QFontDatabase do not see font styles other than regular, italic or/and bold on Mac

This issue is somehow related to QTBUG-736.

I am trying to list the fonts available on my system and would like to have the available styles related to a font family. On Mac, QFontDatabase::styles only replies with either "Normal" or "Italic" or "Bold" or "Bold Italic" even if the fonts themselves have other styles defined. For example Helvetica has "Oblique" which is translated by Qt as "Italic". Helvetica Neue has 11 styles, including "Light", "UltraLight", "Medium", "Condensed Black" and Qt only sees the 4 standard "Normal", "Italic", "Bold" and "Bold Italic".