The preferred logical widths algorithm for flexbox needs to take flex-basis into account. Note it can't do that, though, until the spec changes to make 0 not be the default or content will break.
The algorithm has changed since this bug was created. See: https://crbug.com/240765 https://github.com/w3c/csswg-drafts/issues/7189 I haven't read the spec closely yet nor that issue thread but I suspect this bug will be resolved by implementing the new spec text for the main axis width algorithm.
<rdar://problem/98793922>
WPT failures: https://wpt.fyi/results/css/css-flexbox/intrinsic-size?label=experimental&label=master&aligned We're only passing 2 of these tests. Also need to do a WPT sync as there are more tests than we have in tree.
WPT sync landed in https://commits.webkit.org/253547@main So now there's a target to hit.