[Interest] [Qt5.3+] font issue and questions on OS X

[René J.V. Bertin]

Hi,

Each time I start a Qt 5.3.2 or 5.4.0 application on OS X 10.9, I'm greeted with a list of failures on the terminal or in system.log:

QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "BanglaSangamMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "SinhalaSangamMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "TeluguSangamMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "STSongti-SC-Regular"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "STSongti-TC-Regular"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "BanglaMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "SinhalaMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "TeluguMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "BanglaSangamMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "SinhalaSangamMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "TeluguSangamMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "DFKaiShu-SB-Estd-BF"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "BanglaMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "SinhalaMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "TeluguMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "DFKaiShu-SB-Estd-BF"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "BanglaMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "SinhalaMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "TeluguMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "Baghdad"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "Ayuthaya"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "BanglaSangamMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "SinhalaSangamMN"
QCoreTextFontDatabase: Failed to resolve family name for PostScript name  "TeluguSangamMN"

Apart from the fact that I don't see the point in warning me multiple times about the same fonts, I don't see why I'd get an error at all about fonts that 1) I don't have installed (= I uninstalled because useless to me) and 2) aren't exactly "unmissable" fonts.

What's going on here, and can these messages be made to go away without side-effects?

On a related note, I notice

#> qtdiag | fgrep -i font
  FontsLocation: "Fonts" */System/Library/Fonts*

Two things here: 
- /Library/Fonts is missing here, which should be searched first
- /System/Library/Fonts should not be considered writable; /Library/Fonts can be

Finally, even though it isn't very well documented, OS X does allow some customisation of the certain default fonts, and utilities like TinkerTool exist that expose this functionality. Is there a particular reason Qt ignores that setting and seems to provide hardcoded defaults (or are the system functions to get the default font names at to blame here)?

Cheers,
René