Merge pull request #514 from ispyisail/fix/thread-safe-datadir-configdir

Thank you @ispyisail

sources/qetapp.cpp

@@ -887,10 +887,13 @@ QString QETApp::configDir()
 #ifdef QET_ALLOW_OVERRIDE_CD_OPTION
 	if (config_dir != QString()) return(config_dir);
 #endif
-	QString configdir = QStandardPaths::writableLocation(QStandardPaths::AppConfigLocation);
+	// C++11 static-local init runs exactly once across all threads — safe to
-	while (configdir.endsWith('/')) {
+	// call from QtConcurrent background threads (QStandardPaths is not).
-		configdir.remove(configdir.length()-1, 1);
+	static const QString configdir = []() {
-	}
+		QString d = QStandardPaths::writableLocation(QStandardPaths::AppConfigLocation);
+		while (d.endsWith('/')) d.chop(1);
+		return d;
+	}();
 	return configdir;
 }
 
@@ -911,10 +914,13 @@ QString QETApp::dataDir()
 #ifdef QET_ALLOW_OVERRIDE_DD_OPTION
 	if (data_dir != QString()) return(data_dir);
 #endif
-	QString datadir = QStandardPaths::writableLocation(QStandardPaths::AppDataLocation);
+	// C++11 static-local init runs exactly once across all threads — safe to
-	while (datadir.endsWith('/')) {
+	// call from QtConcurrent background threads (QStandardPaths is not).
-		datadir.remove(datadir.length()-1, 1);
+	static const QString datadir = []() {
-	}
+		QString d = QStandardPaths::writableLocation(QStandardPaths::AppDataLocation);
+		while (d.endsWith('/')) d.chop(1);
+		return d;
+	}();
 	return datadir;
 }