There is an implicit assumption that LinePrograms will only have compilation directories that are the zeroeth index. When converting LinePrograms expect this to be true resulting in the error on the following line:

I've got a workaround of removing the check for the zero index (avoiding the error) and instead using it to produce the comp_dir though I suspect this may not be the entirely correct solution.

cpp_test.zip

Gimli version 28.1.