8bd75747b1
A trace "anchor" is a trace head (CoglTraceHead) that is placed in a certain scope (e.g. function scope), but then only triggered in another scope, e.g. a condition. This makes it possible to have optional trace instrumentation, that is enabled only given e.g. a debug flag. Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1700>