Fixed p4 plugin.

Introduce settings struct again. Add an errorString() to
the settings class. Change checkP4Command to checkP4Configuration
and make it report errors when appropriate. Make errorString show
up in settings page and add "Test" button.
Build options correctly (omit empty settings) and use basic
options for the test (which was the bug causing p4 to be
disabled if options were actually specified).

src/plugins/perforce/perforceplugin.cpp

@@ -488,8 +488,9 @@ void PerforcePlugin::submit()
     if (VCSBase::VCSBaseSubmitEditor::raiseSubmitEditor())
         return;
 
-    if (!checkP4Command()) {
-        showOutput(tr("No p4 executable specified!"), true);
+    QString errorMessage;
+    if (!checkP4Configuration(&errorMessage)) {
+        showOutput(errorMessage, true);
         return;
     }
 
@@ -660,7 +661,7 @@ void PerforcePlugin::updateActions()
 
 bool PerforcePlugin::managesDirectory(const QString &directory) const
 {
-    if (!checkP4Command())
+    if (!checkP4Configuration())
         return false;
     const QString p4Path = directory + QLatin1String("/...");
     QStringList args;
@@ -727,8 +728,7 @@ PerforceResponse PerforcePlugin::runP4Cmd(const QStringList &args,
         qDebug() << "PerforcePlugin::runP4Cmd" << args << extraArgs << debugCodec(outputCodec);
     PerforceResponse response;
     response.error = true;
-    if (!checkP4Command()) {
-        response.message = tr("No p4 executable specified!");
+    if (!checkP4Configuration(&response.message)) {
         m_perforceOutputWindow->append(response.message, true);
         return response;
     }
@@ -959,8 +959,9 @@ bool PerforcePlugin::editorAboutToClose(Core::IEditor *editor)
         if (answer == VCSBase::VCSBaseSubmitEditor::SubmitConfirmed) {
             m_changeTmpFile->seek(0);
             QByteArray change = m_changeTmpFile->readAll();
-            if (!checkP4Command()) {
-                showOutput(tr("No p4 executable specified!"), true);
+            QString errorMessage;
+            if (!checkP4Configuration(&errorMessage)) {
+                showOutput(errorMessage, true);
                 return false;
             }
 
@@ -1005,7 +1006,7 @@ void PerforcePlugin::openFiles(const QStringList &files)
 
 QString PerforcePlugin::clientFilePath(const QString &serverFilePath)
 {
-    if (!checkP4Command())
+    if (!checkP4Configuration())
         return QString();
 
     QApplication::setOverrideCursor(Qt::WaitCursor);
@@ -1040,15 +1041,19 @@ QString PerforcePlugin::currentFileName()
     return fileName;
 }
 
-bool PerforcePlugin::checkP4Command() const
+bool PerforcePlugin::checkP4Configuration(QString *errorMessage /* = 0 */) const
 {
-    return m_settings.isValid();
+    if (m_settings.isValid())
+        return true;
+    if (errorMessage)
+        *errorMessage = tr("Invalid configuration: %1").arg(m_settings.errorString());
+    return false;
 }
 
 QString PerforcePlugin::pendingChangesData()
 {
     QString data;
-    if (!checkP4Command())
+    if (!checkP4Configuration())
         return data;
 
     QString user;
@@ -1124,18 +1129,10 @@ const PerforceSettings& PerforcePlugin::settings() const
     return m_settings;
 }
 
-void PerforcePlugin::setSettings(const QString &p4Command, const QString &p4Port, const QString &p4Client, const QString p4User, bool defaultEnv)
+void PerforcePlugin::setSettings(const Settings &newSettings)
 {
-
-    if (m_settings.p4Command() == p4Command
-        && m_settings.p4Port() == p4Port
-        && m_settings.p4Client() == p4Client
-        && m_settings.p4User() == p4User
-        && m_settings.defaultEnv() == defaultEnv)
-    {
-        // Nothing to do
-    } else {
-        m_settings.setSettings(p4Command, p4Port, p4Client, p4User, defaultEnv);
+    if (newSettings != m_settings.settings()) {
+        m_settings.setSettings(newSettings);
         m_settings.toSettings(Core::ICore::instance()->settings());
     }
 }