Move auto-keying code into a separate C file, such that the related code sits together instead of strewn across multiple C files. Or at least document what can be found where.
Split ed_screen_context() into separate functions, or at least refactor to use early returns.
Move keyframe-insertion code from editors to blenkernel.
Split splineik_evaluate_bone() into separate functions.
Rename BKE_scene_get_depsgraph() to BKE_scene_get_viewport_depsgraph()
Deprecate SELECT and remove #define SELECT 1 from various places in the code.
Split up pyrna_py_to_prop
After the new Alembic exporter has been merged into master
USD/Alembic: replace HierarchyContext & with HierarchyContext *.
ANIM_apply_keyingset() has a short success variable (which is strange to begin with, as success is usually a boolean and not a quantity). The value returned by return success; is then later also compared to constants with values -1 and -2. To summarize: bool, short, and enum are all combined into one variable. Found this while investigating T73773.
USD/Alembic: refactor code to replace std containers with BLI ones: not worth the effort as the Alembic library needs std::vector and blender::Map has slightly different memory management than its std counterpart, causing other issues with the Alembic library.