pango_shape_with_flags crashes with no fonts available
On a system with no fonts at all installed, running pango_shape_with_flags yields analysis->font == NULL, which means the code in shape.c:238 is skipped, but when PANGO_SHAPE_ROUND_POSITIONS is in flags, shape.c:323 dereferences analysis->font, resulting in a crash.
Use e.g. graphviz dot in a chroot without fonts to reproduce this.
Ideally something should have noticed lack of fonts earlier, but since the code partially checks for analysis->font, I consider this a bug. I would adjust PANGO_IS_FC_FONT to return false for null pointers.