Header file inclusion static analysis tools?

Question

A colleague recently revealed to me that a single source file of ours includes over 3,400 headers during compile time. We have over 1,000 translation units that get compiled

Answer 1

GCC Has a flag (-save-temps) with which you can save intermediate files. This includes .ii files, which are the results of the preprocessor (so before compilation). You can write a script to parse this and determine the weight/cost/size of what is included, as well as the dependency tree.

I wrote a Python script to do just this (publicly available here: https://gitlab.com/p_b_omta/gcc-include-analyzer).