Based on patch from Jonathan Kew, as reported on the mailing list.

Email from Jonathan Kew:

My cygwin build kept aborting on certain test words when run with the
uniscribe backend. Turned out this was caused by a bug in the allocation
of scratch buffers in hb-uniscribe.cc.

Commit 2a17f956 introduced a new line

  ALLOCATE_ARRAY (SCRIPT_VISATTR, vis_attr, glyphs_size);

but it failed to account for this in the computation of glyphs_size
(the number of glyphs for which scratch buffer space is available),
with the result that the vis_clusters array ends up overrunning the
end of the scratch buffer and clobbering the beginning of the buffer's
info[].

AFAICS, the vis_attr array is not actually used, so the simple fix is
to remove the line that allocates it. (If/when we -do- need to use
vis_attr for something, we'll need to add another term to the earlier
calculation of glyphs_size.)

With this patch, the uniscribe backend runs reliably again.

JK

We should add for other scripts too, send me the virama codepoint
and script name...

As per Werner's report on the list.

See email thread "Skipping Control for Attaching Marks using OpenType"
from earlier this month.

Destroy lookups before blobs.

'layout->gsub' may depend on data owned by 'layout->gsub_blob', so it must
be deinitialized before the blob is destroyed.

This changes the semantics of get_glyph() callback and expect that
callbacks return false if the requested variant is not available, and
then we will call them back with variation_selector=0 and will retain
the glyph for the selector in the glyph stream.

Apparently most Mongolian fonts implement the Mongolian Variation
Selectors using GSUB, not cmap.

https://bugs.freedesktop.org/show_bug.cgi?id=65258

Note that this doesn't fix the Mongolian shaping yet, because the way
that's implemented is that the, say, 'init' feature ligates the letter
and the variation-selector.  However, since currently the variation
selector doesn't have the 'init' mask on, it will not be matched...

https://bugs.freedesktop.org/show_bug.cgi?id=65544

Oops.

Bug 65246 - Fix build without graphite2

Bug 65246 - Fix build without graphite2

If we don't provide ACTION-IF-NOT-FOUND, configure aborts if it can't
find the libraries.  We handle that ourselves so we don't want the
macro to abort.

Unfortuately Visual Studio (still) does not support the C99 function
lround, so provide a fallback implementation for it.

-Declare hinstLib at the top of block
-Fix the definitions of the typedefs of ScriptItemizeOpenType,
 ScriptShapeOpenType and ScriptPlaceOpenType

Currently it only works with ICU that has .pc files.  I'll
wait till someone complains before fixing it for icu-config
systems.

Fallback to older API if OpenType variants are not available.

Defaults to auto.

Defaults to no.

Defaults to no.

We only want UCDN if we don't have any other Unicode provider.
I'm going to remove ICU from the list of default Unicode providers
as part of moving hb-icu into its own library.  As such, the only
providers will be UCDN and glib.

Will add a way to enable it later.

Bug 64878 - compile error with ICU but not ICU

Will add proper way to enable it later.

Add --with-graphite2.  Defaults to off.