<!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>P2779R0: Make basic_string_view’s range construction conditionally explicit</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;
		}
		#toc .content:hover,
		#toc .content:focus {
			background: rgba(75%, 75%, 75%, .25);
			background: var(--a-hover-bg);
			border-bottom: 3px solid #054572;
			border-bottom: 3px solid var(--toclink-underline);
			margin-bottom: -3px;
		}
		#toc li li li .content {
			margin-left: 1rem;
		}
		#toc li li li li .content {
			margin-left: 2rem;
		}
	}


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

	/* Index Lists: Layout */
	ul.index	  { margin-left: 0; columns: 15em; text-indent: 1em hanging; }
	ul.index li	{ margin-left: 0; list-style: none; break-inside: avoid; }
	ul.index li li { margin-left: 1em; }
	ul.index dl	{ margin-top: 0; }
	ul.index dt	{ margin: .2em 0 .2em 20px;}
	ul.index dd	{ margin: .2em 0 .2em 40px;}
	/* Index Lists: Typography */
	ul.index ul,
	ul.index dl { font-size: smaller; }
	@media not print {
		ul.index li 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 859efb4bd, updated Fri Jan 27 16:04:01 2023 -0800" name="generator">
  <link href="https://isocpp.org/favicon.ico" rel="icon">
<style>
ins  {background-color: #CCFFCC; text-decoration: underline;}
del  {background-color: #FFCACA; text-decoration: line-through;}
</style>
<style>/* style-autolinks */

.css.css, .property.property, .descriptor.descriptor {
    color: var(--a-normal-text);
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 <body class="h-entry">
  <div class="head">
   <p data-fill-with="logo"></p>
   <h1 class="p-name no-ref" id="title">P2779R0<br>Make basic_string_view’s range construction conditionally explicit</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="2023-01-30">2023-01-30</time></span></h2>
   <div data-fill-with="spec-metadata">
    <dl>
     <dt class="editor">Author:
     <dd class="editor p-author h-card vcard"><a class="p-name fn u-email email" href="mailto:giuseppe.dangelo@kdab.com">Giuseppe D'Angelo</a>
     <dt>Audience:
     <dd>SG18, LEWG, SG16, SG9
     <dt>Project:
     <dd>ISO/IEC JTC1/SC22/WG21 14882: Programming Language — C++
    </dl>
   </div>
   <div data-fill-with="warning"></div>
   <hr title="Separator for header">
  </div>
  <div class="p-summary" data-fill-with="abstract">
   <h2 class="no-num no-toc no-ref heading settled" id="abstract"><span class="content">Abstract</span></h2>
   <p>We propose to relax the range constructor of basic_string_view so that that particular construction is implicit when used together with string types.</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>
    <li><a href="#motivation"><span class="secno">2</span> <span class="content">Motivation and Scope</span></a>
    <li>
     <a href="#design"><span class="secno">3</span> <span class="content">Design Decisions</span></a>
     <ol class="toc">
      <li><a href="#identify"><span class="secno">3.1</span> <span class="content">How to identify a string(view) class?</span></a>
      <li><a href="#defect"><span class="secno">3.2</span> <span class="content">Is this a defect fix?</span></a>
     </ol>
    <li><a href="#impact"><span class="secno">4</span> <span class="content">Impact on the Standard</span></a>
    <li><a href="#technicalspecifications"><span class="secno">5</span> <span class="content">Technical Specifications</span></a>
    <li>
     <a href="#proposedwording"><span class="secno">6</span> <span class="content">Proposed wording</span></a>
     <ol class="toc">
      <li><a href="#option1wording"><span class="secno">6.1</span> <span class="content">Option 1: introduce a dedicated type trait</span></a>
      <li><a href="#option2wording"><span class="secno">6.2</span> <span class="content">Option 2: use a compatible inner <code class="highlight"><c- n>type_traits</c-></code> type</span></a>
     </ol>
    <li><a href="#appendixa"><span class="secno"></span> <span class="content">Appendix A: <code class="highlight"><c- n>traits_type</c-></code> in Boost 1.81</span></a>
    <li><a href="#acknowledgements"><span class="secno">7</span> <span class="content">Acknowledgements</span></a>
    <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>
   <ul>
    <li data-md>
     <p>R0</p>
     <ul>
      <li data-md>
       <p>First submission</p>
     </ul>
   </ul>
   <h2 class="heading settled" data-level="2" id="motivation"><span class="secno">2. </span><span class="content">Motivation and Scope</span><a class="self-link" href="#motivation"></a></h2>
   <p><a data-link-type="biblio" href="#biblio-p1989r2" title="Range constructor for std::string_view 2: Constrain Harder">[P1989R2]</a> added a new constructor to <code class="highlight"><c- n>basic_string_view</c-></code> that made it implictly constructible from any <em>compatible</em> range (contiguous, sized, that uses the same character type as the string view, and so on; cf. [string.view.cons]/11).</p>
   <p><a data-link-type="biblio" href="#biblio-p2499r0" title="string_view range constructor should be explicit">[P2499R0]</a> subsequently modified this constructor, by making it unconditionally <code class="highlight"><c- k>explicit</c-></code>.</p>
   <p>The reasoning for this change was that not all compatible ranges are convertible to a string view by using their own size (the "range size"). In many important use cases, the size that is meant to be used is the "<code class="highlight"><c- n>strlen</c-></code> size" (intended as the distance of a given marker, usually <code class="highlight"><c- n>NUL</c-></code>, from the beginning of the range). In those cases, having an implicit conversion towards string views may end up introducing serious bugs in a program.</p>
   <p>For instance, <a data-link-type="biblio" href="#biblio-p2499r0" title="string_view range constructor should be explicit">[P2499R0]</a> has this example featuring "Modern C++" datatypes:</p>
<pre class="highlight"><c- k>extern</c-> <c- b>void</c-> <c- nf>get_string</c-><c- p>(</c-><c- n>std</c-><c- o>::</c-><c- n>span</c-><c- o>&lt;</c-><c- b>char</c-><c- o>></c-> <c- n>buffer</c-><c- p>);</c->
<c- k>extern</c-> <c- b>void</c-> <c- nf>use_string</c-><c- p>(</c-><c- n>std</c-><c- o>::</c-><c- n>string_view</c-> <c- n>str</c-><c- p>);</c->

<c- n>std</c-><c- o>::</c-><c- n>array</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- mi>200</c-><c- o>></c-> <c- n>buf</c-><c- p>;</c->
<c- n>get_string</c-><c- p>(</c-><c- n>buf</c-><c- p>);</c->
<c- n>use_string</c-><c- p>(</c-><c- n>buf</c-><c- p>);</c-> <c- c1>// oops</c->
</pre>
   <p>This code used to compile before <a data-link-type="biblio" href="#biblio-p2499r0" title="string_view range constructor should be explicit">[P2499R0]</a>. However: if the semantics of <code class="highlight"><c- n>get_string</c-></code> is to NUL-terminate its output, <code class="highlight"><c- n>use_string</c-></code> will instead create a view over the entire array, spanning <em>over</em> the embedded <code class="highlight"><c- n>NUL</c-></code>. This opens the door to any sort of bug (incl. UB, by reading uninitialized data in the array), and could have security implications. To prevent this from happening, the conversion from <code class="highlight"><c- n>buf</c-></code> to <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string_view</c-></code> has been made explicit, and the example code above is now ill-formed.</p>
   <hr>
   <p>This change has a few consequences.</p>
   <p>First and foremost it’s worth underlying that the proposed solution is still somehow a band-aid for this sort of use cases. If one uses <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-> <c- nf>s</c-><c- p>(</c-><c- mi>200</c-><c- p>);</c-></code> as a storage type instead of some other contiguous container (like <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>array</c-><c- o>&lt;</c-><c- b>char</c-><c- p>,</c-> <c- mi>200</c-><c- o>></c-></code>), then the example above would still have the problem of using the "wrong" size when <code class="highlight"><c- n>s</c-></code> is converted to a <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string_view</c-></code>. The conversion from <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-></code> to <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string_view</c-></code> remains however implicit.</p>
   <p>Second, and more in general; in a sense, the proposed change splits the types that can be converted to a string view in two families:</p>
   <ol>
    <li data-md>
     <p>types for which we now axiomatically establish that their size is always the "range size", and these convert implictly (e.g. <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-></code>);</p>
    <li data-md>
     <p>types for which don’t necessarily know which one is the "correct" size, and those must be converted explicitly after <a data-link-type="biblio" href="#biblio-p2499r0" title="string_view range constructor should be explicit">[P2499R0]</a> (e.g. <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>vector</c-><c- o>&lt;</c-><c- b>char</c-><c- o>></c-></code>).</p>
   </ol>
   <p><strong>The problem with split (and in particular with 2.) is that it fundamentally kills the usability of string views as an universal interface type for read-only non-owning string-like inputs</strong>.</p>
   <p>For instance, if one has a string type different than <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-></code>, then using it with a <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string_view</c-></code> becomes awkward:</p>
<pre class="highlight"><c- b>void</c-> <c- nf>use</c-><c- p>(</c-><c- n>std</c-><c- o>::</c-><c- n>string_view</c-> <c- n>v</c-><c- p>);</c->

<c- n>std</c-><c- o>::</c-><c- n>string</c-> <c- n>str1</c-><c- p>;</c->
<c- n>use</c-><c- p>(</c-><c- n>str1</c-><c- p>);</c->  <c- c1>// OK</c->

<c- n>my</c-><c- o>::</c-><c- n>string</c-> <c- n>str2</c-><c- p>;</c->
<c- n>use</c-><c- p>(</c-><c- n>str2</c-><c- p>);</c->  <c- c1>// ERROR</c->
</pre>
   <p>Unless <code class="highlight"><c- n>my</c-><c- o>::</c-><c- n>string</c-></code> itself provides an implicit conversion operator towards <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string_view</c-></code>, the code above is ill-formed, requiring an explicit conversion instead.</p>
   <p>So, what’s the problem, just provide the operator, like <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-></code> itself does? That’s not so simple: the user may not be in control of <code class="highlight"><c- n>my</c-><c- o>::</c-><c- n>string</c-></code> to begin with. For instance, <code class="highlight"><c- n>my</c-><c- o>::</c-><c- n>string</c-></code> may belong to a 3rd party library (Boost, Qt, folly, and so on); <em>every</em> sufficiently big codebase has its own string class(es).</p>
   <p>This usability impedance is there also if one goes in the opposite direction. Suppose one has a <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-></code> object, and wants to use it together with a 3rd party string library. That library also defines its own string view types, and <em>following the Standard Library’s lead</em>, these string view types feature explicit construction from compatible ranges.</p>
   <p>Then:</p>
<pre class="highlight"><c- b>void</c-> <c- nf>lib::very_useful_algorithm</c-><c- p>(</c-><c- n>lib</c-><c- o>::</c-><c- n>string_view</c-> <c- n>v</c-><c- p>);</c->

<c- n>std</c-><c- o>::</c-><c- n>string</c-> <c- n>str</c-><c- p>;</c->
<c- n>lib</c-><c- o>::</c-><c- n>very_useful_algorithm</c-><c- p>(</c-><c- n>str</c-><c- p>);</c->  <c- c1>// ERROR</c->
</pre>
   <p><strong>There is absolutely no reason why the above shouldn’t compile.</strong> <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-></code> and <code class="highlight"><c- n>lib</c-><c- o>::</c-><c- n>string_view</c-></code> are perfectly compatible, with <code class="highlight"><c- n>lib</c-><c- o>::</c-><c- n>string_view</c-></code> representing the same "platonic concept" of a non-owning <code class="highlight"><c- k>const</c-> <c- n>std</c-><c- o>::</c-><c- n>string</c-></code>. It should be therefore be <em>implictly</em> convertible.</p>
   <p>Alas, that’s not the case (due to <em>explicit</em> construction from a range), and since we cannot modify either datatype (both belong to 3rd parties), we must add explicit conversions <em>everywhere</em>. This is completely anti-ergonomic for users.</p>
   <p>The idea of adding conversion constructors/operators also does not scale. Again assuming that any 3rd party string view implementation follows <a data-link-type="biblio" href="#biblio-p2499r0" title="string_view range constructor should be explicit">[P2499R0]</a>'s design, should the author of <code class="highlight"><c- n>lib</c-><c- o>::</c-><c- n>string</c-></code> add implicit conversion operators towards <code class="highlight"><c- n>lib</c-><c- o>::</c-><c- n>string_view</c-></code>, <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string_view</c-></code>, <code class="highlight"><c- n>boost</c-><c- o>::</c-><c- n>string_view</c-></code>, <code class="highlight"><c- n>QUtf8StringView</c-></code>, <code class="highlight"><c- n>llvm</c-><c- o>::</c-><c- n>StringRef</c-></code>, ...? This is poor design (requires O(N²) conversion constructors/operators), and obviously it’s completely impossible to implement in practice (unless one controls all the classes in question).</p>
   <p>In Qt, the author <a data-link-type="biblio" href="#biblio-qtpatch" title="String view classes: make their range constructors explicit">implemented</a> the same semantic change of P2499R0 for Qt’s string view classes. The result was that certain implicit conversions got broken, such as from <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>u16string_view</c-></code> to <code class="highlight"><c- n>QStringView</c-></code>, despite the two classes representing exactly the same concept (a view over UTF-16/<code class="highlight"><c- b>char16_t</c-></code> data).</p>
   <hr>
   <p>What we are highlighting here is that there is tension between the safety concerns behind the changes proposed by <a data-link-type="biblio" href="#biblio-p2499r0" title="string_view range constructor should be explicit">[P2499R0]</a>'s, and the usefulness of string views as a vocabulary interface type -- usefulness that gets dramatically reduced (or removed, one could say) by making the range conversion <em>unconditionally</em> explicit.</p>
   <p>We could restore most of this usefulness by making the range conversion implicit in the cases where we know it’s safe to do. The only problematic aspect is: how to identify those cases?</p>
   <h2 class="heading settled" data-level="3" id="design"><span class="secno">3. </span><span class="content">Design Decisions</span><a class="self-link" href="#design"></a></h2>
   <h3 class="heading settled" data-level="3.1" id="identify"><span class="secno">3.1. </span><span class="content">How to identify a string(view) class?</span><a class="self-link" href="#identify"></a></h3>
   <p>Unfortunately there isn’t an universal way to identify all and only string(view)-like classes for which we’d like to enable implicit conversions towards string views. As far as their range properties are concerned, a <code class="highlight"><c- n>some_lib</c-><c- o>::</c-><c- n>string</c-></code> and a <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>vector</c-><c- o>&lt;</c-><c- b>char</c-><c- o>></c-></code> are identical -- both are contiguous, sized, etc.; a view class like <code class="highlight"><c- n>basic_string_view</c-></code> cannot distinguish between them based on those range properties alone.</p>
   <p>We need therefore a trait, which necessarily needs to be opt-in. The point is that we want to err on the side of caution: for an arbitrary contiguous range we want to keep the conversion explicit. A string(view)-like class can enable the opt-in and become implicitly convertible instead, and string view classes such as <code class="highlight"><c- n>basic_string_view</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c-></code> can be adapted to accept implicit conversions from compatible ranges that have the trait enabled.</p>
   <p>There are two alternatives for the design of such a trait.</p>
   <ol>
    <li data-md>
     <p>We can introduce a brand new type trait to specialize, and/or a class to inherit from, similar to various other precedents in the Standard Library (for instance, <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>ranges</c-><c- o>::</c-><c- n>enable_view</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c-></code>). Any string(view)-like class can then enable the trait by specializing/inheriting.</p>
    <li data-md>
     <p>We can use some "unique" feature of string(view)-like types. Specifically, this paper proposes to detect the presence and compatibility of an inner <code class="highlight"><c- n>traits_type</c-></code> type in order to classify a compatible range as a string(view)-like type. This idea was originally proposed as an option by <a data-link-type="biblio" href="#biblio-p2499r0" title="string_view range constructor should be explicit">[P2499R0]</a> but ultimately not chosen; at the time of this writing we do not know the exact reasons.</p>
   </ol>
   <p>Both of these options have some downsides.</p>
   <ul>
    <li data-md>
     <p>In general, both options require an opt-in from existing code. However there is already significant production code that implements approach 2, like <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string</c-></code>, <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string_view</c-></code>, <code class="highlight"><c- n>folly</c-><c- o>::</c-><c- n>fbstring</c-></code>, <code class="highlight"><c- n>boost</c-><c- o>::</c-><c- n>string_view</c-></code>, <code class="highlight"><c- n>absl</c-><c- o>::</c-><c- n>string_view</c-></code>, etc.; while there is obviously no code that implements 1. These existing datatypes will see their compatibility restored "for free".</p>
    <li data-md>
     <p>The inner <code class="highlight"><c- n>traits_type</c-></code> type is not necessarily specific to string(view)-like classes. From simply a naming point of view, it does not have the word "char" or "string" in it or anything like that. The risk here is that some classes might be using it with completely different semantics, and this could result in misdetections.</p>
     <p>It sounds pretty unlikely that a <em>compatible</em> range declares a <em>compatible</em> <code class="highlight"><c- n>traits_type</c-></code> with a string view, but the range in question is <em>not</em> a string(view)-like. The compatibility of <code class="highlight"><c- n>traits_type</c-></code> is checked in the constraints at [string.view.cons]/12 (but cf. <a data-link-type="biblio" href="#biblio-lwg3857" title="basic_string_view should allow explicit conversion when only traits vary">[LWG3857]</a> the <a href="#proposedwording">proposed wording</a>). For reference, in the Standard, <code class="highlight"><c- n>traits_type</c-></code> is used by <code class="highlight"><c- n>basic_string</c-></code> and <code class="highlight"><c- n>basic_string_view</c-></code>; by <code class="highlight"><c- n>basic_regex</c-></code>; and by the hierarchy of classes in iostreams rooted in <code class="highlight"><c- n>basic_ios</c-></code>. Of these, only <code class="highlight"><c- n>basic_string</c-></code> and <code class="highlight"><c- n>basic_string_view</c-></code> are of a compatible range type and with a compatible trait.</p>
     <p>Nonetheless, we sampled various projects in order to back this claim with some real-world data. The results are:</p>
     <table>
      <thead>
       <tr>
        <th>Project
        <th>Findings
      <tbody>
       <tr>
        <td>Folly
        <td>Only used in <code class="highlight"><c- n>fbstring</c-></code>, which has string semantics.
       <tr>
        <td>LLVM (excluding libcxx and tests)
        <td>Used by OpenMP in some flag types (<code class="highlight"><c- n>kmp_flag</c-></code>, <code class="highlight"><c- n>kmp_flag_native</c-></code>, <code class="highlight"><c- n>kmp_flag_atomic</c-></code>), which are not ranges.
       <tr>
        <td>Abseil
        <td>Only used in <code class="highlight"><c- n>string_view</c-></code>, which has string view semantics (it’s a backport of C++17’s <code class="highlight"><c- n>std</c-><c- o>::</c-><c- n>string_view</c-></code>).
       <tr>
        <td>Firefox
        <td>According to Searchfox, only 3rd party code (Abseil, protobuf) defines a <code class="highlight"><c- n>traits_type</c-></code> type (alias).
       <tr>
        <td>Range-v3
        <td>Used in the ostream iterators like <code class="highlight"><c- n>ostream_iterator</c-></code>.
       <tr>
        <td>Qt
        <td>There are no occurrences of <code class="highlight"><c- n>traits_type</c-></code> in Qt.
       <tr>
        <td>Boost
        <td>
          Boost has a considerable number of usages, about 140 (a complete listing is in <a href="#appendixa">Appendix A: traits_type in Boost 1.81</a>), the majority of which are not string related classes at all. This indeed shows that the <code class="highlight"><c- n>traits_type</c-></code> name is quite generic, and somehow gets used as as the "default/go-to name" for a type alias for a traits-like parameter of any sort. 
         <p>Still, there’s a non-trivial amount of string(view)-like classes. Adding transparent interoperability would be a major usability win. Amongst the string classes, these are compatible with <code class="highlight"><c- n>basic_string_view</c-></code>'s range constructor and have a compatible <code class="highlight"><c- n>traits_type</c-></code>:</p>
         <ul>
          <li data-md>
           <p>In Container, <code class="highlight"><c- n>basic_string</c-></code>.</p>
          <li data-md>
           <p>In Core there’s an internal <code class="highlight"><c- n>basic_string_view</c-></code> (also used by Url).</p>
          <li data-md>
           <p>In Log, there’s an internal <code class="highlight"><c- n>basic_string_literal</c-></code>.</p>
          <li data-md>
           <p>In StaticString, <code class="highlight"><c- n>basic_static_string</c-></code>.</p>
          <li data-md>
           <p>In Process V2, <code class="highlight"><c- n>basic_cstring_ref</c-></code>, <code class="highlight"><c- n>key_view</c-></code>, <code class="highlight"><c- n>value_view</c-></code> and <code class="highlight"><c- n>key_value_pair_view</c-></code> .</p>
          <li data-md>
           <p>In Test, <code class="highlight"><c- n>basic_cstring</c-></code>.</p>
          <li data-md>
           <p>In Url, <code class="highlight"><c- n>pct_string_view</c-></code>.</p>
          <li data-md>
           <p>In Utility, <code class="highlight"><c- n>string_view</c-></code>.</p>
          <li data-md>
           <p>In Wave, <code class="highlight"><c- n>flex_string</c-></code>.</p>
         </ul>
         <p>There’s also some non compatible string class:</p>
         <ul>
          <li data-md>
           <p>In Compute, <code class="highlight"><c- n>basic_string</c-></code> defines <code class="highlight"><c- n>traits_type</c-></code>, but it is not a contiguous range (it’s in GPU memory).</p>
         </ul>
         <p>In the rest of usages, the containing datatype is not a range at all, and/or <code class="highlight"><c- n>traits_type</c-></code> is defining some datatype non compatible with <code class="highlight"><c- n>basic_string_view</c-></code> anyways.</p>
     </table>
     <p>In conclusion, these results strongly point towards the conclusion that only string(view)-like types are detected: the detection is correct. It is not complete: types such as <code class="highlight"><c- n>QString</c-></code>/<code class="highlight"><c- n>QStringView</c-></code> from Qt or <code class="highlight"><c- n>llvm</c-><c- o>::</c-><c- n>StringRef</c-></code> are string(view)-like types, but are missing a compatible <code class="highlight"><c- n>traits_type</c-></code> (specifically, they lack <code class="highlight"><c- n>traits_type</c-></code> entirely).</p>
    <li data-md>
     <p>A downside of option 1 is the timing aspect. Adding a brand new trait would mean crippling string views for one additional C++ version cycle, until one can use a C++26 (?) compiler that adds the trait and one can use it. Option 2 could (and in our opinion should) be treated as a defect fix instead.</p>
   </ul>
   <p>Given the results above, the author’s preference would be for option 2, but we would like to gather feedback from SG9, SG16 and LEWG.</p>
   <h3 class="heading settled" data-level="3.2" id="defect"><span class="secno">3.2. </span><span class="content">Is this a defect fix?</span><a class="self-link" href="#defect"></a></h3>
   <p>If option 2 is chosen, we would prefer that the changes proposed by this paper would be considered as a defect fix by implementors and backported to their C++23 modes. For this reason we would not be proposing any new feature-testing macro, nor to bump the value of an existing one. (The change is still entirely detectable by users via type traits, should the need arise.)</p>
   <p>Option 1 is fundamentally a brand new API, so it cannot be considered a fix.</p>
   <h2 class="heading settled" data-level="4" id="impact"><span class="secno">4. </span><span class="content">Impact on the Standard</span><a class="self-link" href="#impact"></a></h2>
   <p>This proposal is a pure library change. Depending on the option chosen, it may extend/change the proposed resolution to <a data-link-type="biblio" href="#biblio-lwg3857" title="basic_string_view should allow explicit conversion when only traits vary">[LWG3857]</a>.</p>
   <p>The impact is strictly positive: code that was ill-formed (after <a data-link-type="biblio" href="#biblio-p2499r0" title="string_view range constructor should be explicit">[P2499R0]</a>) becomes well-formed.</p>
   <h2 class="heading settled" data-level="5" id="technicalspecifications"><span class="secno">5. </span><span class="content">Technical Specifications</span><a class="self-link" href="#technicalspecifications"></a></h2>
   <p>All the proposed changes are relative to <a data-link-type="biblio" href="#biblio-n4928" title="Working Draft, Standard for Programming Language C++">[N4928]</a>.</p>
   <h2 class="heading settled" data-level="6" id="proposedwording"><span class="secno">6. </span><span class="content">Proposed wording</span><a class="self-link" href="#proposedwording"></a></h2>
   <p>The wording is very similar for both options outlined above. Option 1 would add a new feature-testing macro.</p>
   <h3 class="heading settled" data-level="6.1" id="option1wording"><span class="secno">6.1. </span><span class="content">Option 1: introduce a dedicated type trait</span><a class="self-link" href="#option1wording"></a></h3>
   <p>Add to the list in [version.syn]:</p>
   <blockquote>
<pre class="highlight"><ins><c- cp>#define __cpp_lib_is_string_view_like YYYYMML </c-><c- c1>// also in &lt;string>, &lt;string_view></c->
</ins></pre>
   </blockquote>
   <p>with the <code class="highlight"><c- n>YYYYMML</c-></code> replaced as usual (year and month of adoption of the present proposal).</p>
   <p>Modify [string.view.synop] as follows:</p>
   <blockquote>
<pre class="highlight">  <c- c1>// [string.view.template], class template basic_­string_­view</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>char_traits</c-><c- o>&lt;</c-><c- n>charT</c-><c- o>>></c->
  <c- k>class</c-> <c- nc>basic_string_view</c-><c- p>;</c->
  
<ins>  <c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>T</c-><c- o>></c->
    <c- k>constexpr</c-> <c- b>bool</c-> <c- n>is_string_view_like</c-> <c- o>=</c-> false<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- k>constexpr</c-> <c- b>bool</c-> <c- n>is_string_view_like</c-><c- o>&lt;</c-><c- n>basic_string_view</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>>></c-> <c- o>=</c-> true<c- p>;</c-></ins>
</pre>
   </blockquote>
   <p>Add a new section after [string.view.literals]:</p>
   <blockquote>
    <ins><strong>23.4 Enablers for implicit string view construction from ranges [string.view.range.construction]</strong></ins>
<pre class="highlight"><ins>  <c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>T</c-><c- o>></c->
    <c- k>constexpr</c-> <c- b>bool</c-> <c- n>is_string_view_like</c-> <c- o>=</c-> false<c- p>;</c->
</ins></pre>
    <ins>1. <em>Remarks</em>: Pursuant to [namespace.std], users may specialize <code class="highlight"><c- n>is_string_view_like</c-></code> for cv-unqualified program-defined types. Such specializations shall be usable in constant expressions ([expr.const]) and have type <code class="highlight"><c- k>const</c-> <c- b>bool</c-></code>. </ins>
   </blockquote>
   <p>Modify [string.syn] as follows:</p>
   <blockquote>
<pre class="highlight">  <c- c1>// [basic.string], basic_­string</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>char_traits</c-><c- o>&lt;</c-><c- n>charT</c-><c- o>></c-><c- p>,</c-> <c- k>class</c-> <c- nc>Allocator</c-> <c- o>=</c-> <c- n>allocator</c-><c- o>&lt;</c-><c- n>charT</c-><c- o>>></c->
    <c- k>class</c-> <c- nc>basic_string</c-><c- p>;</c->
  
<ins>  <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- k>class</c-> <c- nc>Allocator</c-><c- o>></c->
    <c- k>constexpr</c-> <c- b>bool</c-> <c- n>is_string_view_like</c-><c- o>&lt;</c-><c- n>basic_string</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- p>,</c-> <c- n>Allocator</c-><c- o>>></c-> <c- o>=</c-> true<c- p>;</c-></ins>
</pre>
   </blockquote>
   <p>Modify [string.view.template.general] as shown:</p>
   <blockquote>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>R</c-><c- o>></c->
  <c- k>constexpr</c-> <c- k>explicit</c-><ins><c- p>(</c-><i><c- n>see</c-> <c- n>below</c-></i><c- p>)</c-></ins> <c- n>basic_string_view</c-><c- p>(</c-><c- n>R</c-><c- o>&amp;&amp;</c-> <c- n>r</c-><c- p>);</c->
</pre>
   </blockquote>
   <p>Modify [string.view.cons] as shown:</p>
   <blockquote>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>R</c-><c- o>></c->
  <c- k>constexpr</c-> <c- k>explicit</c-><ins><c- p>(</c-><i><c- n>see</c-> <c- n>below</c-></i><c- p>)</c-></ins> <c- n>basic_string_view</c-><c- p>(</c-><c- n>R</c-><c- o>&amp;&amp;</c-> <c- n>r</c-><c- p>);</c->
</pre>
    <ol start="11">
     <li data-md>
      <p>Let <code class="highlight"><c- n>d</c-></code> be an lvalue of type <code class="highlight"><c- n>remove_cvref_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>></c-></code>.</p>
     <li data-md>
      <p><em>Constraints</em>:</p>
    </ol>
    <p>(12.1) — <code class="highlight"><c- n>remove_cvref_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>></c-></code> is not the same type as <code class="highlight"><c- n>basic_string_view</c-></code>,</p>
    <p>(12.2) — <code class="highlight"><c- n>R</c-></code> models <code class="highlight"><c- n>ranges</c-><c- o>::</c-><c- n>contiguous_range</c-></code> and <code class="highlight"><c- n>ranges</c-><c- o>::</c-><c- n>sized_range</c-></code>,</p>
    <p>(12.3) — <code class="highlight"><c- n>is_same_v</c-><c- o>&lt;</c-><c- n>ranges</c-><c- o>::</c-><c- n>range_value_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>></c-><c- p>,</c-> <c- n>charT</c-><c- o>></c-></code> is <code class="highlight">true</code>,</p>
    <p>
     (12.4) — <code class="highlight"><c- n>is_convertible_v</c-><c- o>&lt;</c-><c- n>R</c-><c- p>,</c-> <c- k>const</c-> <c- n>charT</c-><c- o>*></c-></code> is <code class="highlight">false</code>, 
     <ins>and</ins>
    </p>
    <p>
     (12.5) — <code class="highlight"><c- n>d</c-><c- p>.</c-><c- k>operator</c-> <c- o>::</c-><c- n>std</c-><c- o>::</c-><c- n>basic_string_view</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>></c-><c- p>()</c-></code> is not a valid expression
     <del>, and</del>
     <ins>.</ins>
    </p>
    <del>(12.6) — if the <em>qualified-id</em> <code class="highlight"><c- n>remove_reference_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>>::</c-><c- n>traits_type</c-></code> is valid and denotes a type, <code class="highlight"><c- n>is_same_v</c-><c- o>&lt;</c-><c- n>remove_reference_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>>::</c-><c- n>traits_type</c-><c- p>,</c-> <c- n>traits</c-><c- o>></c-></code> is <code class="highlight">true</code>.</del>
    <ol start="13">
     <li data-md>
      <p><em>Effects</em>: Initializes <code class="highlight"><c- n>data_</c-></code>­ with <code class="highlight"><c- n>ranges</c->​<c- o>::</c->​<c- n>data</c-><c- p>(</c-><c- n>r</c-><c- p>)</c-></code> and <code class="highlight"><c- n>size_</c-></code>­ with <code class="highlight"><c- n>ranges</c->​<c- o>::</c->​<c- n>size</c-><c- p>(</c-><c- n>r</c-><c- p>)</c-></code>.</p>
     <li data-md>
      <p><em>Throws</em>: Any exception thrown by <code class="highlight"><c- n>ranges</c->​<c- o>::</c->​<c- n>data</c-><c- p>(</c-><c- n>r</c-><c- p>)</c-></code> and <code class="highlight"><c- n>ranges</c->​<c- o>::</c->​<c- n>size</c-><c- p>(</c-><c- n>r</c-><c- p>)</c-></code>.</p>
    </ol>
    <ins>15. <em>Remarks</em>: If the <em>qualified-id</em> <code class="highlight"><c- n>remove_reference_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>>::</c-><c- n>traits_type</c-></code> is valid, denotes a type, <code class="highlight"><c- n>is_same_v</c-><c- o>&lt;</c-><c- n>remove_reference_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>>::</c-><c- n>traits_type</c-><c- p>,</c-> <c- n>traits</c-><c- o>></c-></code> is <code class="highlight">true</code>, and <code class="highlight"><c- n>is_string_view_like</c-><c- o>&lt;</c-><c- n>remove_reference_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>>></c-></code> is <code class="highlight">true</code>, then the expression inside <code class="highlight"><c- k>explicit</c-></code> is equivalent to <code class="highlight">false</code>. Otherwise, it is equivalent to <code class="highlight">true</code>.</ins>
   </blockquote>
   <h3 class="heading settled" data-level="6.2" id="option2wording"><span class="secno">6.2. </span><span class="content">Option 2: use a compatible inner <code class="highlight"><c- n>type_traits</c-></code> type</span><a class="self-link" href="#option2wording"></a></h3>
   <p>Modify [string.view.template.general] as shown:</p>
   <blockquote>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>R</c-><c- o>></c->
  <c- k>constexpr</c-> <c- k>explicit</c-><ins><c- p>(</c-><i><c- n>see</c-> <c- n>below</c-></i><c- p>)</c-></ins> <c- n>basic_string_view</c-><c- p>(</c-><c- n>R</c-><c- o>&amp;&amp;</c-> <c- n>r</c-><c- p>);</c->
</pre>
   </blockquote>
   <p>Modify [string.view.cons] as shown:</p>
   <blockquote>
<pre class="highlight"><c- k>template</c-><c- o>&lt;</c-><c- k>class</c-> <c- nc>R</c-><c- o>></c->
  <c- k>constexpr</c-> <c- k>explicit</c-><ins><c- p>(</c-><i><c- n>see</c-> <c- n>below</c-></i><c- p>)</c-></ins> <c- n>basic_string_view</c-><c- p>(</c-><c- n>R</c-><c- o>&amp;&amp;</c-> <c- n>r</c-><c- p>);</c->
</pre>
    <ol start="11">
     <li data-md>
      <p>Let <code class="highlight"><c- n>d</c-></code> be an lvalue of type <code class="highlight"><c- n>remove_cvref_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>></c-></code>.</p>
     <li data-md>
      <p><em>Constraints</em>:</p>
    </ol>
    <p>(12.1) — <code class="highlight"><c- n>remove_cvref_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>></c-></code> is not the same type as <code class="highlight"><c- n>basic_string_view</c-></code>,</p>
    <p>(12.2) — <code class="highlight"><c- n>R</c-></code> models <code class="highlight"><c- n>ranges</c-><c- o>::</c-><c- n>contiguous_range</c-></code> and <code class="highlight"><c- n>ranges</c-><c- o>::</c-><c- n>sized_range</c-></code>,</p>
    <p>(12.3) — <code class="highlight"><c- n>is_same_v</c-><c- o>&lt;</c-><c- n>ranges</c-><c- o>::</c-><c- n>range_value_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>></c-><c- p>,</c-> <c- n>charT</c-><c- o>></c-></code> is <code class="highlight">true</code>,</p>
    <p>
     (12.4) — <code class="highlight"><c- n>is_convertible_v</c-><c- o>&lt;</c-><c- n>R</c-><c- p>,</c-> <c- k>const</c-> <c- n>charT</c-><c- o>*></c-></code> is <code class="highlight">false</code>, 
     <ins>and</ins>
    </p>
    <p>
     (12.5) — <code class="highlight"><c- n>d</c-><c- p>.</c-><c- k>operator</c-> <c- o>::</c-><c- n>std</c-><c- o>::</c-><c- n>basic_string_view</c-><c- o>&lt;</c-><c- n>charT</c-><c- p>,</c-> <c- n>traits</c-><c- o>></c-><c- p>()</c-></code> is not a valid expression
     <del>, and</del>
     <ins>.</ins>
    </p>
    <del>(12.6) — if the <em>qualified-id</em> <code class="highlight"><c- n>remove_reference_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>>::</c-><c- n>traits_type</c-></code> is valid and denotes a type, <code class="highlight"><c- n>is_same_v</c-><c- o>&lt;</c-><c- n>remove_reference_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>>::</c-><c- n>traits_type</c-><c- p>,</c-> <c- n>traits</c-><c- o>></c-></code> is <code class="highlight">true</code>.</del>
    <ol start="13">
     <li data-md>
      <p><em>Effects</em>: Initializes <code class="highlight"><c- n>data_</c-></code>­ with <code class="highlight"><c- n>ranges</c->​<c- o>::</c->​<c- n>data</c-><c- p>(</c-><c- n>r</c-><c- p>)</c-></code> and <code class="highlight"><c- n>size_</c-></code>­ with <code class="highlight"><c- n>ranges</c->​<c- o>::</c->​<c- n>size</c-><c- p>(</c-><c- n>r</c-><c- p>)</c-></code>.</p>
     <li data-md>
      <p><em>Throws</em>: Any exception thrown by <code class="highlight"><c- n>ranges</c->​<c- o>::</c->​<c- n>data</c-><c- p>(</c-><c- n>r</c-><c- p>)</c-></code> and <code class="highlight"><c- n>ranges</c->​<c- o>::</c->​<c- n>size</c-><c- p>(</c-><c- n>r</c-><c- p>)</c-></code>.</p>
    </ol>
    <ins>15. <em>Remarks</em>: If the <em>qualified-id</em> <code class="highlight"><c- n>remove_reference_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>>::</c-><c- n>traits_type</c-></code> is valid, denotes a type, and <code class="highlight"><c- n>is_same_v</c-><c- o>&lt;</c-><c- n>remove_reference_t</c-><c- o>&lt;</c-><c- n>R</c-><c- o>>::</c-><c- n>traits_type</c-><c- p>,</c-> <c- n>traits</c-><c- o>></c-></code> is <code class="highlight">true</code>, then the expression inside <code class="highlight"><c- k>explicit</c-></code> is equivalent to <code class="highlight">false</code>. Otherwise, it is equivalent to <code class="highlight">true</code>.</ins>
   </blockquote>
   <h2 class="heading settled" id="appendixa"><span class="content">Appendix A: <code class="highlight"><c- n>traits_type</c-></code> in Boost 1.81</span><a class="self-link" href="#appendixa"></a></h2>
<pre class="highlight line-numbered"><span class="line-no" data-line="1"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>asio</c-><c- o>/</c-><c- n>basic_deadline_timer</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>148</c-><c- o>:</c->  <c- k>typedef</c-> <c- n>TimeTraits</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="2"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>asio</c-><c- o>/</c-><c- n>basic_waitable_timer</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>170</c-><c- o>:</c->  <c- k>typedef</c-> <c- n>WaitTraits</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="3"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>asio</c-><c- o>/</c-><c- n>experimental</c-><c- o>/</c-><c- n>basic_channel</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>137</c-><c- o>:</c->  <c- k>typedef</c-> <c- k>typename</c-> <c- nc>Traits</c-><c- o>::</c-><c- k>template</c-> <c- n>rebind</c-><c- o>&lt;</c-><c- n>Signatures</c-><c- p>...</c-><c- o>>::</c-><c- n>other</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="4"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>asio</c-><c- o>/</c-><c- n>experimental</c-><c- o>/</c-><c- n>basic_concurrent_channel</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>137</c-><c- o>:</c->  <c- k>typedef</c-> <c- k>typename</c-> <c- nc>Traits</c-><c- o>::</c-><c- k>template</c-> <c- n>rebind</c-><c- o>&lt;</c-><c- n>Signatures</c-><c- p>...</c-><c- o>>::</c-><c- n>other</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="5"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>asio</c-><c- o>/</c-><c- n>experimental</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>channel_service</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>299</c-><c- o>:</c->  <c- k>typedef</c-> <c- k>typename</c-> <c- nc>Traits</c-><c- o>::</c-><c- k>template</c-> <c- n>rebind</c-><c- o>&lt;</c-><c- n>Signatures</c-><c- p>...</c-><c- o>>::</c-><c- n>other</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="6"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>asio</c-><c- o>/</c-><c- n>experimental</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>channel_service</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>396</c-><c- o>:</c->  <c- k>typedef</c-> <c- k>typename</c-> <c- nc>Traits</c-><c- o>::</c-><c- k>template</c-> <c- n>rebind</c-><c- o>&lt;</c-><c- n>R</c-><c- p>()</c-><c- o>>::</c-><c- n>other</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="7"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>asio</c-><c- o>/</c-><c- n>experimental</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>channel_service</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>499</c-><c- o>:</c->    <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="8"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>asio</c-><c- o>/</c-><c- n>experimental</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>impl</c-><c- o>/</c-><c- n>channel_service</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>196</c-><c- o>:</c->      <c- n>Signatures</c-><c- p>...</c-><c- o>>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="9"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>asio</c-><c- o>/</c-><c- n>experimental</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>impl</c-><c- o>/</c-><c- n>channel_service</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>224</c-><c- o>:</c->      <c- n>Signatures</c-><c- p>...</c-><c- o>>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="10"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>asio</c-><c- o>/</c-><c- n>experimental</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>impl</c-><c- o>/</c-><c- n>channel_service</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>260</c-><c- o>:</c->      <c- n>Signatures</c-><c- p>...</c-><c- o>>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="11"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>asio</c-><c- o>/</c-><c- n>experimental</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>impl</c-><c- o>/</c-><c- n>channel_service</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>546</c-><c- o>:</c->      <c- n>Signatures</c-><c- p>...</c-><c- o>>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="12"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>beast</c-><c- o>/</c-><c- n>core</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>ostream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>122</c-><c- o>:</c->    <c- k>using</c-> <c- n>traits_type</c-> <c- o>=</c-> <c- k>typename</c-></span><span class="line-no" data-line="13"></span><span class="line"><c- nc>boost</c-><c- o>/</c-><c- n>beast</c-><c- o>/</c-><c- n>core</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>ostream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>51</c-><c- o>:</c->    <c- k>using</c-> <c- n>traits_type</c-> <c- o>=</c-> <c- k>typename</c-></span><span class="line-no" data-line="14"></span><span class="line"><c- nc>boost</c-><c- o>/</c-><c- n>beast</c-><c- o>/</c-><c- n>core</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>static_ostream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>30</c-><c- o>:</c->    <c- k>using</c-> <c- n>traits_type</c-> <c- o>=</c-> <c- k>typename</c-></span><span class="line-no" data-line="15"></span><span class="line"><c- nc>boost</c-><c- o>/</c-><c- n>compute</c-><c- o>/</c-><c- n>container</c-><c- o>/</c-><c- n>basic_string</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>46</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>Traits</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="16"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>container</c-><c- o>/</c-><c- n>string</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>618</c-><c- o>:</c->   <c- k>typedef</c-> <c- n>Traits</c->                                                                      <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="17"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>context</c-><c- o>/</c-><c- n>fixedsize_stack</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>44</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>traitsT</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="18"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>context</c-><c- o>/</c-><c- n>pooled_fixedsize_stack</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>127</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>traitsT</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="19"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>context</c-><c- o>/</c-><c- n>posix</c-><c- o>/</c-><c- n>protected_fixedsize_stack</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>46</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>traitsT</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="20"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>context</c-><c- o>/</c-><c- n>posix</c-><c- o>/</c-><c- n>segmented_stack</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>46</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>traitsT</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="21"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>context</c-><c- o>/</c-><c- n>windows</c-><c- o>/</c-><c- n>protected_fixedsize_stack</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>38</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>traitsT</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="22"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>core</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>string_view</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>350</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>std</c-><c- o>::</c-><c- n>char_traits</c-><c- o>&lt;</c-><c- n>Ch</c-><c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="23"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>coroutine</c-><c- o>/</c-><c- n>posix</c-><c- o>/</c-><c- n>protected_stack_allocator</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>42</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>traitsT</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="24"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>coroutine</c-><c- o>/</c-><c- n>posix</c-><c- o>/</c-><c- n>segmented_stack_allocator</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>43</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>traitsT</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="25"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>coroutine</c-><c- o>/</c-><c- n>standard_stack_allocator</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>41</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>traitsT</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="26"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>coroutine</c-><c- o>/</c-><c- n>windows</c-><c- o>/</c-><c- n>protected_stack_allocator</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>35</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>traitsT</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="27"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>date_time</c-><c- o>/</c-><c- n>date</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>62</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>calendar</c-><c- o>::</c-><c- n>date_traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="28"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>date_time</c-><c- o>/</c-><c- n>date_parsing</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>145</c-><c- o>:</c->      <c- k>typedef</c-> <c- k>typename</c-> <c- nc>std</c-><c- o>::</c-><c- n>basic_string</c-><c- o>&lt;</c-><c- b>char</c-><c- o>>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="29"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>date_time</c-><c- o>/</c-><c- n>date_parsing</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>314</c-><c- o>:</c->      <c- k>typedef</c-> <c- k>typename</c-> <c- nc>std</c-><c- o>::</c-><c- n>basic_string</c-><c- o>&lt;</c-><c- n>charT</c-><c- o>>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="30"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>date_time</c-><c- o>/</c-><c- n>time_duration</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>285</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>base_duration</c-><c- o>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="31"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>date_time</c-><c- o>/</c-><c- n>time_duration</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>50</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>rep_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="32"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>date_time</c-><c- o>/</c-><c- n>time_parsing</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>57</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>std</c-><c- o>::</c-><c- n>basic_string</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="33"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>fiber</c-><c- o>/</c-><c- n>future</c-><c- o>/</c-><c- n>packaged_task</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>58</c-><c- o>:</c->        <c- o>></c->                                       <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="34"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>fiber</c-><c- o>/</c-><c- n>future</c-><c- o>/</c-><c- n>promise</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>40</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>std</c-><c- o>::</c-><c- n>allocator_traits</c-><c- o>&lt;</c-> <c- k>typename</c-> <c- nc>object_type</c-><c- o>::</c-><c- n>allocator_type</c-> <c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="35"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>format</c-><c- o>/</c-><c- n>alt_sstream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>47</c-><c- o>:</c->            <c- k>typedef</c-> <c- n>Tr</c->     <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="36"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>geometry</c-><c- o>/</c-><c- n>srs</c-><c- o>/</c-><c- n>projections</c-><c- o>/</c-><c- n>impl</c-><c- o>/</c-><c- n>pj_ell_set</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>179</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>srs</c-><c- o>::</c-><c- n>spar</c-><c- o>::</c-><c- n>detail</c-><c- o>::</c-><c- n>ellps_traits</c-><c- o>&lt;</c-><c- n>param_type</c-><c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="37"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>geometry</c-><c- o>/</c-><c- n>srs</c-><c- o>/</c-><c- n>projections</c-><c- o>/</c-><c- n>spar</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>1004</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>proj_traits</c-><c- o>&lt;</c-><c- n>proj_type</c-><c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="38"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>geometry</c-><c- o>/</c-><c- n>srs</c-><c- o>/</c-><c- n>projections</c-><c- o>/</c-><c- n>spar</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>1021</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>proj_traits</c-><c- o>&lt;</c-><c- k>typename</c-> <c- nc>o_proj_type</c-><c- o>::</c-><c- n>type</c-><c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="39"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>graph</c-><c- o>/</c-><c- n>distributed</c-><c- o>/</c-><c- n>adjacency_list</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>1308</c-><c- o>:</c->      <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="40"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>graph</c-><c- o>/</c-><c- n>vertex_and_edge_range</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>24</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>graph_traits</c-><c- o>&lt;</c-> <c- n>Graph</c-> <c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="41"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>histogram</c-><c- o>/</c-><c- n>ostream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>46</c-><c- o>:</c->  <c- k>using</c-> <c- n>traits_type</c-> <c- o>=</c-> <c- k>typename</c-> <c- nc>OStream</c-><c- o>::</c-><c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="42"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>interprocess</c-><c- o>/</c-><c- n>streams</c-><c- o>/</c-><c- n>bufferstream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>274</c-><c- o>:</c->   <c- k>typedef</c-> <c- k>typename</c-> <c- nc>std</c-><c- o>::</c-><c- n>basic_ios</c-><c- o>&lt;</c-><c- n>char_type</c-><c- p>,</c-> <c- n>CharTraits</c-><c- o>>::</c-><c- n>traits_type</c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="43"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>interprocess</c-><c- o>/</c-><c- n>streams</c-><c- o>/</c-><c- n>bufferstream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>345</c-><c- o>:</c->   <c- k>typedef</c-> <c- k>typename</c-> <c- nc>std</c-><c- o>::</c-><c- n>basic_ios</c-><c- o>&lt;</c-><c- n>char_type</c-><c- p>,</c-> <c- n>CharTraits</c-><c- o>>::</c-><c- n>traits_type</c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="44"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>interprocess</c-><c- o>/</c-><c- n>streams</c-><c- o>/</c-><c- n>bufferstream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>417</c-><c- o>:</c->   <c- k>typedef</c-> <c- k>typename</c-> <c- nc>std</c-><c- o>::</c-><c- n>basic_ios</c-><c- o>&lt;</c-><c- n>char_type</c-><c- p>,</c-> <c- n>CharTraits</c-><c- o>>::</c-><c- n>traits_type</c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="45"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>interprocess</c-><c- o>/</c-><c- n>streams</c-><c- o>/</c-><c- n>bufferstream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>72</c-><c- o>:</c->   <c- k>typedef</c-> <c- n>CharTraits</c->                                    <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="46"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>interprocess</c-><c- o>/</c-><c- n>streams</c-><c- o>/</c-><c- n>vectorstream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>388</c-><c- o>:</c->   <c- k>typedef</c-> <c- k>typename</c-> <c- nc>std</c-><c- o>::</c-><c- n>basic_ios</c-><c- o>&lt;</c-><c- n>char_type</c-><c- p>,</c-> <c- n>CharTraits</c-><c- o>>::</c-><c- n>traits_type</c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="47"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>interprocess</c-><c- o>/</c-><c- n>streams</c-><c- o>/</c-><c- n>vectorstream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>469</c-><c- o>:</c->   <c- k>typedef</c-> <c- k>typename</c-> <c- nc>std</c-><c- o>::</c-><c- n>basic_ios</c-><c- o>&lt;</c-><c- n>char_type</c-><c- p>,</c-> <c- n>CharTraits</c-><c- o>>::</c-><c- n>traits_type</c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="48"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>interprocess</c-><c- o>/</c-><c- n>streams</c-><c- o>/</c-><c- n>vectorstream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>544</c-><c- o>:</c->   <c- k>typedef</c-> <c- k>typename</c-> <c- nc>std</c-><c- o>::</c-><c- n>basic_ios</c-><c- o>&lt;</c-><c- n>char_type</c-><c- p>,</c-> <c- n>CharTraits</c-><c- o>>::</c-><c- n>traits_type</c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="49"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>interprocess</c-><c- o>/</c-><c- n>streams</c-><c- o>/</c-><c- n>vectorstream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>76</c-><c- o>:</c->   <c- k>typedef</c-> <c- n>CharTraits</c->                        <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="50"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>io</c-><c- o>/</c-><c- n>ostream_joiner</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>48</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>Traits</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="51"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>chain</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>422</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>Tr</c->                                     <c- n>traits_type</c-><c- p>;</c-> \</span><span class="line-no" data-line="52"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>chain</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>450</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>chain_type</c-><c- o>::</c-><c- n>traits_type</c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="53"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>buffer</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>87</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>iostreams</c-><c- o>::</c-><c- n>char_traits</c-><c- o>&lt;</c-><c- n>Ch</c-><c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="54"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>double_object</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>101</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>boost</c-><c- o>::</c-><c- n>call_traits</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c->                  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="55"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>double_object</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>36</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>Metrowerks</c-><c- o>::</c-><c- n>call_traits</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c->             <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="56"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>double_object</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>38</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>boost</c-><c- o>::</c-><c- n>call_traits</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c->                  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="57"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>double_object</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>59</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>Metrowerks</c-><c- o>::</c-><c- n>call_traits</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c->             <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="58"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>double_object</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>61</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>boost</c-><c- o>::</c-><c- n>call_traits</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c->                  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="59"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>double_object</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>99</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>Metrowerks</c-><c- o>::</c-><c- n>call_traits</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c->             <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="60"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>filter</c-><c- o>/</c-><c- n>grep</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>50</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c->                     <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="61"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>filter</c-><c- o>/</c-><c- n>gzip</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>463</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>char_traits</c-><c- o>&lt;</c-><c- b>char</c-><c- o>></c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="62"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>filter</c-><c- o>/</c-><c- n>line</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>46</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c->                       <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="63"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>filter</c-><c- o>/</c-><c- n>stdio</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>52</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>BOOST_IOSTREAMS_CHAR_TRAITS</c-><c- p>(</c-><c- n>Ch</c-><c- p>)</c->                  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="64"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>filter</c-><c- o>/</c-><c- n>symmetric</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>76</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>BOOST_IOSTREAMS_CHAR_TRAITS</c-><c- p>(</c-><c- n>char_type</c-><c- p>)</c->            <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="65"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>invert</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>53</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c->               <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="66"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>read</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>120</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>BOOST_IOSTREAMS_CHAR_TRAITS</c-><c- p>(</c-><c- n>char_type</c-><c- p>)</c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="67"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>read</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>133</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>iostreams</c-><c- o>::</c-><c- n>char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="68"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>read</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>157</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>iostreams</c-><c- o>::</c-><c- n>char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="69"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>read</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>169</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>iostreams</c-><c- o>::</c-><c- n>char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="70"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>read</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>222</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>iostreams</c-><c- o>::</c-><c- n>char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="71"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>skip</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>40</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>iostreams</c-><c- o>::</c-><c- n>char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c->    <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="72"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>stream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>31</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>Tr</c->                                                 <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="73"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>traits</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>277</c-><c- o>:</c->            <c- o>></c-> <c- n>traits_type</c-><c- p>;</c->      </span><span class="line-no" data-line="74"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>traits</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>353</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>Tr</c->                              <c- n>traits_type</c-><c- p>;</c-> \</span><span class="line-no" data-line="75"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>write</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>81</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>BOOST_IOSTREAMS_CHAR_TRAITS</c-><c- p>(</c-><c- n>char_type</c-><c- p>)</c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="76"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>iostreams</c-><c- o>/</c-><c- n>write</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>98</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>BOOST_IOSTREAMS_CHAR_TRAITS</c-><c- p>(</c-><c- n>char_type</c-><c- p>)</c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="77"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>lexical_cast</c-><c- o>/</c-><c- n>lexical_cast_old</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>98</c-><c- o>:</c->            <c- k>typedef</c-> <c- n>Traits</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="78"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>log</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>attachable_sstream_buf</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>61</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>base_type</c-><c- o>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="79"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>log</c-><c- o>/</c-><c- n>expressions</c-><c- o>/</c-><c- n>formatter</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>59</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>StreamT</c-><c- o>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="80"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>log</c-><c- o>/</c-><c- n>expressions</c-><c- o>/</c-><c- n>formatters</c-><c- o>/</c-><c- n>c_decorator</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>134</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>c_decorator_traits</c-><c- o>&lt;</c-> <c- n>char_type</c-> <c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="81"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>log</c-><c- o>/</c-><c- n>expressions</c-><c- o>/</c-><c- n>formatters</c-><c- o>/</c-><c- n>c_decorator</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>194</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>aux</c-><c- o>::</c-><c- n>c_decorator_traits</c-><c- o>&lt;</c-> <c- n>char_type</c-> <c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="82"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>log</c-><c- o>/</c-><c- n>expressions</c-><c- o>/</c-><c- n>formatters</c-><c- o>/</c-><c- n>csv_decorator</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>93</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>csv_decorator_traits</c-><c- o>&lt;</c-> <c- n>char_type</c-> <c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="83"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>log</c-><c- o>/</c-><c- n>expressions</c-><c- o>/</c-><c- n>formatters</c-><c- o>/</c-><c- n>xml_decorator</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>92</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>xml_decorator_traits</c-><c- o>&lt;</c-> <c- n>char_type</c-> <c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="84"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>log</c-><c- o>/</c-><c- n>sources</c-><c- o>/</c-><c- n>record_ostream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>98</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>base_type</c-><c- o>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="85"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>log</c-><c- o>/</c-><c- n>support</c-><c- o>/</c-><c- n>date_time</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>70</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>TimeDurationT</c-><c- o>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="86"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>log</c-><c- o>/</c-><c- n>utility</c-><c- o>/</c-><c- n>formatting_ostream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>127</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>TraitsT</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="87"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>log</c-><c- o>/</c-><c- n>utility</c-><c- o>/</c-><c- n>string_literal</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>58</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>TraitsT</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="88"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>numeric</c-><c- o>/</c-><c- n>interval</c-><c- o>/</c-><c- n>interval</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>45</c-><c- o>:</c->  <c- k>typedef</c-> <c- n>Policies</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="89"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>polygon</c-><c- o>/</c-><c- n>polygon_90_set_traits</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>56</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>traits_by_concept</c-><c- o>&lt;</c-><c- n>T</c-><c- p>,</c-> <c- n>T2</c-><c- o>>::</c-><c- n>type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="90"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>polygon</c-><c- o>/</c-><c- n>polygon_90_set_traits</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>62</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>traits_by_concept</c-><c- o>&lt;</c-><c- n>T</c-><c- p>,</c-> <c- n>T2</c-><c- o>>::</c-><c- n>type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="91"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>posix</c-><c- o>/</c-><c- n>basic_pipe</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>34</c-><c- o>:</c->    <c- k>typedef</c->          <c- n>Traits</c->            <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="92"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>windows</c-><c- o>/</c-><c- n>basic_pipe</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>31</c-><c- o>:</c->    <c- k>typedef</c->          <c- n>Traits</c->            <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="93"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>pipe</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>105</c-><c- o>:</c->    <c- k>typedef</c->           <c- n>Traits</c->           <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="94"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>pipe</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>306</c-><c- o>:</c->    <c- k>typedef</c->           <c- n>Traits</c->           <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="95"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>pipe</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>40</c-><c- o>:</c->    <c- k>typedef</c->          <c- n>Traits</c->            <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="96"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>pipe</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>417</c-><c- o>:</c->    <c- k>typedef</c->           <c- n>Traits</c->           <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="97"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>pipe</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>526</c-><c- o>:</c->    <c- k>typedef</c->           <c- n>Traits</c->           <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="98"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>v2</c-><c- o>/</c-><c- n>cstring_ref</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>55</c-><c- o>:</c->    <c- k>using</c-> <c- n>traits_type</c->            <c- o>=</c-> <c- n>Traits</c-><c- p>;</c-></span><span class="line-no" data-line="99"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>v2</c-><c- o>/</c-><c- n>environment</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>117</c-><c- o>:</c->    <c- k>using</c-> <c- n>traits_type</c->      <c- o>=</c-> <c- n>key_char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c-><c- p>;</c-></span><span class="line-no" data-line="100"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>v2</c-><c- o>/</c-><c- n>environment</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>208</c-><c- o>:</c->    <c- k>using</c-> <c- n>traits_type</c->      <c- o>=</c-> <c- n>value_char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c-><c- p>;</c-></span><span class="line-no" data-line="101"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>v2</c-><c- o>/</c-><c- n>environment</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>303</c-><c- o>:</c->  <c- k>using</c-> <c- n>traits_type</c->      <c- o>=</c-> <c- n>std</c-><c- o>::</c-><c- n>char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c-><c- p>;</c-></span><span class="line-no" data-line="102"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>v2</c-><c- o>/</c-><c- n>environment</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>487</c-><c- o>:</c->    <c- k>using</c-> <c- n>traits_type</c->      <c- o>=</c-> <c- n>key_char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c-><c- p>;</c-></span><span class="line-no" data-line="103"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>v2</c-><c- o>/</c-><c- n>environment</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>707</c-><c- o>:</c->    <c- k>using</c-> <c- n>traits_type</c->      <c- o>=</c-> <c- n>value_char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c-><c- p>;</c-></span><span class="line-no" data-line="104"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>process</c-><c- o>/</c-><c- n>v2</c-><c- o>/</c-><c- n>environment</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>934</c-><c- o>:</c->    <c- k>using</c-> <c- n>traits_type</c->      <c- o>=</c-> <c- n>std</c-><c- o>::</c-><c- n>char_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>></c-><c- p>;</c-></span><span class="line-no" data-line="105"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>range</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>collection_traits_detail</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>288</c-><c- o>:</c->                <c- k>typedef</c-> <c- n>array_traits</c-><c- o>&lt;</c-><c- n>T</c-><c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="106"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>regex</c-><c- o>/</c-><c- n>concepts</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>301</c-><c- o>:</c->   <c- k>typedef</c-> <c- k>typename</c-> <c- nc>regex_traits_computer</c-><c- o>&lt;</c-><c- n>Regex</c-><c- o>>::</c-><c- n>type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="107"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>regex</c-><c- o>/</c-><c- n>v4</c-><c- o>/</c-><c- n>basic_regex</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>333</c-><c- o>:</c->   <c- k>typedef</c-> <c- n>traits</c->                                <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="108"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>regex</c-><c- o>/</c-><c- n>v4</c-><c- o>/</c-><c- n>match_results</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>384</c-><c- o>:</c->      <c- k>typedef</c-> <c- o>::</c-><c- n>boost</c-><c- o>::</c-><c- n>regex_traits_wrapper</c-><c- o>&lt;</c-><c- k>typename</c-> <c- nc>RegexT</c-><c- o>::</c-><c- n>traits_type</c-><c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="109"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>regex</c-><c- o>/</c-><c- n>v4</c-><c- o>/</c-><c- n>match_results</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>396</c-><c- o>:</c->      <c- k>typedef</c-> <c- o>::</c-><c- n>boost</c-><c- o>::</c-><c- n>regex_traits_wrapper</c-><c- o>&lt;</c-><c- k>typename</c-> <c- nc>RegexT</c-><c- o>::</c-><c- n>traits_type</c-><c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="110"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>regex</c-><c- o>/</c-><c- n>v5</c-><c- o>/</c-><c- n>basic_regex</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>322</c-><c- o>:</c->   <c- k>typedef</c-> <c- n>traits</c->                                <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="111"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>regex</c-><c- o>/</c-><c- n>v5</c-><c- o>/</c-><c- n>match_results</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>355</c-><c- o>:</c->      <c- k>typedef</c-> <c- o>::</c-><c- n>boost</c-><c- o>::</c-><c- n>regex_traits_wrapper</c-><c- o>&lt;</c-><c- k>typename</c-> <c- nc>RegexT</c-><c- o>::</c-><c- n>traits_type</c-><c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="112"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>regex</c-><c- o>/</c-><c- n>v5</c-><c- o>/</c-><c- n>match_results</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>367</c-><c- o>:</c->      <c- k>typedef</c-> <c- o>::</c-><c- n>boost</c-><c- o>::</c-><c- n>regex_traits_wrapper</c-><c- o>&lt;</c-><c- k>typename</c-> <c- nc>RegexT</c-><c- o>::</c-><c- n>traits_type</c-><c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="113"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>spirit</c-><c- o>/</c-><c- n>home</c-><c- o>/</c-><c- n>karma</c-><c- o>/</c-><c- n>stream</c-><c- o>/</c-><c- n>ostream_iterator</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>36</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>Traits</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="114"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>static_string</c-><c- o>/</c-><c- n>static_string</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>833</c-><c- o>:</c->  <c- k>using</c-> <c- n>traits_type</c-> <c- o>=</c-> <c- n>Traits</c-><c- p>;</c-></span><span class="line-no" data-line="115"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>test</c-><c- o>/</c-><c- n>utils</c-><c- o>/</c-><c- n>basic_cstring</c-><c- o>/</c-><c- n>basic_cstring</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>50</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>ut_detail</c-><c- o>::</c-><c- n>bcs_char_traits</c-><c- o>&lt;</c-><c- n>CharT</c-><c- o>></c->           <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="116"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>test</c-><c- o>/</c-><c- n>utils</c-><c- o>/</c-><c- n>basic_cstring</c-><c- o>/</c-><c- n>basic_cstring</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>622</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>basic_cstring</c-><c- o>&lt;</c-><c- n>CharT1</c-><c- o>>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="117"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>test</c-><c- o>/</c-><c- n>utils</c-><c- o>/</c-><c- n>basic_cstring</c-><c- o>/</c-><c- n>compare</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>105</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>boost</c-><c- o>::</c-><c- n>unit_test</c-><c- o>::</c-><c- n>basic_cstring</c-><c- o>&lt;</c-><c- n>CharT</c-><c- o>>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="118"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>test</c-><c- o>/</c-><c- n>utils</c-><c- o>/</c-><c- n>nullstream</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>46</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>base_type</c-><c- o>::</c-><c- n>traits_type</c->  <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="119"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>url</c-><c- o>/</c-><c- n>grammar</c-><c- o>/</c-><c- n>string_view_base</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>86</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>std</c-><c- o>::</c-><c- n>char_traits</c-><c- o>&lt;</c-><c- b>char</c-><c- o>></c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="120"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>utility</c-><c- o>/</c-><c- n>string_view</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>58</c-><c- o>:</c->      <c- k>typedef</c-> <c- n>traits</c->                                <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="121"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>wave</c-><c- o>/</c-><c- n>util</c-><c- o>/</c-><c- n>flex_string</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>1445</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>T</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="122"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>wave</c-><c- o>/</c-><c- n>util</c-><c- o>/</c-><c- n>flex_string</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>2381</c-><c- o>:</c->    <c- k>typedef</c-> <c- k>typename</c-> <c- nc>flex_string</c-><c- o>&lt;</c-><c- n>E</c-><c- p>,</c-> <c- n>T</c-><c- p>,</c-> <c- n>A</c-><c- p>,</c-> <c- n>S</c-><c- o>>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="123"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>xpressive</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>core</c-><c- o>/</c-><c- n>linker</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>117</c-><c- o>:</c->        <c- k>typedef</c-> <c- k>typename</c-> <c- nc>regex_traits_type</c-><c- o>&lt;</c-><c- n>Locale</c-><c- p>,</c-> <c- n>BidiIter</c-><c- o>>::</c-><c- n>type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="124"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>xpressive</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>core</c-><c- o>/</c-><c- n>matcher</c-><c- o>/</c-><c- n>charset_matcher</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>31</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>Traits</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="125"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>xpressive</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>core</c-><c- o>/</c-><c- n>matcher</c-><c- o>/</c-><c- n>posix_charset_matcher</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>33</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>Traits</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="126"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>xpressive</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- k>static</c-><c- o>/</c-><c- n>compile</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>77</c-><c- o>:</c->        <c- k>typedef</c-> <c- k>typename</c-> <c- nc>default_regex_traits</c-><c- o>&lt;</c-><c- n>char_type</c-><c- o>>::</c-><c- n>type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="127"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>xpressive</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- k>static</c-><c- o>/</c-><c- n>compile</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>90</c-><c- o>:</c->        <c- k>typedef</c-> <c- k>typename</c-> <c- nc>regex_traits_type</c-><c- o>&lt;</c-><c- n>locale_type</c-><c- p>,</c-> <c- n>BidiIter</c-><c- o>>::</c-><c- n>type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="128"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>xpressive</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- k>static</c-><c- o>/</c-><c- n>transforms</c-><c- o>/</c-><c- n>as_set</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>107</c-><c- o>:</c->        <c- k>typedef</c-> <c- k>typename</c-> <c- nc>Data</c-><c- o>::</c-><c- n>traits_type</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="129"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>xpressive</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- k>static</c-><c- o>/</c-><c- n>visitor</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>108</c-><c- o>:</c->        <c- k>typedef</c-> <c- n>Traits</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="130"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>xpressive</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>utility</c-><c- o>/</c-><c- n>boyer_moore</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>42</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>Traits</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="131"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>xpressive</c-><c- o>/</c-><c- n>detail</c-><c- o>/</c-><c- n>utility</c-><c- o>/</c-><c- n>chset</c-><c- o>/</c-><c- n>chset</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>34</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>Traits</c-> <c- n>traits_type</c-><c- p>;</c-></span><span class="line-no" data-line="132"></span><span class="line"><c- n>boost</c-><c- o>/</c-><c- n>xpressive</c-><c- o>/</c-><c- n>regex_compiler</c-><c- p>.</c-><c- n>hpp</c-><c- o>:</c-><c- mi>59</c-><c- o>:</c->    <c- k>typedef</c-> <c- n>RegexTraits</c-> <c- n>traits_type</c-><c- p>;</c-></span></pre>
   <h2 class="heading settled" data-level="7" id="acknowledgements"><span class="secno">7. </span><span class="content">Acknowledgements</span><a class="self-link" href="#acknowledgements"></a></h2>
   <p>Thanks to KDAB for supporting this work.</p>
   <p>All remaining errors are ours and ours only.</p>
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  <h2 class="no-num no-ref heading settled" id="references"><span class="content">References</span><a class="self-link" href="#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-lwg3857">[LWG3857]
   <dd>Casey Carter. <a href="https://wg21.link/lwg3857"><cite>basic_string_view should allow explicit conversion when only traits vary</cite></a>. Tentatively Ready. URL: <a href="https://wg21.link/lwg3857">https://wg21.link/lwg3857</a>
   <dt id="biblio-n4928">[N4928]
   <dd>Thomas Köppe. <a href="https://wg21.link/n4928"><cite>Working Draft, Standard for Programming Language C++</cite></a>. 18 December 2022. URL: <a href="https://wg21.link/n4928">https://wg21.link/n4928</a>
   <dt id="biblio-p1989r2">[P1989R2]
   <dd>Corentin Jabot. <a href="https://wg21.link/p1989r2"><cite>Range constructor for std::string_view 2: Constrain Harder</cite></a>. 17 March 2021. URL: <a href="https://wg21.link/p1989r2">https://wg21.link/p1989r2</a>
   <dt id="biblio-p2499r0">[P2499R0]
   <dd>James Touton. <a href="https://wg21.link/p2499r0"><cite>string_view range constructor should be explicit</cite></a>. 7 December 2021. URL: <a href="https://wg21.link/p2499r0">https://wg21.link/p2499r0</a>
   <dt id="biblio-qtpatch">[QTPATCH]
   <dd><a href="https://codereview.qt-project.org/c/qt/qtbase/+/448981"><cite>String view classes: make their range constructors explicit</cite></a>. URL: <a href="https://codereview.qt-project.org/c/qt/qtbase/+/448981">https://codereview.qt-project.org/c/qt/qtbase/+/448981</a>
  </dl>