Never leave a collection folder without a name, and say when it is broken

Fixes https://qelectrotech.org/bugtracker/view.php?id=332

localName() set a non-root folder's label only inside the success path of
loading its qet_directory file. If that load failed -- file missing,
malformed, or unopenable because of the Windows path-encoding problem with
accented characters that plc-user diagnosed on the tracker -- nothing was
set at all, and since a fresh item's text() is null the folder rendered
with a completely blank label. That is the reported symptom.

Resolve the name into a local and always fall back to the folder's own
directory name, so the label is never empty whatever went wrong.

The fallback is applied *after* NamesList::name() rather than passed into
it. This matters: name() returns a caller-supplied fallback before it
reaches its "first available translation" step, so passing m_path in would
replace a perfectly good name in some other language with the raw
directory name. A folder named only in French, viewed under an English
locale, previously showed "Accentué" and must keep doing so.

Falling back on its own would then hide the broken file -- the user sees a
plausible name and never learns there is anything to repair. So a folder
whose qet_directory could not be read now says so in its tooltip, naming
the file, above the collection path that tooltip already carried.
Suggested by plc-user on PR #622. The flag is recorded in localName() and
consumed in setUpData(), because setUpData() assigns the tooltip after
localName() runs and would otherwise discard it.

Only a file-level failure is flagged. A readable qet-directory with no
entry for the current language is not an error; NamesList::name() resolves
that itself and no warning is shown.

Verified on a fixture collection of four folders -- valid, malformed,
missing, and one named only in French:

                  master        this patch
  fr-only         Accentué      Accentué        (no warning)
  malformed       <blank>       malformed       (warning)
  no qet_directory <blank>      no_file         (warning)
  valid           Valid Folder  Valid Folder    (no warning)

sources/ElementsCollection/fileelementcollectionitem.cpp

@@ -136,18 +136,41 @@ QString FileElementCollectionItem::localName()
 		}
 		else
 		{
+			// Fall back to the raw directory name (m_path) whenever the
+			// translated name can't be obtained -- qet_directory missing,
+			// unreadable (e.g. a Windows path-encoding issue with special
+			// characters, see bugtracker #332), malformed, or present but
+			// without a usable name entry -- rather than leaving the item
+			// blank.
+			QString display_name;
+			bool readable = false;
 			QString str(fileSystemPath() % "/qet_directory");
 			pugi::xml_document docu;
-			if(docu.load_file(str.toStdWString().c_str()))
+			if (docu.load_file(str.toStdWString().c_str()))
 			{
 				if (QString(docu.document_element().name())
 					== "qet-directory")
 				{
+					readable = true;
 					NamesList nl;
 					nl.fromXml(docu.document_element());
-					setText(nl.name());
+						// Deliberately no fallback argument: a non-empty one
+						// is returned *before* NamesList::name() reaches its
+						// "first available translation" step, so passing
+						// m_path here would replace a perfectly good name in
+						// some other language with the raw directory name.
+						// The fallback belongs after the chain, not inside it.
+					display_name = nl.name();
 				}
 			}
+			setText(display_name.isEmpty() ? m_path : display_name);
+
+				// Only a file-level failure counts: a readable qet-directory
+				// with no entry for the current language is not an error,
+				// NamesList::name() resolves that on its own. Recorded here
+				// and reported by setUpData(), which sets the tooltip after
+				// this runs.
+			m_qet_directory_unreadable = !readable;
 		}
 	}
 	else if (isElement()) {
@@ -350,7 +373,21 @@ void FileElementCollectionItem::setUpData()
 		}
 	}
 
-	setToolTip(collectionPath());
+		// Falling back to the raw directory name keeps the folder usable, but
+		// on its own it hides the fact that a file is broken: the user sees a
+		// plausible name and never learns there is anything to repair. Say so
+		// above the collection path, which stays as the last line the way the
+		// element tooltip above builds it.
+	QStringList tip;
+	if (isDir() && m_qet_directory_unreadable)
+	{
+		tip << QObject::tr("Le fichier « %1 » est absent ou illisible : "
+				   "le nom traduit de ce dossier n'a pas pu être lu, "
+				   "son nom de dossier est affiché à la place.")
+		       .arg(fileSystemPath() % "/qet_directory");
+	}
+	tip << collectionPath();
+	setToolTip(tip.join(QLatin1Char('\n')));
 }
 
 /**

sources/ElementsCollection/fileelementcollectionitem.h

@@ -64,6 +64,11 @@ class FileElementCollectionItem : public ElementCollectionItem
 
 	private:
 		QString m_path;
+			/// True when this directory's qet_directory file is missing or
+			/// unreadable, so setUpData() can say so in the tooltip. Recorded
+			/// rather than acted on in localName(), because setUpData() resets
+			/// the tooltip afterwards and would otherwise discard it.
+		bool m_qet_directory_unreadable = false;
 };
 
 #endif // FILEELEMENTCOLLECTIONITEM2_H