Block-in-inline: Stay in parallel flow, once established.

mstensho · chromium-wpt-export-bot · commit 6f1be26ec00e · 2025-07-08T15:16:09.000-07:00
When a block has been overflowed, we normally establish a parallel fragmentation flow for content inside it, but this is disabled if preceded by a column spanner. If the column spanner is discovered "too" late, we may have entered a parallel flow. Then stay in this parallel flow even if a spanner is discovered, or else the outgoing break tokens are lost. It could be that the inline layout algorithm ought to be refactored to handle this better, but this is all thanks to crbug.com/430249827 and is a situation that should never occur, so probably not worth it. Also update a DCHECK, so that it makes the same exception for inline break tokens as it already did for block break tokens. Bug: 364933065 Change-Id: I5051ca952f6247f691b956f68111a9d811158de7 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6714627 Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org> Reviewed-by: Koji Ishii <kojii@chromium.org> Commit-Queue: Morten Stenshorne <mstensho@chromium.org> Cr-Commit-Position: refs/heads/main@{#1484003}
diff --git a/css/css-multicol/crashtests/block-in-inline-with-spanner-in-overflowed-parent-nested-multicol.html b/css/css-multicol/crashtests/block-in-inline-with-spanner-in-overflowed-parent-nested-multicol.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<title>Nested multicol, overflowed block with spanner in next outer column</title>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://issues.chromium.org/issues/364933065">
+<div style="columns:2; column-fill:auto; height:100px;">
+  <div style="columns:2; column-fill:auto;">
+    <span>
+      <div style="height:10px;">
+        <span style="outline:solid;">
+          <div style="height:205px;"></div>
+          <div style="column-span:all; height:20px;"></div>
+        </span>
+      </div>
+    </span>
+  </div>
+</div>
diff --git a/css/css-multicol/crashtests/block-in-inline-with-spanner-in-overflowed-parent.html b/css/css-multicol/crashtests/block-in-inline-with-spanner-in-overflowed-parent.html
@@ -0,0 +1,12 @@
+<!DOCTYPE html>
+<title>Overflowed block with spanner</title>
+<link rel="author" title="Morten Stenshorne" href="mailto:mstensho@chromium.org">
+<link rel="help" href="https://issues.chromium.org/issues/364933065">
+<div style="columns:2; column-fill:auto; height:100px; line-height:50px;">
+  <span>
+    <div style="height:100px;">
+      <div style="height:150px;"></div>
+      <div style="column-span:all; height:20px;"></div>
+    </div>
+  </span>
+</div>
