[css-flexbox] Provisionally rename flex-basis:auto to flex-basis:main-size, per f2f discsussion. Keep flex:auto shorthand for compat.

Author: tabatkins

css-flexbox/Overview.bs

@@ -887,7 +887,7 @@ Implied Minimum Size of Flex Items</h3>
 			this keyword specifies as the minimum size the smallest of:
 
 			<ul>
-				<li>the used 'flex-basis', if the computed 'flex-basis' was ''flex-basis/auto'',
+				<li>the used 'flex-basis', if the computed 'flex-basis' was ''flex-basis/main-size'',
 				<li>the computed 'max-width' ('max-height'), if that value is <a>definite</a>,
 				<li>if the item has no intrinsic aspect ratio, its <a>min-content size</a>,
 				<li>if the item has an intrinsic aspect ratio,
@@ -1422,7 +1422,7 @@ The 'flex' Shorthand</h3>
 
 	<pre class='propdef'>
 	Name: flex
-	Value: none | [ <<'flex-grow'>> <<'flex-shrink'>>? || <<'flex-basis'>> ]
+	Value: none | auto | [ <<'flex-grow'>> <<'flex-shrink'>>? || <<'flex-basis'>> ]
 	Initial: see individual properties
 	Applies to: <a>flex items</a>
 	Inherited: see individual properties
@@ -1474,9 +1474,8 @@ The 'flex' Shorthand</h3>
 				before free space is distributed according to the flex factors.
 				When omitted from the 'flex' shorthand, its specified value is ''0%''.
 			<p>
-				If the specified 'flex-basis' is <a value for=flex-basis>auto</a>,
+				If the specified 'flex-basis' is <a value for=flex-basis>main-size</a>,
 				the used <i>flex basis</i> is the value of the flex item’s <i>main size property</i>.
-				(This can itself be the keyword <a value for=width>auto</a>, which sizes the flex item based on its contents.)
 
 			<figure>
 				<img src='images/rel-vs-abs-flex.svg' width='504' height='240'>
@@ -1489,13 +1488,20 @@ The 'flex' Shorthand</h3>
 				</figcaption>
 			</figure>
 
+		<dt><dfn>auto</dfn>
+		<dd>
+			The keyword ''flex/auto'' expands to ''1 1 main-size''.
+
+			<!-- This is a legacy value, because the "main-size" keyword used to be "auto", but that was confusing. -->
+
+
 		<dt><dfn>none</dfn>
 		<dd>
-			<p>The keyword ''none'' computes to ''0 0 auto''.
+			<p>The keyword ''none'' computes to ''0 0 main-size''.
 	</dl>
 
 	<p>
-		The initial values of the 'flex' components are equivalent to <a class="css-code" href="#flex-initial">flex: 0 1 auto</a>.
+		The initial values of the 'flex' components are equivalent to <a class="css-code" href="#flex-initial">flex: 0 1 main-size</a>.
 	<p class="note">
 		Note that the initial values of 'flex-grow' and 'flex-basis'
 		are different from their defaults when omitted in the 'flex' shorthand.
@@ -1517,10 +1523,10 @@ Common Values of 'flex'</h3>
 		The list below summarizes the effects of the most common 'flex' values:
 
 	<dl>
-		<dt id="flex-initial">''flex: 0 auto''
+		<dt id="flex-initial">''flex: 0 main-size''
 		<dt>''flex: initial''
 		<dd>
-			Equivalent to ''flex: 0 1 auto''. (This is the initial value.)
+			Equivalent to ''flex: 0 1 main-size''. (This is the initial value.)
 			Sizes the item based on the 'width'/'height' properties.
 			(If the item's <i>main size property</i> computes to <a value for=width>auto</a>,
 			this will size the flex item based on its contents.)
@@ -1531,15 +1537,15 @@ Common Values of 'flex'</h3>
 
 		<dt>''flex: auto''
 		<dd>
-			Equivalent to ''flex: 1 1 auto''.
+			Equivalent to ''flex: 1 1 main-size''.
 			Sizes the item based on the 'width'/'height' properties,
 			but makes them fully flexible, so that they absorb any free space along the <i>main axis</i>.
 			If all items are either ''flex: auto'', ''flex: initial'', or ''flex: none'',
 			any positive free space after the items have been sized will be distributed evenly to the items with ''flex: auto''.
 
 		<dt>''flex: none''
 		<dd>
-			Equivalent to ''flex: 0 0 auto''.
+			Equivalent to ''flex: 0 0 main-size''.
 			This value sizes the item according to the 'width'/'height' properties,
 			but makes the flex item fully inflexible.
 			This is similar to ''initial'',
@@ -1616,8 +1622,8 @@ The 'flex-basis' property</h4>
 
 	<pre class='propdef'>
 	Name: flex-basis
-	Value: auto | <<'width'>>
-	Initial: auto
+	Value: main-size | <<'width'>>
+	Initial: main-size
 	Applies to: <a>flex items</a>
 	Inherited: no
 	Computed value: as specified, with lengths made absolute
@@ -1631,9 +1637,8 @@ The 'flex-basis' property</h4>
 		It accepts the same values as the 'width' and 'height' property.
 
 	<p>
-		The <dfn value for=flex-basis>auto</dfn> keyword, when specified on a <i>flex item</i>,
+		The <dfn value for=flex-basis>main-size</dfn> keyword, when specified on a <i>flex item</i>,
 		retrieves the value of the <i>main size property</i>.
-		Note, this may result in a used <i>flex basis</i> of ''auto''.
 
 	<p>
 		The <i>flex basis</i> is resolved the same way as 'width' in horizontal writing modes [[!CSS21]]:
@@ -2253,7 +2258,7 @@ Line Length Determination</h3>
 					If the flex item has ...
 					<ul>
 						<li>an intrinsic aspect ratio,
-						<li>a <i>flex basis</i> of ''flex-basis/auto'', and
+						<li>a <i>flex basis</i> of ''flex-basis/main-size'', and
 						<li>a <i>definite</i> <i>cross size</i>
 					</ul>
 					then the <i>flex base size</i> is calculated from its inner <i>cross size</i>