogeneous <code class="highlight"><c- n>erase</c-></code> would allow to do the same things more efficiently, without traversing
the interval [<code class="highlight"><c- n>eq_range</c-><c- p>.</c-><c- n>first</c-><c- p>,</c-> <c- n>eq_range</c-><c- p>.</c-><c- n>second</c-></code>) twice (the first time to determine the equal range
and the second time for erasure). It adds a performance penalty for the containers with non-unique keys
(like <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>multimap</c-></code>, <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>multiset</c-></code>, etc.) where the number of elements with the same key can be quite large.</p>
   <p class="note" role="note"><span>Note:</span> This paragraph and <a href="#perf">§ 4 Performance evaluation</a> contain examples for the <code class="highlight"><c- n>erase</c-></code> method.
But the problems and benefits are similar for both <code class="highlight"><c- n>erase</c-></code> and <code class="highlight"><c- n>extract</c-></code> member functions.</p>
   <h2 class="heading settled" data-level="2" id="prior"><span class="secno">2. </span><span class="content">Prior Work</span><a class="self-link" href="#prior"></a></h2>
   <p>Possibility to add heterogeneous <code class="highlight"><c- n>erase</c-></code> overload was reviewed in the <a data-link-type="biblio" href="#biblio-n3465">[N3465]</a>. But it was
found, that heterogeneous <code class="highlight"><c- n>erase</c-></code> brakes backward compatibility and causes wrong overload
resolution for the case when an <code class="highlight"><c- n>iterator</c-></code> is passed as the argument. The <code class="highlight"><c- n>iterator</c-></code> type is
implicitly converted into <code class="highlight"><c- n>const_iterator</c-></code> and the following overload of the erase method is called:</p>
<pre class="language-cpp highlight"><c- n>iterator</c-> <c- n>erase</c-><c- p>(</c-> <c- n>const_iterator</c-> <c- n>pos</c-> <c- p>)</c->
</pre>
   <p>If there was the following heterogeneous overload of the erase method:</p>
<pre class="language-cpp highlight"><c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>size_type</c-> <c- n>erase</c-><c- p>(</c-> <c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-> <c- p>);</c->
</pre>
   <p>template overload would be chosen in C++14 when an <code class="highlight"><c- n>iterator</c-></code> object passed as the
argument. So, it can cause the wrong effect or compilation error for legacy code.</p>
   <p>C++17 introduces a new overload for <code class="highlight"><c- n>erase</c-></code> method, which accepts exactly an object of <code class="highlight"><c- n>iterator</c-></code> type
as an argument:</p>
<pre class="language-cpp highlight"><c- n>iterator</c-> <c- n>erase</c-><c- p>(</c-> <c- n>iterator</c-> <c- n>pos</c-> <c- p>)</c->
</pre>
   <p>This change intended to fix the ambiguity issue <a data-link-type="biblio" href="#biblio-lwg2059">[LWG2059]</a> in the <code class="highlight"><c- n>erase</c-></code> method overloads (for <code class="highlight"><c- n>key_type</c-></code> and for <code class="highlight"><c- n>const_iterator</c-></code>) when a <code class="highlight"><c- n>key_type</c-></code> object can be constructed from the <code class="highlight"><c- n>iterator</c-></code>.</p>
   <p>Adding the overload with the <code class="highlight"><c- n>iterator</c-></code> argument solves the problem described above,
but overload with template <code class="highlight"><c- n>K</c-></code> parameter still will be chosen when passing an object of a type,
which is implicitly convertible to either <code class="highlight"><c- n>iterator</c-></code> or <code class="highlight"><c- n>const_iterator</c-></code> that is not what
user might expect.</p>
   <h2 class="heading settled" data-level="3" id="over"><span class="secno">3. </span><span class="content">Proposal overview</span><a class="self-link" href="#over"></a></h2>
   <p>We analyzed the prior work and basing on that we propose to add heterogeneous overloads for <code class="highlight"><c- n>erase</c-></code> and <code class="highlight"><c- n>extract</c-></code> methods in <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>map</c-></code>, <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>multimap</c-></code>, <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>set</c-></code>, <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>multiset</c-></code>, <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>unordered_map</c-></code>, <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>unordered_multimap</c-></code>, <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>unordered_set</c-></code> and <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>unordered_multiset</c-></code>:</p>
<pre class="language-cpp highlight"><c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>size_type</c-> <c- n>erase</c-><c- p>(</c-> <c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-> <c- p>);</c->
</pre>
   <p>and</p>
<pre class="language-cpp highlight"><c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>node_type</c-> <c- n>extract</c-><c- p>(</c-> <c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-> <c- p>);</c->
</pre>
   <p>To maintain backward compatibility and avoid wrong overload resolution or compilation errors
these overloads should impose extra restrictions on the type <code class="highlight"><c- n>K</c-></code>.</p>
   <p>For ordered associative containers these overloads should participate in overload resolution
only if all the following statements are true:</p>
   <ol>
    <li data-md>
     <p>Qualified-id <code class="highlight"><c- n>Compare</c-><c- o>::</c-><c- n>is_transparent</c-></code> is valid and denotes a type.</p>
    <li data-md>
     <p>The type <code class="highlight"><c- n>K</c-></code> is not convertible to the <code class="highlight"><c- n>iterator</c-></code>.</p>
    <li data-md>
     <p>The type <code class="highlight"><c- n>K</c-></code> is not convertible to the <code class="highlight"><c- n>const_iterator</c-></code>.</p>
   </ol>
   <p>where <code class="highlight"><c- n>Compare</c-></code> is a type of comparator passed to an ordered container.</p>
   <p>For unordered associative containers these overloads should participate in overload resolution
if all the following statements are true:</p>
   <ol>
    <li data-md>
     <p>Qualified-id <code class="highlight"><c- n>Hash</c-><c- o>::</c-><c- n>is_transparent</c-></code> is valid and denotes a type.</p>
    <li data-md>
     <p>Qualified-id <code class="highlight"><c- n>Pred</c-><c- o>::</c-><c- n>is_transparent</c-></code> is valid and denotes a type.</p>
    <li data-md>
     <p>The type <code class="highlight"><c- n>K</c-></code> is not convertible to the <code class="highlight"><c- n>iterator</c-></code>.</p>
    <li data-md>
     <p>The type <code class="highlight"><c- n>K</c-></code> is not convertible to the <code class="highlight"><c- n>const_iterator</c-></code>.</p>
   </ol>
   <p>where <code class="highlight"><c- n>Hash</c-></code> and <code class="highlight"><c- n>Pred</c-></code> are types of hash function and key equality predicate passed to
an unordered container respectively.</p>
   <h2 class="heading settled" data-level="4" id="perf"><span class="secno">4. </span><span class="content">Performance evaluation</span><a class="self-link" href="#perf"></a></h2>
   <p>We estimated the performance impact on two synthetic benchmarks:</p>
   <ul>
    <li data-md>
     <p>Erase all elements consistently from the <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>unordered_map</c-><c- o>&lt;</c-><c- n>std</c-><c- o>::</c-><c- n>string</c-><c- p>,</c-> <c- b>int</c-><c- o>></c-></code>, filled by 10000 values with unique keys. Size of each <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-></code> key is 1000.</p>
    <li data-md>
     <p>Erase all elements from the <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>unordered_multimap</c-><c- o>&lt;</c-><c- n>std</c-><c- o>::</c-><c- n>string</c-><c- p>,</c-> <c- b>int</c-><c- o>></c-></code> filled by 10000 values with duplicated keys. Size of each <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-></code> key is 1000.</p>
   </ul>
   <p>To do that we have implemented heterogeneous <code class="highlight"><c- n>erase</c-></code> method for <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>unordered_map</c-></code> and <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>unordered_multimap</c-></code> on the base of LLVM Standard Library implementation.</p>
   <p>We have compared the performance of three possible erasure algorithms:</p>
   <ul>
    <li data-md>
     <p>Erasure by <code class="highlight"><c- n>key_type</c-></code> object.</p>
    <li data-md>
     <p>Erasure by the pair of iterators, obtained by the heterogeneous <code class="highlight"><c- n>equal_range</c-></code>.</p>
    <li data-md>
     <p>Heterogeneous erasure with the <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string_view</c-></code> as an argument.</p>
   </ul>
   <p>The benchmark for <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>unordered_map</c-></code> shows that the erasure by the pair of iterators (as well
as heterogeneous erasure) increases performance by ~20%.</p>
   <p><img class="resize" src="data:image/png;base64,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"></p>
   <p>The benchmark for <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>unordered_multimap</c-></code> shows the same performance increase for
erasure by the pair of iterators and an additional performance increase by ~10% for
heterogeneous erasure (due to double traversal of <code class="highlight"><c- n>equal_range</c-></code>).</p>
   <p><img class="resize" src="data:image/png;base64,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"></p>
   <p>To do the additional analysis with different memory allocation source we took an open-source
application <a href="https://github.com/pmem/pmemkv"><em>pmemkv</em></a>. It is an embedded key/value data
storage designed for emergent persistent memory. <i>pmemkv</i> has several storage engines optimized
for different use cases. For the analysis we chose <i>vsmap</i> engine that is built on <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>map</c-></code> data structure with allocator for persistent memory from the <a href="https://github.com/memkind/memkind"><em>memkind library</em></a>. <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>basic_string</c-></code> with the <i>memkind</i> allocator was used as a key and value type.</p>
<pre class="language-cpp highlight"><c- k>using</c-> <c- n>storage_type</c-> <c- o>=</c-> <c- n>std</c-><c- o>::</c-><c- n>basic_string</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>std</c-><c- o>::</c-><c- n>char_traits</c-><c- o>&lt;</c-><c- b>char</c-><c- o>></c-><c- p>,</c->
                                       <c- n>libmemkind</c-><c- o>::</c-><c- n>pmem</c-><c- o>::</c-><c- n>allocator</c-><c- o>&lt;</c-><c- b>char</c-><c- o>>></c-><c- p>;</c->
<c- k>using</c-> <c- n>key_type</c-> <c- o>=</c-> <c- n>storage_type</c-><c- p>;</c->
<c- k>using</c-> <c- n>mapped_type</c-> <c- o>=</c-> <c- n>storage_type</c-><c- p>;</c->
<c- k>using</c-> <c- n>map_allocator_type</c-> <c- o>=</c-> <c- n>libmemkind</c-><c- o>::</c-><c- n>pmem</c-><c- o>::</c-><c- n>allocator</c-><c- o>&lt;</c-><c- n>std</c-><c- o>::</c-><c- n>pair</c-><c- o>&lt;</c-><c- k>const</c-> <c- n>key_type</c-><c- p>,</c->
                                                                 <c- n>mapped_type</c-><c- o>>></c-><c- p>;</c->
<c- k>using</c-> <c- n>map_type</c-> <c- o>=</c-> <c- n>std</c-><c- o>::</c-><c- n>map</c-><c- o>&lt;</c-><c- n>key_type</c-><c- p>,</c-> <c- n>mapped_type</c-><c- p>,</c-> <c- n>std</c-><c- o>::</c-><c- n>less</c-><c- o>&lt;</c-><c- b>void</c-><c- o>></c-><c- p>,</c->
                          <c- n>std</c-><c- o>::</c-><c- n>scoped_allocator_adaptor</c-><c- o>&lt;</c-><c- n>map_allocator_type</c-><c- o>>></c-><c- p>;</c->
</pre>
   <p>Initial implementation of <code class="highlight"><c- n>remove</c-></code> method of <i>vsmap</i> engine was the following:</p>
<pre class="language-cpp highlight"><c- n>status</c-> <c- n>vsmap</c-><c- o>::</c-><c- n>remove</c-><c- p>(</c-> <c- n>std</c-><c- o>::</c-><c- n>string_view</c-> <c- n>key</c-> <c- p>)</c-> <c- p>{</c->
    <c- n>std</c-><c- o>::</c-><c- b>size_t</c-> <c- n>erased</c-> <c- o>=</c-> <c- n>c</c-><c- p>.</c-><c- n>erase</c-><c- p>(</c-><c- n>key_type</c-><c- p>(</c-><c- n>key</c-><c- p>.</c-><c- n>data</c-><c- p>(),</c-> <c- n>key</c-><c- p>.</c-><c- n>size</c-><c- p>(),</c-> <c- n>a</c-><c- p>));</c->
    <c- k>return</c-> <c- p>(</c-><c- n>erased</c-> <c- o>==</c-> <c- mi>1</c-><c- p>)</c-> <c- o>?</c-> <c- n>status</c-><c- o>::</c-><c- nl>OK</c-> <c- p>:</c-> <c- n>status</c-><c- o>::</c-><c- n>NOT_FOUND</c-><c- p>;</c->
<c- p>}</c->
</pre>
   <p>The initial implementation explicitly creates temporary object of <code class="highlight"><c- n>key_type</c-></code> when <code class="highlight"><c- n>erase</c-></code> method is called. To estimate performance impact of the heterogeneous <code class="highlight"><c- n>erase</c-></code> overload
we re-designed <code class="highlight"><c- n>remove</c-></code> operation of the <i>vsmap</i> engine in the following way:</p>
<pre class="language-cpp highlight"><c- n>status</c-> <c- n>vsmap</c-><c- o>::</c-><c- n>remove</c-><c- p>(</c-> <c- n>std</c-><c- o>::</c-><c- n>string_view</c-> <c- n>key</c-> <c- p>)</c-> <c- p>{</c->
    <c- k>auto</c-> <c- n>it</c-> <c- o>=</c-> <c- n>c</c-><c- p>.</c-><c- n>find</c-><c- p>(</c-><c- n>key</c-><c- p>);</c->
    <c- k>if</c-> <c- p>(</c-><c- n>it</c-> <c- o>!=</c-> <c- n>c</c-><c- p>.</c-><c- n>end</c-><c- p>())</c-> <c- p>{</c->
        <c- n>c</c-><c- p>.</c-><c- n>erase</c-><c- p>(</c-><c- n>it</c-><c- p>);</c->
        <c- k>return</c-> <c- n>status</c-><c- o>::</c-><c- n>OK</c-><c- p>;</c->
    <c- p>}</c->
    <c- k>return</c-> <c- n>status</c-><c- o>::</c-><c- n>NOT_FOUND</c-><c- p>;</c->
<c- p>}</c->
</pre>
   <p>To understand the performance impact we used <a href="https://github.com/pmem/pmemkv-tools"><em>pmemkv utility</em></a>.
We run <i>deleterandom</i> benchmark on prefilled storage
and measured throughput as a number of operations per second. We executed the test with
different key sizes (16 bytes, 200 bytes, 1024 bytes). The chart below shows performance increase,
comparing to initial implementation, for all tests. The throughput of the <code class="highlight"><c- n>remove</c-></code> operation increased
up to 9x for the 1024 bytes key.</p>
   <p><img class="resize" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAwoAAAILCAMAAAB/zZsCAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAEdUExURdnZ2dra2tra2tnZ2UBAQENDQ0REREZGRkhISExMTFFRUVJSUlZWVllZWVub1VxcXF1dXV5eXmBgYGRkZGVlZWZmZmhoaGtra2xsbG5ubm9vb3Nzc3Z2dnh4eHl5eXp6ent7e35+foKCgoWFhYeHh4qKiouLi4yMjI2NjZKSkpWVlZiYmJubm5ycnJ+fn6GhoaOjo6SkpKWlpaenp6mpqaurq66urrCwsLGxsbOzs7S0tLW1tbi4uLm5ubu7u729vb+/v8LCwsXFxcrKyszMzM3NzdDQ0NLS0tTU1NbW1tfX19nZ2dvb2+Li4uPj4+Tk5Obm5unp6erq6uvr6+zs7O/v7/Hx8fLy8vT09PX19ff39/j4+Pn5+fz8/P///ydTkQgAAAAEdFJOU4efx9+nhZkZAAAACXBIWXMAABcRAAAXEQHKJvM/AAAkfUlEQVR4Xu3dD38bV3be8aRVt+tWqFJzu2Vqh0pcL2trFYftxmkaJVnKSSybdhOz9bp1DOj9v4zce+5vgBlgIAI4c8gD8Pl+bOH/wQFwHswMQA5/7/e+EZFvfl9JEDElCm9FHj1FQcQoCiJGURAxioKIURREjKIgYhQFEaMoiBhFQcQoCiJGURAxioKIURREjKIgYhQFEaMoiBhFQcQoCiJGURAxioKIURREzMlHYXH57FuOYn7+/g8cncTmPWxxe3bxE0d3s/cNzGG32rC4nH3B0cfh5KOwOfgTjcrSztFSFFI7+ShsDsbN7BOOdXZ+Xx+18+gpCqmdfBSuZ59zrLN5zu2ZZ5Vps94WikJqJx+Fq/UXdGQRsLmc2MfGPWyjKKR2wlH48vls9uJHBv/7z2blVB2RbtV+ec5NOSxqGvrXuvjxs5nd1ur841U9Xs/98mz27K9qgfV7+Ljc9qN/rEfL1X6qV3ttV+muXWf0x78tZ/+6Tard4EW9we3ZJ4t6AVf8qlxgV+puYOfXK/2mFX3dDop6s9kHdrxebh23KMw/mrWrFMvWujva6GB4nMdVo0CuWi7Wbn5iTjcKvykzUuZkZoN/XUbh5XM7zou7OuercvDRy5f/sHatX13Ontdjrc4zW4eyc5+VqvZ+uX4Pz/6k/F9j0V3t2Te9a9ezP/xo9qyMmTVwczb79GU5XW5we/ZxOVKuaGtaVCrRbDfgfLtSvb/XrWg7b/bhyzLD7Xi50w/KfdkDLLP761qsKtf69OXHv7Q7qo2NdDA4XhsoCT4biUL/5qfmZKNwYy9reW+uL9vN7P3yftdez7Y21D+nW2UaXstO1CP1wq/OuNXs2d/VVaI6e2v3UC9YXPWuVgrZm3e7dlFGsl6pHJQ7KAunWv/Leut6Qbnil4TQ3s6//PN2g/757b5LGOq42r1+WGuUvrncHkad3nLftZFmtQZHwXKw1sFaN+U6339kEV6LQu/mJ+dUozA/by+XbdPOz21I2uu5eQ5bzWvXanM1qNOdS4nBPbQTbSq5Wpnaema7aXF71mpe1zHlXIshF7RI2qXN4HxOMIc0a9rx5YDW6W2RhK3bma0dDI/bbdtDWotC7+Yn51SjcGPvmrwj2oJg8U+f1fPaXPXPaSfWr8X8Dup051K0d0l7k67DUqKwuprVXb4pM1btlld1payo09VdUK/Zhq7pn9+dYFOnPYymi0q7cj3y17NP2nFTklkWJ1V3nY0OhsetgW767RaDE8uHflpONQqslbQpqSsVVd0gbqPUP6d7Sxxei0kb1FkuN1rRwT20+bUh4WqDa1fdJNW8lNlCubS7oEWhu/rqBu+IwuLvr9oAL69cjpQtCusNZWu6rNjUC7d1sHb8rij4PnzO6kSj0L2e3bv0py9f/uUbXsbycg7OYY43r9XOXNXpzrVpXLsH5tdWHbja8qCbm65oPae7ueku2DsKdcjbAK+uXI982dbQlv6pbFp/uHoA5XDYwdjxdsgtBifs5vXwtJxoFLp3dVtxYXoaWw0anMPwbV6r6Op0m8N2rk3E2j20E21i+itcq1KrSaqLjv7wLS9oUVhd0D+/OzGIwtWsbje3492V7ch1+1hr5Xvbju6us97BoJv2zsB53GJwwm5eD0/LaUehbEqWNYXBkNva0OAc3uM2r1VQ56Z9Xsm5Ntxr92AnyiW1BlcbHhTdVqflqr/p2Y2YDWFvi3dwPif6USDEI1Eoo7sqb+zirR2MHP+ezWaenHaid/OTc7orSGUAv2yf6fff89rx/jndqz28VnvN65n9Ot0ktBKDe6jz3qZncLXlQVFiU7dfv7KPesqJ1/XM7/+mHu+NfIldveCrP1s7nxPDKFjt9oFVd+V2pMxul8D5r2o7r+v40kHpeqOD9ePl33ql9sjKA+MWq5ufnFPdbL62r78u/tSmskzXhy9ffnxWXkAmqXdOnZpnz8v0bF6r6NfpT+HYPfBdF1cbXrtq36Q9b19s2+1fvnxe1zUGI1+/uVt+xdY7fyQKtcanpcRIFEpH3f2Waf5w+V3eB8+tA/v6rdfB4PhVOf589uH/tG7KBeUG73/WWujf/NScahTqDyd88Hpx2Ub6q4/KtuWf/GV5mbuBWZ1j73LP6qu+ea2iV2c4jMN7uF393AJXGx5U9qMTZbL4+Yq6LTu8OxYg9ecePtg4nxPDhNWrfvh39sXB8o440n2+W677m/IOz094XPxYO7AlQL+D4fH6gx2/LtsbrZtyY06s3fzEnGwUZMQyLodx3jw5ReExURTeQVF4TBSFd1AUHhNF4R0UBRGjKIgYRUHEKAoiRlEQMYqCiFEURIyiIGIUBRGjKBxi8JOqzeLrNxzr7Pjd7OYNC9/3uvxMqexFUThE+yXNwbyufj+gs+M4b96w8EWh7p2Po7IzReEQbc9Cg3n99qz+Hn3fjuO8ecNi+235nYbl4ah3XijjFIUDMKh3zPqOURjljMJq1wKyM0XhAPzmft4odL9oJ3tQFA7AGJZ57e/o2obXfnmyKKM4uPjt2o6z2Uu3nbIbLvd2bbrbru/y+rrWns0+7w77l/XrvjMoMkpR2F+3q5e1HV3XieZX6mef/ln95f3excMdZ7PPa9NueLvc2zVnju90+9uXba/f3eG2uqs9zsiuFIX9dTuHq/tCef12uaPrOrVtH0Lt38HFZZWlvnEvd5zdzXx3w7W3cXazUg7K2f3brq8gbamrjYX9KQr763YOxx6y2s4n+hPdvdH3LuZt2k60Ae9wQ7vuUrfzLQtV/7brUdhS9zT3XxdLUdjfKgrt0KayP9FdFHoXj+04u2mnVnu7Nt1V7K76t+0i0B1uqTu8C9mForC/d0RhuIK0urhsQ2BLFFZ7uzbdVeq62OC2a1HYVrdbh5PdKQr7e0cU5ue22Wxz2L+4jGyb4Ko3skV3qtvbtenOJAqr225GYbTu8C5kF4rC/t61gjT7tNsT3eDiHaLwlr1dm+7MeleHRKFrUXanKOxv9QlSm7dVFAY//DO4uK0zNb2RLXqnVke37vJ6LQrb6uoTpP0pCvtbfa/Qm/V2ov9B0NrFmzvObuxUb2/Xpn4uOrrT7eXsc7ilrr5X2J+isL9urWRt1uuJuvf12eyDj+qnQYOLy3Bu7Di7sVOlZLe3a87cstPt8n4/e3ZW5rw7HK/LMkP2oCgcgPfcwayvJvole5cfXDy24+ymnVrt7dps3en22+V+v7vDsbr6GaQDKAoHGM5yz/oG9UPRpsIBFIUDtO99R3Qj2H5G4uFo/egAisIhtr3rzssK/qd1zX1LVO6JfovtEIrCIbq/tbNh8bdlU3f2wa//D6cfhn63+RCKgohRFESMoiBiFAURoyiIGEVBxCgKIkZREDGKgohRFESMoiBiFAURoyiIGEVBxCgKIkZREDGKgohRFESMoiBiFAURoyiIGEVBxLijsNyt+bzuLlQ7HZFj5Y3CTTf/t21ftsqCHClnFEoAbtr4X9Udsi0utVs2OVL+bYUWhfm57Vz6+mH3kChysKmicHtmywYWESJHZ6ookAFFQY5VfBS+EcmFyVwTv4LE3YtkwWSumS4K2myWozZVFNrHqPowVY7WVFEoB/UrNi0U5Fg5o3B7NqvqsqB+76wkyG7ePHny5Gdfc+Lt2/nTcvq35Ug9/8mTn/+unX2v/EsFkb29qnP/YpmF7977jPPe9PJxzxQFuX/zp3+8/Ld68Yt/LhuaF+VfRUEeFVsKtNmv5k/rybevSgwUBXlUWhTevmCb4Lv36mZC2U74raIgj8viok78d+8RhZoBDmyz+WHioCjIA1hclIn/xSebUTAvuiP3SlGQB2Nby0VvBcmstqfvk6IgD2U58Ww61M1ms9yevleKgjyUtdFfBUBLBXlUXj2py4L2xVo9WpOxuCinFhf6tlkeixfLz4ksCvbBkZ22T5AeYvVIURCBoiBiFAURoyiIGEVBxCgKIkZREDGKgohRFESMoiBiJouCdnghx22qKNgfGblSFuRoTRSF+fkny39FjtFEUWi7TNV+IuV4TRqFt1fv/2AnRY7ORFFYXNbNhNuzkSiwI295vP7DBCg1CSZzzVSbzYvLuuvUP1UUZBPT7EKpSTCZa6aKQmN/plNkiGl2oVSgSaOgT5BkDNPsQqlAk0ZBf15BxjDNLpQKNGUUrutfGxFZxzS7UCrQVFG40s9dyDZMswulAk272Swygml2oVQgRUHCMc0ulAqkKEg4ptmFUoEUBQnHNLtQKpCiIOGYZhdKBVIUJBzT7EKpQIqChGOaXSgVSFGQcEyzC6UCKQoSjml2oVQgRUHCMc0ulAqkKEg4ptmFUoEUBQnHNLtQKpCiIOGYZhdKBVIUJBzT7EKpQIqChGOaXSgVSFGQcEyzC6UCKQoSjml2oVQgRUHCMc0ulAqkKEg4ptmFUoEUBQnHNLtQKtBkUah/X0F7vJAxTLMLpQJNFYWb+vcVbpQFGcE0u1Aq0FRRsF1ELi61dzzZxDS7UCrQZFGoOw7WjiJlDNPsQqlAU0Wh7k9+cak/ryAjmGYXSgWabLP59mw20zJBxjDNLpQKNFkUrmcfnM3G9inPPu3l8WKaXSg1CSZzzWTbCnWHqTdjWeDu5fFiml0oNQkmc81EUeBvsWmv8jKCaXahVCBFQcIxzS6UCjRRFLo/S6gNZ9nENLtQKtBkm831Dyzoy2YZwzS7UCrQZFEQ2YZpdqFUIEVBwjHNLpQKpChIOKbZhVKBFAUJxzS7UCqQoiDhmGYXSgVSFCQc0+xCqUCKgoRjml0oFUhRkHBMswulAikKEo5pdqFUIEVBwjHNLpQKpChIOKbZhVKBFAUJxzS7UCqQoiDhmGYXSgVSFCQc0+xCqUCKgoRjml0oFUhRkHBMswulAikKEo5pdqFUIEVBwjHNLpQKpChIOKbZhVKBFAUJxzS7UCqQoiDhmGYXSgWaKArz87rDC+01VcYwzS6UCjTpUoEdg4kMMM0ulAo0aRTsjyyIrGGaXSgVaMoo6C+NyCim2YVSgaaMgvaYKqOYZhdKBZowCovLsT+vUO5BHjmm2YVSk2Ay10wYBfsjnZu4e3m8mGYXSk2CyVwzXRT0l9hkC6bZhVKBpouCPkmVLZhmF0oFmi4K9ieoRDYxzS6UCjRZFPRJqmzDNLtQKtBkUbge32gWeXwfpoqMY5pdKBVIUZBwTLMLpQIpChKOaXahVCBFQcIxzS6UCqQoSDim2YVSgRQFCcc0u1AqkKIg4ZhmF0oFUhQkHNPsQqlAioKEY5pdKBVIUZBwTLMLpQIpChKOaXahVCBFQcIxzS6UCqQoSDim2YVSgRQFCcc0u1AqkKIg4ZhmF0oFUhQkHNPsQqlAioKEY5pdKBVIUZBwTLMLpQIpChKOaXahVCBFQcIxzS6UCqQoSDim2YVSgaaLwu3ZbDbTXsFkE9PsQqlAk0VBO3+RbZhmF0oFmioK2k2kbMU0u1Aq0M5RaH9tbXS38dW19h0s2zDNLpQKtGsUbmoQii07Rt3ytxVECqbZhVKBdoxCt8f427PxkV9c/uqyBGXsQvZpL48X0+xCqUkwmWt2jML8nE2BLStC8/O6uJifj2SBu5fHi2l2odQkmMw1Oy8VuihsWyrYfrT119hkBNPsQqlAu28r2Gelt2fjH5myraAoyAim2YVSgXaNwnK7uRpZSWorTvrDzTKCaXahVKCdtxVIgRkZ+NuzsoZ0o2+bZQTT7EKpQDsvFe5iP3ehL5xlBNPsQqlAk0VBZBum2YVSgRQFCcc0u1Aq0N7bCtowln0xzS6UCrR3FMa/VxDZjml2oVSgPVeQ+HpBZA9MswulAu27rXClpYLsi2l2oVSgfaOgH8aWvTHNLpQKtGcUup9QFdkd0+xCqUB7bzbr+2TZF9PsQqlA+0ZBSZC9Mc0ulAq077aCyN6YZhdKBVIUklpcPPljjhbfvffkyZPPypE35dCOlMuf9K+RGdPsQqlAikJSr372n1aD/urJb9uRN/XIm5qFF+XSN0eSBabZhVKBFIWc5k//5mI559+9V5cD1Ytf/HNdIHSXvPj57ziWGtPsQqlAO0TBfvx6SR+m3osXv/j/qyi8Wk68zf78aXfJ6oLUmGYXSgXaOwr6tvk+fPfvvl699y8u6rLAfPfez3+3uBgmIz+m2YVSgXZdQbppv7Wsn0G6FzUG/Sj8Ud1GtjzU7efl0mK14pQb0+xCqUA7RuGuPV7IpN6Ud/tVFOZPf/Z1/bdm4dWTP3ivhaJG5DgWCqcVhbv2gyRTmj8t7/b9pYIde1UC8aKG4g1ZsBPHgGl2oVSgnZcKbQVpdKdfMjH78qBqH6GyrVCiwBpRDUVdQPAJa3pMswulAu26rbDcdt6yrdD2DaNFxnRWSwU+KCrbyP0ovLJv2o4C0+xCqUC7RqEsF94562xW37P+V7L29WudmfnT9pbaLhl+a3tEWhTsrf+798rR+sXa4qKGYHnyWDDNLpQKtHMU7vAwUeh/JfuijMb86XJDsvt0ZfCt7THpRcE+N2qrQy9qyMsjs+AXR/HYmGYXSgU66igMvpI1bS264iP3zavIvWOaXSgVaOco1I2FL1afJK17kCgMvpI1yyh038huXkXuHdPsQqlAu0bBNovLJvO23222y+85DoOvZM1qBZpMbF5F7h/T7EKpQDtGoe4pe35eovDO7xWuxj5fYp/207v5w/9i/+PmD8uq839bnviPb+xgcBV5GEyzC6UmwWSu2TEKNQYWhZt3RWF+bn9lYYi7n96rf/v363P+1b//N39tR149+e92sHkVuX9MswulJsFkrtk3Cu9cKtzrX2Rb+0q2YROBH0kYvYrcO6bZhVKBdt1WuHr/hxoF23f8VqNLhShrX8k2fDHLJ6mjV5F7xzS7UCrQrlHofs9/y0JhcVmWGA+wZ5gtS4X+T+doqfDgmGYXSgXaNQp1m7jY+q5vnyDd/88ntTmv30PNn5a3/vZtbBeIRlF4cEyzC6UC7R6FlFZRaGtD7Uc2Bz+opig8OKbZhVKBjjwKcgyYZhdKBdo5Cnd82yyyFdPsQqlAu0bhrm+bRbZiml0oFWjHKOz2bbPIGKbZhVKBdozC8iu2d37bLIfjFfehVjZ050KpQPtGQUuFILziPtTKhu5cKBVo122Fnb5tlsPxivtQKxu6c6FUoF2jcMe3zeLFK+5DrWzozoVSgXaNwl3fNosTr7gPtbKhOxdKBdo9ChKKV9yHWtnQnQulAikKSfCK+1ArG7pzoVSgnaPQNhb0BVsUXnEfamVDdy6UCrRrFNouv+7915cfD15xH2plQ3culAq0YxS6X0W4PdNyIQavuA+1sqE7F0oF2jEKOXYfzLPiQ61s6M6HWtnQnQulAu28VMiwU3meFR9qZUN3PtTKhu5cKBVo922FL+rB7ZkdPBCeFR9qZUN3PtTKhu5cKBVo1ygst5urh1pJ4lnxoVY2dOdDrWzozoVSgXbeViAFRlGYHt35UCsbunOhVKCdlwoZ8Kz4UCsbuvOhVjZ050KpQBNGYXEZ/SNKPCs+1MqG7nyolQ3duVAq0IRRuH72XFE4GN35UCsbunOhVKB9onD9zi+b5+evLxWFg9GdD7WyoTsXSgXaKQrXloA79ht/dfGjonA4uvOhVjZ050KpQLtEoe0VeH7+/g/ln23TfvvLbxeKwuHozoda2dCdC6UC7RKF9lMX17P679WWD1JrDMajwI68p8Cz4kOtbOjOh1rZ0J0LpSbBZK7ZOQr8QN62n0Gqe8JQFBzozoda2dCdC6UmwWSu2XkF6bp9UrplqUBatIJ0MLrzoVY2dOdCqUA7bTbbBrNlYNu2wvLHMkJ/RIlnxYda2dCdD7WyoTsXSgXaKQr1Y9S2NLh+16xrqeBAdz7UyobuXCgVaLco7EZRcKA7H2plQ3culAqkKCRBdz7UyobuXCgVaMoohONZ8aFWNnTnQ61s6M6FUoEUhSTozoda2dCdC6UCKQpJ0J0PtbKhOxdKBVIUkqA7H2plQ3culAqkKCRBdz7UyobuXCgVSFFIgu58qJUN3blQKpCikATd+VArG7pzoVQgRSEJuvOhVjZ050KpQIpCEnTnQ61s6M6FUoEUhSTozoda2dCdC6UCKQpJ0J0PtbKhOxdKBVIUkqA7H2plQ3culAqkKCRBdz7UyobuXCgVSFFIgu58qJUN3blQKpCikATd+VArG7pzoVQgRSEJuvOhVjZ050KpQIpCEnTnQ61s6M6FUoEUhSTozoda2dCdC6UCKQpJ0J0PtbKhOxdKBVIUkqA7H2plQ3culAo0VRQWl7P4v8bDs+JDrWzozoda2dCdC6UCTRWFq8/ZwXAknhUfamVDdz7UyobuXCgVaNIVpLbz+Tg8Kz7UyobufKiVDd25UCqQopAE3flQKxu6c6FUoCmjcGO7nQ/Es+JDrWzozoda2dCdC6UCTbrZHJwEjctdqJUN3blQKtCUS4X5+dgKEvu0nwLPig+1sqE7H2plQ3culJoEk7lm0m2F0V3Oc/dT4FnxoVY2dOdDrWzozoVSk2Ay10wahfZH2+LwrPhQKxu686FWNnTnQqlA8UuFCfGs+FArG7rzoVY2dOdCqUATRWF+/kVdKOjD1IPRnQ+1sqE7F0oFmmqpYH+BKnb1SONyJ2plQ3culAo06QpSNJ4VH2plQ3c+1MqG7lwoFUhRSILufKiVDd25UCqQopAE3flQKxu6c6FUIEUhCbrzoVY2dOdCqUCKQhJ050OtbOjOhVKBFIUk6M6HWtnQnQulAikKSdCdD7WyoTsXSgVSFJKgOx9qZUN3LpQKpCgkQXc+1MqG7lwoFUhRSILufKiVDd25UCqQopAE3flQKxu6c6FUIEUhCbrzoVY2dOdCqUCKQhJ050OtbOjOhVKBFIUk6M6HWtnQnQulAikKSdCdD7WyoTsXSgVSFJKgOx9qZUN3LpQKpCgkQXc+1MqG7lwoFUhRSILufKiVDd25UCqQopAE3flQKxu6c6FUIEUhCbrzoVY2dOdCqUCKQhJ050OtbOjOhVKBpoqC7TM1di9IGpc7USsbunOhVKCponBVYnATnQWeFR9qZUN3PtTKhu5cKBVo0hWkK/3VnYPRnQ+1sqE7F0oFmjQK14rCwejOh1rZ0J0LpQJpqZAE3flQKxu6c6FUoCmjcHs29rdG2JH3FHhWfKiVDd35UCsbunOh1CSYzDUTRmFxObpQ4O6nwLPiQ61s6M6HWtnQnQulJsFkrpkwClfB+9HWSsSdqJUN3blQKtB0UbiefcGxMDwrPtTKhu58qJUN3blQKtBkUbgO/6OEGpc7USsbunOhVKCpohD+h2ornhUfamVDdz7UyobuXCgVaKIo2M9dhP/oBc+KD7WyoTsfamVDdy6UCjThZnM8nhUfamVDdz7UyobuXCgVSFFIgu58qJUN3blQKpCikATd+VArG7pzoVQgRSEJuvOhVjZ050KpQIpCEnTnQ61s6M6FUoEUhSTozoda2dCdC6UCKQpJ0J0PtbKhOxdKBVIUkqA7H2plQ3culAqkKCRBdz7UyobuXCgVSFFIgu58qJUN3blQKpCikATd+VArG7pzoVQgRSEJuvOhVjZ050KpQIpCEnTnQ61s6M6FUoEUhSTozoda2dCdC6UCKQpJ0J0PtbKhOxdKBVIUkqA7H2plQ3culAqkKCRBdz7UyobuXCgVSFFIgu58qJUN3blQKpCikATd+VArG7pzoVQgRSEJuvOhVjZ050KpQIpCEnTnQ61s6M6FUoGmi8LiMnyfYDwrPtTKhu58qJUN3blQKtBkUbiZzRQFB7rzoVY2dOdCqUBTReH27PMbRcGB7nyolQ3duVAq0ITbCoqCB935UCsbunOhVCBFIQm686FWNnTnQqlA8VFgn/ZT4FnxoVY2dOdDrWzozoVSk2Ay1ygKSdCdD7WyoTsXSk2CyVyjFaQk6M6HWtnQnQulAikKSdCdD7WyoTsXSgVSFJKgOx9qZUN3LpQKpCgkQXc+1MqG7lwoFWiqKNye2Z8aufiJ0yF4VnyolQ3d+VArG7pzoVSgCZcK8XhWfKiVDd35UCsbunOhVCBFIQm686FWNnTnQqlAikISdOdDrWzozoVSgRSFJOjOh1rZ0J0LpQIpCknQnQ+1sqE7F0oFUhSSoDsfamVDdy6UCqQoJEF3PtTKhu5cKBVIUUiC7nyolQ3duVAqkKKQBN35UCsbunOhVCBFIQm686FWNnTnQqlAikISdOdDrWzozoVSgRSFJOjOh1rZ0J0LpQIpCknQnQ+1sqE7F0oFUhSSoDsfamVDdy6UCqQoJEF3PtTKhu5cKBVIUUiC7nyolQ3duVAqkKKQBN35UCsbunOhVCBFIQm686FWNnTnQqlAikISdOdDrWzozoVSgRSFJOjOh1rZ0J0LpQJNFoX5efxe5XlWfKiVDd35UCsbunOhVKCponB79vnbt9fBWeBZ8aFWNnTnQ61s6M6FUoGmisJV3e3L4lI7fzkU3flQKxu6c6FUoImiMD8vC4WyWHj2rZ0MwrPiQ61s6M6HWtnQnQulAk0UhdszWzUK3kEez4oPtbKhOx9qZUN3LpQKNFEUyICicDC686FWNnTnQqlA8VFgn/YiWTCZa+JXkLh7kSyYzDWTReE+NptF4kwUhfYxavSHqSJxJopCWTWqX7FpoSBHa6oolCzMZkqCHK/JoiBy3BQFEaMoiBhFQcQoCiJGURAxioKIURREjKIgYhQFEaMoiJhTicL1+z9w7DTp8YU7wigsLrtfELo9m83qT8QWRz4q5THNZp/Y0eUOpQZ7ljrWx7d8sbpH03ukdoKjisIB6o/Atme3v9ulkafy5oh+UPaqTMSNjcVyh1LDPUttPr6jeHjLF2v5aFaPtLh+9nx7FO77AR5dFMpzyq+N8ptzzZFHwVzVx7DcodRwz1LHGYXVizV8NPZI65Li9aWi4MGzO3j2rt//v2UJXLLRnuWbZ9/UBXF996lvTPX5rkvmzec7k/qAljuU+nq4Z6n1x1cf3ODhZX187cVa208WL93VxY+rKDz463e8URj+9uh1/b2h+qt07cL6JtTeVerpuvxY1Cf9hic+pzoFy/0l/MVwxwmbj2/48NI+vtbv2m4g2rzf/vJb67pK8PodcxR+Vd84yENbqS7PoD1l9iZkT2V7rsu7EO9LidlEMyw3s5fdETsYeXzDh9e976bTHsDyYdmBPVLrvfVfJHj9jjcK8/P6VM3PWxbaIrcugOv/9izaP+3tqBwty9ecs9JZXNaHsJyZ9ShsPL7hwys3z/n42gNYPqx60B7p25vy7yoKD//6HfNSwZ7F+szVg+VTWd9y6vK1eyrrKqf91vVV7m2FK3sgW1eQNh7f+sNL+vjaAxisILVHam/zI1F4sNfv6LcVhlEo/5bz/58tTHvvKrg9Szgr4GPTtu5QHtUX3RF7eCOPb/PhpXx8XRRWj4ZHypY/H7YmeP2ONwo8e20LjJGxd5PrZ//LTthTOVzFtLNSumbx3wJe/v2xO1LzPvb4Rh5exsfXf9+yf7tHalZLhY3Hd++v3xFH4fasPI22/6WCTyDqBfPzti3d3onsPejm4qfy32qw0ukeBsfqYCyPmM3HN3x49n/Gx8eLNXxYS6soPPzrd3RRYOWxPid21J7o8oxd/O9yqp244vB6+bl0vXY51Z7ihOpn5lWdi9qvBWB5pBp5fMOHl/Lx9V4sHk3/kRarKDz863eMS4W7sM50svT4QpxgFObnvNOcKD2+GCcYheX69YnS44txiitIIgdQFESMoiBiFAURoyiIGEVBxCgKIkZREDGKgohRFESMoiBiFAURoyiIGEVBxCgKIkZROEaDX5WXaSgKabRfa297OruDohBAUUjDorBY/vEIuWeKQhoWhSu93z8URSGNGoVr9orS/Y2atk/F7qAmxXaWWHcYZFexvcN0VxYXRSGNEgXby5kdLYd1Z1htB1rdPpJttyi3//Uni0Jl+8haXllcFIU0bs/+x3Lk62Gd82732m2tablblC4KFoDlle0sOZSikEbdlVybZ0a+LgPasLOPrMUlK0pEwZYWvSuLh6KQRllB4kNS9q9YNwvq2s9qH1nlAgsDUbA9BvWuLB6KQholCnyU2m0yFHUNqVsdqrr9iNZzWkR6VxYPRSGN+gnS/Ly+ua8WA7Y5MFz3qZ8mtSh0f7JDUZiEopBGjUIZ8rL6z19oMvPzj4ez3vbMXqLA4qB/ZXFQFNKwKJSlQBnw27O6/Xxto361+s7g9j/XPz9YLrIodAuL/pXlcIpCGi0KbXPBvjVrw33T2yDu/sZAjUL7iq1uZ/euLIdTFLLTZvE9URSy0/fI90RRSE5bxfdFUUjuRlsB90RREDGKgohRFESMoiBiFAURoyiIGEVBxCgKIkZREDGKgohRFESMoiBiFAURoyiIGEVBxCgKIkZREDGKgohRFESMoiBiFAURoyiIGEVBxCgKIkZREDGKgoixKIhIicK/4ojIY/bNv/4XDZXnwn2uB4YAAAAASUVORK5CYII="></p>
   <h2 class="heading settled" data-level="5" id="word"><span class="secno">5. </span><span class="content">Formal wording</span><a class="self-link" href="#word"></a></h2>
   <p>Modify Table 69 "Associative container requirements" in <a href="http://eel.is/c++draft/tab:container.assoc.req">[<strong>tab:container.assoc.req</strong>]</a> as follows:</p>
   <blockquote>
    <div style="text-align: center;"> Table 69 — Associative container requirements (in addition to container) </div>
    <table border="1" style="margin: auto;">
     <tbody>
      <tr>
       <th>Expression 
       <th>Return type 
       <th>Assertion/ note/ pre-/ post-condition 
       <th>Complexity 
      <tr>
       <td>[...] 
       <td>
       <td>
       <td>
      <tr>
       <td>a.extract(k) 
       <td>node_type 
       <td><i>Effects</i>: removes the
                                                                                first element in the
                                                                                container with key
                                                                                equivalent to <i>k</i>.<br> <i>Returns</i>: A <i>node_type</i> owning the element if found,
                                                                                otherwise an empty <i>node_type</i> 
       <td>log(a.size()) 
      <tr>
       <td>
        <ins>a_tran.extract(ke)</ins>
       <td>
        <ins>node_type</ins>
       <td>
        <ins><i>Effects</i>: removes the
                                                                                first element in the
                                                                                container with key <i>r</i> such that <br> <i>!c(r, ke) &amp;&amp; !c(ke, r)</i>.<br> <i>Returns</i>: A <i>node_type</i> owning the element if found,
                                                                                otherwise an empty <i>node_type</i></ins>
       <td>
        <ins>log(a_tran.size())</ins>
      <tr>
       <td>[...] 
       <td>
       <td>
       <td>
      <tr>
       <td>a.erase(k) 
       <td>size_type 
       <td><i>Effects</i>: Erases all
                                                                                elements in the container
                                                                                with key equivalent to <i>k</i>.<br> <i>Returns</i>: The number of
                                                                                erased elements 
       <td>log(a.size()) + a.count(k)) 
      <tr>
       <td>
        <ins>a_tran.erase(ke)</ins>
       <td>
        <ins>size_type</ins>
       <td>
        <ins><i>Effects</i>: Erases all
                                                                                elements in the container
                                                                                with key <i>r</i> such that<br> <i>!c(r, ke) &amp;&amp; !c(ke, r)</i>.<br> <i>Returns</i>: The number of
                                                                                erased elements</ins>
       <td>
        <ins>log(a_tran.size()) + a_tran.count(ke))</ins>
      <tr>
       <td>[...] 
       <td>
       <td>
       <td>
    </table>
   </blockquote>
   <p>Add paragraph 16 in section 22.2.6 <a href="http://eel.is/c++draft/associative.reqmts">[<strong>associative.reqmts</strong>]</a>:</p>
   <blockquote>
     [...] 
    <div>
     <ins> The member function templates <i>erase</i> and <i>extract</i> shall participate
in overload resolution only if all of the following conditions are true:<br> (16.1) - the <i>qualified-id Compare::is_transparent</i> is valid and denotes a type<br> (16.2) - a type of template parameter <i>K</i> is not convertible to <i>iterator
(std::is_convertible_v&lt;K, iterator> != true)</i><br> (16.3) - a type of template parameter <i>K</i> is not convertible to <i>const_iterator
(std::is_convertible_v&lt;K, const_iterator> != true)</i><br> </ins>
    </div>
     [...] 
   </blockquote>
   <p>Modify 22.4.4.1 <a href="http://eel.is/c++draft/map.overview">[<strong>map.overview</strong>]</a>,
class template <i>map</i> synopsis, as indicated</p>
   <blockquote>
     [...] 
<pre class="highlight"><c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>node_type</c-> <c- n>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
<pre class="highlight"><c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>size_type</c-> <c- nf>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>size_type</c-> <c- n>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
   </blockquote>
   <p>Modify 22.4.5.1 <a href="http://eel.is/c++draft/multimap.overview">[<strong>multimap.overview</strong>]</a>,
class template <i>multimap</i> synopsis, as indicated</p>
   <blockquote>
     [...] 
<pre class="highlight"><c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>node_type</c-> <c- n>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
<pre class="highlight"><c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>size_type</c-> <c- nf>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>size_type</c-> <c- n>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
   </blockquote>
   <p>Modify 22.4.6.1 <a href="http://eel.is/c++draft/set.overview">[<strong>set.overview</strong>]</a>,
class template <i>set</i> synopsis, as indicated</p>
   <blockquote>
     [...] 
<pre class="highlight"><c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>node_type</c-> <c- n>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
<pre class="highlight"><c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>size_type</c-> <c- nf>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>size_type</c-> <c- n>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
   </blockquote>
   <p>Modify 22.4.7.1 <a href="http://eel.is/c++draft/multiset.overview">[<strong>multiset.overview</strong>]</a>,
class template <i>multiset</i> synopsis, as indicated</p>
   <blockquote>
     [...] 
<pre class="highlight"><c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>node_type</c-> <c- n>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
<pre class="highlight"><c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>size_type</c-> <c- nf>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>size_type</c-> <c- n>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
   </blockquote>
   <p>Modify Table 70 "Unordered associative container requirements" in <a href="http://eel.is/c++draft/tab:container.hash.req">[<strong>tab:container.hash.req</strong>]</a> as follows:</p>
   <blockquote>
    <div style="text-align: center;"> Table 70 — Unordered associative container requirements (in addition to container) </div>
    <table border="1" style="margin: auto;">
     <tbody>
      <tr>
       <th>Expression 
       <th>Return type 
       <th>Assertion/ note/ pre-/ post-condition 
       <th>Complexity 
      <tr>
       <td>[...] 
       <td>
       <td>
       <td>
      <tr>
       <td>a.extract(k) 
       <td>node_type 
       <td><i>Effects</i>: removes an
                                                                                element in the
                                                                                container with key
                                                                                equivalent to <i>k</i>.<br> <i>Returns</i>: A <i>node_type</i> owning the element if found,
                                                                                otherwise an empty <i>node_type</i> 
       <td>Average case <i>O(1)</i>, worst case <i>O(a.size())</i>. 
      <tr>
       <td>
        <ins>a_tran.extract(ke)</ins>
       <td>
        <ins>node_type</ins>
       <td>
        <ins><i>Effects</i>: removes an
                                                                                element in the
                                                                                container with key
                                                                                equivalent to <i>ke</i>.<br> <i>Returns</i>: A <i>node_type</i> owning the element if found,
                                                                                otherwise an empty <i>node_type</i></ins>
       <td>
        <ins>Average case <i>O(1)</i>, worst case <i>O(a_tran.size())</i>.</ins>
      <tr>
       <td>[...] 
       <td>
       <td>
       <td>
      <tr>
       <td>a.erase(k) 
       <td>size_type 
       <td><i>Effects</i>: Erases all
                                                                                elements with key
                                                                                equivalent to <i>k</i>.<br> <i>Returns</i>: The number of
                                                                                elements erased 
       <td>Average case <i>O(a.count(k))</i>.<br>Worst case <i>O(a.size())</i>. 
      <tr>
       <td>
        <ins>a_tran.erase(ke)</ins>
       <td>
        <ins>size_type</ins>
       <td>
        <ins><i>Effects</i>: Erases all
                                                                                elements with key
                                                                                equivalent to <i>ke</i>.<br> <i>Returns</i>: The number of
                                                                                elements erased</ins>
       <td>
        <ins>Average case <i>O(a_tran.count(k))</i>.<br>Worst case <i>O(a_tran.size())</i>.</ins>
      <tr>
       <td>[...] 
       <td>
       <td>
       <td>
    </table>
   </blockquote>
   <p>Add paragraph 19 in section 22.2.7.1 <a href="http://eel.is/c++draft/unord.req">[<strong>unord.req</strong>]</a>:</p>
   <blockquote>
     [...] 
    <div>
     <ins> The member function templates <i>erase</i> and <i>extract</i> shall participate
in overload resolution only if all of the following conditions are true:<br> (19.1) - the <i>qualified-id</i>s <i>Pred::is_transparent</i> and <i>Hash::is_transparent</i> are both valid and denote types<br> (19.2) - a type of template parameter <i>K</i> is not convertible to <i>iterator
(std::is_convertible_v&lt;K, iterator> != true)</i><br> (19.3) - a type of template parameter <i>K</i> is not convertible to <i>const_iterator
(std::is_convertible_v&lt;K, const_iterator> != true)</i><br> </ins>
    </div>
     [...] 
   </blockquote>
   <p>Modify 22.5.4.1 <a href="http://eel.is/c++draft/unord.map.overview">[<strong>unord.map.overview</strong>]</a>,
class template <i>unordered_map</i> synopsis, as indicated</p>
   <blockquote>
     [...] 
<pre class="highlight"><c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>node_type</c-> <c- n>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
<pre class="highlight"><c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>size_type</c-> <c- nf>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>size_type</c-> <c- n>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
   </blockquote>
   <p>Modify 22.5.5.1 <a href="http://eel.is/c++draft/unord.multimap.overview">[<strong>unord.multimap.overview</strong>]</a>,
class template <i>unordered_multimap</i> synopsis, as indicated</p>
   <blockquote>
     [...] 
<pre class="highlight"><c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>node_type</c-> <c- n>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
<pre class="highlight"><c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>size_type</c-> <c- nf>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>size_type</c-> <c- n>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
   </blockquote>
   <p>Modify 22.5.6.1 <a href="http://eel.is/c++draft/unord.set.overview">[<strong>unord.set.overview</strong>]</a>,
class template <i>unordered_set</i> synopsis, as indicated</p>
   <blockquote>
     [...] 
<pre class="highlight"><c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>node_type</c-> <c- n>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
<pre class="highlight"><c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>size_type</c-> <c- nf>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>size_type</c-> <c- n>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
   </blockquote>
   <p>Modify 22.5.7.1 <a href="http://eel.is/c++draft/unord.multiset.overview">[<strong>unord.multiset.overview</strong>]</a>,
class template <i>unordered_multiset</i> synopsis, as indicated</p>
   <blockquote>
     [...] 
<pre class="highlight"><c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>node_type</c-> <c- nf>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>node_type</c-> <c- n>extract</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
<pre class="highlight"><c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>iterator</c-> <c- nf>erase</c-><c- p>(</c-><c- n>const_iterator</c-> <c- n>position</c-><c- p>);</c->
<c- n>size_type</c-> <c- nf>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>key_type</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
<ins>
<c- k>template</c-> <c- o>&lt;</c-><c- k>class</c-> <c- nc>K</c-><c- o>></c->
<c- n>size_type</c-> <c- n>erase</c-><c- p>(</c-><c- k>const</c-> <c- n>K</c-><c- o>&amp;</c-> <c- n>x</c-><c- p>);</c->
</ins></pre>
    <p>[...]</p>
   </blockquote>
   <h2 class="heading settled" data-level="6" id="changes"><span class="secno">6. </span><span class="content">Revision history</span><a class="self-link" href="#changes"></a></h2>
   <h3 class="heading settled" data-level="6.1" id="r0r1"><span class="secno">6.1. </span><span class="content">R0 ➡ R1</span><a class="self-link" href="#r0r1"></a></h3>
   <p>Addressed feedback from the presentation on LEWG-I to align wording and approach with <a data-link-type="biblio" href="#biblio-p1690r1">[P1690R1]</a>.</p>
  </main>
<script>
(function() {
  "use strict";
  var collapseSidebarText = '<span aria-hidden="true">←</span> '
                          + '<span>Collapse Sidebar</span>';
  var expandSidebarText   = '<span aria-hidden="true">→</span> '
                          + '<span>Pop Out Sidebar</span>';
  var tocJumpText         = '<span aria-hidden="true">↑</span> '
                          + '<span>Jump to Table of Contents</span>';

  var sidebarMedia = window.matchMedia('screen and (min-width: 78em)');
  var autoToggle   = function(e){ toggleSidebar(e.matches) };
  if(sidebarMedia.addListener) {
    sidebarMedia.addListener(autoToggle);
  }

  function toggleSidebar(on) {
    if (on == undefined) {
      on = !document.body.classList.contains('toc-sidebar');
    }

    /* Don’t scroll to compensate for the ToC if we’re above it already. */
    var headY = 0;
    var head = document.querySelector('.head');
    if (head) {
      // terrible approx of "top of ToC"
      headY += head.offsetTop + head.offsetHeight;
    }
    var skipScroll = window.scrollY < headY;

    var toggle = document.getElementById('toc-toggle');
    var tocNav = document.getElementById('toc');
    if (on) {
      var tocHeight = tocNav.offsetHeight;
      document.body.classList.add('toc-sidebar');
      document.body.classList.remove('toc-inline');
      toggle.innerHTML = collapseSidebarText;
      if (!skipScroll) {
        window.scrollBy(0, 0 - tocHeight);
      }
      tocNav.focus();
      sidebarMedia.addListener(autoToggle); // auto-collapse when out of room
    }
    else {
      document.body.classList.add('toc-inline');
      document.body.classList.remove('toc-sidebar');
      toggle.innerHTML = expandSidebarText;
      if (!skipScroll) {
        window.scrollBy(0, tocNav.offsetHeight);
      }
      if (toggle.matches(':hover')) {
        /* Unfocus button when not using keyboard navigation,
           because I don’t know where else to send the focus. */
        toggle.blur();
      }
    }
  }

  function createSidebarToggle() {
    /* Create the sidebar toggle in JS; it shouldn’t exist when JS is off. */
    var toggle = document.createElement('a');
      /* This should probably be a button, but appearance isn’t standards-track.*/
    toggle.id = 'toc-toggle';
    toggle.class = 'toc-toggle';
    toggle.href = '#toc';
    toggle.innerHTML = collapseSidebarText;

    sidebarMedia.addListener(autoToggle);
    var toggler = function(e) {
      e.preventDefault();
      sidebarMedia.removeListener(autoToggle); // persist explicit off states
      toggleSidebar();
      return false;
    }
    toggle.addEventListener('click', toggler, false);


    /* Get <nav id=toc-nav>, or make it if we don’t have one. */
    var tocNav = document.getElementById('toc-nav');
    if (!tocNav) {
      tocNav = document.createElement('p');
      tocNav.id = 'toc-nav';
      /* Prepend for better keyboard navigation */
      document.body.insertBefore(tocNav, document.body.firstChild);
    }
    /* While we’re at it, make sure we have a Jump to Toc link. */
    var tocJump = document.getElementById('toc-jump');
    if (!tocJump) {
      tocJump = document.createElement('a');
      tocJump.id = 'toc-jump';
      tocJump.href = '#toc';
      tocJump.innerHTML = tocJumpText;
      tocNav.appendChild(tocJump);
    }

    tocNav.appendChild(toggle);
  }

  var toc = document.getElementById('toc');
  if (toc) {
    createSidebarToggle();
    toggleSidebar(sidebarMedia.matches);

    /* If the sidebar has been manually opened and is currently overlaying the text
       (window too small for the MQ to add the margin to body),
       then auto-close the sidebar once you click on something in there. */
    toc.addEventListener('click', function(e) {
      if(e.target.tagName.toLowerCase() == "a" && document.body.classList.contains('toc-sidebar') && !sidebarMedia.matches) {
        toggleSidebar(false);
      }
    }, false);
  }
  else {
    console.warn("Can’t find Table of Contents. Please use <nav id='toc'> around the ToC.");
  }

  /* Wrap tables in case they overflow */
  var tables = document.querySelectorAll(':not(.overlarge) > table.data, :not(.overlarge) > table.index');
  var numTables = tables.length;
  for (var i = 0; i < numTables; i++) {
    var table = tables[i];
    var wrapper = document.createElement('div');
    wrapper.className = 'overlarge';
    table.parentNode.insertBefore(wrapper, table);
    wrapper.appendChild(table);
  }

})();
</script>
  <h2 class="no-num no-ref heading settled" id="references"><span class="content">References</span><a class="self-link" href="#references"></a></h2>
  <h3 class="no-num no-ref heading settled" id="informative"><span class="content">Informative References</span><a class="self-link" href="#informative"></a></h3>
  <dl>
   <dt id="biblio-lwg2059">[LWG2059]
   <dd>Christopher Jefferson. <a href="https://wg21.link/lwg2059">C++0x ambiguity problem with map::erase</a>. C++17. URL: <a href="https://wg21.link/lwg2059">https://wg21.link/lwg2059</a>
   <dt id="biblio-n3465">[N3465]
   <dd>Joaquín Mª López Muñoz. <a href="https://wg21.link/n3465">Adding heterogeneous comparison lookup to associative containers for TR2 (Rev 2)</a>. 29 October 2012. URL: <a href="https://wg21.link/n3465">https://wg21.link/n3465</a>
   <dt id="biblio-n3657">[N3657]
   <dd>J. Wakely, S. Lavavej, J. Muñoz. <a href="https://wg21.link/n3657">Adding heterogeneous comparison lookup to associative containers (rev 4)</a>. 19 March 2013. URL: <a href="https://wg21.link/n3657">https://wg21.link/n3657</a>
   <dt id="biblio-p0919r0">[P0919R0]
   <dd>Mateusz Pusz. <a href="https://wg21.link/p0919r0">Heterogeneous lookup for unordered containers</a>. 8 February 2018. URL: <a href="https://wg21.link/p0919r0">https://wg21.link/p0919r0</a>
   <dt id="biblio-p1690r1">[P1690R1]
   <dd>Xiao Shi, Mateusz Pusz, Geoffrey Romer. <a href="https://wg21.link/p1690r1">Refinement Proposal for P0919 Heterogeneous lookup for unordered containers</a>. 12 August 2019. URL: <a href="https://wg21.link/p1690r1">https://wg21.link/p1690r1</a>
  </dl>