OpenSCAD fails to open inlined file that uses the BOSL2 library

[tbjers]

Describe the bug

When opening an inlined model that uses a larger library like BOSL2, OpenSCAD produces an error:

ERROR: Recursion detected calling function 'is_num' in file inline-hex-grid-test.scad, line 40782
TRACE: called by 'is_finite' in file inline-hex-grid-test.scad, line 23609
TRACE: called by 'is_vector' in file inline-hex-grid-test.scad, line 8223
TRACE: called by 'attachable' in file inline-hex-grid-test.scad, line 9789
TRACE: called by 'cube' in file inline-hex-grid-test.scad, line 6036
TRACE: called by '_cube' in file inline-hex-grid-test.scad, line 9790
TRACE: called by 'children' in file inline-hex-grid-test.scad, line 8250
TRACE: called by 'children' in file inline-hex-grid-test.scad, line 6034
TRACE: called by 'if' in file inline-hex-grid-test.scad, line 6034
TRACE: called by '_color' in file inline-hex-grid-test.scad, line 8250
TRACE: called by 'if' in file inline-hex-grid-test.scad, line 8249
TRACE: called by 'multmatrix' in file inline-hex-grid-test.scad, line 8242
TRACE: called by 'attachable' in file inline-hex-grid-test.scad, line 9789
Geometries in cache: 1
Geometry cache size in bytes: 0
CGAL Polyhedrons in cache: 0
CGAL cache size in bytes: 0
Total rendering time: 0:00:00.000

To Reproduce

Steps to reproduce the behavior:

1. Enter command arguments scadi inline hex-grid-test.scad
2. Run openscad -o inline-hex-grid-test.stl inline-hex-grid-test.scad
3. See the error

Expected behavior

OpenSCAD should export an STL without errors.

Proposed solution

• Add revarbat/BOSL2 as a submodule in tests/samples
• Add hex-grid.scad to tests/samples
• Create end-to-end tests using OpenSCAD
• Add installation of OpenSCAD to CI/CD pipeline

[tbjers]

@Loki44 originally reported this bug as part of evaluating #42.

[Loki44]

Thanks for looking into this.

To answer your question from the other issue, I'm on windows 10, and I had the same result with both 2021.01 and 2023.04.04.

[tbjers]

I have managed to track down what causes the recursion error. By including a file inline that is loaded with use <builtins.scad> it brings those modules into the global scope, when they should be in their own context. I am currently working on solving this.

[tbjers]

Looks like the BOSL2 library is taking advantage of the isolated context provided by use<> in order to work around the recursion problem. Even though there are no commands to execute inside builtins.scad, it still benefits from having a separate context in order for it to not count against the internal recursion counter in OpenSCAD. Sneaky.

How to reproduce:
Change use <builtins.scad> in the files color.scad, shapes2d.scad, and shapes3d.scad to include <builtins.scad> and the recursion error occurs as you open the original file.