Build, run & profiles¶

Build¶

qgis-dev build is an ordinary CMake/Ninja build in the working tree — nix provisions the toolchain, never a store build of QGIS (constraint C10), because a store build would forfeit incrementality.

Build sequence

Key mechanics visible above: configure happens automatically on first build with the active profile's flags (ccache launchers, mold-wrapped linker, -UGDAL_DEBUG, compile_commands.json export); ccache counters are snapshotted before and after so the logged hit-rate is per build; the optional performance-mode boost wraps the ninja run and is always restored; and every build appends a row to the machine-global log that stats and report read.

Run¶

qgis-dev run launches the build-tree binary — and self-heals the two configure-time artefacts that, if missing, silently break it.

Run sequence

qgisbuildpath.txt tells QGIS it is running from a build tree, so resources and PyQGIS resolve against build/output rather than an uninstalled prefix. It's written at configure time only, so run rewrites it if absent.
The qgis.PyQt shim is configure_file-staged; if it went missing, run reconfigures to restore it.
The launch is bare — no QGIS_PREFIX_PATH (which would force install-layout paths) — with a throwaway --profiles-path so your real QGIS profile is untouchable.

Profiles¶

A profile is a committed CMAKE_ARGS fragment. Switching reconfigures the tree; ccache is namespaced per profile so objects never mix.

Profile states

See Build profiles & flags for the everyday usage, and Troubleshooting for the field-tested reasons behind -UGDAL_DEBUG, mold-wrapped and the self-healing markers.