face->num_charmaps is not set correctly for a specific ttf file.
There was no error when calling FT_New_Face, but face->num_charmaps is set to zero.
The font file is attached below.
I checked if the file really has no cmap by using ttf_parser(https://github.com/RazrFalcon/ttf-parser). ttf_parser said the file has a cmap ( Unicode encoding , Windows platform ).
Thanks.