Loads qt plugin paths as registered...

pkgs/development/libraries/qt-5/5.11/default.nix

@@ -51,6 +51,7 @@ let
   patches = {
     qtbase = [
       ./qtbase.patch
+      ./qtbase-additional.patch
       ./qtbase-darwin.patch
       ./qtbase-revert-no-macos10.10.patch
       ./qtbase-fixguicmake.patch

pkgs/development/libraries/qt-5/5.11/qtbase-additional.patch

@@ -0,0 +1,32 @@
+diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
+index 5ae3fd62e5..ec3fccfc76 100644
+--- a/src/corelib/kernel/qcoreapplication.cpp
++++ b/src/corelib/kernel/qcoreapplication.cpp
+@@ -2533,6 +2533,27 @@ QStringList QCoreApplication::libraryPaths()
+         QStringList *app_libpaths = new QStringList;
+         coreappdata()->app_libpaths.reset(app_libpaths);
+
++		{
++			// Start at the binary; this allows us to *always* start by stripping the last part.
++			QStringList components = applicationFilePath().split(QDir::separator());
++
++			// We don't care about /nix/store/nix-support, only /nix/store/*/nix-support
++			// This is why we're checking for more than 3 parts. It will bail out once /nix/xtore/*/nix-support/qt-plugin-paths has been tested.
++			while (components.length() > 3) {
++				components.removeLast();
++				const QString support_plugin_paths = QDir::cleanPath(QDir::separator() + components.join(QDir::separator()) + QStringLiteral("/nix-support/qt-plugin-paths"));
++				if (QFile::exists(support_plugin_paths)) {
++					QFile file(support_plugin_paths);
++					if (file.open(QIODevice::ReadOnly | QIODevice::Text)) {
++						QTextStream in(&file);
++						while (!in.atEnd()) {
++							app_libpaths->append(in.readLine());
++						}
++					}
++				}
++			}
++		}
++
+         // Add library paths derived from PATH
+         const QStringList paths = QFile::decodeName(qgetenv("PATH")).split(':');
+         const QString plugindir = QStringLiteral("../" NIXPKGS_QT_PLUGIN_PREFIX);

pkgs/development/libraries/qt-5/5.12/default.nix

@@ -51,6 +51,7 @@ let
   patches = {
     qtbase = [
       ./qtbase.patch
+      ./qtbase-additional.patch
       ./qtbase-darwin.patch
       ./qtbase-revert-no-macos10.10.patch
       ./qtbase-fixguicmake.patch

pkgs/development/libraries/qt-5/5.12/qtbase-additional.patch

@@ -0,0 +1,32 @@
+diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
+index 5ae3fd62e5..ec3fccfc76 100644
+--- a/src/corelib/kernel/qcoreapplication.cpp
++++ b/src/corelib/kernel/qcoreapplication.cpp
+@@ -2533,6 +2533,27 @@ QStringList QCoreApplication::libraryPaths()
+         QStringList *app_libpaths = new QStringList;
+         coreappdata()->app_libpaths.reset(app_libpaths);
+
++		{
++			// Start at the binary; this allows us to *always* start by stripping the last part.
++			QStringList components = applicationFilePath().split(QDir::separator());
++
++			// We don't care about /nix/store/nix-support, only /nix/store/*/nix-support
++			// This is why we're checking for more than 3 parts. It will bail out once /nix/xtore/*/nix-support/qt-plugin-paths has been tested.
++			while (components.length() > 3) {
++				components.removeLast();
++				const QString support_plugin_paths = QDir::cleanPath(QDir::separator() + components.join(QDir::separator()) + QStringLiteral("/nix-support/qt-plugin-paths"));
++				if (QFile::exists(support_plugin_paths)) {
++					QFile file(support_plugin_paths);
++					if (file.open(QIODevice::ReadOnly | QIODevice::Text)) {
++						QTextStream in(&file);
++						while (!in.atEnd()) {
++							app_libpaths->append(in.readLine());
++						}
++					}
++				}
++			}
++		}
++
+         // Add library paths derived from PATH
+         const QStringList paths = QFile::decodeName(qgetenv("PATH")).split(':');
+         const QString plugindir = QStringLiteral("../" NIXPKGS_QT_PLUGIN_PREFIX);

pkgs/development/libraries/qt-5/5.9/default.nix

@@ -38,7 +38,7 @@ let
   srcs = import ./srcs.nix { inherit fetchurl; inherit mirror; };
 
   patches = {
-    qtbase = [ ./qtbase.patch ./qtbase-fixguicmake.patch ] ++ optional stdenv.isDarwin ./qtbase-darwin.patch;
+    qtbase = [ ./qtbase.patch ./qtbase-additional.patch ./qtbase-fixguicmake.patch ] ++ optional stdenv.isDarwin ./qtbase-darwin.patch;
     qtdeclarative = [ ./qtdeclarative.patch ];
     qtscript = [ ./qtscript.patch ];
     qtserialport = [ ./qtserialport.patch ];

pkgs/development/libraries/qt-5/5.9/qtbase-additional.patch

@@ -0,0 +1,32 @@
+diff --git a/src/corelib/kernel/qcoreapplication.cpp b/src/corelib/kernel/qcoreapplication.cpp
+index 5ae3fd62e5..ec3fccfc76 100644
+--- a/src/corelib/kernel/qcoreapplication.cpp
++++ b/src/corelib/kernel/qcoreapplication.cpp
+@@ -2533,6 +2533,27 @@ QStringList QCoreApplication::libraryPaths()
+         QStringList *app_libpaths = new QStringList;
+         coreappdata()->app_libpaths.reset(app_libpaths);
+
++		{
++			// Start at the binary; this allows us to *always* start by stripping the last part.
++			QStringList components = applicationFilePath().split(QDir::separator());
++
++			// We don't care about /nix/store/nix-support, only /nix/store/*/nix-support
++			// This is why we're checking for more than 3 parts. It will bail out once /nix/xtore/*/nix-support/qt-plugin-paths has been tested.
++			while (components.length() > 3) {
++				components.removeLast();
++				const QString support_plugin_paths = QDir::cleanPath(QDir::separator() + components.join(QDir::separator()) + QStringLiteral("/nix-support/qt-plugin-paths"));
++				if (QFile::exists(support_plugin_paths)) {
++					QFile file(support_plugin_paths);
++					if (file.open(QIODevice::ReadOnly | QIODevice::Text)) {
++						QTextStream in(&file);
++						while (!in.atEnd()) {
++							app_libpaths->append(in.readLine());
++						}
++					}
++				}
++			}
++		}
++
+         // Add library paths derived from PATH
+         const QStringList paths = QFile::decodeName(qgetenv("PATH")).split(':');
+         const QString plugindir = QStringLiteral("../" NIXPKGS_QT_PLUGIN_PREFIX);

pkgs/development/libraries/qt-5/hooks/qtbase-setup-hook.sh

@@ -62,3 +62,59 @@ postPatchMkspecs() {
 if [ -z "$dontPatchMkspecs" ]; then
     postPhases="${postPhases}${postPhases:+ }postPatchMkspecs"
 fi
+
+_Qt_sortless_uniq() {
+	# `uniq`, but keeps initial order.
+	# This is to remove risks of combinatorial explosion of plugin paths.
+	cat -n | sort -uk2 | sort -nk1 | cut -f2-
+}
+
+_QtGetPluginPaths() {
+	# Lists all plugin paths for current Qt for given buildInputs and propagatedBuildInputs
+	local i
+	local _i
+	local o
+	local inputs
+
+	# FIXME : this causes output path cycles...
+	# I am unsure if it is even needed, though.
+	## Outputs self's plugins paths
+	#for o in $outputs; do
+	#	o="${!o}/@qtPluginPrefix@"
+	#	if [ -e "$o" ]; then
+	#		echo "$o"
+	#	fi
+	#done
+
+	inputs="$(
+		for i in $buildInputs $propagatedBuildInputs; do
+			echo "$i"
+		done | uniq
+	)"
+
+	for i in $inputs; do
+		_i="$i/@qtPluginPrefix@"
+		if [ -e "$_i" ]; then
+			echo "$_i"
+		fi
+		_i="$i/nix-support/qt-plugin-paths"
+		if [ -e "$_i" ]; then
+			cat "$_i"
+		fi
+	done
+}
+
+postAddPluginPaths() {
+	# Dumps all plugins paths to a nix-support file inside all outputs.
+	local o
+
+	for o in $outputs; do
+		o="${!o}/nix-support"
+		mkdir -p "$o"
+		_QtGetPluginPaths | _Qt_sortless_uniq > $o/qt-plugin-paths
+	done
+}
+
+if [ -z "$dontAddPluginPaths" ]; then
+    postPhases="${postPhases}${postPhases:+ }postAddPluginPaths"
+fi

pkgs/development/libraries/qt-5/modules/qtbase.nix

@@ -386,7 +386,13 @@ stdenv.mkDerivation {
           sed -i "$dev/lib/pkgconfig/Qt5Core.pc" \
               -e "/^host_bins=/ c host_bins=$dev/bin"
         ''
-    );
+      )
+    + ''
+        # Adds `qtbase-bin` as a basic dependency to *all* qtbase builds.
+        mkdir -p $dev/nix-support
+        echo "$bin/$qtPluginPrefix" >> $dev/nix-support/qt-plugin-paths
+      ''
+   ;
 
   setupHook = ../hooks/qtbase-setup-hook.sh;