Eigen’s .inc plugin headers were read by Doxygen but never preprocessed as C++ — meaning macros like EIGEN_PARSED_BY_DOXYGEN were silently ignored. Here’s how I verified it in Docker and what the one-line fix looks like.
A day-long battle fixing a CI pipeline that builds Docker images on a self-hosted Jetson Xavier runner. From stale git submodules to GCC-15 assembler errors, expired tokens, DNS failures inside Docker, and deleted upstream branches — every layer of the stack had something broken.
How a missing overflow check in Eigen’s TensorUInt128 division operator caused an infinite loop for any dividend above 2^127 — and the one-line fix that stopped it.