adding drivers in the compositor always results in a dependency cycle which often causes blender to hang when reopening the saved .blend file. #77279

System Information
Operating system: Windows-10-10.0.17763-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.92

Blender Version
Broken: version: 2.90.0 Alpha, branch: master, commit date: 2020-06-01 20:37, hash: 1d4bae8566
Worked: (newest version of Blender that worked as expected)

Short description of error
adding drivers in the compositor always results in a dependency cycle which causes blender to hang when reopening the saved .blend file.

Exact steps for others to reproduce the error

Just to clarify, the append issue I mention in the video only happens if you copy and paste 3d objects from a file with the dependancy cycle problem into a new file, save the new file, and then try and append that new file into another new file, in this instance it also results in a missing data block if trying to re-open the file you copied into.

compositor dependancy cycle on all drivers.blend

2020-06-02 17-50-21.mp4

Added subscriber: @3di

Changed status from 'Needs Triage' to: 'Confirmed'

Added subscriber: @mano-wii

Added subscriber: @dr.sybren

The drivers in the example file are defined on the compositor nodes, but also read values from compositor nodes. This is what is causing the dependency cycle. It is possible to resolve this, but that would count as new functionality (rather than a fix for existing functionality). As such I'll mark this as a known issue.

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adding drivers in the compositor always results in a dependency cycle which often causes blender to hang when reopening the saved .blend file. #77279