[Nix-dev] how to build qt5 via nix-shell?

[Ellis Whitehead]

Could someone please enlighten me as to how to properly use nix-shell
to build qt5?

I'm trying to create a patch for Qt that makes QSettings use
XDG_DATA_DIRS instead of hardcoded paths (with the ultimate goal of
getting lxqt into nixpkgs).  I have not been able to get the qt5
package to configure when using nix-shell, although it works fine with
``nix-build ~/src/nixpkgs -A qt5``.  I try the following:

```
nix-shell ~/src/nixpkgs -A qt5
eval "$prePatch"
patchPhase
configurePhase
```

The configure phase aborts on this line, where the error is apparently
due to having an INCLUDE path to `dbus-tools` instead of `dbus-libs`:

```
g++ -c -pipe -O2 -Wall -W -fPIE  -I../../../mkspecs/linux-g++ -I.
-I/nix/store/n8l5j8nxd85as0x5p9ghflngipbjim1p-dbus-tools-1.8.6/include/dbus-1.0
-I/nix/store/n8l5j8nxd85as0x5p9ghflngipbjim1p-dbus-tools-1.8.6/lib/dbus-1.0/include
-o dbus.o dbus.cpp
dbus.cpp:43:23: fatal error: dbus/dbus.h: No such file or directory
```

With ``nix-build``, the corresponding line is as follows -- notice
that `dbus-libs` is used instead of `dbus-tools`:

```
g++ -c -pipe -O2 -Wall -W -fPIE  -I../../../mkspecs/linux-g++ -I.
-I/nix/store/m2zwqdrbwmckn6yxa8xn8j30spvrikg5-dbus-libs-1.8.6/include/dbus-1.0
-I/nix/store/m2zwqdrbwmckn6yxa8xn8j30spvrikg5-dbus-libs-1.8.6/lib/dbus-1.0/include
-o dbus.o dbus.cpp
```

Many thanks!
Ellis