Official NixOS Wiki

Qt: Difference between revisions

← Older edit
VisualWikitext
Added a section for explicitly specifying development dependencies
Sandro (talk | contribs)
64 edits
 
(5 intermediate revisions by 2 users not shown)
Line 16: Line 16:
   pkgs.mkShell {
   pkgs.mkShell {
     buildInputs = [
     buildInputs = [
                    pkgs.qt5.full
      pkgs.qt5.full
                    pkgs.qtcreator
      pkgs.qtcreator
                  ];
    ];
}
}
</syntaxHighlight>
</syntaxHighlight>
Tip: if you want use clang-format, add '''clang-format''' to '''buildinputs''' list.


Also create '''.envrc''' file and paste: <code>use_nix</code> into it.
Also create '''.envrc''' file and paste: <code>use_nix</code> into it.
Line 32: Line 30:
However if fetching the entirety of <code>pkgs.qt6.full</code> is not appealing and you know which parts of Qt you need, your first instinct might be adding something like <code>pkgs.qt6.qtdeclarative</code> for creating QML-based Qt programs to <code>buildInputs</code>, '''however''' that will not work and you will get compile errors for missing libraries. <code>pkgs.qt6.full</code> is actually [https://github.com/NixOS/nixpkgs/blob/nixos-24.11/pkgs/development/libraries/qt-6/default.nix#L94-L144 creating an environment that contains all Qt libraries] that allows <code>qmake</code> and tools to find those libraries, so you must do the same and <code>pkgs.qt6.env</code> will help make one. For example:
However if fetching the entirety of <code>pkgs.qt6.full</code> is not appealing and you know which parts of Qt you need, your first instinct might be adding something like <code>pkgs.qt6.qtdeclarative</code> for creating QML-based Qt programs to <code>buildInputs</code>, '''however''' that will not work and you will get compile errors for missing libraries. <code>pkgs.qt6.full</code> is actually [https://github.com/NixOS/nixpkgs/blob/nixos-24.11/pkgs/development/libraries/qt-6/default.nix#L94-L144 creating an environment that contains all Qt libraries] that allows <code>qmake</code> and tools to find those libraries, so you must do the same and <code>pkgs.qt6.env</code> will help make one. For example:


<syntaxHighlight lang=nix>
<syntaxhighlight lang="nix">
# shell.nix
# shell.nix
{ pkgs ? import <nixpkgs> {} }:
{ pkgs ? import <nixpkgs> {} }:
Line 38: Line 36:
   # pkgs.qt6.env already includes pkgs.qt6.qtbase
   # pkgs.qt6.env already includes pkgs.qt6.qtbase
   # And using `with` to prevent a lot of typing.
   # And using `with` to prevent a lot of typing.
   qtEnv = with pkgs.qt6; env "qt-custom-${qtbase.version}" {
   qtEnv = with pkgs.qt6; env "qt-custom-${qtbase.version}" [
     [
     qtdeclarative
      qtdeclarative
  ];
    ]
  };
in
in
   pkgs.mkShell {
   pkgs.mkShell {
Line 53: Line 49:
     ];
     ];
}
}
</syntaxHighlight>
</syntaxhighlight>


== Packaging ==
== Packaging ==
Line 196: Line 192:


== Troubleshooting ==
== Troubleshooting ==
=== Cannot mix incompatible Qt library (version 0x_____) with this library (version 0x_____) ===
This is a known issue, see {{issue|30551}} for the current status.
Starting with the 19.09 release, the issue should be fixed by {{pull|65526}}


=== This application failed to start because it could not find or load the Qt platform plugin ??? in "" ===
=== This application failed to start because it could not find or load the Qt platform plugin ??? in "" ===
==== qt4 ====
Qt4 depends on the environment variable <code>QT_PLUGIN_PATH</code> to find plugins. It is normally already
present in the environment on NixOS at least, but for example systemd user units are launched in a pretty empty environment. A solution is to use the command {{Commands|systemctl --user import-environment QT_PLUGIN_PATH}} from a sane environment. For example add it to the <code>services.xserver.displayManager.sessionCommands</code> option.


==== qt5 ====
{{warning|This recommendation is deprecated for 19.09 and up, see {{issue|65399}}. Failing packages should be updated to use <code>wrapQtAppsHook</code>.}}
{{warning|This recommendation is deprecated for 19.09 and up, see {{issue|65399}}. Failing packages should be updated to use <code>wrapQtAppsHook</code>.}}
Qt5 seems (?) to look for plugins in the <code>PATH</code>. This will fail from a systemd user unit for example, because their path is nearly empty by default. As an example, here is a workaround to have <code>usbguard-applet</code> launched from a systemd user unit:
{{File|/etc/nixos/configuration.nix|nix|<nowiki>
  systemd.user.services.usbguard-applet = {
    description = "USBGuard applet";
    partOf = [ "graphical-session.target" ];
    wantedBy = [ "graphical-session.target" ];
    path = [ "/run/current-system/sw/" ]; ### Fix empty PATH to find qt plugins
    serviceConfig = {
      ExecStart = "${pkgs.usbguard}/bin/usbguard-applet-qt";
    };
  };
</nowiki>}}
====  qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "" ====
Here is a concrete example:


<pre>
<pre>
Line 234: Line 204:
The package will need to be fixed to use [the new https://github.com/NixOS/nixpkgs/issues/65399 <code>wrapQtAppsHook</code>]. The hook wraps every qt application with adding <code>QT_PLUGIN_PATH</code> and <code>XDG_DATA_DIRS</code> as well as <code>XDG_CONFIG_DIRS</code>.See [https://github.com/NixOS/nixpkgs/blob/nixos-19.09/pkgs/development/libraries/qt-5/hooks/wrap-qt-apps-hook.sh wrap-qt-apps-hook.sh in nixpkgs]
The package will need to be fixed to use [the new https://github.com/NixOS/nixpkgs/issues/65399 <code>wrapQtAppsHook</code>]. The hook wraps every qt application with adding <code>QT_PLUGIN_PATH</code> and <code>XDG_DATA_DIRS</code> as well as <code>XDG_CONFIG_DIRS</code>.See [https://github.com/NixOS/nixpkgs/blob/nixos-19.09/pkgs/development/libraries/qt-5/hooks/wrap-qt-apps-hook.sh wrap-qt-apps-hook.sh in nixpkgs]


==== Debugging methods ====
=== Debugging methods ===
As a general rule, exporting <code>QT_DEBUG_PLUGINS=1</code> make qt print where it looks for plugins.
As a general rule, exporting <code>QT_DEBUG_PLUGINS=1</code> make qt print where it looks for plugins.


If a plugin exists in a directory but is ignored with a message like <code>QLibraryPrivate::loadPlugin failed on "/nix/store/...-teamspeak-client-3.1.6/lib/teamspeak/platforms/libqxcb.so" : "Cannot load library /nix/store/...-client-3.1.6/lib/teamspeak/platforms/libqxcb.so: "</code> it can be that the library cannot be <code>dlopen()</code>ed because of dependencies/rpath issues and needs <code>patchelf</code>ing. Exporting <code>LD_DEBUG=libs</code> may prove helpful in this scenario.
If a plugin exists in a directory but is ignored with a message like <code>QLibraryPrivate::loadPlugin failed on "/nix/store/...-teamspeak-client-3.1.6/lib/teamspeak/platforms/libqxcb.so" : "Cannot load library /nix/store/...-client-3.1.6/lib/teamspeak/platforms/libqxcb.so: "</code> it can be that the library cannot be <code>dlopen()</code>ed because of dependencies/rpath issues and needs <code>patchelf</code>ing. Exporting <code>LD_DEBUG=libs</code> may prove helpful in this scenario.
Retrieved from "https://wiki.nixos.org/wiki/Qt"