QA & diagnostics

One keystroke from "it crashes / leaks / is slow" to actionable, source-line evidence. All reports are archived under .dev-env/diagnostics/<timestamp>-<tool>/ (<leader>pal to browse) — exactly what an upstream bug report wants attached.

Choosing the right tool

graph TD
    A{Symptom?} -->|crash / memory corruption / leak| B[qa asan — first resort]
    B -->|"needs uninstrumented binary"| C[qa memcheck]
    A -->|too slow| D[qa perf → hotspot]
    D -->|"instruction-level detail"| E[qa callgrind]
    A -->|memory keeps growing| F[qa heaptrack]
    A -->|"Qt widget/model weirdness"| G[qa gammaray]
    A -->|"suspicious code, no repro"| H[qa cppcheck / clang-tidy]

Sanitizers first (qgis-dev qa asan, <leader>pas)

Switches to the asan-ubsan profile, rebuilds (own ccache namespace), runs QGIS with AddressSanitizer + UBSan, and prints the reports. At ~2× slowdown this is the default memory-bug tool; valgrind's 20–50× makes whole-app runs impractical. Switch back with qgis-dev profile debug.

Valgrind when it must be (qa memcheck, <leader>pam)

For uninstrumented binaries and the tools only valgrind has. Committed suppression files for Qt6, glib and CPython's pymalloc are applied automatically — without them, PyQGIS drowns real leaks in interpreter false positives. Findings are resolved to file:line and land in quickfix; the full log stays in the archive.

Profiling

• CPU — qa perf records with dwarf call graphs and opens hotspot. Requires boot.kernel.sysctl."kernel.perf_event_paranoid" = 1; (or lower) in your NixOS config. qa callgrind + kcachegrind for per-instruction detail.
• Heap — qa heaptrack (better fit for Qt apps than massif); the GUI opens when QGIS exits.
• Profile against the release profile — Debug timings mislead.

Live Qt introspection (qa gammaray, <leader>pag)

Attaches GammaRay to the running QGIS for live widget-tree, model and signal/slot inspection. Start QGIS first (<leader>pr).

Static analysis

qa cppcheck [path] sweeps beyond what clang-tidy covers; <leader>pl runs clang-tidy (upstream .clang-tidy) on the current file. Both report to quickfix.