In the backward compatibility design, an "ambiguous script" is one that doesn't have either OpenSCAD1 or OpenSCAD2 specific syntax. It may contain "assignment statements" and geometry, but no include, use, function or module definitions.
Ambiguous scripts must have the same meaning in OpenSCAD1 and OpenSCAD2. Therefore, OpenSCAD2 cannot change the scoping rules for scripts containing only assignments and geometry, in a non-backward compatible way.
The new scoping rules violate this, and need to be redesigned.
In the backward compatibility design, an "ambiguous script" is one that doesn't have either OpenSCAD1 or OpenSCAD2 specific syntax. It may contain "assignment statements" and geometry, but no include, use, function or module definitions.
Ambiguous scripts must have the same meaning in OpenSCAD1 and OpenSCAD2. Therefore, OpenSCAD2 cannot change the scoping rules for scripts containing only assignments and geometry, in a non-backward compatible way.
The new scoping rules violate this, and need to be redesigned.