[Libreoffice-bugs] [Bug 132445] New: Assertion failure when checking font preview for certain fonts in LOOL

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=132445

            Bug ID: 132445
           Summary: Assertion failure when checking font preview for
                    certain fonts in LOOL
           Product: LibreOffice Online
           Version: unspecified
          Hardware: All
                OS: All
            Status: UNCONFIRMED
          Keywords: haveBacktrace
          Severity: normal
          Priority: medium
         Component: Writer
          Assignee: libreoffice-bugs at lists.freedesktop.org
          Reporter: baron at caesar.elte.hu
                CC: glogow at fbihome.de
            Blocks: 105537

Created attachment 159979
  --> https://bugs.documentfoundation.org/attachment.cgi?id=159979&action=edit
Backtrace

The following requires a debug LO build coupled with LO Online to trigger.
The assert seems to indicate some kind of font fallback handling problem, so
far I found the following fonts trigger it:
Fira Mono, Fira Sans, Optima, TeX Gyre Adventor (and probably other Tex Gyre
ones), Vegur.

- Open a document in LOOL.
- Open Format -> Character, and choose one of the above fonts in the font list.
=> Crash with assertion failure when it tries to render the preview.
There's no crash if a non-debug LO build is used (and the preview is still
shown).

The console shows the following assert:
"vcl/unx/generic/gdi/freetypetextrender.cxx:166: virtual
std::unique_ptr<GenericSalLayout> FreeTypeTextRenderImpl::GetTextLayout(int):
Assertion `mpFreetypeFont[nFallbackLevel]' failed."

Attaching backtrace. The bug could perhaps be reproduced just with a core build
in some way, but I haven't found how. Opening the Character properties dialog
in gtktiledviewer, and switching to one of the reproducer fonts there doesn't
trigger assert. Briefly the assert was triggered upon document load, but that's
fixed (see bug 132424).

The assert was added with the following commit:
https://cgit.freedesktop.org/libreoffice/core/commit/?id=8d7435aa72af7fd0b454d7314c6c79f61f112679
author          Jan-Marek Glogowski <glogow at fbihome.de> 2019-01-23 19:59:45
+0100
committer       Jan-Marek Glogowski <glogow at fbihome.de> 2019-01-25 19:03:55
+0100

"Assert missing SalGraphics font on GetTextLayout"

Two details I don't understand:
- why does it only trigger in LOOL?
- since it looks like the fonts can be rendered, what is actually going wrong?


Referenced Bugs:

https://bugs.documentfoundation.org/show_bug.cgi?id=105537
[Bug 105537] [META] Assertion failed crashes
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