Bug 270190 – [ iOS17 ] Rebasline: 12X fast/* css* layout-tests are rebaslines after OS migration

• Component: New Bugs
• Status: RESOLVED FIXED

[Dawn Morningstar]

css1/box_properties/acid_test.html
css2.1/t09-c5526c-display-00-e.html
fast/block/basic/011.html
fast/block/basic/minheight.html
fast/block/margin-collapse/103.html
fast/css/002.html
fast/forms/search-styled.html
fast/invalid/008.html
fast/overflow/003.xml
fast/table/rowindex.html
fast/text/capitalize-boundaries.html
fast/text/international/bidi-explicit-embedding.html

These tests are are text failures after the migration and the diff for each is just pixel differences which we've seen before and have been rebaslines before. 

HISTORY:
https://results.webkit.org/?suite=layout-tests&suite=layout-tests&suite=layout-tests&suite=layout-tests&suite=layout-tests&suite=layout-tests&suite=layout-tests&suite=layout-tests&suite=layout-tests&suite=layout-tests&suite=layout-tests&suite=layout-tests&test=css1%2Fbox_properties%2Facid_test.html&test=css2.1%2Ft09-c5526c-display-00-e.html&test=fast%2Fblock%2Fbasic%2F011.html&test=fast%2Fblock%2Fbasic%2Fminheight.html&test=fast%2Fblock%2Fmargin-collapse%2F103.html&test=fast%2Fcss%2F002.html&test=fast%2Fforms%2Fsearch-styled.html&test=fast%2Finvalid%2F008.html&test=fast%2Foverflow%2F003.xml&test=fast%2Ftable%2Frowindex.html&test=fast%2Ftext%2Fcapitalize-boundaries.html&test=fast%2Ftext%2Finternational%2Fbidi-explicit-embedding.html&platform=ios 

DIFF:
--- /Volumes/Data/worker/Apple-iOS-17-Simulator-Release-WK2-Tests/build/layout-test-results/fast/block/basic/minheight-expected.txt
+++ /Volumes/Data/worker/Apple-iOS-17-Simulator-Release-WK2-Tests/build/layout-test-results/fast/block/basic/minheight-actual.txt
@@ -10,14 +10,14 @@
         RenderText {#text} at (0,1) size 53x16
           text run at (0,1) width 53: "Content"
       RenderBlock {P} at (10,40) size 780x30
-        RenderText {#text} at (0,1) size 473x16
-          text run at (0,1) width 473: "Please resize the browser window to see how your 100% CSS footer behaves."
+        RenderText {#text} at (0,1) size 472x16
+          text run at (0,1) width 472: "Please resize the browser window to see how your 100% CSS footer behaves."
       RenderBlock {P} at (10,70) size 780x102
-        RenderText {#text} at (0,1) size 779x88
-          text run at (0,1) width 762: "Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Cras porttitor. Ut nonummy vestibulum arcu. Nulla eros eros, mattis"
-          text run at (0,19) width 771: "et, dictum quis, convallis vel, mauris. Ut sed mauris vel metus pretium pretium. Curabitur tristique sem id justo. Nunc sit amet"
-          text run at (0,37) width 779: "felis. Duis luctus pharetra urna. Sed enim arcu, cursus a, posuere sed, sollicitudin in, justo. Pellentesque enim lacus, egestas ut,"
-          text run at (0,55) width 761: "elementum eu, molestie vel, urna. Integer quam. Phasellus tempor. Sed commodo porttitor justo. Vestibulum rhoncus lacinia"
+        RenderText {#text} at (0,1) size 780x88
+          text run at (0,1) width 780: "Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Cras porttitor. Ut nonummy vestibulum arcu. Nulla eros eros, mattis et,"
+          text run at (0,19) width 749: "dictum quis, convallis vel, mauris. Ut sed mauris vel metus pretium pretium. Curabitur tristique sem id justo. Nunc sit amet"
+          text run at (0,37) width 778: "felis. Duis luctus pharetra urna. Sed enim arcu, cursus a, posuere sed, sollicitudin in, justo. Pellentesque enim lacus, egestas ut,"
+          text run at (0,55) width 758: "elementum eu, molestie vel, urna. Integer quam. Phasellus tempor. Sed commodo porttitor justo. Vestibulum rhoncus lacinia"
           text run at (0,73) width 436: "pede. Aliquam lectus velit, auctor a, fermentum a, accumsan et, neque."
 layer at (0,562) size 620x38
   RenderBlock (positioned) {DIV} at (0,562) size 620x38 [bgcolor=#0066B2]

DIFF-URL:
https://build.webkit.org/results/Apple-iOS-17-Simulator-Release-WK2-Tests/275368@main%20(2298)/fast/block/basic/minheight-diff.txt

[Radar WebKit Bug Importer]

<rdar://problem/123712678>

[Dawn Morningstar]

Test-run-url: https://build.webkit.org/results/Apple-iOS-17-Simulator-Release-WK2-Tests/275368@main%20(2298)/results.html 

To check each test in this list.

[Dawn Morningstar]

It might be worth noting that some of these tests are 20~ years old... I wonder their relevance on modern webkit.

[Sam Sneddon [:gsnedders]]

So, of the twelve tests above:

css1/box_properties/acid_test.html
css2.1/t09-c5526c-display-00-e.html
fast/block/basic/011.html
fast/block/basic/minheight.html
fast/block/margin-collapse/103.html
fast/css/002.html
fast/forms/search-styled.html
fast/invalid/008.html
fast/overflow/003.xml

All (eight) of these use Verdana as a font, and all have metrics differing by a few pixels per text run (except where the location of line breaks has changed).

The other four all use Lucida Grande, and again metrics differ by a few pixels per text run.

If we look at every test in fast using Verdana, we end up with:

fast/block/basic/011.html
fast/block/basic/minheight.html
fast/block/margin-collapse/103.html
fast/block/positioning/051.html
fast/canvas/canvas-composite-alpha.html
fast/canvas/canvas-composite-canvas.html
fast/canvas/canvas-composite-image.html
fast/canvas/canvas-composite-stroke-alpha.html
fast/canvas/canvas-composite-text-alpha.html
fast/canvas/canvas-composite-transformclip.html
fast/canvas/canvas-composite.html
fast/css/002.html
fast/css/003.html
fast/css/css2-system-color.html
fast/dom/HTMLTableElement/insert-row.html
fast/forms/negativeLineHeight.html
fast/forms/search-styled.html
fast/forms/text-control-intrinsic-widths.html
fast/forms/textAreaLineHeight.html
fast/forms/textarea-width.html
fast/invalid/008.html
fast/overflow/resources/rss.css
fast/sub-pixel/auto-table-layout-should-avoid-text-wrapping.html
fast/text/basic/generic-family-reset.html
fast/text/combining-character-sequence-fallback-crash.html
fast/text/font-face-set-remove-safely.html
fast/text-autosizing/ios/font-family-case-insensitive.html

Many of these are also regressed from iOS 17.0 to iOS 17.2, which suggests somehow Verdana (and at least some other fonts) are rendered differently now — whether that's a change to Verdana itself or a change in CoreText.

I don't think there's anything inherently special about the tests in this issue: this is a problem we have with anything dumping a render tree including text runs, because changes to font rendering can change those metrics. We don't really have good options aside from "don't include text in render tree dumps" or "don't use render tree dumps", and neither are really viable given all the tests we already have.

It might be that we have changes less often where tests are using the generic sans-serif (or serif, etc.) families, but that's far from a guarantee if we make broad changes to font rendering.