Text breaking exception on version 52.4

I’m using Weasyprint to convert a HTML page to PNG, which works really nicely, thanks for the great tool!

In a rare case weasyprint consistently crashes on a page, while doing text-breaking on a text block. Below is the exception I get when this happens. The text it crashes on is a Dutch sentence that includes a phone number, no special characters at all. Considering my page size I would expect it to wrap to 2 lines.

If it helps I can share the HTML content and/or line of text in private.

• Weasyprint 52.4
• Ubuntu 20.04.2 LTS
• Started using the command line, with stdin and stdout: weasyprint --encoding utf8 --format png --resolution 203 - -
• On the stdin I feed it the HTML page, on the stdout I usually receive the PNG

Exception:

  File "/usr/local/bin/weasyprint", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/__main__.py", line 214, in main
    getattr(html, 'write_' + format_)(output, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/__init__.py", line 320, in write_png
    self.render(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/__init__.py", line 172, in render
    return Document._render(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/document.py", line 406, in _render
    [Page(page_box, enable_hinting) for page_box in page_boxes],
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/document.py", line 406, in <listcomp>
    [Page(page_box, enable_hinting) for page_box in page_boxes],
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/__init__.py", line 123, in layout_document
    pages = list(make_all_pages(context, root_box, html, pages))
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/pages.py", line 801, in make_all_pages
    page, resume_at = remake_page(i, context, root_box, html)
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/pages.py", line 738, in remake_page
    page, resume_at, next_page = make_page(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/pages.py", line 548, in make_page
    root_box, resume_at, next_page, _, _ = block_level_layout(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 58, in block_level_layout
    return block_level_layout_switch(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 72, in block_level_layout_switch
    return block_box_layout(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 126, in block_box_layout
    block_container_layout(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 517, in block_container_layout
    collapsing_through) = block_level_layout(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 58, in block_level_layout
    return block_level_layout_switch(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 72, in block_level_layout_switch
    return block_box_layout(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 126, in block_box_layout
    block_container_layout(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 517, in block_container_layout
    collapsing_through) = block_level_layout(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 58, in block_level_layout
    return block_level_layout_switch(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 72, in block_level_layout_switch
    return block_box_layout(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 126, in block_box_layout
    block_container_layout(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 517, in block_container_layout
    collapsing_through) = block_level_layout(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 58, in block_level_layout
    return block_level_layout_switch(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/blocks.py", line 88, in block_level_layout_switch
    return flex_layout(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/flex.py", line 141, in flex_layout
    content_size = min_content_width(context, new_child, outer=False)
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/preferred.py", line 48, in min_content_width
    return block_min_content_width(context, box, outer)
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/preferred.py", line 169, in block_min_content_width
    return _block_content_width(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/preferred.py", line 98, in _block_content_width
    children_widths = [
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/preferred.py", line 99, in <listcomp>
    function(context, child, outer=True) for child in box.children
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/preferred.py", line 52, in min_content_width
    return inline_min_content_width(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/preferred.py", line 194, in inline_min_content_width
    widths = list(widths)
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/layout/preferred.py", line 298, in inline_line_widths
    text.split_first_line(
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/text.py", line 1050, in split_first_line
    can_break_text(first_line_text.strip(), style['lang']))
  File "/usr/local/lib/python3.8/dist-packages/weasyprint/text.py", line 1312, in can_break_text
    return any(attr.is_line_break for attr in log_attrs[1:length - 1])
IndexError: index too large (expected 12 <= 11)

If you need any more information, let me know.

[liZe]

Thanks a lot for the report.

It’s fixed, tests are welcome!

[grewn0uille]

Thanks, we’ll investigate!