Bug 290231 – REGRESSION(291808@main): [macOS Debug]: ASSERTION FAILED: !index in CSSFontSelector::fallbackFontAt on html5lib/generated/run-entities01-data.html (290012)

• Status: RESOLVED
• Resolution: FIXED
• Component: Text

[Vitor Roriz]

Settings control how we resolve generic font-family names.

This bug happens because we were setting setFontFallbackPrefersPictographs(true)
from another test, on the same process, before running run-entities01-data.html.

This made the cached FontCascadeFont object to have its m_lastRealizedFallbackIndex
expanded beyound effectiveFamilyCount(), making fontSelectorFallbackIndex turning 1.

When running run-entities01-data.html, m_lastRealizedFallbackIndex is still
retaining that value. However, fontSelector->fallbackFontCount() that comes from Settings
is now 0 and we won't pass the check `fontSelectorFallbackIndex == fontSelector->fallbackFontCount()`.

This lead us to a inconsistent state in which we call fallbackFontAt for resolving the pictographFontFamily,
although we are stating by the index != 0 that we already did.

We can fix this issue by considering the generic font families configuration from settings for building
FontCascadeCache key. That way, we won't have false positive hits when settings differ.

[Vitor Roriz]

rdar://147365119

[Vitor Roriz]

Pull request: https://github.com/WebKit/WebKit/pull/42857

[Alexey Proskuryakov]

*** Bug 290012 has been marked as a duplicate of this bug. ***

[Alexey Proskuryakov]

*** Bug 290230 has been marked as a duplicate of this bug. ***

[EWS]

Committed 292764@main (0d680136cb51): <https://commits.webkit.org/292764@main>

Reviewed commits have been landed. Closing PR #42857 and removing active labels.

[EWS]

Test gardening commit 289651.418@safari-7621-branch (8fdeff9ee1d6): <https://commits.webkit.org/289651.418@safari-7621-branch>

Reviewed commits have been landed. Closing PR #2979 and removing active labels.