May be relevant to the discussion: SQLite is also compiled from a single, 220k LOC C file called "the amalgamation".<p><a href="https://www.sqlite.org/amalgamation.html" rel="nofollow">https://www.sqlite.org/amalgamation.html</a>
I've been working on a project that auto generates c programs - sometimes up to 1.5m lines of code - in a single file (actually two files but the second is only 35 lines)<p>Not open source but happy to share benchmarks if that would be useful.
I like to code this way. You just include "foo.c" instead of "foo.h", which does not exist at all. The compilation is really simple, and there's half of the files!