This project demonstrates an issue with shader inclusion (shaderinc) in Godot4, resulting in inconsistent behavior between the Compatibility, Mobile and Forward+ rendering modes.

• Godot_v4.2.1-stable_win64
• Godot_v4.3-dev5_win64

The discrepancy in behavior is due to a conflict between the variable names in the main shader and the included shader, where the shading variable depends on the current rendering mode:

• Compatibility mode:

  The parameter of the included function takes precedence.

• Forward+ and Mobile modes:

  The imported function parameter is silently substituted in favor of the importing shader variable.

To reproduce the issue:

1. Open the project in Godot 4.2-stable
2. Open DemoScene.tscn
3. Switch between Compatibility, Mobile and Forward+ rendering modes, and witness the color of the Sprite2D.