add new obscure qt post

content/blog/obscure-qt2/index.md

@@ -0,0 +1,42 @@
+---
+title: "Obscure Qt: GDB pretty printers"
+date: 2023-05-02
+draft: false
+tags:
+- Qt
+---
+
+Outside of Qt Creator, GDB has a hard time understanding Qt times and you'll regularly get garbage or unusable debugging output.
+
+![An example of CLion (which uses GDB) trying to show the contents of a QList.](bad.png)
+
+Luckily, [GDB has a system where you can use Python scripts](https://github.com/ruediger/Boost-Pretty-Printer/blob/master/HACKING.org) to print information from custom types[^1]. The printers we're using is [Ezike Ebuka's GDB_Printers](https://invent.kde.org/ebuka/gdb_printers). First clone the repository, and extract it somewhere where you won't accidentally delete it. Here I copy it into my Development folder:
+
+```bash
+$ cd ~/Development
+$ git clone git@invent.kde.org:ebuka/gdb_printers.git
+```
+
+Then edit your `~/.gdbinit` file and add this to it (or create it if you haven't already):
+
+```python
+python
+import sys
+
+# change the path below to the correct path
+sys.path.append('/home/josh/Development/gdb_printers')
+
+from printers import register_qt_printers
+register_qt_printers(None)
+end
+
+set print pretty on
+```
+
+Now if you run GDB again, you'll get pretty prints for a lot of Qt types! This includes QString, QVector, and of course QList:
+
+![The same m_attachments variable, but it's actually useful for debugging now!](good.png)
+
+If you want a full list of supported types, take a look in [qtprinters.py](https://invent.kde.org/ebuka/gdb_printers/-/blob/master/printers/qtprinters.py).
+
+[^1]: Just make sure your GDB has been compiled with Python support, or else this won't work.