Qt: Always rebuild columns when fields changed

The columns must be recreated even if no capture file is loaded
because custom columns may have reference to deregistered fields.

Change-Id: I4ed7345b3200e5af211695f1a6511ee229d5f13c
Reviewed-on: https://code.wireshark.org/review/10076
Reviewed-by: Stig Bjørlykke <stig@bjorlykke.org>

ui/qt/main_window_slots.cpp

@@ -1306,7 +1306,6 @@ void MainWindow::redissectPackets()
 
 void MainWindow::fieldsChanged()
 {
-    // Reload color filters
     color_filters_reload();
 
     // Syntax check filter
@@ -1325,8 +1324,8 @@ void MainWindow::fieldsChanged()
     }
 
     if (have_custom_cols(&CaptureFile::globalCapFile()->cinfo)) {
-        // Recreate packet list according to new/changed/deleted fields
-        packet_list_->columnsChanged();
+        // Recreate packet list columns according to new/changed/deleted fields
+        packet_list_->fieldsChanged(CaptureFile::globalCapFile());
     }
 }
 
@@ -2487,11 +2486,7 @@ void MainWindow::on_actionAnalyzeReloadLuaPlugins_triggered()
     (void) wsApp->readConfigurationFiles(&gdp_path, &dp_path);
 
     fieldsChanged();
-
-    if (CaptureFile::globalCapFile()->state != FILE_CLOSED) {
-        // Redissect packets if we have any
-        redissectPackets();
-    }
+    redissectPackets();
 
     wsApp->setReloadingLua(false);
     SimpleDialog::displayQueuedMessages();

ui/qt/packet_list.cpp

@@ -642,6 +642,14 @@ void PacketList::columnsChanged()
     redrawVisiblePackets();
 }
 
+// Fields have changed, update custom columns
+void PacketList::fieldsChanged(capture_file *cf)
+{
+    prefs.num_cols = g_list_length(prefs.col_list);
+    col_cleanup(&cf->cinfo);
+    build_column_format_array(&cf->cinfo, prefs.num_cols, FALSE);
+}
+
 // Column widths should
 // - Load from recent when we load a new profile (including at starting up).
 // - Persist across freezes and thaws.

ui/qt/packet_list.h

@@ -148,6 +148,7 @@ public slots:
     void unsetAllTimeReferences();
     void redrawVisiblePackets();
     void columnsChanged();
+    void fieldsChanged(capture_file *cf);
     void applyRecentColumnWidths();
     void elideModeChanged();