pub unsafe extern "C" fn pango_glyph_string_index_to_x_full(
    glyphs: *mut PangoGlyphString,
    text: *const c_char,
    length: c_int,
    analysis: *mut PangoAnalysis,
    attrs: *mut PangoLogAttr,
    index_: c_int,
    trailing: gboolean,
    x_pos: *mut c_int
)
This is supported on crate feature v1_50 only.