As reported by datao zhang on the mailing list.

https://www.microsoft.com/typography/otfntdev/devanot/shaping.aspx

Makes number of failures against Uniscribe with hi_IN dictionary from
OO.o to go down from 6334 to 4290.  Not bad for a one-line change!

Mozilla Bug 729626 - ASAN: heap-buffer-overflow HTML

Find the base consonant and apply basic Indic features accordingly.
Nothing complete, but does something for now.  Specifically:
no Ra handling right now, and no ZWJ/ZWNJ.

Number of failing shape-complex tests goes from 174 down to 125.

Next: reorder matras.

Still not much there.

Using an incredible tool called Ragel.