[Buildroot] Config.in for both Qt4 and Qt5 in grantlee

[Thomas Petazzoni]

Hello Zoltan,

On Sun, 09 Nov 2014 02:53:04 +0100, Zoltan Gyarmati wrote:

> i'm trying to update the package grantlee (http://grantlee.org) in 
> Buildroot to the current upstream version. Historically grantlee 
> supported only Qt4 (this version is present now in Buildroot), and for a 
> while both Qt4 and Qt5, and with the last release it dropped the Qt4 
> support.

Too bad :/

>   As for one of my legacy projects i still might need the Qt4 version, i 
> would like to keep the Qt4 support by using the last upstream version 
> which built on Qt4 when Buildroot configured to build Qt4,  and use the 
> newest version when build on Qt5. It's easy to implement in the .mk file 
> with "ifeq ($(BR2_PACKAGE_QT),y)", although i'm not sure this is the 
> most elegant solution. (qjson using this for example to distinguish the 
> dependencies between the two Qt version, but it doesn't use 2 different 
> upstream versions for the 2 Qt versions)

Yes, for the .mk file, this is fine. At some point in the future, we'll
drop the old version that supports qt4, but for a little while, we can
keep both. So indeed, something like:

ifeq ($(BR2_PACKAGE_QT),y)
GRANTLE_VERSION = ...
else ifeq ($(BR2_PACKAGE_QT5),y)
GRANTLE_VERSION = ...
endif

>   I got into trouble in the Config.in though. Currently the grantlee.mk 
> selects a few Qt options with the kconfig 'select' statement (namely  
> BR2_PACKAGE_QT_STL, BR2_PACKAGE_QT_SCRIPT, BR2_PACKAGE_QT_GUI_MODULE), 
> and it also supposed to select the corresponding Qt5 options, but i 
> can't find any explicit trace that using conditional 'select' is 
> possible in kconfig, nor the correct syntax to express this.
> 
> What is the preferred solution to handle this scenario? Would it be 
> better to have a new grantlee package (let's say grantleeqt5) for this 
> latest version, and enable it in the menu only for Qt5? Or is there any 
> kconfig trick i could use here? An other option would be just to drop 
> Qt4 support (if the upstream already did it) at least in the official 
> Buildroot version (and i can use any nasty trick in my own Buildroot 
> tree to support my legacy project till i'm able to port it to Qt5). Is 
> there anybody out there who is using this lib with Qt4?

Just do:

	depends on BR2_PACKAGE_QT || BR2_PACKAGE_QT5
	select BR2_PACKAGE_QT_STL if BR2_PACKAGE_QT
	select BR2_PACKAGE_QT_SCRIPT if BR2_PACKAGE_QT
	select BR2_PACKAGE_QT_GUI_MODULE if BR2_PACKAGE_QT
	select BR2_PACKAGE_QT5_FOOBAR if BR2_PACKAGE_QT5
	select BR2_PACKAGE_QT5_BARFOO if BR2_PACKAGE_QT5

(of course, adapt the select for the qt5 case)

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com