mention GDB pretty printers

Author: ferdymercury

blog/_posts/2022-03-01-code-horsepower-f1.md

@@ -22,6 +22,7 @@ If you've ever rubbed your eyes trying to decrypt *C++* compilation errors from
 - [Debugging tools](#debugging-tools)
   * [Building ROOT in Debug Mode](#building-root-in-debug-mode)
   * [Debugging your ROOT scripts or executables with GDB](#debugging-your-root-scripts-or-executables-with-gdb)
+  * [GDB pretty printers](#gdb-pretty-printers)
   * [Memory error detection](#memory-error-detection)
   * [Data race detection](#data-race-detection)
   * [Performance analysis](#performance-analysis)
@@ -204,6 +205,13 @@ Below a screenshot of another example, while debugging [a deadlock in the TThrea
 
 Side note: if at some point, your *ROOT* script gets very complex long, I recommend instead to use a standalone *C++* application using *CMake*, and link the *ROOT* libraries easily to it, as explained [here](https://root.cern/manual/integrate_root_into_my_cmake_project/#full-example-event-project).
 
+### GDB pretty printers
+
+In the debugger, classes such as TString are complex objects where one does not immediately see the string it represents. To get a better visual overview, one can deploy the predefined GDB pretty printers embedded in the ROOT project by:
+
+- Creating a file `~/.gdbinit` with content `add-auto-load-safe-path /path/to/build-root_src-Desktop-Debug/lib/` to avoid a warning with `libCore.so-gdb.py`
+- Going to "Preferences", "Debugger", "GDB", checking "Load system GDB printers" to use the GDB and not the default Qt pretty-printers.
+
 ### Memory error detection
 
 To check for memory leaks and corruption, *QtCreator* offers a seamless integration with valgrind (or [heob on Windows](https://doc.qt.io/qtcreator/creator-analyzer.html)), making the backtrace of your errors fully interactive. To run it, press on the big "Debug button" on the left. Then, on the dropdown menu, change from "Debugger" to "Memcheck" and click on the small play button.