Editor manager: Abort with a single message if file is not readable.

We show a dialog that offers opening a file in a different editor type
if opening a file fails, but we should not do that if opening the file
fails because it is not readable.
With this change, documents now specify if they failed to open a file
because reading failed, or because they could not handle the file
contents.

Task-number: QTCREATORBUG-14495
Change-Id: I5d4b7cfa74b87ef21b9b55bc30b3ebe2f8238dfa
Reviewed-by: Daniel Teske <daniel.teske@theqtcompany.com>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@theqtcompany.com>

src/plugins/tasklist/taskfile.cpp

@@ -94,12 +94,11 @@ bool TaskFile::reload(QString *errorString, ReloadFlag flag, ChangeType type)
         deleteLater();
         return true;
     }
-    return open(errorString, filePath().toString(), filePath().toString());
+    return load(errorString, filePath().toString());
 }
 
-bool TaskFile::open(QString *errorString, const QString &fileName, const QString &realFileName)
+bool TaskFile::load(QString *errorString, const QString &fileName)
 {
-    Q_UNUSED(realFileName)
     setFilePath(Utils::FileName::fromString(fileName));
     return TaskListPlugin::loadFile(errorString, m_baseDir, fileName);
 }

src/plugins/tasklist/taskfile.h

@@ -55,7 +55,7 @@ public:
     ReloadBehavior reloadBehavior(ChangeTrigger state, ChangeType type) const;
     bool reload(QString *errorString, ReloadFlag flag, ChangeType type);
 
-    bool open(QString *errorString, const QString &fileName, const QString &realFileName);
+    bool load(QString *errorString, const QString &fileName);
 
     QString baseDir() const;
     void setBaseDir(const QString &base);

src/plugins/tasklist/tasklistplugin.cpp

@@ -177,7 +177,7 @@ IDocument *TaskListPlugin::openTasks(const QString &base, const QString &fileNam
     file->setBaseDir(base);
 
     QString errorString;
-    if (!file->open(&errorString, fileName, fileName)) {
+    if (!file->load(&errorString, fileName)) {
         QMessageBox::critical(ICore::mainWindow(), tr("File Error"), errorString);
         delete file;
         return 0;