[Follow-up] I have been taking a deeper look, and at some point the whole "libc" **was not recompiling** on any header change - which looked and was a Makefile error. The fix was simple: Remove the double "$(DELIM)" from the dependencies, as it turns out the "Make.dep" file only has one delimiter. This was introduced in an attempt to fix Windows compilation problems, but caused incremental builds to stop working on any other machine as "make" is looking for a file with double delimiter on its name.
We were using an older version of NuttX, that's why we had this problem. However, it has already been fixed on PR https://github.com/apache/nuttx/pull/7572. We will pull the changes and cherry-pick those. PS: Full explanation with images is available at https://github.com/apache/nuttx/pull/16564#issuecomment-2994364394. Best regards, Javier Alonso
