<!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>P3154R1: Deprecating signed character types in iostreams</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
 *     -> ins/del.c### for candidate and proposed changes (amendments)
 *
 * Code
 *   - pre and code
 *
 * Special Sections
 *   - .note       for informative notes             (div, p, span, aside, details)
 *   - .example    for informative examples          (div, p, pre, span)
 *   - .issue      for issues                        (div, p, span)
 *   - .advisement for loud normative statements     (div, p, strong)
 *   - .annoying-warning for spec obsoletion notices (div, aside, details)
 *   - .correction for "candidate corrections"       (div, aside, details, section)
 *   - .addition   for "candidate additions"         (div, aside, details, section)
 *   - .correction.proposed for "proposed corrections" (div, aside, details, section)
 *   - .addition.proposed   for "proposed additions"   (div, aside, details, section)
 *
 * Definition Boxes
 *   - pre.def   for WebIDL definitions
 *   - table.def for tables that define other entities (e.g. CSS properties)
 *   - dl.def    for definition lists that define other entitles (e.g. HTML elements)
 *
 * Numbering
 *   - .secno for section numbers in .toc and headings (<span class='secno'>3.2</span>)
 *   - .marker for source-inserted example/figure/issue numbers (<span class='marker'>Issue 4</span>)
 *   - ::before styled for CSS-generated issue/example/figure numbers:
 *     -> Documents wishing to use this only need to add
 *        figcaption::before,
 *        .caption::before { content: "Figure "  counter(figure) " ";  }
 *        .example::before { content: "Example " counter(example) " "; }
 *        .issue::before   { content: "Issue "   counter(issue) " ";   }
 *
 * Header Stuff (ignore, just don't conflict with these classes)
 *   - .head for the header
 *   - .copyright for the copyright
 *
 * Outdated warning for old specs
 *
 * Miscellaneous
 *   - .overlarge for things that should be as wide as possible, even if
 *     that overflows the body text area. This can be used on an item or
 *     on its container, depending on the effect desired.
 *     Note that this styling basically doesn't help at all when printing,
 *     since A4 paper isn't much wider than the max-width here.
 *     It's better to design things to fit into a narrower measure if possible.
 *
 *   - js-added ToC jump links (see fixup.js)
 *
 ******************************************************************************/

/* color variables included separately for reliability */

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

	html {
	}

	body {
		counter-reset: example figure issue;

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

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

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


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	p {
		margin: 1em 0;
	}

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

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

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

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

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

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

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

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

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


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

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

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

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

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

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

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

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

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

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

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

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

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

	/* Do something nice. */

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

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

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

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

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

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

	img {
		border-style: none;
	}

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

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

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

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

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

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

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


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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


/*
Alternate table alignment rules

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

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

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

Possible extra rowspan handling

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

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

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


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

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

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

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

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

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

		.toc li {
			clear: both;
		}

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

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

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


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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

.outdated-warning span {
	display: block;
}

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

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

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

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

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



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

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

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

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

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

    del { background: #fcc; color: #000; text-decoration: line-through; }
    ins { background: #cfc; color: #000; }
    blockquote .highlight:not(.idl) { background: initial; margin: initial; padding: 0.5em }
    blockquote ul { background: inherit; }
    blockquote code.highlight:not(.idl) { padding: initial; }
    blockquote c-[a] { color: inherit; } /* Keyword.Declaration */
    blockquote c-[b] { color: inherit; } /* Keyword.Type */
    blockquote c-[c] { color: inherit; } /* Comment */
    blockquote c-[d] { color: inherit; } /* Comment.Multiline */
    blockquote c-[e] { color: inherit; } /* Name.Attribute */
    blockquote c-[f] { color: inherit; } /* Name.Tag */
    blockquote c-[g] { color: inherit; } /* Name.Variable */
    blockquote c-[k] { color: inherit; } /* Keyword */
    blockquote c-[l] { color: inherit; } /* Literal */
    blockquote c-[m] { color: inherit; } /* Literal.Number */
    blockquote c-[n] { color: inherit; } /* Name */
    blockquote c-[o] { color: inherit; } /* Operator */
    blockquote c-[p] { color: inherit; } /* Punctuation */
    blockquote c-[s] { color: inherit; } /* Literal.String */
    blockquote c-[t] { color: inherit; } /* Literal.String.Single */
    blockquote c-[u] { color: inherit; } /* Literal.String.Double */
    blockquote c-[cp] { color: inherit; } /* Comment.Preproc */
    blockquote c-[c1] { color: inherit; } /* Comment.Single */
    blockquote c-[cs] { color: inherit; } /* Comment.Special */
    blockquote c-[kc] { color: inherit; } /* Keyword.Constant */
    blockquote c-[kn] { color: inherit; } /* Keyword.Namespace */
    blockquote c-[kp] { color: inherit; } /* Keyword.Pseudo */
    blockquote c-[kr] { color: inherit; } /* Keyword.Reserved */
    blockquote c-[ld] { color: inherit; } /* Literal.Date */
    blockquote c-[nc] { color: inherit; } /* Name.Class */
    blockquote c-[no] { color: inherit; } /* Name.Constant */
    blockquote c-[nd] { color: inherit; } /* Name.Decorator */
    blockquote c-[ni] { color: inherit; } /* Name.Entity */
    blockquote c-[ne] { color: inherit; } /* Name.Exception */
    blockquote c-[nf] { color: inherit; } /* Name.Function */
    blockquote c-[nl] { color: inherit; } /* Name.Label */
    blockquote c-[nn] { color: inherit; } /* Name.Namespace */
    blockquote c-[py] { color: inherit; } /* Name.Property */
    blockquote c-[ow] { color: inherit; } /* Operator.Word */
    blockquote c-[mb] { color: inherit; } /* Literal.Number.Bin */
    blockquote c-[mf] { color: inherit; } /* Literal.Number.Float */
    blockquote c-[mh] { color: inherit; } /* Literal.Number.Hex */
    blockquote c-[mi] { color: inherit; } /* Literal.Number.Integer */
    blockquote c-[mo] { color: inherit; } /* Literal.Number.Oct */
    blockquote c-[sb] { color: inherit; } /* Literal.String.Backtick */
    blockquote c-[sc] { color: inherit; } /* Literal.String.Char */
    blockquote c-[sd] { color: inherit; } /* Literal.String.Doc */
    blockquote c-[se] { color: inherit; } /* Literal.String.Escape */
    blockquote c-[sh] { color: inherit; } /* Literal.String.Heredoc */
    blockquote c-[si] { color: inherit; } /* Literal.String.Interpol */
    blockquote c-[sx] { color: inherit; } /* Literal.String.Other */
    blockquote c-[sr] { color: inherit; } /* Literal.String.Regex */
    blockquote c-[ss] { color: inherit; } /* Literal.String.Symbol */
    blockquote c-[vc] { color: inherit; } /* Name.Variable.Class */
    blockquote c-[vg] { color: inherit; } /* Name.Variable.Global */
    blockquote c-[vi] { color: inherit; } /* Name.Variable.Instance */
    blockquote c-[il] { color: inherit; } /* Literal.Number.Integer.Long */
  </style>
  <meta content="Bikeshed version 4416b18d5, updated Tue Jan 2 15:52:39 2024 -0800" name="generator">
  <link href="http://wg21.link/P3154R1.html" rel="canonical">
  <link href="https://isocpp.org/favicon.ico" rel="icon">
  <meta content="44d2908dc59d0454dcb1d546ccd95e2329705631" name="revision">
<style>/* Boilerplate: style-autolinks */
.css.css, .property.property, .descriptor.descriptor {
    color: var(--a-normal-text);
    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;
}

@media (prefers-color-scheme: dark) {
    :root {
        --selflink-text: black;
        --selflink-bg: silver;
        --selflink-hover-text: white;
    }
}
</style>
<style>/* Boilerplate: style-colors */
/* Any --*-text not paired with a --*-bg is assumed to have a transparent bg */
:root {
    color-scheme: light dark;

    --text: black;
    --bg: white;

    --unofficial-watermark: url(https://www.w3.org/StyleSheets/TR/2016/logos/UD-watermark);

    --logo-bg: #1a5e9a;
    --logo-active-bg: #c00;
    --logo-text: white;

    --tocnav-normal-text: #707070;
    --tocnav-normal-bg: var(--bg);
    --tocnav-hover-text: var(--tocnav-normal-text);
    --tocnav-hover-bg: #f8f8f8;
    --tocnav-active-text: #c00;
    --tocnav-active-bg: var(--tocnav-normal-bg);

    --tocsidebar-text: var(--text);
    --tocsidebar-bg: #f7f8f9;
    --tocsidebar-shadow: rgba(0,0,0,.1);
    --tocsidebar-heading-text: hsla(203,20%,40%,.7);

    --toclink-text: var(--text);
    --toclink-underline: #3980b5;
    --toclink-visited-text: var(--toclink-text);
    --toclink-visited-underline: #054572;

    --heading-text: #005a9c;

    --hr-text: var(--text);

    --algo-border: #def;

    --del-text: red;
    --del-bg: transparent;
    --ins-text: #080;
    --ins-bg: transparent;

    --a-normal-text: #034575;
    --a-normal-underline: #bbb;
    --a-visited-text: var(--a-normal-text);
    --a-visited-underline: #707070;
    --a-hover-bg: rgba(75%, 75%, 75%, .25);
    --a-active-text: #c00;
    --a-active-underline: #c00;

    --blockquote-border: silver;
    --blockquote-bg: transparent;
    --blockquote-text: currentcolor;

    --issue-border: #e05252;
    --issue-bg: #fbe9e9;
    --issue-text: var(--text);
    --issueheading-text: #831616;

    --example-border: #e0cb52;
    --example-bg: #fcfaee;
    --example-text: var(--text);
    --exampleheading-text: #574b0f;

    --note-border: #52e052;
    --note-bg: #e9fbe9;
    --note-text: var(--text);
    --noteheading-text: hsl(120, 70%, 30%);
    --notesummary-underline: silver;

    --assertion-border: #aaa;
    --assertion-bg: #eee;
    --assertion-text: black;

    --advisement-border: orange;
    --advisement-bg: #fec;
    --advisement-text: var(--text);
    --advisementheading-text: #b35f00;

    --warning-border: red;
    --warning-bg: hsla(40,100%,50%,0.95);
    --warning-text: var(--text);

    --amendment-border: #330099;
    --amendment-bg: #F5F0FF;
    --amendment-text: var(--text);
    --amendmentheading-text: #220066;

    --def-border: #8ccbf2;
    --def-bg: #def;
    --def-text: var(--text);
    --defrow-border: #bbd7e9;

    --datacell-border: silver;

    --indexinfo-text: #707070;

    --indextable-hover-text: black;
    --indextable-hover-bg: #f7f8f9;

    --outdatedspec-bg: rgba(0, 0, 0, .5);
    --outdatedspec-text: black;
    --outdated-bg: maroon;
    --outdated-text: white;
    --outdated-shadow: red;

    --editedrec-bg: darkorange;
}

@media (prefers-color-scheme: dark) {
    :root {
        --text: #ddd;
        --bg: black;

        --unofficial-watermark: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='400' height='400'%3E%3Cg fill='%23100808' transform='translate(200 200) rotate(-45) translate(-200 -200)' stroke='%23100808' stroke-width='3'%3E%3Ctext x='50%25' y='220' style='font: bold 70px sans-serif; text-anchor: middle; letter-spacing: 6px;'%3EUNOFFICIAL%3C/text%3E%3Ctext x='50%25' y='305' style='font: bold 70px sans-serif; text-anchor: middle; letter-spacing: 6px;'%3EDRAFT%3C/text%3E%3C/g%3E%3C/svg%3E");

        --logo-bg: #1a5e9a;
        --logo-active-bg: #c00;
        --logo-text: white;

        --tocnav-normal-text: #999;
        --tocnav-normal-bg: var(--bg);
        --tocnav-hover-text: var(--tocnav-normal-text);
        --tocnav-hover-bg: #080808;
        --tocnav-active-text: #f44;
        --tocnav-active-bg: var(--tocnav-normal-bg);

        --tocsidebar-text: var(--text);
        --tocsidebar-bg: #080808;
        --tocsidebar-shadow: rgba(255,255,255,.1);
        --tocsidebar-heading-text: hsla(203,20%,40%,.7);

        --toclink-text: var(--text);
        --toclink-underline: #6af;
        --toclink-visited-text: var(--toclink-text);
        --toclink-visited-underline: #054572;

        --heading-text: #8af;

        --hr-text: var(--text);

        --algo-border: #456;

        --del-text: #f44;
        --del-bg: transparent;
        --ins-text: #4a4;
        --ins-bg: transparent;

        --a-normal-text: #6af;
        --a-normal-underline: #555;
        --a-visited-text: var(--a-normal-text);
        --a-visited-underline: var(--a-normal-underline);
        --a-hover-bg: rgba(25%, 25%, 25%, .2);
        --a-active-text: #f44;
        --a-active-underline: var(--a-active-text);

        --borderedblock-bg: rgba(255, 255, 255, .05);

        --blockquote-border: silver;
        --blockquote-bg: var(--borderedblock-bg);
        --blockquote-text: currentcolor;

        --issue-border: #e05252;
        --issue-bg: var(--borderedblock-bg);
        --issue-text: var(--text);
        --issueheading-text: hsl(0deg, 70%, 70%);

        --example-border: hsl(50deg, 90%, 60%);
        --example-bg: var(--borderedblock-bg);
        --example-text: var(--text);
        --exampleheading-text: hsl(50deg, 70%, 70%);

        --note-border: hsl(120deg, 100%, 35%);
        --note-bg: var(--borderedblock-bg);
        --note-text: var(--text);
        --noteheading-text: hsl(120, 70%, 70%);
        --notesummary-underline: silver;

        --assertion-border: #444;
        --assertion-bg: var(--borderedblock-bg);
        --assertion-text: var(--text);

        --advisement-border: orange;
        --advisement-bg: #222218;
        --advisement-text: var(--text);
        --advisementheading-text: #f84;

        --warning-border: red;
        --warning-bg: hsla(40,100%,20%,0.95);
        --warning-text: var(--text);

        --amendment-border: #330099;
        --amendment-bg: #080010;
        --amendment-text: var(--text);
        --amendmentheading-text: #cc00ff;

        --def-border: #8ccbf2;
        --def-bg: #080818;
        --def-text: var(--text);
        --defrow-border: #136;

        --datacell-border: silver;

        --indexinfo-text: #aaa;

        --indextable-hover-text: var(--text);
        --indextable-hover-bg: #181818;

        --outdatedspec-bg: rgba(255, 255, 255, .5);
        --outdatedspec-text: black;
        --outdated-bg: maroon;
        --outdated-text: white;
        --outdated-shadow: red;

        --editedrec-bg: darkorange;
    }
    /* In case a transparent-bg image doesn't expect to be on a dark bg,
       which is quite common in practice... */
    img { background: white; }
}
</style>
<style>/* Boilerplate: 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>/* Boilerplate: style-issues */
a[href].issue-return {
    float: right;
    float: inline-end;
    color: var(--issueheading-text);
    font-weight: bold;
    text-decoration: none;
}
</style>
<style>/* Boilerplate: 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>/* Boilerplate: style-selflinks */
:root {
    --selflink-text: white;
    --selflink-bg: gray;
    --selflink-hover-text: black;
}
.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%;
}
.example > a.self-link,
.note > a.self-link,
.issue > a.self-link {
    /* These blocks are overflow:auto, so positioning outside
       doesn't work. */
    left: auto;
    right: 0;
}
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: var(--selflink-bg);
    color: var(--selflink-text);
    font-style: normal;
    transition: opacity .2s, background-color .2s, color .2s;
}
dfn:hover > a.self-link {
    opacity: 1;
}
dfn > a.self-link:hover {
    color: var(--selflink-hover-text);
}

a.self-link::before            { content: "¶"; }
.heading > a.self-link::before { content: "§"; }
dfn > a.self-link::before      { content: "#"; }
</style>
<style>/* Boilerplate: style-syntax-highlighting */
code.highlight { padding: .1em; border-radius: .3em; }
pre.highlight, pre > code.highlight { display: block; padding: 1em; margin: .5em 0; overflow: auto; border-radius: 0; }

.highlight:not(.idl) { background: rgba(0, 0, 0, .03); }
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 */

@media (prefers-color-scheme: dark) {
    .highlight:not(.idl) { background: rgba(255, 255, 255, .05); }

    c-[a] { color: #d33682 } /* Keyword.Declaration */
    c-[b] { color: #d33682 } /* Keyword.Type */
    c-[c] { color: #2aa198 } /* Comment */
    c-[d] { color: #2aa198 } /* Comment.Multiline */
    c-[e] { color: #268bd2 } /* Name.Attribute */
    c-[f] { color: #b58900 } /* Name.Tag */
    c-[g] { color: #cb4b16 } /* Name.Variable */
    c-[k] { color: #d33682 } /* Keyword */
    c-[l] { color: #657b83 } /* Literal */
    c-[m] { color: #657b83 } /* Literal.Number */
    c-[n] { color: #268bd2 } /* Name */
    c-[o] { color: #657b83 } /* Operator */
    c-[p] { color: #657b83 } /* Punctuation */
    c-[s] { color: #6c71c4 } /* Literal.String */
    c-[t] { color: #6c71c4 } /* Literal.String.Single */
    c-[u] { color: #6c71c4 } /* Literal.String.Double */
    c-[ch] { color: #2aa198 } /* Comment.Hashbang */
    c-[cp] { color: #2aa198 } /* Comment.Preproc */
    c-[cpf] { color: #2aa198 } /* Comment.PreprocFile */
    c-[c1] { color: #2aa198 } /* Comment.Single */
    c-[cs] { color: #2aa198 } /* Comment.Special */
    c-[kc] { color: #d33682 } /* Keyword.Constant */
    c-[kn] { color: #d33682 } /* Keyword.Namespace */
    c-[kp] { color: #d33682 } /* Keyword.Pseudo */
    c-[kr] { color: #d33682 } /* Keyword.Reserved */
    c-[ld] { color: #657b83 } /* Literal.Date */
    c-[nc] { color: #268bd2 } /* Name.Class */
    c-[no] { color: #268bd2 } /* Name.Constant */
    c-[nd] { color: #268bd2 } /* Name.Decorator */
    c-[ni] { color: #268bd2 } /* Name.Entity */
    c-[ne] { color: #268bd2 } /* Name.Exception */
    c-[nf] { color: #268bd2 } /* Name.Function */
    c-[nl] { color: #268bd2 } /* Name.Label */
    c-[nn] { color: #268bd2 } /* Name.Namespace */
    c-[py] { color: #268bd2 } /* Name.Property */
    c-[ow] { color: #657b83 } /* Operator.Word */
    c-[mb] { color: #657b83 } /* Literal.Number.Bin */
    c-[mf] { color: #657b83 } /* Literal.Number.Float */
    c-[mh] { color: #657b83 } /* Literal.Number.Hex */
    c-[mi] { color: #657b83 } /* Literal.Number.Integer */
    c-[mo] { color: #657b83 } /* Literal.Number.Oct */
    c-[sa] { color: #6c71c4 } /* Literal.String.Affix */
    c-[sb] { color: #6c71c4 } /* Literal.String.Backtick */
    c-[sc] { color: #6c71c4 } /* Literal.String.Char */
    c-[dl] { color: #6c71c4 } /* Literal.String.Delimiter */
    c-[sd] { color: #6c71c4 } /* Literal.String.Doc */
    c-[se] { color: #6c71c4 } /* Literal.String.Escape */
    c-[sh] { color: #6c71c4 } /* Literal.String.Heredoc */
    c-[si] { color: #6c71c4 } /* Literal.String.Interpol */
    c-[sx] { color: #6c71c4 } /* Literal.String.Other */
    c-[sr] { color: #6c71c4 } /* Literal.String.Regex */
    c-[ss] { color: #6c71c4 } /* Literal.String.Symbol */
    c-[fm] { color: #268bd2 } /* Name.Function.Magic */
    c-[vc] { color: #cb4b16 } /* Name.Variable.Class */
    c-[vg] { color: #cb4b16 } /* Name.Variable.Global */
    c-[vi] { color: #cb4b16 } /* Name.Variable.Instance */
    c-[vm] { color: #cb4b16 } /* Name.Variable.Magic */
    c-[il] { color: #657b83 } /* 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">P3154R1<br>Deprecating signed character types in iostreams</h1>
   <h2 class="no-num no-toc no-ref heading settled" id="profile-and-date"><span class="content">Published Proposal, <time class="dt-updated" datetime="2024-05-20">2024-05-20</time></span></h2>
   <div data-fill-with="spec-metadata">
    <dl>
     <dt>This version:
     <dd><a class="u-url" href="http://wg21.link/P3154R1.html">http://wg21.link/P3154R1.html</a>
     <dt class="editor">Author:
     <dd class="editor p-author h-card vcard"><a class="p-name fn u-email email" href="mailto:isocpp@eliaskosunen.com">Elias Kosunen</a>
     <dt>Audience:
     <dd>LEWG
     <dt>Project:
     <dd>ISO/IEC 14882 Programming Languages — C++, ISO/IEC JTC1/SC22/WG21
    </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>This paper proposes deprecating overloads under iostreams,
that take some variant of <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> or <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code>,
and treat these as characters, rather than integers.
The behavior of these overloads is unexpected, especially
when using the aliases <code class="highlight"><c- b>int8_t</c-></code> or <code class="highlight"><c- b>uint8_t</c-></code>.</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="#changelog"><span class="secno">1</span> <span class="content">Changelog</span></a>
     <ol class="toc">
      <li><a href="#changelog-since-r0"><span class="secno">1.1</span> <span class="content">Changes since R0</span></a>
     </ol>
    <li><a href="#motivation"><span class="secno">2</span> <span class="content">Motivation</span></a>
    <li>
     <a href="#impact"><span class="secno">3</span> <span class="content">Impact</span></a>
     <ol class="toc">
      <li><a href="#study"><span class="secno">3.1</span> <span class="content">Impact study</span></a>
     </ol>
    <li>
     <a href="#wording"><span class="secno">4</span> <span class="content">Wording</span></a>
     <ol class="toc">
      <li><a href="#modify-istreamgeneral-p1"><span class="secno">4.1</span> <span class="content">Modify <span>[istream.general</span>] p1</span></a>
      <li><a href="#modify-istreamextractors-around-p7-to-p12"><span class="secno">4.2</span> <span class="content">Modify <span>[istream.extractors</span>], around p7 to p12</span></a>
      <li><a href="#modify-ostreamgeneral-p1"><span class="secno">4.3</span> <span class="content">Modify <span>[ostream.general</span>] p1</span></a>
      <li><a href="#modify-ostreaminserterscharacter"><span class="secno">4.4</span> <span class="content">Modify <span>[ostream.inserters.character</span>]</span></a>
      <li><a href="#add-a-new-subclause-in-annex-d-after-depratomics"><span class="secno">4.5</span> <span class="content">Add a new subclause in Annex D after <span>[depr.atomics</span>]</span></a>
      <li><a href="#add-a-new-subclause-in-annex-d-after-the-above-depristreamextractors"><span class="secno">4.6</span> <span class="content">Add a new subclause in Annex D after the above ([depr.istream.extractors])</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="changelog"><span class="secno">1. </span><span class="content">Changelog</span><a class="self-link" href="#changelog"></a></h2>
   <h3 class="heading settled" data-level="1.1" id="changelog-since-r0"><span class="secno">1.1. </span><span class="content">Changes since R0</span><a class="self-link" href="#changelog-since-r0"></a></h3>
   <ul>
    <li data-md>
     <p>Add a study on possible impact</p>
    <li data-md>
     <p>Update the code example in Motivation</p>
    <li data-md>
     <p>Add note about <code class="highlight"><c- b>char8_t</c-></code> in C</p>
    <li data-md>
     <p>Add note about <a data-link-type="biblio" href="#biblio-p0487r1" title="Fixing operator>>(basic_istream&amp;, CharT*) (LWG 2499)">[P0487R1]</a></p>
   </ul>
   <h2 class="heading settled" data-level="2" id="motivation"><span class="secno">2. </span><span class="content">Motivation</span><a class="self-link" href="#motivation"></a></h2>
<pre class="language-cpp highlight"><c- cp>#include</c-> &lt;iostream>
<c- cp>#include</c-> &lt;format>

<c- b>int</c-> <c- nf>main</c-><c- p>()</c-> <c- p>{</c->
    <c- c1>// Prints:</c->
    <c- n>std</c-><c- o>::</c-><c- n>cout</c->
        <c- o>&lt;&lt;</c-> <c- k>static_cast</c-><c- o>&lt;</c->         <c- b>char</c-><c- o>></c-><c- p>(</c-><c- mi>48</c-><c- p>)</c-> <c- o>&lt;&lt;</c-> <c- sc>'\n'</c->  <c- c1>// 0</c->
        <c- o>&lt;&lt;</c-> <c- k>static_cast</c-><c- o>&lt;</c->  <c- b>signed</c-> <c- b>char</c-><c- o>></c-><c- p>(</c-><c- mi>48</c-><c- p>)</c-> <c- o>&lt;&lt;</c-> <c- sc>'\n'</c->  <c- c1>// 0 (Proposing deprecation)</c->
        <c- o>&lt;&lt;</c-> <c- k>static_cast</c-><c- o>&lt;</c-><c- b>unsigned</c-> <c- b>char</c-><c- o>></c-><c- p>(</c-><c- mi>48</c-><c- p>)</c-> <c- o>&lt;&lt;</c-> <c- sc>'\n'</c->  <c- c1>// 0 (Proposing deprecation)</c->
        <c- o>&lt;&lt;</c-> <c- k>static_cast</c-><c- o>&lt;</c->       <c- b>int8_t</c-><c- o>></c-><c- p>(</c-><c- mi>48</c-><c- p>)</c-> <c- o>&lt;&lt;</c-> <c- sc>'\n'</c->  <c- c1>// 0 (Proposing deprecation)</c->
        <c- o>&lt;&lt;</c-> <c- k>static_cast</c-><c- o>&lt;</c->      <c- b>uint8_t</c-><c- o>></c-><c- p>(</c-><c- mi>48</c-><c- p>)</c-> <c- o>&lt;&lt;</c-> <c- sc>'\n'</c->  <c- c1>// 0 (Proposing deprecation)</c->
        <c- o>&lt;&lt;</c-> <c- k>static_cast</c-><c- o>&lt;</c->        <c- b>short</c-><c- o>></c-><c- p>(</c-><c- mi>48</c-><c- p>)</c-> <c- o>&lt;&lt;</c-> <c- sc>'\n'</c->  <c- c1>// 48</c->

        <c- o>&lt;&lt;</c-> <c- n>std</c-><c- o>::</c-><c- n>format</c-><c- p>(</c-><c- s>"{}</c-><c- se>\n</c-><c- s>"</c-><c- p>,</c-> <c- k>static_cast</c-><c- o>&lt;</c->         <c- b>char</c-><c- o>></c-><c- p>(</c-><c- mi>48</c-><c- p>))</c->  <c- c1>// 0</c->
        <c- o>&lt;&lt;</c-> <c- n>std</c-><c- o>::</c-><c- n>format</c-><c- p>(</c-><c- s>"{}</c-><c- se>\n</c-><c- s>"</c-><c- p>,</c-> <c- k>static_cast</c-><c- o>&lt;</c->  <c- b>signed</c-> <c- b>char</c-><c- o>></c-><c- p>(</c-><c- mi>48</c-><c- p>))</c->  <c- c1>// 48</c->
        <c- o>&lt;&lt;</c-> <c- n>std</c-><c- o>::</c-><c- n>format</c-><c- p>(</c-><c- s>"{}</c-><c- se>\n</c-><c- s>"</c-><c- p>,</c-> <c- k>static_cast</c-><c- o>&lt;</c-><c- b>unsigned</c-> <c- b>char</c-><c- o>></c-><c- p>(</c-><c- mi>48</c-><c- p>))</c->  <c- c1>// 48</c->
        <c- o>&lt;&lt;</c-> <c- n>std</c-><c- o>::</c-><c- n>format</c-><c- p>(</c-><c- s>"{}</c-><c- se>\n</c-><c- s>"</c-><c- p>,</c-> <c- k>static_cast</c-><c- o>&lt;</c->       <c- b>int8_t</c-><c- o>></c-><c- p>(</c-><c- mi>48</c-><c- p>))</c->  <c- c1>// 48</c->
        <c- o>&lt;&lt;</c-> <c- n>std</c-><c- o>::</c-><c- n>format</c-><c- p>(</c-><c- s>"{}</c-><c- se>\n</c-><c- s>"</c-><c- p>,</c-> <c- k>static_cast</c-><c- o>&lt;</c->      <c- b>uint8_t</c-><c- o>></c-><c- p>(</c-><c- mi>48</c-><c- p>))</c->  <c- c1>// 48</c->
        <c- o>&lt;&lt;</c-> <c- n>std</c-><c- o>::</c-><c- n>format</c-><c- p>(</c-><c- s>"{}</c-><c- se>\n</c-><c- s>"</c-><c- p>,</c-> <c- k>static_cast</c-><c- o>&lt;</c->        <c- b>short</c-><c- o>></c-><c- p>(</c-><c- mi>48</c-><c- p>));</c-> <c- c1>// 48</c->
<c- p>}</c->
</pre>
   <p>There are overloads for <code class="highlight"><c- k>operator</c-><c- o>&lt;&lt;</c-></code> for <code class="highlight"><c- n>basic_ostream</c-></code>,
that take an <code class="highlight"><c- p>(</c-><c- n>un</c-><c- p>)</c-><c- b>signed</c-> <c- b>char</c-></code>, and a <code class="highlight"><c- k>const</c-> <c- p>(</c-><c- n>un</c-><c- p>)</c-><c- b>signed</c-> <c- b>char</c-><c- o>*</c-></code>.
In addition, there are overloads for <code class="highlight"><c- k>operator</c-><c- o>>></c-></code> for <code class="highlight"><c- n>basic_istream</c-></code>,
that take an <code class="highlight"><c- p>(</c-><c- n>un</c-><c- p>)</c-><c- b>signed</c-> <c- b>char</c-><c- o>&amp;</c-></code> and an <code class="highlight"><c- p>(</c-><c- n>un</c-><c- p>)</c-><c- b>signed</c-> <c- b>char</c-> <c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]</c-></code>.
These overloads are specified to have equivalent behavior to
the non-signedness qualified overloads: <a href="https://eel.is/c++draft/istream.extractors">[istream.extractors</a>] <a href="https://eel.is/c++draft/ostream.inserters.character">[ostream.inserters.character</a>].</p>
   <p>This is surprising. Per <a href="https://eel.is/c++draft/basic.fundamental#1">[basic.fundamental</a>] p1 and p2:</p>
   <blockquote>
    <p>There are five <i>standard signed integer types</i>:
"<code class="highlight"><c- b>signed</c-> <c- b>char</c-></code>", "<code class="highlight"><c- b>short</c-> <c- b>int</c-></code>", "<code class="highlight"><c- b>int</c-></code>", "<code class="highlight"><c- b>long</c-> <c- b>int</c-></code>", and "<code class="highlight"><c- b>long</c-> <c- b>long</c-> <c- b>int</c-></code>"...
There may also be implementation-defined <i>extended signed integer types</i>.
The standard and extended signed integer types are collectively called <i>signed integer types</i>.</p>
    <p>For each of the standard signed integer types,
there exists a corresponding (but different) <i>standard unsigned integer type</i>:
"<code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code>", "<code class="highlight"><c- b>unsigned</c-> <c- b>short</c-> <c- b>int</c-></code>", "<code class="highlight"><c- b>unsigned</c-> <c- b>int</c-></code>", "<code class="highlight"><c- b>unsigned</c-> <c- b>long</c-> <c- b>int</c-></code>", and "<code class="highlight"><c- b>unsigned</c-> <c- b>long</c-> <c- b>long</c-> <c- b>int</c-></code>"...
Likewise, for each of the extended signed integer types, there exists a corresponding <i>extended unsigned integer types</i>.
The standard and extended unsigned integer types are collectively called <i>unsigned integer types</i>.</p>
   </blockquote>
   <p>Thus, <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> and <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code> should be treated as integers, not as characters.
This is highlighted by the fact, that <code class="highlight"><c- b>int8_t</c-></code> and <code class="highlight"><c- b>uint8_t</c-></code> are specified to be aliases to (un)signed integer types,
which are in practice going to be <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> and <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code>.</p>
   <p class="note" role="note"><span class="marker">Note:</span> The Solaris implementation is different, and defines <code class="highlight"><c- b>int8_t</c-></code> to be <code class="highlight"><c- b>char</c-></code> by default.
This is not conformant.</p>
   <p><code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> and <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code> are not character types.
Per <a href="https://eel.is/c++draft/basic.fundamental#11">[basic.fundamental</a>] p11, since <a data-link-type="biblio" href="#biblio-p2314r4" title="Character sets and encodings">[P2314R4]</a>:</p>
   <blockquote>
    <p>The types <code class="highlight"><c- b>char</c-></code>, <code class="highlight"><c- b>wchar_t</c-></code>, <code class="highlight"><c- b>char8_t</c-></code>, <code class="highlight"><c- b>char16_t</c-></code>, and <code class="highlight"><c- b>char32_t</c-></code> are collectively called <i>character types</i>.</p>
   </blockquote>
   <p><code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> and <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code> are included in the set of <i>ordinary character types</i> and <i>narrow character types</i> (<a href="https://eel.is/c++draft/basic.fundamental#7">[basic.fundamental</a>] p7),
but these definitions are used for specifying alignment, padding, and <i>indeterminate values</i> (<a href="https://eel.is/c++draft/basic.indet">[basic.indet</a>]),
and are arguably not related to characters in the sense of pieces of text.</p>
   <p><code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>format</c-></code> has already taken a step in the right direction here,
by treating <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> and <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code> as integers.
It’s specified to not give special treatment to these types,
but to use the standard definitions of (un)signed integer type
to determine whether a type is to be treated as an integer when formatting.</p>
   <p>This paper proposes that these overloads in iostreams should be deprecated.</p>
   <h2 class="heading settled" data-level="3" id="impact"><span class="secno">3. </span><span class="content">Impact</span><a class="self-link" href="#impact"></a></h2>
   <p>It’s difficult to find examples where this is the sought-after behavior, and would become deprecated with this change.
These snippets aren’t easily greppable.</p>
   <p>It’s easy to find counter-examples, however, where workarounds have to be employed to insert or extract <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code>s or <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code>s
as integers. Some of them can be found with <a href="https://codesearch.isocpp.org/cgi-bin/cgi_ppsearch?q=%3C%3C+static_cast%3Cint%3E&amp;search=Search">isocpp.org codesearch</a> by searching for <code class="highlight"><c- o>&lt;&lt;</c-> <c- k>static_cast</c-><c- o>&lt;</c-><c- b>int</c-><c- o>></c-></code> or <code class="highlight"><c- o>&lt;&lt;</c-> <c- p>(</c-><c- b>int</c-><c- p>)</c-></code>, although false positives there are very prevalent.</p>
<pre class="language-cpp highlight"><c- d>/* ... */</c-> <c- o>&lt;&lt;</c-> <c- k>static_cast</c-><c- o>&lt;</c-><c- b>int</c-><c- o>></c-><c- p>(</c-><c- n>my_schar</c-><c- p>);</c->
</pre>
   <p>These overloads have existed since C++98.
The signature of <code class="highlight"><c- k>operator</c-><c- o>>></c-></code> for <code class="highlight"><c- n>basic_istream</c-></code> was updated for C++20 in <a data-link-type="biblio" href="#biblio-p0487r1" title="Fixing operator>>(basic_istream&amp;, CharT*) (LWG 2499)">[P0487R1]</a>,
where these functions were changed to take <code class="highlight"><c- n>T</c-> <c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]</c-></code> instead of <code class="highlight"><c- n>T</c-><c- o>*</c-></code>, for safety reasons.
No other changes to these overloads have been made in standard C++.</p>
<pre class="highlight"><c- c1>// Changes in P0487, applied to C++20</c->

<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><ins><c- p>,</c-> <c- b>size_t</c-> <c- n>N</c-></ins><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <del><c- n>charT</c-><c- o>*</c-></del><ins><c- n>charT</c-><c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]</c-></ins><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><ins><c- p>,</c-> <c- b>size_t</c-> <c- n>N</c-></ins><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <del><c- b>unsigned</c-> <c- b>char</c-><c- o>*</c-></del><ins><c- b>unsigned</c-> <c- b>char</c-><c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]</c-></ins><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><ins><c- p>,</c-> <c- b>size_t</c-> <c- n>N</c-></ins><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <del><c- b>signed</c-> <c- b>char</c-><c- o>*</c-></del><ins><c- b>signed</c-> <c- b>char</c-><c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]</c-></ins><c- p>);</c->

</pre>
   <p>It should be noted, that the C standard has defined <code class="highlight"><c- b>char8_t</c-></code> to be an alias (typedef) to <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code>.
In C++, <code class="highlight"><c- b>char8_t</c-></code> is a distinct type with an underlying type of <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code>.</p>
   <h3 class="heading settled" data-level="3.1" id="study"><span class="secno">3.1. </span><span class="content">Impact study</span><a class="self-link" href="#study"></a></h3>
   <p>To gauge the potential impact of this deprecation,
the author tried building open source C++ code bases,
using a patched version of libc++.
Below are the instances where the overloads proposed for deprecation were used in these builds.</p>
   <p>For reference, the author built <a href="https://github.com/tensorflow/tensorflow/tree/master/tensorflow/lite">tensorflow-lite</a> and <a href="https://github.com/tenzir/tenzir">Tenzir</a> using a custom version of libc++ where these overloads
were marked as <code class="highlight"><c- o>=</c-> <c- k>delete</c-></code>d. These code bases number ~1½ MLoC in total, with a large number of dependencies,
are reasonably modern, and use iostreams.</p>
   <h4 class="heading settled" data-level="3.1.1" id="study-abseil"><span class="secno">3.1.1. </span><span class="content">Abseil</span><a class="self-link" href="#study-abseil"></a></h4>
   <p>The <a href="https://github.com/abseil/abseil-cpp/tree/master/absl/log">Abseil logging library</a> seems to
treat <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> and <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code> as character types.
This is likely because the syntax used by the library is very similar to that
used by iostreams:</p>
<pre class="language-cpp highlight"><c- b>signed</c-> <c- b>char</c-> <c- n>my_schar</c-> <c- o>=</c-> <c- mi>65</c-><c- p>;</c->
<c- n>LOG</c-><c- p>(</c-><c- n>ERROR</c-><c- p>)</c-> <c- o>&lt;&lt;</c-> <c- n>my_schar</c-><c- p>;</c->
<c- c1>// Will output:</c->
<c- c1>// E0520 13:49:47.968463  123694 absl_log.cpp:8] A</c->
<c- c1>// where the message itself is the 'A' here -----^</c->
</pre>
   <p>Internally in the library, this is achieved with this overload set:</p>
<pre class="language-cpp highlight"><c- c1>// Abseil, version 20230802.1:</c->
<c- c1>// absl/log/internal/check_op.cc</c->

<c- b>void</c-> <c- nf>MakeCheckOpValueString</c-><c- p>(</c-><c- n>std</c-><c- o>::</c-><c- n>ostream</c-><c- o>&amp;</c-> <c- n>os</c-><c- p>,</c-> <c- k>const</c-> <c- b>char</c-> <c- n>v</c-><c- p>)</c-> <c- p>{</c->
  <c- k>if</c-> <c- p>(</c-><c- n>v</c-> <c- o>>=</c-> <c- mi>32</c-> <c- o>&amp;&amp;</c-> <c- n>v</c-> <c- o>&lt;=</c-> <c- mi>128</c-><c- p>)</c-> <c- p>{</c->
    <c- n>os</c-> <c- o>&lt;&lt;</c-> <c- s>"'"</c-> <c- o>&lt;&lt;</c-> <c- n>v</c-> <c- o>&lt;&lt;</c-> <c- s>"'"</c-><c- p>;</c->
  <c- p>}</c-> <c- k>else</c-> <c- p>{</c->
    <c- n>os</c-> <c- o>&lt;&lt;</c-> <c- s>"char value "</c-> <c- o>&lt;&lt;</c-> <c- b>int</c-><c- p>{</c-><c- n>v</c-><c- p>};</c->
  <c- p>}</c->
<c- p>}</c->

<c- b>void</c-> <c- nf>MakeCheckOpValueString</c-><c- p>(</c-><c- n>std</c-><c- o>::</c-><c- n>ostream</c-><c- o>&amp;</c-> <c- n>os</c-><c- p>,</c-> <c- k>const</c-> <c- b>signed</c-> <c- b>char</c-> <c- n>v</c-><c- p>)</c-> <c- p>{</c->
  <c- k>if</c-> <c- p>(</c-><c- n>v</c-> <c- o>>=</c-> <c- mi>32</c-> <c- o>&amp;&amp;</c-> <c- n>v</c-> <c- o>&lt;=</c-> <c- mi>128</c-><c- p>)</c-> <c- p>{</c->
    <c- n>os</c-> <c- o>&lt;&lt;</c-> <c- s>"'"</c-> <c- o>&lt;&lt;</c-> <c- n>v</c-> <c- o>&lt;&lt;</c-> <c- s>"'"</c-><c- p>;</c->
  <c- p>}</c-> <c- k>else</c-> <c- p>{</c->
    <c- n>os</c-> <c- o>&lt;&lt;</c-> <c- s>"signed char value "</c-> <c- o>&lt;&lt;</c-> <c- b>int</c-><c- p>{</c-><c- n>v</c-><c- p>};</c->
  <c- p>}</c->
<c- p>}</c->

<c- b>void</c-> <c- nf>MakeCheckOpValueString</c-><c- p>(</c-><c- n>std</c-><c- o>::</c-><c- n>ostream</c-><c- o>&amp;</c-> <c- n>os</c-><c- p>,</c-> <c- k>const</c-> <c- b>unsigned</c-> <c- b>char</c-> <c- n>v</c-><c- p>)</c-> <c- p>{</c->
  <c- k>if</c-> <c- p>(</c-><c- n>v</c-> <c- o>>=</c-> <c- mi>32</c-> <c- o>&amp;&amp;</c-> <c- n>v</c-> <c- o>&lt;=</c-> <c- mi>128</c-><c- p>)</c-> <c- p>{</c->
    <c- n>os</c-> <c- o>&lt;&lt;</c-> <c- s>"'"</c-> <c- o>&lt;&lt;</c-> <c- n>v</c-> <c- o>&lt;&lt;</c-> <c- s>"'"</c-><c- p>;</c->
  <c- p>}</c-> <c- k>else</c-> <c- p>{</c->
    <c- n>os</c-> <c- o>&lt;&lt;</c-> <c- s>"unsigned char value "</c-> <c- o>&lt;&lt;</c-> <c- b>int</c-><c- p>{</c-><c- n>v</c-><c- p>};</c->
  <c- p>}</c->
<c- p>}</c->
</pre>
   <p>where <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> and <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code> are explicitly and intentionally
treated similarly to <code class="highlight"><c- b>char</c-></code>, and are passed to an underlying <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>ostream</c-></code>.
Notably, the values between <code class="highlight"><c- mi>32</c-></code> and <code class="highlight"><c- mi>128</c-></code> are really treated as character values,
as they are printed with <code class="highlight">'<c- n>single</c-> <c- n>quotes</c-> <c- n>around</c-> <c- n>them</c->'</code>, and are cast to integers otherwise.</p>
   <h4 class="heading settled" data-level="3.1.2" id="study-flatbuffers"><span class="secno">3.1.2. </span><span class="content">FlatBuffers</span><a class="self-link" href="#study-flatbuffers"></a></h4>
   <p>In the implementation of <code class="highlight"><c- n>flatc</c-></code> (the FlatBuffers schema compiler), there’s the following
function template:</p>
<pre class="language-cpp highlight"><c- c1>// Flatbuffers, version 23.5.26:</c->
<c- c1>// src/annotated_binary_text_gen.cpp</c->

<c- k>template</c-><c- o>&lt;</c-><c- k>typename</c-> <c- nc>T</c-><c- o>></c-> <c- n>std</c-><c- o>::</c-><c- n>string</c-> <c- n>ToString</c-><c- p>(</c-><c- n>T</c-> <c- n>value</c-><c- p>)</c-> <c- p>{</c->
  <c- k>if</c-> <c- p>(</c-><c- n>std</c-><c- o>::</c-><c- n>is_floating_point</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>value</c-><c- p>)</c-> <c- p>{</c->
    <c- n>std</c-><c- o>::</c-><c- n>stringstream</c-> <c- n>ss</c-><c- p>;</c->
    <c- n>ss</c-> <c- o>&lt;&lt;</c-> <c- n>value</c-><c- p>;</c->
    <c- k>return</c-> <c- n>ss</c-><c- p>.</c-><c- n>value</c-><c- p>();</c->
  <c- p>}</c-> <c- k>else</c-> <c- p>{</c->
    <c- k>return</c-> <c- n>std</c-><c- o>::</c-><c- n>to_string</c-><c- p>(</c-><c- n>value</c-><c- p>);</c->
  <c- p>}</c->
<c- p>}</c->
</pre>
   <p>where the proposed-for-deprecation overload of <code class="highlight"><c- k>operator</c-><c- o>&lt;&lt;</c-></code> is instantiated,
if <code class="highlight"><c- n>T</c-></code> is <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> or <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code>. The overloads are never actually called,
but because the above code is using <code class="highlight"><c- k>if</c-></code> instead of <code class="highlight"><c- k>if</c-> <c- k>constexpr</c-></code>, the compiler
warns about usage, anyway.</p>
   <p>The current behavior when using <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> or <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code> is to use <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>to_string</c-></code>,
which formats the value as an integer, as the overload <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>to_string</c-><c- p>(</c-><c- b>int</c-><c- p>)</c-></code> is picked
in overload resolution.</p>
   <h4 class="heading settled" data-level="3.1.3" id="study-simdjson"><span class="secno">3.1.3. </span><span class="content">simdjson</span><a class="self-link" href="#study-simdjson"></a></h4>
   <p>The following piece of code is present in the implementation of <a href="https://github.com/simdjson/simdjson/">simdjson</a>:</p>
<pre class="language-cpp highlight"><c- c1>// simdjson, version 3.9.1:</c->
<c- c1>// include/simdjson/dom/document-inl.h</c->

<c- kr>inline</c-> <c- b>bool</c-> <c- nf>document::dump_raw_tape</c-><c- p>(</c-><c- n>std</c-><c- o>::</c-><c- n>ostream</c-> <c- o>&amp;</c-><c- n>os</c-><c- p>)</c-> <c- k>const</c-> <c- k>noexcept</c-> <c- p>{</c->
  <c- b>uint32_t</c-> <c- n>string_length</c-><c- p>;</c->
  <c- b>size_t</c-> <c- n>tape_idx</c-> <c- o>=</c-> <c- mi>0</c-><c- p>;</c->
  <c- b>uint64_t</c-> <c- n>tape_val</c-> <c- o>=</c-> <c- n>tape</c-><c- p>[</c-><c- n>tape_idx</c-><c- p>];</c->
  <c- b>uint8_t</c-> <c- n>type</c-> <c- o>=</c-> <c- b>uint8_t</c-><c- p>(</c-><c- n>tape_val</c-> <c- o>>></c-> <c- mi>56</c-><c- p>);</c->
  <c- n>os</c-> <c- o>&lt;&lt;</c-> <c- n>tape_idx</c-> <c- o>&lt;&lt;</c-> <c- s>" : "</c-> <c- o>&lt;&lt;</c-> <c- n>type</c-><c- p>;</c->
  <c- c1>// ...</c->
  <c- n>os</c-> <c- o>&lt;&lt;</c-> <c- n>tape_idx</c-> <c- o>&lt;&lt;</c-> <c- s>" : "</c-> <c- o>&lt;&lt;</c-> <c- n>type</c-> <c- o>&lt;&lt;</c-> <c- s>"</c-><c- se>\t</c-><c- s>// pointing to "</c-> <c- o>&lt;&lt;</c->
  <c- c1>// ...</c->
  <c- k>if</c-> <c- p>(</c-><c- n>type</c-> <c- o>==</c-> <c- sc>'r'</c-><c- p>)</c->
  <c- c1>// ...</c->
  <c- k>switch</c-> <c- p>(</c-><c- n>type</c-><c- p>)</c-> <c- p>{</c->
  <c- k>case</c-> <c- sc>'"'</c-><c- p>:</c->
  <c- c1>// ...</c->
  <c- k>case</c-> <c- sc>'l'</c-><c- p>:</c->
  <c- c1>// ...</c->
  <c- p>}</c->
<c- p>}</c->
</pre>
   <p>This member function is apparently intended to be used for debugging.
The <code class="highlight"><c- n>tape</c-></code> referenced is a library-internal representation of a parsed JSON document.</p>
   <p>Above, <code class="highlight"><c- n>type</c-></code> has the type of <code class="highlight"><c- b>uint8_t</c-></code>, but is clearly treated as a character type.
Its value is compared to character literals, and thus, when written to a <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>ostream</c-></code>,
is intended to be formatted as a character. The proposed deprecation would break this.</p>
   <h4 class="heading settled" data-level="3.1.4" id="study-yaml"><span class="secno">3.1.4. </span><span class="content">yaml-cpp</span><a class="self-link" href="#study-yaml"></a></h4>
   <p>In <a href="https://github.com/jbeder/yaml-cpp">yaml-cpp</a>, the following piece of code can be found,
where the <code class="highlight"><c- k>operator</c-><c- o>&lt;&lt;</c-></code> overload is called with <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> and <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code>:</p>
<pre class="language-cpp highlight"><c- c1>// yaml-cpp, version 0.8.0:</c->
<c- c1>// include/yaml-cpp/node/convert.h</c->

<c- c1>// Used with T=signed char and T=unsigned char</c->
<c- k>template</c-> <c- o>&lt;</c-><c- k>typename</c-> <c- nc>T</c-><c- o>></c->
<c- k>typename</c-> <c- nc>std</c-><c- o>::</c-><c- n>enable_if</c-><c- o>&lt;!</c-><c- n>std</c-><c- o>::</c-><c- n>is_floating_point</c-><c- o>&lt;</c-><c- n>T</c-><c- o>>::</c-><c- n>value</c-><c- p>,</c-> <c- b>void</c-><c- o>>::</c-><c- n>type</c->
<c- n>inner_encode</c-><c- p>(</c-><c- k>const</c-> <c- n>T</c-><c- o>&amp;</c-> <c- n>rhs</c-><c- p>,</c-> <c- n>std</c-><c- o>::</c-><c- n>stringstream</c-><c- o>&amp;</c-> <c- n>stream</c-><c- p>){</c->
  <c- n>stream</c-> <c- o>&lt;&lt;</c-> <c- n>rhs</c-><c- p>;</c->
<c- p>}</c->
</pre>
   <p>This function template is instantiated and called when writing to an existing YAML document:</p>
<pre class="language-cpp highlight"><c- b>signed</c-> <c- b>char</c-> <c- n>my_schar</c-> <c- o>=</c-> <c- mi>65</c-><c- p>;</c->
<c- b>unsigned</c-> <c- b>char</c-> <c- n>my_uchar</c-> <c- o>=</c-> <c- mi>65</c-><c- p>;</c->
<c- k>auto</c-> <c- n>node</c-> <c- o>=</c-> <c- n>YAML</c-><c- o>::</c-><c- n>Load</c-><c- p>(</c-><c- s>"{schar: 0, uchar: 0}"</c-><c- p>);</c->
<c- n>node</c-><c- p>[</c-><c- s>"schar"</c-><c- p>]</c-> <c- o>=</c-> <c- n>my_schar</c-><c- p>;</c->
<c- n>node</c-><c- p>[</c-><c- s>"uchar"</c-><c- p>]</c-> <c- o>=</c-> <c- n>my_uchar</c-><c- p>;</c->
<c- n>std</c-><c- o>::</c-><c- n>cout</c-> <c- o>&lt;&lt;</c-> <c- n>node</c-><c- p>;</c->
<c- c1>// Outputs: {schar: A, uchar: A}</c->
</pre>
   <p>It’s unclear whether treating <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> as a character type here is the desired behavior,
or simply an oversight caused by the usage of <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>stringstream</c-></code>.
Elsewhere in the library, <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> is treated unambiguously as an integer,
whereas <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code> is treated as a character:</p>
<pre class="language-cpp highlight"><c- b>signed</c-> <c- b>char</c-> <c- n>my_schar</c-> <c- o>=</c-> <c- mi>65</c-><c- p>;</c->
<c- b>unsigned</c-> <c- b>char</c-> <c- n>my_uchar</c-> <c- o>=</c-> <c- mi>65</c-><c- p>;</c->
<c- n>YAML</c-><c- o>::</c-><c- n>Emitter</c-> <c- n>out</c-><c- p>;</c->
<c- n>out</c-> <c- o>&lt;&lt;</c-> <c- n>YAML</c-><c- o>::</c-><c- n>BeginMap</c->
    <c- o>&lt;&lt;</c-> <c- n>YAML</c-><c- o>::</c-><c- n>Key</c-> <c- o>&lt;&lt;</c-> <c- s>"schar"</c->
    <c- o>&lt;&lt;</c-> <c- n>YAML</c-><c- o>::</c-><c- n>Value</c-> <c- o>&lt;&lt;</c-> <c- n>my_schar</c->
    <c- o>&lt;&lt;</c-> <c- n>YAML</c-><c- o>::</c-><c- n>Key</c-> <c- o>&lt;&lt;</c-> <c- s>"uchar"</c->
    <c- o>&lt;&lt;</c-> <c- n>YAML</c-><c- o>::</c-><c- n>Value</c-> <c- o>&lt;&lt;</c-> <c- n>my_uchar</c->
    <c- o>&lt;&lt;</c-> <c- n>YAML</c-><c- o>::</c-><c- n>EndMap</c-><c- p>;</c->
<c- n>std</c-><c- o>::</c-><c- n>cout</c-> <c- o>&lt;&lt;</c-> <c- n>out</c-><c- p>.</c-><c- n>c_str</c-><c- p>();</c->
<c- c1>// Outputs:</c->
<c- c1>// schar: 65</c->
<c- c1>// uchar: A</c->
</pre>
   <p>There are two <a href="https://github.com/jbeder/yaml-cpp/issues/1245">long-standing</a> <a href="https://github.com/jbeder/yaml-cpp/issues/1081">issues</a> against yaml-cpp to inquire about this inconsistency,
without a resolution before the mailing deadline.</p>
   <h4 class="heading settled" data-level="3.1.5" id="study-conclusion"><span class="secno">3.1.5. </span><span class="content">Conclusion</span><a class="self-link" href="#study-conclusion"></a></h4>
   <p>Only four instances of use were found during this study, which is not a lot.
Notably, only uses of <code class="highlight"><c- k>operator</c-><c- o>&lt;&lt;</c-></code> taking a <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> or <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code> were found.
No uses of the array-version of <code class="highlight"><c- k>operator</c-><c- o>&lt;&lt;</c-></code> or any of the <code class="highlight"><c- k>operator</c-><c- o>>></c-></code> overloads were identified.</p>
   <p>In these four cases:</p>
   <ul>
    <li data-md>
     <p>One (probably) contained a bug, which could have been identified with the deprecation proposed here <a href="#study-yaml">§ 3.1.4 yaml-cpp</a></p>
    <li data-md>
     <p>One was essentially a false-positive, where the deprecated overloads were never called, only instantiated <a href="#study-flatbuffers">§ 3.1.2 FlatBuffers</a></p>
    <li data-md>
     <p>Two were cases were the deprecated behavior was the desired one <a href="#study-abseil">§ 3.1.1 Abseil</a> <a href="#study-simdjson">§ 3.1.3 simdjson</a></p>
   </ul>
   <p>So, the use in the wild for these overloads seems to be quite limited.
In some cases, the current behavior is asked for, but it’s difficult to ascertain whether the developers writing that code
initially got tripped up by this behavior.
With this deprecation, at least a single possible bug was identified, and it’s possible even more could be found,
once developers are forced to check their usages as their compilers start warning them.
If anything, forcing users to cast to <code class="highlight"><c- b>char</c-></code>/<code class="highlight"><c- b>int</c-></code>/<code class="highlight"><c- b>unsigned</c-></code> could be argued to be an increase in readability,
in favor of relying on the current behavior with <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> and <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code>.</p>
   <h2 class="heading settled" data-level="4" id="wording"><span class="secno">4. </span><span class="content">Wording</span><a class="self-link" href="#wording"></a></h2>
   <p>This wording is relative to <a data-link-type="biblio" href="#biblio-n4971" title="Working Draft, Programming Languages — C++">[N4971]</a>.</p>
   <h3 class="heading settled" data-level="4.1" id="modify-istreamgeneral-p1"><span class="secno">4.1. </span><span class="content">Modify <a href="https://eel.is/c++draft/istream.general#1">[istream.general</a>] p1</span><a class="self-link" href="#modify-istreamgeneral-p1"></a></h3>
<pre class="highlight"><c- c1>// ...</c->

<c- c1>// [istream.extractors], character extraction templates</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- n>charT</c-><c- o>&amp;</c-><c- p>);</c->
<del><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>unsigned</c-> <c- b>char</c-><c- o>&amp;</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>signed</c-> <c- b>char</c-><c- o>&amp;</c-><c- p>);</c-></del>

<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><c- p>,</c-> <c- b>size_t</c-> <c- n>N</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- n>charT</c-><c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]);</c->
<del><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- p>,</c-> <c- b>size_t</c-> <c- n>N</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>unsigned</c-> <c- b>char</c-><c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- p>,</c-> <c- b>size_t</c-> <c- n>N</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>signed</c-> <c- b>char</c-><c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]);</c-></del>

</pre>
   <h3 class="heading settled" data-level="4.2" id="modify-istreamextractors-around-p7-to-p12"><span class="secno">4.2. </span><span class="content">Modify <a href="https://eel.is/c++draft/istream.extractors">[istream.extractors</a>], around p7 to p12</span><a class="self-link" href="#modify-istreamextractors-around-p7-to-p12"></a></h3>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><c- p>,</c-> <c- b>size_t</c-> <c- n>N</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- n>charT</c-><c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]);</c->
<del><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- p>,</c-> <c- b>size_t</c-> <c- n>N</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>unsigned</c-> <c- b>char</c-><c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- p>,</c-> <c- b>size_t</c-> <c- n>N</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>signed</c-> <c- b>char</c-><c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]);</c-></del>

</pre>
   <p><i>Effects:</i> Behaves like a formatted input member (as described in [istream.formatted.reqmts]) of <code class="highlight"><c- n>in</c-></code>.
After a sentry object is constructed, <code class="highlight"><c- k>operator</c-><c- o>>></c-></code> extracts characters and stores them into <code class="highlight"><c- n>s</c-></code>.
If <code class="highlight"><c- n>width</c-><c- p>()</c-></code> is greater than zero, <code class="highlight"><c- n>n</c-></code> is <code class="highlight"><c- n>min</c-><c- p>(</c-><c- b>size_t</c-><c- p>(</c-><c- n>width</c-><c- p>()),</c-> <c- n>N</c-><c- p>)</c-></code>.
Otherwise <code class="highlight"><c- n>n</c-></code> is <code class="highlight"><c- n>N</c-></code>. <code class="highlight"><c- n>n</c-></code> is the maximum number of characters stored.</p>
   <p>Characters are extracted and stored until any of the following occurs:</p>
   <ul>
    <li data-md>
     <p><code class="highlight"><c- n>n</c-><c- mi>-1</c-></code> characters are stored;</p>
    <li data-md>
     <p>end of file occurs on the input sequence;</p>
    <li data-md>
     <p>letting <code class="highlight"><c- n>ct</c-></code> be <code class="highlight"><c- n>use_facet</c-><c- o>&lt;</c-><c- n>ctype</c-><c- o>&lt;</c-><c- n>charT</c-><c- o>>></c-><c- p>(</c-><c- n>in</c-><c- p>.</c-><c- n>getloc</c-><c- p>())</c-></code>, <code class="highlight"><c- n>ct</c-><c- p>.</c-><c- n>is</c-><c- p>(</c-><c- n>ct</c-><c- p>.</c-><c- n>space</c-><c- p>,</c-> <c- n>c</c-><c- p>)</c-></code> is <code class="highlight">true</code>.</p>
   </ul>
   <p><code class="highlight"><c- k>operator</c-><c- o>>></c-></code> then stores a null byte (<code class="highlight"><c- n>charT</c-><c- p>()</c-></code>) in the next position, which may be the first position if no characters were extracted. <code class="highlight"><c- k>operator</c-><c- o>>></c-></code> then calls <code class="highlight"><c- n>width</c-><c- p>(</c-><c- mi>0</c-><c- p>)</c-></code>.</p>
   <p>If the function extracted no characters, <code class="highlight"><c- n>ios_base</c->​<c- o>::</c->​<c- n>failbit</c-></code> is set in the input function’s local error state before <code class="highlight"><c- n>setstate</c-></code> is called.</p>
   <p><i>Returns:</i> <code class="highlight"><c- n>in</c-></code>.</p>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- n>charT</c-><c- o>&amp;</c-><c- p>);</c->
<del><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>unsigned</c-> <c- b>char</c-><c- o>&amp;</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>signed</c-> <c- b>char</c-><c- o>&amp;</c-><c- p>);</c-></del>

</pre>
   <p><i>Effects:</i> Behaves like a formatted input member (as described in [istream.formatted.reqmts]) of <code class="highlight"><c- n>in</c-></code>.
A character is extracted from <code class="highlight"><c- n>in</c-></code>, if one is available, and stored in <code class="highlight"><c- n>c</c-></code>.
Otherwise, <code class="highlight"><c- n>ios_base</c->​<c- o>::</c->​<c- n>failbit</c-></code> is set in the input function’s local error state before <code class="highlight"><c- n>setstate</c-></code> is called.</p>
   <p><i>Returns:</i> <code class="highlight"><c- n>in</c-></code>.</p>
   <h3 class="heading settled" data-level="4.3" id="modify-ostreamgeneral-p1"><span class="secno">4.3. </span><span class="content">Modify <a href="https://eel.is/c++draft/ostream.general">[ostream.general</a>] p1</span><a class="self-link" href="#modify-ostreamgeneral-p1"></a></h3>
<pre class="highlight"><c- c1>// ...</c->

<c- c1>// [ostream.inserters.character], character inserters</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- n>charT</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>char</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>char</c-><c- p>);</c->

<del><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>signed</c-> <c- b>char</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>unsigned</c-> <c- b>char</c-><c- p>);</c-></del>

<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>wchar_t</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>char8_t</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>char16_t</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>char32_t</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>wchar_t</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c->
    <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>wchar_t</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>char8_t</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>wchar_t</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c->
    <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>wchar_t</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>char16_t</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>wchar_t</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c->
    <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>wchar_t</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>char32_t</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->

<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- n>charT</c-><c- o>*</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>char</c-><c- o>*</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>char</c-><c- o>*</c-><c- p>);</c->

<del><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>signed</c-> <c- b>char</c-><c- o>*</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>unsigned</c-> <c- b>char</c-><c- o>*</c-><c- p>);</c-></del>

<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c->
    <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>wchar_t</c-><c- o>*</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c->
    <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>char8_t</c-><c- o>*</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c->
    <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>char16_t</c-><c- o>*</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c->
    <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>char32_t</c-><c- o>*</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>wchar_t</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c->
    <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>wchar_t</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>char8_t</c-><c- o>*</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>wchar_t</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c->
    <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>wchar_t</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>char16_t</c-><c- o>*</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>wchar_t</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c->
    <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>wchar_t</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>char32_t</c-><c- o>*</c-><c- p>)</c-> <c- o>=</c-> <c- k>delete</c-><c- p>;</c->

<c- c1>// ...</c->

</pre>
   <h3 class="heading settled" data-level="4.4" id="modify-ostreaminserterscharacter"><span class="secno">4.4. </span><span class="content">Modify <a href="https://eel.is/c++draft/ostream.inserters.character">[ostream.inserters.character</a>]</span><a class="self-link" href="#modify-ostreaminserterscharacter"></a></h3>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- n>charT</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>char</c-><c- p>);</c->
<c- c1>// specialization</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>char</c-><c- p>);</c->
<c- c1>// signed and unsigned</c->
<del><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>signed</c-> <c- b>char</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- b>unsigned</c-> <c- b>char</c-><c- p>);</c-></del>

</pre>
   <p><i>Effects:</i> Behaves as a formatted output function of <code class="highlight"><c- n>out</c-></code>.
Constructs a character sequence <code class="highlight"><c- n>seq</c-></code>.
If <code class="highlight"><c- n>c</c-></code> has type <code class="highlight"><c- b>char</c-></code> and the character container type of the stream is not <code class="highlight"><c- b>char</c-></code>,
then <code class="highlight"><c- n>seq</c-></code> consists of <code class="highlight"><c- n>out</c-><c- p>.</c-><c- n>widen</c-><c- p>(</c-><c- n>c</c-><c- p>)</c-></code>; otherwise <code class="highlight"><c- n>seq</c-></code> consists of <code class="highlight"><c- n>c</c-></code>.
Determines padding for <code class="highlight"><c- n>seq</c-></code> as described in [ostream.formatted.reqmts].
Inserts <code class="highlight"><c- n>seq</c-></code> into <code class="highlight"><c- n>out</c-></code>.
Calls <code class="highlight"><c- n>os</c-><c- p>.</c-><c- n>width</c-><c- p>(</c-><c- mi>0</c-><c- p>)</c-></code>.</p>
   <p><i>Returns:</i> <code class="highlight"><c- n>out</c-></code>.</p>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- n>charT</c-><c- o>*</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>charT</c-><c- p>,</c-> <c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>char</c-><c- o>*</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>char</c-><c- o>*</c-><c- p>);</c->
<del><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>signed</c-> <c- b>char</c-><c- o>*</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-><c- p>,</c-> <c- k>const</c-> <c- b>unsigned</c-> <c- b>char</c-><c- o>*</c-><c- p>);</c-></del>

</pre>
   <p><i>Preconditions:</i> <code class="highlight"><c- n>s</c-></code> is not a null pointer.</p>
   <p><i>Effects:</i> Behaves like a formatted inserter (as described in [ostream.formatted.reqmts]) of <code class="highlight"><c- n>out</c-></code>.
Creates a character sequence <code class="highlight"><c- n>seq</c-></code> of <code class="highlight"><c- n>n</c-></code> characters starting at <code class="highlight"><c- n>s</c-></code>, each widened using <code class="highlight"><c- n>out</c-><c- p>.</c-><c- n>widen</c-><c- p>()</c-></code> ([basic.ios.members]),
where <code class="highlight"><c- n>n</c-></code> is the number that would be computed as if by:</p>
   <ul>
    <li data-md>
     <p><code class="highlight"><c- n>traits</c->​<c- o>::</c->​<c- n>length</c-><c- p>(</c-><c- n>s</c-><c- p>)</c-></code> for the overload where the first argument is of type <code class="highlight"><c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-></code> and
the second is of type <code class="highlight"><c- k>const</c-> <c- n>charT</c-><c- o>*</c-></code>, and also for the overload where the first argument is of type <code class="highlight"><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-></code> and the second is of type <code class="highlight"><c- k>const</c-> <c- b>char</c-><c- o>*</c-></code>,</p>
    <li data-md>
     <p>
      <code class="highlight"><c- n>char_traits</c-><c- o>&lt;</c-><c- b>char</c-><c- o>></c->​<c- o>::</c->​<c- n>length</c-><c- p>(</c-><c- n>s</c-><c- p>)</c-></code> for the overload where the first argument is of type <code class="highlight"><c- n>basic_ostream</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-></code> and
the second is of type <code class="highlight"><c- k>const</c-> <c- b>char</c-><c- o>*</c-></code>
      <ins>.</ins>
      <del>,</del>
     </p>
    <li data-md>
     <del><code class="highlight"><c- n>traits</c->​<c- o>::</c->​<c- n>length</c-><c- p>(</c-><c- k>reinterpret_cast</c-><c- o>&lt;</c-><c- k>const</c-> <c- b>char</c-><c- o>*></c-><c- p>(</c-><c- n>s</c-><c- p>))</c-></code> for the other two overloads.</del>
   </ul>
   <p>Determines padding for <code class="highlight"><c- n>seq</c-></code> as described in [ostream.formatted.reqmts].
Inserts <code class="highlight"><c- n>seq</c-></code> into <code class="highlight"><c- n>out</c-></code>.
Calls <code class="highlight"><c- n>width</c-><c- p>(</c-><c- mi>0</c-><c- p>)</c-></code>.</p>
   <p><i>Returns:</i> <code class="highlight"><c- n>out</c-></code>.</p>
   <h3 class="heading settled" data-level="4.5" id="add-a-new-subclause-in-annex-d-after-depratomics"><span class="secno">4.5. </span><span class="content">Add a new subclause in Annex D after <a href="https://eel.is/c++draft/depr.atomics">[depr.atomics</a>]</span><a class="self-link" href="#add-a-new-subclause-in-annex-d-after-depratomics"></a></h3>
   <p><b>Deprecated <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> and <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code> extraction [depr.istream.extractors]</b></p>
   <p>The following function overloads are declared in addition to those specified in <a href="https://eel.is/c++draft/istream.extractors">[istream.extractors</a>]:</p>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- n>in</c-><c- p>,</c-> <c- b>unsigned</c-> <c- b>char</c-><c- o>&amp;</c-> <c- n>c</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- n>in</c-><c- p>,</c-> <c- b>signed</c-> <c- b>char</c-><c- o>&amp;</c-> <c- n>c</c-><c- p>);</c->

</pre>
   <p><i>Effects:</i> Behaves like a formatted input member (as described in [istream.formatted.reqmts]) of <code class="highlight"><c- n>in</c-></code>.
A character is extracted from <code class="highlight"><c- n>in</c-></code>, if one is available, and stored in <code class="highlight"><c- n>c</c-></code>.
Otherwise, <code class="highlight"><c- n>ios_base</c->​<c- o>::</c->​<c- n>failbit</c-></code> is set in the input function’s local error state before <code class="highlight"><c- n>setstate</c-></code> is called.</p>
   <p><i>Returns:</i> <code class="highlight"><c- n>in</c-></code>.</p>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- p>,</c-> <c- b>size_t</c-> <c- n>N</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- n>in</c-><c- p>,</c-> <c- b>unsigned</c-> <c- b>char</c-><c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]</c-> <c- n>s</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- p>,</c-> <c- b>size_t</c-> <c- n>N</c-><c- o>></c->
  <c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>>></c-><c- p>(</c-><c- n>basic_istream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- n>in</c-><c- p>,</c-> <c- b>signed</c-> <c- b>char</c-><c- p>(</c-><c- o>&amp;</c-><c- p>)[</c-><c- n>N</c-><c- p>]</c-> <c- n>s</c-><c- p>);</c->

</pre>
   <p><i>Effects:</i> Behaves like a formatted input member (as described in [istream.formatted.reqmts]) of <code class="highlight"><c- n>in</c-></code>.
After a sentry object is constructed, <code class="highlight"><c- k>operator</c-><c- o>>></c-></code> extracts characters and stores them into <code class="highlight"><c- n>s</c-></code>.
If <code class="highlight"><c- n>width</c-><c- p>()</c-></code> is greater than zero, <code class="highlight"><c- n>n</c-></code> is <code class="highlight"><c- n>min</c-><c- p>(</c-><c- b>size_t</c-><c- p>(</c-><c- n>width</c-><c- p>()),</c-> <c- n>N</c-><c- p>)</c-></code>.
Otherwise <code class="highlight"><c- n>n</c-></code> is <code class="highlight"><c- n>N</c-></code>. <code class="highlight"><c- n>n</c-></code> is the maximum number of characters stored.</p>
   <p>Characters are extracted and stored until any of the following occurs:</p>
   <ul>
    <li data-md>
     <p><code class="highlight"><c- n>n</c-><c- mi>-1</c-></code> characters are stored;</p>
    <li data-md>
     <p>end of file occurs on the input sequence;</p>
    <li data-md>
     <p>letting <code class="highlight"><c- n>ct</c-></code> be <code class="highlight"><c- n>use_facet</c-><c- o>&lt;</c-><c- n>ctype</c-><c- o>&lt;</c-><c- n>charT</c-><c- o>>></c-><c- p>(</c-><c- n>in</c-><c- p>.</c-><c- n>getloc</c-><c- p>())</c-></code>, <code class="highlight"><c- n>ct</c-><c- p>.</c-><c- n>is</c-><c- p>(</c-><c- n>ct</c-><c- p>.</c-><c- n>space</c-><c- p>,</c-> <c- n>c</c-><c- p>)</c-></code> is <code class="highlight">true</code>.</p>
   </ul>
   <p><code class="highlight"><c- k>operator</c-><c- o>>></c-></code> then stores a null byte (<code class="highlight"><c- n>charT</c-><c- p>()</c-></code>) in the next position, which may be the first position if no characters were extracted. <code class="highlight"><c- k>operator</c-><c- o>>></c-></code> then calls <code class="highlight"><c- n>width</c-><c- p>(</c-><c- mi>0</c-><c- p>)</c-></code>.</p>
   <p>If the function extracted no characters, <code class="highlight"><c- n>ios_base</c->​<c- o>::</c->​<c- n>failbit</c-></code> is set in the input function’s local error state before <code class="highlight"><c- n>setstate</c-></code> is called.</p>
   <p><i>Returns:</i> <code class="highlight"><c- n>in</c-></code>.</p>
   <h3 class="heading settled" data-level="4.6" id="add-a-new-subclause-in-annex-d-after-the-above-depristreamextractors"><span class="secno">4.6. </span><span class="content">Add a new subclause in Annex D after the above ([depr.istream.extractors])</span><a class="self-link" href="#add-a-new-subclause-in-annex-d-after-the-above-depristreamextractors"></a></h3>
   <p><b>Deprecated <code class="highlight"><c- b>signed</c-> <c- b>char</c-></code> and <code class="highlight"><c- b>unsigned</c-> <c- b>char</c-></code> insertion [depr.ostream.inserters]</b></p>
   <p>The following function overloads are declared in addition to those specified in <a href="https://eel.is/c++draft/ostream.inserters.character">[ostream.inserters</a>]:</p>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- n>out</c-><c- p>,</c-> <c- b>signed</c-> <c- b>char</c-> <c- n>c</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- n>out</c-><c- p>,</c-> <c- b>unsigned</c-> <c- b>char</c-> <c- n>c</c-><c- p>);</c->

</pre>
   <p><i>Effects:</i> Equivalent to: <code class="highlight"><c- k>return</c-> <c- n>out</c-> <c- o>&lt;&lt;</c-> <c- k>static_cast</c-><c- o>&lt;</c-><c- b>char</c-><c- o>></c-><c- p>(</c-><c- n>c</c-><c- p>);</c-></code>.</p>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- n>out</c-><c- p>,</c-> <c- k>const</c-> <c- b>signed</c-> <c- b>char</c-><c- o>*</c-> <c- n>s</c-><c- p>);</c->
<c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>traits</c-><c- o>></c->
  <c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- k>operator</c-><c- o>&lt;&lt;</c-><c- p>(</c-><c- n>basic_ostream</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- n>traits</c-><c- o>>&amp;</c-> <c- n>out</c-><c- p>,</c-> <c- k>const</c-> <c- b>unsigned</c-> <c- b>char</c-><c- o>*</c-> <c- n>s</c-><c- p>);</c->

</pre>
   <p><i>Effects:</i> Equivalent to: <code class="highlight"><c- k>return</c-> <c- n>out</c-> <c- o>&lt;&lt;</c-> <c- k>reinterpret_cast</c-><c- o>&lt;</c-><c- k>const</c-> <c- b>char</c-><c- o>*></c-><c- p>(</c-><c- n>s</c-><c- p>);</c-></code>.</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-n4971">[N4971]
   <dd>Thomas Köppe. <a href="https://wg21.link/n4971"><cite>Working Draft, Programming Languages — C++</cite></a>. 18 December 2023. URL: <a href="https://wg21.link/n4971">https://wg21.link/n4971</a>
   <dt id="biblio-p0487r1">[P0487R1]
   <dd>Zhihao Yuan. <a href="https://wg21.link/p0487r1"><cite>Fixing operator>>(basic_istream&amp;, CharT*) (LWG 2499)</cite></a>. 23 August 2018. URL: <a href="https://wg21.link/p0487r1">https://wg21.link/p0487r1</a>
   <dt id="biblio-p2314r4">[P2314R4]
   <dd>Jens Maurer. <a href="https://wg21.link/p2314r4"><cite>Character sets and encodings</cite></a>. 15 October 2021. URL: <a href="https://wg21.link/p2314r4">https://wg21.link/p2314r4</a>
  </dl>